Preliminary results from phase 2 of CC-92480- MM- 001: Mezigdomide plus dexamethasone in relapsed/refractory multiple myeloma (RRMM)

In phase 1 of CC-92480- MM- 001 (NCT03374085), the recommended phase 2 dose (RP2D) of mezigdomide plus dexamethasone (MEZI-d) was selected at 1 mg once daily for 21/28 days. Here we report preliminary results from the MEZI-d dose-expansion cohort in patients with heavily pretreated RRMM. Key eligibility criteria were: RRMM;>=3 prior lines of therapy;disease progression <=60 days of last myeloma therapy;refractoriness to lenalidomide/pomalidomide, a proteasome inhibitor, a glucocorticoid, and an anti-CD38 monoclonal antibody. Oral mezigdomide 1 mg was given on days 1-21 of each 28-day cycle, plus weekly dexamethasone (40 mg;20 mg if >75 years of age). Primary objective was to evaluate efficacy (overall response rate [ORR]);secondary objectives included safety/tolerability and additional efficacy assessments. Pharmacodynamics was an exploratory objective. As of 16/Sep/2022, 101 patients had received MEZI-d at the RP2D. Median age was 67 (range 42-85) years, median time since initial diagnosis was 7.4 (1.1-37.0) years;39.6% of patients had plasmacytomas and 37/101 patients had high-risk cytogenetics (56/101 not evaluable). Median number of prior regimens was 6 (3-15);prior therapies included stem cell transplantation (77.2%) and anti-BCMA therapy (29.7%). All patients were refractory to last myeloma regimen and triple-class refractory. Median follow-up was 7.5 (0.5-21.9) months, with a median of 4 (1-20) cycles;10.0% of patients continued treatment;progressive disease was the main reason for discontinuation (60.4%). ORR was 40.6% for all patients. Whilst data are not mature yet, median PFS was 4.4 (95% CI 3.0-5.5) months and median duration of response was 7.6 (95% CI 5.4-9.5) months. ORR was 30.0% in patients with plasmacytomas (N = 40) and 50.0% in patients with prior anti-BCMA therapy (N = 30). Ninety-one (91.1%) patients experienced a grade 3/4 treatment-emergent adverse event (TEAE). Most frequent hematologic grade 3/4 TEAEs were neutropenia (75.2%), anaemia (35.6%), and thrombocytopenia (27.7%);34.7% of patients had grade 3/4 infections, including grade 3/4 pneumonia (15.8%) and COVID-19 (7.0%). Occurrence of other grade 3/4 non-hematologic TEAEs was generally low. Due to TEAEs, 76.2% and 29.7% of patients had mezigdomide dose interruptions and reductions, respectively;90.1% of patients discontinued mezigdomide. Mezigdomide induced substrate degradation and increases in activated and proliferating T cells in patients, including those directly refractory to pomalidomide-based therapies. MEZI-d had a manageable safety profile with encouraging efficacy in patients with triple-class refractory RRMM, including patients with prior BCMA-targeted therapies. These results strongly support the continued development of mezigdomide in MM, and especially in combination.

IgM Multiple Myeloma Presenting With Diarrhea

Introduction: IgM Multiple Myeloma (MM) is a rare subtype of MM consisting of <1% cases of MM. It is distinguished from Waldenstrom Macroglobinemia, which also produces IgM, by the absence of somatic mutation MYD88. We present a patient with a chief complaint of diarrhea which unknowingly led to his hematological diagnosis Case Description/Methods: A 64 year old male with RA-SLE overlap syndrome on steroids, and recent COVID19 pneumonia, had presented with 5 episodes of watery diarrhea every day and 40 Ib weight loss within 2 months. CT revealed small bowel enteritis and stool studies, including C. diff, cultures, ova and parasites were negative. Diarrhea persisted despite antibiotics, therefore an EGD and Colonoscopy were performed which showed duodenal lymphangiectasia and a normal colon. Duodenal biopsy revealed eosinophilic deposits in the villous lamina propria which stained for IgM and stained negative under congo red ruling out amyloidosis. SPEP and a bone marrow biopsy revealed monoclonal IgMspikes and plasma cells in the bone marrow suggesting MMalong with a co-existing population of CLL. Next-generation sequencing was negative forMYD88, supporting IgM MM instead of Waldenstrom. He developed a protein-losing enteropathy with dramatic hypoalbuminemia (albumin 0.9) and lower extremity edema and DVTs. He was started on chemotherapy and frequent albumin infusions. His diarrhea completely resolved, however not in time, as his other medical comorbidities lagged behind and he developed anasarca and continued to deteriorate. Discussion(s): Plasma cell dyscrasias such as IgM MM or more commonly Waldenstrom have rarely been reported to cause GI symptoms. GI involvement can include direct GI infiltration of plasma cells, IgM deposition, or the finding of a plasmacytoma. It has been speculated that IgM deposits can lead to interstitial viscosity and obstructive lymphangiectasia leading to diarrhea and a protein-losing enteropathy as in our patient. Protein loss has led him to have hypoalbuminemia and possibly loss of antithrombotic proteins that have caused DVTs. Few case reports have suggested that treating the underlying cause with chemotherapy stops diarrhea entirely. Although our patient's diarrhea ceased, we believe that it was not in time for him to entirely recover from the later complications of the disease. We hope that this case can help clinicians to attempt prompt treatment of patients when they find GI specimens showing IgM deposits and they suspect a plasma cell dyscrasia.

Anaplastic extramedullary plasmacytoma resistant to novel therapies: A case report

The treatment of choice for extramedullary plasmacytoma (EMP) is radiotherapy (RT). It is under discussion whether the management of an anaplastic form of EMP requires the addition of systemic therapy. We present a case of a 66-year-old male who was diagnosed with anaplastic plasmacytoma of the maxillary sinus. After the exclusion of multiple myeloma, Dara-VMP (daratumumab, bortezomib, melphalan, and prednisolone) regimen was initiated. During the third cycle of Dara-VMP, a progression of the tumor was observed. RT and BRd (bendamustine, dexamethasone, and lenalidomide) regimen were initiated. After 4 cycles of BRd, disease progression was established. KRd (carfilzomib, lenalidomide, and dexamethasone) regimen was initiated. The first cycle of KRd was not completed, as the patient was diagnosed with COVID-19. After the infection, the progression of EMP was observed. In this case, the anaplastic EMP was resistant to RT and chemotherapy regimens with novel agents, including a monoclonal antibody, an immunomodulatory drug, and proteasome inhibitors. Copyright © 2023 the author(s), published by De Gruyter, Berlin/Boston.

Hairy Cell Leukemia in a Filipino Male during the COVID-19 Pandemic - Report of a Rare Case

Hairy cell leukemia (HCL) is a rare, chronic, mature B-cell lymphoproliferative disorder accounting for 2% of all leukemias. In this paper, we would like to present our experience in the management of HCL in a financially limited setting where other diagnostic tests and chemotherapy are unavailable. The case report aims to emphasize the recognition of the distinctive morphology of hairy cells in the peripheral blood in the consideration of the initial diagnosis. A 60-year-old Filipino male was incidentally found to have anemia, thrombocytopenia and an absolute neutrophilic count below 1,000 in a pre-operative clearance for elective herniorrhaphy. Blood smear revealed atypical lymphocytes with hair like cytoplasmic projections. CT-scan of the abdomen showed splenomegaly and prominent paraaortic nodes. Flow cytometry of the bone marrow aspirate was consistent with an involvement of a Mature B cell neoplasm markers CD19, CD20, CD22 and surface immunoglobulin lambda and hairy cell leukemia markers CD11c, CD103 and CD25. He responded to six-weekly sessions of Cladribine with remission of the bone marrow and hematologic parameters. HCL is a rare type of a mature B cell neoplasm characterized by pancytopenia, splenomegaly, bone marrow fibrosis and the presence of atypical lymphoid cells with hairy projections in blood, bone marrow and spleen. Immunophenotyping express CD11c, CD103, CD123, and CD25. BRAF V600E mutation is the disease defining genetic event. Cladribine and Pentostatin are the first line of treatment. Cases of leukemia can be easily overlooked because of the mild derangement in the complete blood count. A meticulous differential review of the atypical lymphocyte, is the first step in the diagnosis of this rare disease.Copyright © 2022, Philippine College of Physicians. All rights reserved.

