A multicenter proof-of-concept study on deep learning-based intraoperative discrimination of primary central nervous system lymphoma.

Accurate intraoperative differentiation of primary central nervous system lymphoma (PCNSL) remains pivotal in guiding neurosurgical decisions. However, distinguishing PCNSL from other lesions, notably glioma, through frozen sections challenges pathologists. Here we sought to develop and validate a deep learning model capable of precisely distinguishing PCNSL from non-PCNSL lesions, especially glioma, using hematoxylin and eosin (H&E)-stained frozen whole-slide images. Also, we compared its performance against pathologists of varying expertise. Additionally, a human-machine fusion approach integrated both model and pathologic diagnostics. In external cohorts, LGNet achieved AUROCs of 0.965 and 0.972 in distinguishing PCNSL from glioma and AUROCs of 0.981 and 0.993 in differentiating PCNSL from non-PCNSL lesions. Outperforming several pathologists, LGNet significantly improved diagnostic performance, further augmented to some extent by fusion approach. LGNet's proficiency in frozen section analysis and its synergy with pathologists indicate its valuable role in intraoperative diagnosis, particularly in discriminating PCNSL from glioma, alongside other lesions.

[New classifications of malignant lymphomas - What changes are relevant for practice?] / Neue Klassifikationen maligner Lymphome ­ Welche Änderungen sind für die Praxis relevant?

An internationally uniform lymphoma classification is of fundamental importance for the comparability of clinical studies. There are currently 2 parallel classifications: the "International Consensus Classification" and the WHO-classification. Follicular lymphoma 3B is classified separately as follicular large cell lymphoma in WHO-HAEM5. The diagnostic criteria of lymphoplasmocytic lymphoma (LPL) have been adjusted, both classifications recommend molecular testing for MYD88 and CXCR4 mutations. There are no significant diagnostic changes in aggressive B-cell lymphomas. The ICC classify NLPBL and THRLBCL into the group of large B-cell lymphomas (LBCL). NLPHL/NLPBL-specific therapy must be considered, which differs greatly from the therapy of DLBCL, especially in the early stages. Peripheral T-cell lymphomas are a group of nodal T-cell lymphomas with a TFH phenotype and frequent mutations; peripheral T-cell lymphoma (NOS) is therefore a diagnosis of exclusion. Indolent T-cell lymphomas/lymphoproliferations of the GI tract are rare but must be differentiated from aggressive T-cell lymphomas. The WHO-HAEM5 also includes reactive/non-neoplastic lymph node lesions classified according to B or T cell predominance.

(2,6-Dimethylphenyl)arsonic Acid Induces Apoptosis through the Mitochondrial Pathway, Downregulates XIAP, and Overcomes Multidrug Resistance to Cytostatic Drugs in Leukemia and Lymphoma Cells In Vitro.

Cancer treatment is greatly challenged by drug resistance, highlighting the need for novel drug discoveries. Here, we investigated novel organoarsenic compounds regarding their resistance-breaking and apoptosis-inducing properties in leukemia and lymphoma. Notably, the compound (2,6-dimethylphenyl)arsonic acid (As2) demonstrated significant inhibition of cell proliferation and induction of apoptosis in leukemia and lymphoma cells while sparing healthy leukocytes. As2 reached half of its maximum activity (AC50) against leukemia cells at around 6.3 µM. Further experiments showed that As2 overcomes multidrug resistance and sensitizes drug-resistant leukemia and lymphoma cell lines to treatments with the common cytostatic drugs vincristine, daunorubicin, and cytarabine at low micromolar concentrations. Mechanistic investigations of As2-mediated apoptosis involving FADD (FAS-associated death domain)-deficient or Smac (second mitochondria-derived activator of caspases)/DIABLO (direct IAP binding protein with low pI)-overexpressing cell lines, western blot analysis of caspase-9 cleavage, and measurements of mitochondrial membrane integrity identified the mitochondrial apoptosis pathway as the main mode of action. Downregulation of XIAP (x-linked inhibitor of apoptosis protein) and apoptosis induction independent of Bcl-2 (B-cell lymphoma 2) and caspase-3 expression levels suggest the activation of additional apoptosis-promoting mechanisms. Due to the selective apoptosis induction, the synergistic effects with common anti-cancer drugs, and the ability to overcome multidrug resistance in vitro, As2 represents a promising candidate for further preclinical investigations with respect to refractory malignancies.

Ageing microenvironment mediates lymphocyte carcinogenesis and lymphoma drug resistance: From mechanisms to clinical therapy (Review).