HEMORRHAGIC PLEURAL EFFUSION IN A PATIENT WITH CHRONIC LYMPHOCYTIC LEUKEMIA ON IBRUTINIB THERAPY

SESSION TITLE: Problems in the Pleura Case Posters 1 SESSION TYPE: Case Report Posters PRESENTED ON: 10/17/2022 12:15 pm - 01:15 pm INTRODUCTION: Ibrutinib is an irreversible inhibitor of Bruton's tyrosine kinase (Btk), approved for treatment of a variety of B-cell malignancies, including chronic lymphocytic leukemia (CLL). There is an association of increased risk of bleeding with ibrutinib due to platelet dysfunction caused by the medication. Bleeding is usually non-life threating such as subcutaneous or mucosal bleeding, epistaxis, and ecchymosis. But major bleeding has been reported such as intracranial hemorrhage and gastrointestinal hemorrhage. Thoracic complications from ibrutinib are rare. Below is a case report discussing a hemorrhagic pleural effusion thought to be caused by Ibrutinib. CASE PRESENTATION: Patient is a 78-year-old male initially diagnosed with CLL on flow cytometry showing a low-grade B cell lymphoproliferative process. Patient was monitored by Hematology and when kappa light chain numbers began to rise, a bone marrow biopsy was performed showing 90% infiltration of the marrow with lymphoid cells. Patient was started on Ibrutinib therapy and responded well to treatment. A year after starting therapy, patient presented to the emergency room with increased shortness of breath and fatigue. Patient was found to be COVID-19 positive and chest x-ray showed a large right sided pleural effusion. Thoracentesis was performed draining 1650cc of bloody fluid. Fluid studies revealed a lymphocytic effusion with RBC count 1,185375, WBC of 1751. Cultures and cytology were negative. On further history, patient was without recent trauma or surgery, CTA chest was negative for pulmonary embolism. QuantiFERON Gold test was negative, indicating low likelihood of tuberculosis. Patient was not on any antiplatelet or systemic anticoagulation medications. Ibrutinib therapy was held during hospitalization and pleural effusion did not reaccumulate. Patient passed away during hospital stay secondary to respiratory failure due to COVID-19. DISCUSSION: Ibrutinib is an orally bioavailable bruton tyrosine kinase inhibitor (BTKi) and forms an irreversible covalent bound to BTK at the Cysteine-481 residue. Ibrutinib predisposes to bleeding by inhibiting BTK and Tec, which play a role in the inhibitory signaling pathway of platelet collagen receptors such as glycoprotein VI (GP VI) and C-type lectin-like receptor 2 (CLEC-2). Our patient had no other risk factors for developing a hemorrhagic effusion. CLL itself can cause malignant effusions, one study found the incidence of malignant effusions among patients with CLL to be 9%, but the effusion was noted to be serous or serosanguinous and there was pleural involvement in all patients which was not the case in our patient. CONCLUSIONS: There is currently a minimal amount of data to guide clinicians regarding the use of ibrutinib in patients at high risk of bleeding or on anticoagulant or antiplatelet therapy. It is important to realize bleeding complications related to ibrutinib therapy can occur. Reference #1: Shatzel JJ, Olson SR, Tao DL, McCarty OJT, Danilov AV, DeLoughery TG. Ibrutinib-associated bleeding: pathogenesis, management and risk reduction strategies. J Thromb Haemost. 2017;15(5):835-847. doi:10.1111/jth.13651 Reference #2: Burger JA, Tedeschi A, Barr PM, et al. Ibrutinib as Initial Therapy for Patients with Chronic Lymphocytic Leukemia. N Engl J Med. 2015;373(25):2425-2437. doi:10.1056/NEJMoa1509388 Reference #3: Paydas S. Management of adverse effects/toxicity of ibrutinib. Crit Rev Oncol Hematol. 2019;136:56-63. doi:10.1016/j.critrevonc.2019.02.001 DISCLOSURES: No relevant relationships by fatima ali No relevant relationships by Joan Wiley

SIGNIFICANT INCREASE IN NEWLY DIAGNOSED HEMATOLOGICAL MALIGNANCIES FOLLOWING LOCKDOWN EASE IN CROATIA

Background: Special epidemiological measures aimed at suppressing SARS-CoV-2 outbreak were introduced in Croatia in March 2020, thus reducing regular work capacity in hematological outpatient and inpatient care. In our hospital, this included relocating the entire Hematology Department to a remote location, reduction of hospital beds in the Hematology Inpatient Unit by approximately 60%, Day Clinic operating at a reduced capacity, and a complete suspension of Hematology Polyclinic during first lockdown. Aims: Herein we report our observation of unusually high incidence of newly diagnosed malignant hematological diseases following first lockdown ease in May/June 2020. Methods: We collected data of patients hospitalized in Hematology Department for 4 periods: May 1 - June 15, 2020 for the test arm, and the same calendar period during previous 3 years (May 1 - June 15 of each of the calendar years 2017, 2018 and 2019), for the control arm. The rationale for such design was that a phenomenon of re-establishing regular work capacity, following temporary restriction, was only observed in the test arm. The study included patients of both sexes older than 18 who were diagnosed with either: Hodgkin lymphoma (C81.0 -C81.9 according to the 10th ICD Revision), different types of non-Hodgkin lymphoma (subsections C82.0 - C83.9 and C85.1-C85), as well as multiple myeloma and malignant plasma cell neoplasms (C90.0 - C90.3). Excluded from our study were diagnoses of T/NK cell lymphoma (C84.0- C84.9;C86.0 - C86.6), malignant immunoproliferative diseases (C88.0 - C88.9), leukemias and other specified malignant neoplasms of lymphatic, hematopoietic and related tissues (C91.0 - C96.9) as well as polycythemia vera and non-malignant hematological diseases (D45 and D50 - D89 in ICD-10). Results: In years 2017-2019, similar numbers of patients were diagnosed with a hematological malignancy in our Department (n=4 for 2017, n=8 for 2018, n=4 for 2019) whereas in 2020, a total of 28 patients were diagnosed during the same calendar period (Hodgkin lymphoma: n=5, NHL n=12, multiple myeloma n=7, CLL/SLL n=4). Statistical analysis revealed a significant increase (p ≤0.05) of newly diagnosed hematological malignancies in May and first half of June 2020, when compared to the same calendar periods during previous three years. Further statistical analysis has not established significant differences in outcome (difference in EFS statistically insignificant, p=0.86), as we had expected in the short follow-up period. (Table Presented) Summary/Conclusion: Facilitating treatment of patients affected by the novel coronavirus represented a welcome change in healthcare system in early 2020, in our country and abroad. At the same time, however, the reduction of tertiary health care capacity aimed at population with hematological diseases presented serious risks for successful diagnosis and treatment outcome, a subject that gained wide attention in literature. It has been reported that, also due to psychological reasons, a fraction of patients delayed seeking medical attention after noticing symptoms. In our study we aimed at analyzing the effects of lockdown ease on the number of newly diagnosed hematological malignancies. We were able to demonstrate the effect of pandemic-related measures on detecting new disease cases. It remains to be clarified if a sudden surge in new diagnoses was due to delayed first physician's appointments/hospitalizations, as is suggested by available literature. The results of our study suggest that longer follow-up period will be required in order to clarify the effects of possible late diagnoses on the treatment outcome.

B-CELL MALIGNANCIES TREATED WITH TARGETED DRUGS AND SARS-COV-2 INFECTION. A EUROPEAN HEMATOLOGY ASSOCIATION SURVEY (EPICOVIDEHA)

Background: Patients with lymphoproliferatie diseases (LPD) appear particularly ulnerable to SARS-CoV-2 infection, partly because of the effects of the anti-neoplastic regimens (chemotherapy, signaling pathway inhibitors, and monoclonal antibodies) on the immune system. The real impact of COVID-19 on the life expectancy of patients with different subtypes of lymphoma and targeted treatment is still unknown. Aims: The aim of this study is to describe and analyse the outcome of COVID-19 patients with underlying LPD treated with targeted drugs such as monoclonal antibodies (obinutuzumab, ofatumumab, brentuximab, niolumab or pembrolizumab), BTK inhibitors (ibrutinib, acalabrutinib), PI3K inhibitors (idelalisib), BCL2 inhibitors (enetoclax) and IMIDs, (lenalidomide). Methods: The surey was supported by EPICOVIDEHA registry. Adult patients with baseline CLL or non-Hodgkin Lymphoma (NHL) treated with targeted drugs and laboratory-confirmed COVID-19 diagnosed between January 2020 and January 2022 were selected. Results: The study included 368 patients (CLL n=205, 55.7%;NHL n=163, 44.3%) treated with targeted drugs (Table 1). Median follow-up was 70.5 days (range 19-159). Most used targeted drugs were ITKs (51.1%), anti-CD20 other than rituximab (16%), BCL2 inhibitors (7.3%) and lenalidomide (7.9%). Of note, only 16.0% of the patients were accinated with 2 or more doses of accine at the onset of COVID-19. Pulmonary symptoms were present at diagnosis in 244 patients (66.2%). Seere COVID-19 was obsered in 47.8 % patients while 21.7% were admitted to to intensie care unit (ICU), being 55 (26.8%) CLL patients and 25 (15.3%) NHL patients. More comorbidities were reported in patients with seere-critical COVID-19 compared to those with mild- asymptomatic infection (p=0.002). This difference was releant in patients with chronic heart diseases (p=0.005). Oerall, 134 patients (36.4%) died. Primary cause of death was COVID-19 in 92 patients (68.7%), LPD in 14 patients (10.4%), and a combination of both in 28 patients (20.9%).Mortality was 24.2% (89/368) at day 30 and 34.5%(127/368) at day 200. After a Cox multiariable regression age >75 years (p<0.001, HR 1.030), actie malignancy (p=0.011, HR 1.574) and admission to ICU (p<0.00, HR 4.624) were obsered as risk factors. Surial in patients admitted to ICU was 33.7% (LLC 38.1%, NHL 24%). Mortality rate decreased depending on accination status, being 34.2% in not accinated patients, 15.9-18% with one or two doses, decreasing to 9.7% in patients with booster dose (p<0.001). There was no difference in OS in NLH s CLL patients (p=0.344), nor in ITKs s no ITKs treated patients (p=0.987). Additionally, mortality rate dropped from the first semester 2020 (41.3%) to last semester 2021 (25%). Summary/Conclusion: - Our results confirm that patients with B--mallignancies treatted with targeted drugs hae a high risk off seere infection (47.8%) and mortality (36.4%) from COVID-19. - Pressence of comorbidities,, especially heart disease,, is a risk factor for seere COVIID--19 infection in ourr series. - Age >75 years,, actie mallignancy att COVIID--19 onset and ICU admission were mortality risk factors. - COVIID--19 acination was a protectie factor for mortality,, een iin this popullation wiitth humorall immunity impairment. - The learning cure in the management of the infection throughout the pandemiic and the deelopmentt off COVIID--19 treatments showed benefit in this partticullarlly ullnerablle popullation? (Table Presented).

Breakthrough COVID-19 cases and hospitalization risk: ASCO COVID-19 registry

Background: The ASCO Registry was created to analyze the impact of COVID-19 (COVID) on treatment (Tx) and outcomes of patients (pts) with cancer. Vaccination questions were added in 2021, enabling examination of breakthrough cases i.e., SARS-CoV-2 infection after vaccination. Methods: The Registry includes pts who test positive for SARS-CoV-2 and have clinically evident cancer receiving Tx or resected cancer on adjuvant Tx <12 months since surgery at the time of the positive test. Practices report data on COVID vaccine type and dates, positive SARS-CoV-2 test date, and subsequent Tx. Breakthrough cases were defined as 1) > 35 days after 1st Pfizer dose, 2) > 42 days after 1st Moderna dose, 3) > 14 days after 1st Janssen dose, or 4) > 42 days after 1st unknown vaccine dose. Data submission cutoff for all practices was February 2, 2022. Summary statistics and exact binomial 95% confidence intervals (CIs) were calculated. Results: This analysis reports on 231 pts with breakthrough cases. Median age is 68 years and 57% of pts are over age 65. Of 73 pts with non-metastatic solid tumors, 19% were hospitalized. Of 74 with metastatic solid tumors, 39% were hospitalized. Of 75 with B-cell malignancies, 32% were hospitalized. Of 9 with other hematologic malignancies, 56% were hospitalized. While the fraction of patients in the ASCO registry with breakthrough cases who were hospitalized remained fairly constant throughout 2021 (approximately 40%), those with breakthrough cases occurring in the last month of 2021 and early 2022 had a lower hospitalization rate (approximately 20%), which is consistent with less severe cases of COVID-19 in patients infected with the omicron variant (the predominant variant in the US in Dec 2021-Jan 2022) (Table). The majority of breakthrough cases occurred more than 6 months after initial vaccination (71%) and the median time to breakthrough infection from initial vaccination was 7.3 months (IQR: 5.6 9.9). The Registry continues to accrue cases and additional vaccine data;analysis will be updated with most current vaccination data for possible Annual Meeting presentation. Conclusions: Hospitalizations among patients with cancer and breakthrough COVID in the ASCO Registry occur at a high rate, particularly among patients with advanced cancers and hematologic malignancies. This decrease in recent months is likely due to increased incidence of the Omicron variant that resulted in milder COVID symptoms among those infected. A majority of SARS-CoV-2 infections occurring six months or more after vaccination suggests waning vaccine efficacy over time that could be impacted by additional doses.

Immune response to COVID-19 vaccination in patients with B-cell malignancies after CD19 CART cell therapy

Introduction: Patients with hematologic malignancies are at an increased risk of morbid/mortality from COVID-19. Our prospective clinical study evaluated immune responses to COVID-19 mRNA vaccines in patients with B-cell lymphoma who had received CD19-directed chimeric antigen receptor (CAR) T cell therapy. Methods: We measured SARS-CoV-2 neutralizing activity of plasma from 18 patients and 4 healthy controls (HC) and antibody titers against viral spike proteins (S1, S2, RBD) including their delta variants using an enzyme-linked immunoassay (ELISA). We measured B cell subpopulations in the patients' blood using flow cytometry. Results: We found that the peripheral blood plasma from 3/4 HCs showed substantial SARS-CoV-2 neutralizing activity already at 4 weeks after the first dose of COVID-19 mRNA vaccine while none of the CD19 CART patients evidenced any antibody-mediated neutralizing activity at the same point in time. At 4 weeks after receiving the second dose of the vaccine, all 4 HCs showed complete neutralizing activity. In marked contrast, only 1 of 14 CART patients evidenced any relevant antibody-mediated SARS-CoV-2 neutralizing activity. Assessing whether a globally insufficient antibody-mediated immunity was the underlying cause of the lack of a response to the COVID-19 vaccine in our CART patients, we found that IgG antibody levels against common microbial and viral antigens like influenza, Epstein-Barr virus (EBV), Cytomegalovirus (CMV), and tetanus toxoid, were comparable to those observed in HCs. However, while at 4 weeks post second dose of the vaccine the HCs showed high levels of vaccine-induced IgG antibody titers against all the viral spike proteins (S1, S2, RBD), including the delta variants of the S1 and RBD proteins, the vast majority of our CART patients did not evidence any SARS-CoV-2-specific antibodies. Importantly, a third booster vaccination did not lead to an improvement in the antiviral immunity in the 4 CART patients analyzed. When we assessed B cell subpopulations in the blood of patients and HCs, we found that prior treatments had completely eradicated all CD19+/CD20+ B cells in the patients while numbers of long-lived memory plasma cells were comparable to those of HCs. Conclusions: In this study, 17 of 18 patients with lymphoma who received CD19 CART therapy had very poor immunoreactivity to 1-3 doses of mRNA-based COVID-19 vaccines. Importantly, antibody responses to common recall antigens were preserved, suggesting impaired immune response primarily against novel antigens like SARS-COV-2. This lack of immunoreactivity against novel antigens was probably based on the eradication of earlier-stage B cell subpopulations after treatment with anti-CD19 and anti-CD20 immunotherapies.

Single-cell RNA-sequencing for immune profiling of SARS-CoV2 vaccine response in healthy individuals and patients with precursor plasma cell malignancies

Introduction: Patients with hematological malignancies exhibit inferior response to SARS-CoV2 vaccination, compared to healthy individuals, however little is known about patients with precursor hematological malignancies and the cellular underpinnings of vaccination response. Monoclonal Gammopathy of Undetermined Significance (MGUS) and Smoldering Myeloma (SMM) are plasma cell premalignancies that precede Multiple Myeloma (MM) and exhibit signs of immune dysregulation;they affect approximately 5% of the population over 50 years of age, who remain largely undiagnosed, due to lack of screening. In November 2019, we launched the IMPACT study to characterize the immune response to SARS-CoV2 vaccination in patients with plasma cell dyscrasias and healthy individuals. Methods: We performed single-cell RNA-sequencing on 224 peripheral blood mononuclear cell samples drawn from 118 IMPACT (IRB #20-332) participants with MGUS (n=20), SMM (n=48), or MM (n=24), as well as healthy individuals (n=26). Samples were collected before vaccination and after 2 doses of BNT162b2 (Pfizer-BioNtech) (n=123), mRNA-1273 (Moderna) (n=83) or 1 dose of Ad26.COV2.S (Janssen) (n=14). Results: Overall, we sequenced 2,025,611 cells from 224 samples of 118 patients with MGUS, SMM, MM and healthy individuals pre- and post-vaccination for SARS-CoV2, and profiled 553,082 T-cells, 95,392 B-cells, 74,394 NK cells, 195,371 Monocytes, and 35,236 Dendritic cells (DC). We identified activated clusters of B-cells, NK cells and DCs expressing genes such as CD83, CD69, CXCR4, and genes related to the NF-kB and AP-1 pathways. We compared cell type abundances pre- and post-vaccination within each participant population and found that activated CD83+ cells significantly increased post-vaccination in healthy individuals and patients with MGUS (paired t-test, q < 0.1), but not in patients with SMM or overt MM. At baseline, patients with SMM and MM had significantly fewer memory B-cells and significantly more cytotoxic T-cells and NK cells, compared to healthy individuals (Wilcoxon, q < 0.1), which could partly explain the differences observed post-vaccination. Patients with MM also had significantly higher levels of tolerogenic IL-10-expressing DCs (DC10) at baseline (Wilcoxon, q < 0.1), which could be dampening antigen-specific T-cell responses. Conclusion: We identified a significant expansion of activated B-cell, NK cell and DC subpopulations expressing CD83, CD69 and CXCR4, following vaccination in healthy individuals and patients with MGUS, but less so in patients with SMM and overt MM. Our results provide insight into the cellular mechanisms of immune response to SARS-CoV2 vaccination in healthy individuals and patients with precursor plasma cell malignancies and suggest that asymptomatic individuals with SMM may exhibit inferior response to vaccination.

Intracerebral Plasmacytoma in a Patient with HIV-1 Infection and SARS-CoV-2 Superinfection.

We present a rare case of intracranial solitary plasmacytoma arising in brain parenchyma in the basal nuclei. Clinical management and autopsy results of the case are described. Background: Intracranial plasmacytomas arising from brain parenchyma are extremely rare, and data from the literature are limited. Primary intracranial plasmacytomas are rare because plasma cells are not found in the brain in normal conditions. Commonly, intracranial plasmacytoma is associated with multiple myeloma, which is why multiple myeloma must be ruled out to diagnose solitary intracranial plasmacytoma. Considering that solitary plasmacytoma and multiple myeloma have some histopathological similarities, it is important to differentiate them because their respective treatments and prognoses are different. Imaging features of primary extramedullary plasmacytoma are nonspecific but are compatible with solid tumors with invariable enhancement. Plasmacytoma was aggressive because it was not diagnosed after the first MRI, but 1.5 months later, MRI showed a large object. We present a rare case of intracranial solitary plasmacytoma arising in brain parenchyma in the basal nuclei.

Are we looking for Monoclonal Gammopathy of Renal Significance ( MGRS )? An audit of investigations in current clinical practice

Monoclonal gammopathy of unknown significance (MGUS) is a premalignant condition defined as the presence of a monoclonal protein with no evidence of plasma cell/B-cell-related malignancy. The risk of progression from MGUS to a related malignancy is approximately 1% per year. MGUS patients are closely monitored for signs of progression allowing for rapid initiation of treatment. In 2012, the International Kidney and Monoclonal Gammopathy Research Group (IKMG) introduced the term Monoclonal Gammopathy of Renal Significance (MGRS). MGRS is the clonal proliferation of a nephrotoxic monoclonal protein without meeting the criteria for any other plasma cell/B-cell malignancy. The diagnosis of MGRS allows for the initiation of urgent treatment required to prevent further deterioration in renal function. Updated diagnostic criteria from the IKMG made renal biopsy essential for diagnosis of MGRS. Consequently, the IKMG set out an algorithm to guide clinicians on when to consider a renal biopsy. The parameters measured to evaluate the need for a renal biopsy include urine albumin creatinine ratio (ACR). This audit was conducted in the Clatterbridge Cancer Centre Liverpool (CCC-L) a leading cancer centre in the Northwest of England. Urine ACR was chosen as the parameter to audit as it is a cheap, non-invasive, quantitative investigation. The primary outcome of this audit is to assess the number of MGUS patients who had an ACR measured at diagnosis in the Myeloma clinic from January 2014 to December 2020. Data were collected retrospectively from electronic clinic letters and notes. The date of diagnosis was defined as the date of clinic letter in which diagnosis was first confirmed. Patients were considered to have had an ACR performed at diagnosis if ACR was measured between 28 days prior to and post the date of diagnosis. ACR performed during disease was defined as any ACR measured from 28 days prior to date of diagnosis and date of death/data collection. Data from 503 patients (249 females, 254 males) were analysed. The median age at diagnosis was 73. Table 1 shows data for patients who had an ACR measurement performed at diagnosis and during disease. There is a trend towards greater compliance to measuring ACR at diagnosis in successive years from 2014 to 2019 (Table 1). This trend reverses in 2020 when only 40.0% of patients had an ACR measured at diagnosis. For all patients where ACR was performed during disease;56.8% ( n = 179) had the highest ACR measurement of <3.0 mg/mmol with only 14.0% ( n = 44) having the highest ACR measurement of >30.0 mg/mmol. If ACR was performed at diagnosis it was more commonly repeated if the value was higher;the frequencies with which ACR was repeated were 85.7% ( n = 12), 65.1% ( n = 28) and 28.4% ( n = 31) when ACR value at diagnosis was >30.0 mg/mmol, 3.0-30.0 mg/mmol and <3.0 mg/mmol respectively. This audit has shown an increased recognition for the importance of ACR measurement with increased compliance year on year. A likely hypothesis for the reduced measurements in 2020 is the need for remote clinic appointments during the Coronavirus 2019 (Covid-19) pandemic. Following IKMG guidelines 14.0% ( n = 44) of patients would be advised to have a renal biopsy due to their ACR measurement of >30.0 mg/ mmol. Further evaluation of this patient cohort is required to audit compliance with other parameters suggested by the IKMG. A diagnostic pathway to be used at the earliest opportunity for MGUS patients may then be developed..

Diagnostic value of FDG-PET/CT in fever of unknown origin

Background: Fever of unknown origin (FUO) is a challenging clinical problem in medicine that needs collaboration of various diagnostic techniques to establish the accurate diagnosis. We evaluated the diagnostic performance of 18F-FDG PET/CT in patients who presented themselves with FUO. Our study included 40 patients with FUO who underwent PET/CT examination and their results were compared to the results of laboratory, histopathological, microbiological investigations and/or response to therapy. Results: The final diagnosis included malignancy in 20 patients (50%), infectious causes in 7 patients (17.5%) and non-infectious inflammatory causes in 6 patients (15%). Fever resolved without diagnosis in 4 patients (10%), while no definite diagnosis was reached in 3 patients (7%). PET/CT successfully contributed to diagnosis of 35 out of 40 patients with diagnostic accuracy of 87.5%. The sensitivity, specificity, positive predictive value and negative predictive value of PET/CT in our study were 93.5%, 66.7%, 90.6% and 75%, respectively. Conclusion: PET/CT is a useful tool to investigate and diagnose the cause of FUO. It provides information that can guide the treatment strategy of the patients.

The selective bruton tyrosine kinase (BTK) inhibitor TG-1701 as monotherapy and in combination with ublituximab and umbralisib (U2) in patients with B-cell malignancies

Introduction: TG-1701 is an irreversible, selective, novel Bruton's tyrosine kinase inhibitor (BTKi) administered once daily (QD). BTK inhibitors, as well as the U2 combination (anti-CD20 mAb ublituximab + the PI3Kδ-CK1ϵ inhibitor umbralisib), are highly efficacious in chronic lymphocytic leukemia (CLL), each of which have been previously demonstrated to be superior over standard chemoimmunotherapy. Treatment with a more selective BTK inhibitor could result in improved efficacy and safety outcomes compared with ibrutinib (ALPINE study, EHA 2021), and we hypothesized that dual blockade of the B-cell receptor (BCR) pathway through combination of TG-1701 with U2 may confer greater depth of response compared to either regimen alone. Methods: Patients with CLL and non-Hodgkin lymphoma (NHL) were enrolled in an ongoing Phase 1 study. After characterizing the safety profile of TG-1701 monotherapy, a parallel dose escalation arm of TG-1701+U2 was implemented. Select dose levels of TG-1701 monotherapy and TG-1701+U2 were also expanded. All patients were treated until disease progression, unacceptable toxicity, or investigator/patient decision to withdraw. Safety was evaluated in all treated patients, and efficacy was evaluated in all treated patients who had at least 1 post-baseline assessment. TG-1701 monotherapy data were previously presented;herein we present data from the TG-1701+U2 dose escalation/expansion and the TG-1701 monotherapy CLL expansion cohorts Results: As of July 2021, 142 patients were treated with TG-1701, 36 of whom were enrolled in the TG-1701+U2 arm. The median # of prior therapies across all treated patients was 1 (range, 0-10) and all patients were BTKi-naïve. Among the 36 patients treated with U2+1701, 19 were evaluable for efficacy and safety (17 too early to evaluate). The median age was 69 years (range 47-81), and 56% were male. TG-1701+U2 was well tolerated at 4 different dose levels without dose-limiting toxicities. The most common (>30%) all-causality, all grade treatment-emergent adverse events (TEAEs) were diarrhea (53%) contusion (42%), nausea (37%), hypertension, ALT/AST increase, and fatigue (all 32% each) with TG-1701+U2. Grade 3/4 AEs >15% were limited to ALT/AST increase (21%). Dose reduction occurred in 1 patient due to an AE, and 4 patients discontinued at least 1 study drug due to an AE: 2 discontinued umbralisib, 1 discontinued umbralisib and TG-1701, and 1 discontinued all 3 agents. At the data cut-off, overall response rate (ORR) was 84% (4 CR and 12 PR) among 19 evaluable patients, with remaining patients awaiting post-baseline assessment. In the monotherapy CLL-specific cohorts (200 mg QD, n=20;and 300 mg QD, n=20), 40 pts were evaluable for safety, and 39 for efficacy (1 pt withdrew due to COVID prior to first response assessment). The median age was 71 (range 49-86), and 43% were male. The most common TEAEs were increased ALT/AST (all grades: 18%;grade ≥3: 3%), followed by diarrhea (all grades: 15%;grade ≥3: none), and neutropenia (all grades: 13%;grades ≥3: 13%). There were no cases of atrial fibrillation, major bleeding, or ventricular tachyarrhythmia in the CLL cohorts at a median follow-up of 12.8 months (range 2.5 - 20.8). TEAEs leading to TG-1701 dose reduction occurred in 1 (3%) patient. No patients in the 200 mg or 300 mg CLL cohorts have discontinued due to AEs. In patients with anemia and thrombocytopenia at baseline, sustained improvement in hematologic variables was observed. The ORR among 39 patients was 97% (all PR/PR-L). Lymphocytosis resolved to normal value or <50% of baseline in 69% (24 of 35 of patients with lymphocytosis). Consistent response rates were observed across all subgroups, including the following high-risk genomic features: del17p/TP53 mutations, unmutated immunoglobulin heavy-chain variable-region (IGHV), and complex karyotype (defined as 3 ≤cytogenetic abnormalities). The median duration of response has not been reached in either cohort. Best change in tumor burden from baseline in patients with CLL is presented in Figure 1. C nclusions: TG-1701 exhibits an encouraging safety and efficacy profile as monotherapy in patients with CLL and additionally shows promising activity and a manageable tolerability profile in combination with U2. Future registration trials are being planned in CLL with TG-1701. Recruitment to this study (NCT03671590) continues. (Figure Presented).

Zanubrutinib in patients with B-cell malignancies intolerant to ibrutinib and/or acalabrutinib

Introduction: Bruton tyrosine kinase inhibitor (BTKi) therapy is remarkably effective in a number of B-cell malignancies;however, its continuous use is limited by adverse events (AE) leading to discontinuation. Zanubrutinib is a potent and selective BTKi with the potential to be a safe and effective therapy after intolerance to previous BTKi therapy. Here, we report preliminary results of a phase 2 study of zanubrutinib in patients with B-cell malignancies intolerant to ibrutinib and/or acalabrutinib based on a median follow-up of 6 months. Methods: Patients meeting protocol criteria for intolerance to ibrutinib, acalabrutinib, or both (without documented progressive disease on ibrutinib or acalabrutinib) were given zanubrutinib monotherapy (160mg twice daily or 320mg once daily at investigator's discretion). Recurrence of adverse events that led to intolerance to prior BTKi and additional safety measures were assessed based on the Common Terminology Criteria for AEs v5.0. Investigators determined responses using disease status at study entry as baseline and standard established disease response criteria. Results: As of 1 March 2021 (cutoff), 64 patients (n=48 chronic lymphocytic leukemia/small lymphocytic lymphoma, n=10 Waldenström macroglobulinemia, n=3 mantle cell lymphoma, n=3 marginal zone lymphoma) were enrolled, received ≥1 dose of zanubrutinib, and were analyzed for safety. The median age was 71 y (range, 49-91);the median duration of treatment was 5.9 months (range, 0.6-16.6). The median number of prior regimens was 2 (range, 1-12). Regarding prior BTKi, 55 patients had received ibrutinib monotherapy, eight had received ibrutinib combination therapy, and seven had received acalabrutinib monotherapy. The median number of ibrutinib- or acalabrutinib-intolerant adverse events per patient was 2 (range, 1-5). Most ibrutinib- (75%) and acalabrutinib-intolerant events (75%) did not recur with zanubrutinib (Table 1). A majority (90%) of the recurrent ibrutinib-intolerant events were less severe with zanubrutinib than with ibrutinib. Ibrutinib intolerance events present in >1 patient that did not recur on zanubrutinib were alanine aminotransferase increased, aspartate transaminase increased, neutropenia, and pain in extremity. The ibrutinib-intolerant events that recurred were diarrhea, dizziness, insomnia, nausea, constipation, myalgia, stomatitis, arthralgia, headache, muscle spasm, rash, atrial fibrillation, fatigue, hemorrhage, and hypertension. One-third of the recurrent acalabrutinibintolerant events were less severe with zanubrutinib than with acalabrutinib. The acalabrutinib-intolerant events that recurred were myalgia and arthralgia. Two events of arthralgia that induced acalabrutinib intolerance did not recur with zanubrutinib. No ibrutinib- or acalabrutinib-intolerant events recurred at a higher severity while patients were on zanubrutinib. At cutoff, 57 patients remained on treatment;one withdrew consent due to zanubrutinib-unrelated grade 3 syncope. Grade ≥3 adverse events were reported in 14 patients (21.9%), serious adverse events in five patients (7.8%;pain in jaw;COVID-19 pneumonia;anemia;febrile neutropenia and salmonella infection [occurred in the same patient]), adverse events requiring dose interruptions in 15 patients (23.4%), and adverse events leading to dose reduction in three patients (4.7%). Adverse events led to zanubrutinib discontinuation for three patients (4.7%). One death was reported (COVID-19 pneumonia). Among efficacy evaluable patients (n=48), the disease control rate was 89.6% and the overall response rate was 50.0%. Conclusions: In patients with B-cell malignancies intolerant to ibrutinib and/or acalabrutinib, zanubrutinib therapy was effective and controlled patient's disease or induced responses to therapy, and was well-tolerated;most adverse events that led to discontinuation of previous BTKi therapy did not recur while patients were on zanubrutinib.

Impaired mRNA Based COVID-19 Vaccine Response in Patients with B-Cell Malignancies after CD19 Directed CAR-T Cell Therapy

Introduction: Patients with hematologic malignancies are at an increased risk of morbidity and mortality from COVID-19 disease (Vijenthira, Blood 2020). This is likely a result of combination of immunodeficiency conferred by the disease and the therapeutics. The immunogenicity of the COVID-19 vaccines in patients with exposure to CD19 directed Chimeric Antigen Receptor (CAR)-T cell therapy is not established. CD19 CAR-T cell therapies cause B-cell aplasia, which in turn can affect humoral immune response against novel antigens. Herein, we present results from our prospectively conducted clinical study to evaluate immune responses against mRNA based COVID-19 vaccines in patients with lymphoma who have received CD19 directed CAR-T cell therapy. Methods: All patients and healthy controls were enrolled in a prospective clinical study evaluating immune responses against commercial COVID-19 RNA vaccines in patients with hematologic malignancies. Plasma samples were generated from heparinized peripheral blood of 4 heathy controls (HCs) receiving the same vaccines and 19 B cell lymphoma patients treated with CD19 CAR- T cells. Samples from ~4 weeks post second dose of the vaccine (d56) were available for 14 CAR-T patients, for 5 CAR-T patients samples were available from ~4 weeks after the first dose (d28). Plasma samples were analyzed in an enzyme-linked immunosorbent assay (ELISA) using different full-length recombinant SARS-CoV-2 proteins and control proteins. Neutralizing activity was measured using the cPass Neutralization Antibody Detection Kit (GenScript Biotech). Results: Results from 4 healthy controls and 19 patients (12 males and 7 females) with lymphoma are reported. Median age for the lymphoma patients is 65 years. Eleven patients had large B cell lymphoma, 5 had follicular lymphoma and 3 had mantle cell lymphoma as primary diagnoses. Seventeen patients had advance stage disease (III/IV stage) and had received a median of 3 prior lines of therapy. All patients received CD19 directed CAR-T cell therapy. Ten patients received Moderna vaccine and 9 received Pfizer vaccine. Median time between CAR-T infusion and first COVID-19 vaccine was 258 days. While the peripheral blood plasma from 3/4 HCs already showed substantial SARS-CoV-2 neutralizing activity at ~4 weeks after the first dose of COVID-19 mRNA vaccine, none of the 5 CD19 CAR-T patients analyzed evidenced any antibody-mediated neutralizing activity in their blood at the same point in time (Figure 1A). Around 4 weeks after receiving the second dose of the vaccine, all 4 HCs tested evidenced complete or almost complete neutralizing activity (Figure 1B). In marked contrast, only 1 out of 14 CAR-T patients analyzed evidenced any relevant antibody-mediated SARS-CoV-2 neutralizing activity in their blood (Figure 1B). Interestingly, when we asked whether a globally insufficient antibody-mediated immunity was the underlying cause of the lack of a response to the COVID-19 vaccine in our CAR-T patients, we found that that was clearly not the case since anti-Flu, -TT, and -EBV responses were equivalent to the ones observed in HCs (Figure 2A). However, while at ~4 weeks post second dose of the vaccine the HCs showed marked antibody titers against all the viral spike proteins including their “delta” variants (Figure 2B), that was not the case for our CAR-T patients. The vast majority of our CAR-T patients did not evidence IgG antibody responses against any of the SARS-CoV-2 proteins analyzed such as S1, S1 delta, RBD, RBD delta, or S2 (Figure 2B). Conclusion: In this prospectively conducted clinical study, 18 of 19 patients with lymphoma who have received CD19 CAR-T therapy had poor immunogenicity against mRNA based COVID-19 vaccines as measured by neutralization assays and antibody titers. The antibody titers against B.1.617.2 (delta variant, S1 and RBD protein) were also demonstrably poor. The antibody response to common pathogens (flu, EBV, TT) were preserved, suggesting impaired immune response against novel antigens. Long-term follow-up of this study is ongoin . APR and DJ contributed equally [Formula presented] Disclosures: Dahiya: Kite, a Gilead Company: Consultancy;Atara Biotherapeutics: Consultancy;BMS: Consultancy;Jazz Pharmaceuticals: Research Funding;Miltenyi Biotech: Research Funding. Hardy: American Gene Technologies, International: Membership on an entity's Board of Directors or advisory committees;InCyte: Membership on an entity's Board of Directors or advisory committees;Kite/Gilead: Membership on an entity's Board of Directors or advisory committees.

Evaluation of Antibody Response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Immunizations in Patients with B-Cell Malignancies

Background Multiple vaccines have been granted emergency use authorization by the Food and Drug Administration against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Of the currently available vaccines, none have been systematically studied for efficacy or toxicity in patients with immunodeficiency or with immunosuppressed states, such as B cell malignancy. The purpose of the study was to evaluate the immune response to currently available vaccines against COVID-19 in patients with hematologic and solid organ malignancies. Methods This prospective study enrolled 53 patients;12 with CLL, 10 with multiple myeloma (MM), 11 with non-Hodgkin's lymphoma (NHL) and 21 with a solid organ malignancy. Using a quantitative assay, IgG antibodies to SARS-CoV-2 Spike (S) protein, and nucleocapsid (N) protein by enzyme immunoassay were measured at baseline prior to vaccination and at 2 weeks after completion of vaccination. A fourfold increase in IgG was considered a positive response to vaccination. Through a predesigned survey, patients also self-reported side effects from each dose of vaccination. Results Seroconversion with vaccination was seen in 9/10 (90%) patients with MM, 5/12 (41.7%) patients with CLL, 6/11 (54.1%) patients with NHL, and 17/21 (80.9%) patients with solid organ malignancy. Per univariate analysis, CLL (OR 0.23, 95% CI 0.05-0.88;p= 0.033) was associated with lower odds of seroconversion while NHL (OR 0.48, 95% CI 0.12-1.8;p =0.291), MM (OR 5.33, 95% CI 0.61-46.08;p= 0.128) and solid organ malignancy (OR 2.90, 95% CI 0.79-10.64;p= 0.107) were not. Among patients with hematological malignancies, 5/13 (38.3%) patients treated with rituximab and 2/7 (28.5%) patients on immunoglobulin replacement (IgR) therapy responded to vaccination. This corresponded to reduced odds of seroconversion, 0.18 (95% CI 0.047-0.69;p = 0.013) in patients treated with rituximab and 0.14 (95% CI 0.024-0.826;p=0.030) in patients on IgR. Among patients with solid organ malignancies, treatment with chemotherapy (OR 2.05, 95% CI 0.48-8.61;p=0.320), immunotherapy (OR 4.57, 95% CI 0.52-39.9;p=0.169) or endocrine therapy (OR 1.0) did not lower odds of seroconversion with vaccination. Multivariate analysis revealed patients who received rituximab were less likely to respond to vaccination as compared to patients not previously treated with rituximab (OR 0.22, 95% CI 0.05-0.955;p=0.044). Injection site soreness was the most commonly reported side effect. The only severe side effect occurred in a patient with solid organ malignancy who developed Parsonage Turner syndrome. Conclusion Our study, to the best of our knowledge, is the first study comparing pre and post vaccination IgG titers against the SARS-CoV-2 S protein. Majority of patients with MM and solid organ malignancies, including those receiving active treatment, responded adequately to immunization. Patients with CLL appear less likely to respond to vaccination against COVID-19 as compared to patients with NHL, MM or solid organ malignancies. Previous treatment with rituximab was the most significant risk factor for suboptimal response to vaccination, regardless of underlying hematologic malignancy. These data highlight the importance of continuing risk mitigation strategies against COVID-19 in individuals with hematologic malignancy, particularly those with CLL or on treatment with rituximab. Future research is needed to investigate approaches to provide protective IgG against SARS-CoV-2 in this at-risk population. [Formula presented] Disclosures: Mustafa: Genentech: Speakers Bureau;GalaxoSmithKline: Speakers Bureau;CSL Behring: Speakers Bureau;Regeneron: Speakers Bureau;AstraZeneca: Speakers Bureau. Walsh: Janssen: Research Funding;Merck: Research Funding;Pfizer: Research Funding. Jamshed: Takeda: Honoraria.

Intra tumoral electroporation of IL-12 and SARS-Cov-2 spike plasmids drives a coordinated vaccine response and elicits robust anti-tumor immunity

Despite extensive clinical evidence on the efficacy and safety of SARS-CoV-2 vaccines, there remains a paucity of data on their effectiveness in cancer patients who are actively receiving antineoplastic therapeutics. A recent study demonstrated only ∼30% of cancer patients had positive serologic test following 2 doses of FDA-authorized SARS-CoV-2 vaccines, in contrast to ∼80% positivity rate in healthy individuals, regardless of the age. Therefore, furtherinvestigation into novel approaches to boost immune response to SARS-CoV-2 vaccines in cancer patients isrequired. Our previous preclinical and clinical studies have established intratumoral IL-12 plasmid (TAVO)electroporation (EP) induces localized expression of IL-12p70, converting immune-excluded tumors into inflamedimmunogenic lesions, thereby generating objective responses in both treated and untreated, distant tumors. Basedon the enhancement of immunotherapy efficacy by IL-12, we leveraged the flexibility of our DNA plasmid-EPplatform to express SARS-CoV-2 spike protein in addition to IL-12 (CORVax12) as an intratumoral vaccine candidate which we hypothesized could not only drive anti-SARS-CoV-2 immune responses but also generate aproductive anti-tumor response. Naïve mice were vaccinated via intradermal injection of SARS-CoV-2 spike plasmidfollowed immediately by EP with or without plasmid-encoded mIL-12 on days 1 and 21. Longitudinal serum samples were collected to interrogate virus-specific cellular responses as well anti-spike IgG antibody. A surrogate viralneutralization test (sVNT) assessed serum blockade of soluble human ACE2 binding to immobilized SARS-CoV-2spike. Our data demonstrated that intradermally electroporated CORVax12 elicits significantly higher anti-SARS-CoV-2 spike IgG antibodies and neutralization when compared with EP of SARS-CoV-2 spike alone. Next, we askedif improved SARS-CoV-2 immune response may be observed when CORVax12 is incorporated into intratumoral EPin single-tumor bearing mice. CORVax12 robustly inhibited tumor growth, induced high percentages of germinal-center B cells and class switched B cells in tumor draining lymph nodes, and generated high of anti-spike IgG and neutralization antibodies. To further investigate systemic effects of this combination, we continued with contralateraltumor mice models. In both CT26 and B16-F10 tumor models, CORVax12 intratumoral EP induced strong systemicanti-tumor responses similar to IL-12 EP alone while also producing high serum levels of anti-SARS-CoV-2 spikeIgG and neutralization antibodies. Critically, this anti-viral immunity did not limit this IL-12-based intratumoral anti-tumor therapy. In summary, our preclinical data indicates that intratumoral EP of CORVax12 can induce IgGresponses to SARS-CoV-2 spike as well as apparent viral neutralizing activity all while maintaining local and systemic anti-tumor effects expected from TAVO Treatment. This combined intratumoral therapy represents a novelstrategy to address both tumor burden and anti-SARS-CoV-2 immunity in patients with cancer.

Factors Associated with Seroconversion after COVID-19 Vaccination in Patients with Hematologic Malignancies

Background: Recent studies reported low rates of seroconversion response to COVID-19 vaccination in patients (pts) with hematologic malignancies (HMs). Vaccine choice among the 3 FDA-authorized products (BNT162b2/Pfizer-BioNTech, mRNA-1273/Moderna, or Ad26.COV2.S/J&J), prior therapy, and disease-specific factors may affect seroconversion. Addressing these factors may improve seroconversion rates and identify pts at risk of severe COVID-19 infection despite vaccination. Methods: We conducted a retrospective study of adults with HMs vaccinated in our center between 2/2021 and 7/2021, excluding pts with prior COVID-19 infection. Seroconversion was assessed by the qualitative SARS-CoV-2 Total Antibody Test (IgG/IgM against Receptor Binding Domain [RBD], Wondfo USA, Willowbrook, IL). A subset of samples was tested by the semi-quantitative Abbott AdviseDx SARS-CoV-2 IgG II assay (IgG against RBD). For univariate associations (UVA) we used Fisher's exact test for categorical variables, and fractional polynomial fits for continuous variables to examine non-linearity. Multivariable analysis (MVA) used a robust Poisson model reporting risk ratio (RR) with 95% confidence intervals (CI). Results: Among 239 eligible pts, median age was 70 (range, 28-94), and 112 (47%) were female. HMs included aggressive B-cell lymphomas (n=74, 31%), indolent B-cell lymphomas (n=52, 22%), chronic lymphocytic leukemia (CLL, n=30, 13%), other lymphomas (n-19, 8%), plasma cell neoplasms (n=43, 18%), and myeloid cancers (n=21, 9%);140 pts (59%) received BNT162b2/Pfizer, 74 (31%) mRNA-1273/Moderna, and 23 (10%) Ad26.COV2.S/J&J vaccines (2 pts had undetermined vaccine type). HM was active in 100 pts (42%), whereas 108 (45%) pts were in remission after treatment, and 31 (13%) on watchful waiting (WW, never treated);141 (59%) had a prior exposure to an anti-B-cell monoclonal antibody, and 22 (9%) prior stem cell transplantation. Overall, 99 pts (41%;binomial 95% CI, 35-48%) showed post-vaccination seroconversion upon testing at median 10 weeks from first vaccine. Seroconversion was significantly less frequent among pts with lymphomas compared with plasma cell or myeloid neoplasms (overall P=.020;Fig A). It was also less frequent after prior anti-B-cell antibody exposure (29% vs 59%, P<.0001;Fig. B), and in those with active disease (28%, vs 49% for remission [P=.0027], vs 58% for WW [P=.0045];Fig. C). Furthermore, seroconversion was significantly more frequent after mRNA-1273/Moderna vaccine (57%) compared with BNT162b2/Pfizer (36%, P=.006) or Ad26.COV2.S/J&J (22%, P=.004;Fig. D). It was not associated with age (Fig. E), WBC (Fig. G), or time from vaccination (Fig. I), but was significantly higher with increased lymphocyte count (P<.0001;Fig F) and time elapsed from last chemotherapy (P=.0039;Fig. H). In a MVA (Fig. J), vaccination with mRNA-1273 remained significantly associated with higher rate of seroconversion compared with BNT162b2 (RR=0.59;95%CI, 0.44-0.79) or Ad26.COV2.S (RR=0.35;95%CI, 0.16-0.77). Higher seroconversion rate was also associated with remission (RR=1.98;95%CI, 1.42-2.76) or WW status (RR=1.72;95%CI 1.02-2.89) compared with active disease, and higher lymphocyte count. Exposure to anti-B-cell antibodies remained associated with lack of seroconversion (RR=0.66;95%CI, 0.44-0.99). Seroconversion was borderline less frequent in CLL than lymphomas, and higher with plasma cell or myeloid disorders. Results were similar in the subset of pts (n=191) with prior treatment, adjusting for time from last chemotherapy(data not shown). The anti-COVID-19 IgG titers on semiquantitative test (n=47, all after mRNA-based vaccines) were also lower in pts with active disease compared with those in remission (P=.065) or under WW (P=.028), and in those with prior anti-B-cell antibody (P=.0095). Conclusions: Pts with HMs demonstrate overall low rates of seroconversion after vaccination against COVID-19, particularly when they have active disease or are on/after B-cell depleting monoclonal antibody therapy. The mRNA vaccines (particularly mRNA- 273) appear to have elicited superior responses compared with the adenovirus-based product. Pts with active HMs or those within 2 years of last therapy should be particularly aware of the risk of infection despite vaccines and should be considered for strategies to enhance anti-COVID-19 immunity regardless of age. [Formula presented] Disclosures: Olszewski: TG Therapeutics: Research Funding;PrecisionBio: Research Funding;Celldex Therapeutics: Research Funding;Acrotech Pharma: Research Funding;Genentech, Inc.: Research Funding;Genmab: Research Funding.

Patients with Multiple Myeloma on Anti-CD38 or Anti-BCMA Based Regimens and Patients with Waldenstrom's Macroglobulinemia Under Rituximab or BTK Inhibitors Have a Poor Humoral Response Following COVID-19 Vaccination

[Formula presented] Introduction: Recent data suggest a suboptimal antibody response to COVID-19 vaccination in patients with hematological malignancies. Herein, we evaluated the development of neutralizing antibodies (NAbs) against SARS-CoV-2 in patients with plasma cell neoplasms (PCNs) after vaccination with either the mRNA BNT162b2 or viral vector AZD1222 vaccine, up to 50 days post their first vaccine dose. Methods: This is an ongoing large prospective study (NCT04743388) evaluating the kinetics of anti-SARS-CoV-2 antibodies after COVID-19 vaccination in healthy subjects and in patients with hematological malignancies or solid tumors. Here we present the data on patients with PCNs in comparison to controls of similar age and gender, who were vaccinated during the same time period (January to March 2021) in Athens (Greece). Major exclusion criteria for both patients and controls included the presence of: (i) autoimmune disorder under immunosuppressive therapy or other active malignant disease;(ii) HIV or active hepatitis B and C infection, (iii) end-stage renal disease and (iv) prior diagnosis of COVID-19. Serum was collected on day 1 (D1;before the first vaccine dose), on day 22 (D22;before the second dose of the BNT162b2 or 3 weeks post the first AZD1222 dose) and on day 50 (D50;4 weeks post second dose of the BNT162b2 or 7 weeks post the first AZD1222 dose). NAbs against SARS-CoV-2 were measured using an FDA approved-ELISA methodology (cPass™ SARS-CoV-2 NAbs Detection Kit, GenScript, Piscataway, NJ, USA). Results: We evaluated 382 patients with PCNs after vaccination with either the BNT162b2 or the AZD1222 vaccine. Patients with MM (n=213), WM (n=106), SMM (n=38) and MGUS (n=25) and 226 healthy controls were enrolled in the study. Of MM/SMM/MGUS patients, 215 (77.9%) were vaccinated with the BNT162b2 and 61 (22.1%) with the AZD1222 vaccine, while out of 106 WM patients 90 (84.9%) were vaccinated with the BNT162b2 and 16 (15.1%) with the AZD1222 vaccine. Vaccination with either two doses of the BNT162b2 or one dose of the AZD1222 vaccine led to lower production of NAbs against SARS-CoV-2 in patients compared with controls both on day 22 and on day 50 (P<0.001 for all comparisons). After the first dose of the vaccine, on D22, the patient group had lower NAb titers compared with controls: the median NAb inhibition titer was 27% (IQR: 15.3-42%) for MM/SMM/MGUS versus 20.5% (IQR: 10-37%) for WM patients versus 38.7% (IQR: 22-54.3%) for controls (P<0.001 for all comparisons). On D50 the median NAb inhibition titer was 62.8% (IQR: 26-88.9%) for MM/SMM/MGUS versus 36% (IQR: 18-78%) for WM patients versus 90% (IQR: 58-96.4%) for controls (P<0.001 for all comparisons). 57.3% MM/SMM/MGUS, 42% WM patients and 81% controls developed NAb titers ≥50% (p<0.001 for patients versus controls). Furthermore, MM patients showed an inferior NAb response compared with MGUS on day 22 (p=0.009) and on day 50 (p=0.003). Importantly, active treatment with either anti-CD38 monoclonal antibodies or belantamab mafodotin and lymphopenia at the time of vaccination were independent prognostic factors for suboptimal antibody response following vaccination in MM (p<0.05). Disease-related immune dysregulation and therapy-related immunosuppression were involved in the low humoral response in patients with WM. Importantly, active treatment with either rituximab or Bruton's Tyrosine Kinase inhibitors (BTKIs) was proven as an independent prognostic factor for suboptimal antibody response following vaccination in WM (p<0.05). Regarding adverse events, 33% and 31.6% patients reported mild reactions after the first and second dose of the BNT162b2 vaccine, respectively;32.8% patients vaccinated with the first dose of AZD1222 also presented with local reactions. Conclusion: Patients with MM and WM have a low humoral response following SARS-CoV-2 vaccination, especially those who are under treatment with anti-CD38-, anti-BCMA-, anti-CD20- or BTKIs-based regimens. This result suggest that these patients have to continue the protective measures ag inst SARS-CoV-2 as they are at high risk for COVID-19. Further studies on the kinetics of immune subpopulations following COVID-19 vaccination will elucidate the underlying immune landscape and determine the potential need for additional booster vaccine doses or protective administration of antibodies against SARS-CoV-2 in MM/WM patients with poor response after full vaccination. Disclosures: Terpos: Janssen-Cilag: Consultancy, Honoraria, Research Funding;BMS: Honoraria;Celgene: Consultancy, Honoraria, Research Funding;Genesis: Consultancy, Honoraria, Research Funding;GSK: Honoraria, Research Funding;Takeda: Consultancy, Honoraria, Research Funding;Sanofi: Consultancy, Honoraria, Research Funding;Novartis: Honoraria;Amgen: Consultancy, Honoraria, Research Funding. Gavriatopoulou: Janssen: Honoraria;Takeda: Honoraria;Sanofi: Honoraria;Karyopharm: Honoraria;Genesis: Honoraria;GSK: Honoraria;Amgen: Honoraria. Kastritis: Amgen: Honoraria, Research Funding;Janssen: Honoraria, Research Funding;Genesis: Honoraria;Takeda: Honoraria;Pfizer: Honoraria. Dimopoulos: Janssen: Honoraria;BeiGene: Honoraria;Takeda: Honoraria;Amgen: Honoraria;BMS: Honoraria.