Cellular senescence has a complex role in lymphocyte carcinogenesis and drug resistance of lymphomas. Senescent lymphoma cells combine with immunocytes to create an ageing environment that can be reprogrammed with a senescence­associated secretory phenotype, which gradually promotes therapeutic resistance. Certain signalling pathways, such as the NF­κB, Wnt and PI3K/AKT/mTOR pathways, regulate the tumour ageing microenvironment and induce the proliferation and progression of lymphoma cells. Therefore, targeting senescence­related enzymes or their signal transduction pathways may overcome radiotherapy or chemotherapy resistance and enhance the efficacy of relapsed/refractory lymphoma treatments. Mechanisms underlying drug resistance in lymphomas are complex. The ageing microenvironment is a novel factor that contributes to drug resistance in lymphomas. In terms of clinical translation, some senolytics have been used in clinical trials on patients with relapsed or refractory lymphoma. Combining immunotherapy with epigenetic drugs may achieve better therapeutic effects; however, senescent cells exhibit considerable heterogeneity and lymphoma has several subtypes. Extensive research is necessary to achieve the practical application of senolytics in relapsed or refractory lymphomas. This review summarises the mechanisms of senescence­associated drug resistance in lymphoma, as well as emerging strategies using senolytics, to overcome therapeutic resistance in lymphoma.

Lymphoma presenting as preauricular tumor in unilateral parotid gland agenesis: a case report and review of literature.

BACKGROUND: Parotid gland agenesis is a rare, congenital, usually asymptomatic disorder. Until now, only 24 cases with unilateral, incidentally found, parotid gland agenesis have been described. Here, we present the first reported case of an ipsilateral preauricular neoplasm in a patient with unilateral parotid gland agenesis. During surgery, the position of the greater auricular- and facial nerves was documented. Furthermore, we performed the first sialendoscopy for this rare disorder to assess the number of duct branches, which might be indicative of the abundance of parotid tissue. Moreover, we looked for sialendoscopic characteristic features that could aid in identifying these patients in the ambulatory setting. CASE PRESENTATION: A 50-year-old Greek man presented with a painless, slowly enlarging mass in the right parotid space. Magnetic resonance imaging revealed a complete absence of the right parotid gland without accessory parotid tissue. The right parotid gland was replaced by fatty tissue and the radiologist suggested a benign parotid tumor. Fine needle aspiration was indicative of a reactive lymph node. Sialendoscopy revealed only two branches within the right parotid duct. Surgical resection was performed through a conventional lateral parotidectomy. This revealed typical anatomic position of the greater auricular- and facial nerves despite the parotid tissue agenesis. Histopathology revealed a small lymphocytic lymphoma. CONCLUSIONS: Surgeons should feel confident to resect tumors of the parotid space in patients with parotid gland agenesis. Reduced branching observed during sialendoscopy might indicate parotid gland agenesis. Physicians should be even more cautious than usual with the watch and wait strategy in patients with tumors of parotid gland agenesis, since the probability of a tumor being a benign salivary gland tumor might be lower than usual.

Genomic landscape and distinct molecular subtypes of primary testicular lymphoma.

Primary testicular lymphoma (PTL) is a rare lymphoma predominantly occurring in the elderly male population. It is characterized by a limited response to treatment and a heightened tendency towards relapse. Histologically, approximately 90% of PTL cases are classified as diffuse large B-cell lymphomas (DLBCL). Genetic features of PTL were delineated in a limited scope within several independent studies. Some of the articles which analyzed the genetic characterization of DLBCL have incorporated PTL samples, but these have been constrained by small sample sizes. In addition, there have been an absence of independent molecular typing studies of PTL. This report summarizes the common mutational features, copy number variations (CNVs) and molecular typing of PTL patients, based on whole-exome sequencing (WES) conducted on a cohort of 25 PTL patients. Among them, HLA, CDKN2A and MYD88 had a high mutation frequency. In addition, we found two core mutational characteristics in PTL including mutation in genes linked to genomic instability (TP53 and CDKN2A) and mutation in immune-related genes (HLA, MYD88, CD79B). We performed molecular typing of 25 PTL patients into C1 subtype with predominantly TP53 mutations and C2 subtype with predominantly HLA mutations. Notably, mutations in the TP53 gene predicted a poor outcome in most types of lymphomas. However, the C1 subtype, dominated by TP53 mutations, had a better prognosis compared to the C2 subtype in PTL. C2 subtype exhibited a worse prognosis, aligning with our finding that the mechanism of immune escape in PTL was primarily the deletions of HLA rather than PD-L1/PD-L2 alterations, a contrast to other DLBCLs. Moreover, we calculated the tumor mutation burden (TMB) and identified that TMB can predict prognosis and recurrence rate in PTL. Our study underscores the significance of molecular typing in PTL based on mutational characteristics, which plays a crucial role in prognostication and guiding therapeutic strategies for patients.

Diagnosis of cervical lymphoma using a YOLO-v7-based model with transfer learning.

To investigate the ability of an auxiliary diagnostic model based on the YOLO-v7-based model in the classification of cervical lymphadenopathy images and compare its performance against qualitative visual evaluation by experienced radiologists. Three types of lymph nodes were sampled randomly but not uniformly. The dataset was randomly divided into for training, validation, and testing. The model was constructed with PyTorch. It was trained and weighting parameters were tuned on the validation set. Diagnostic performance was compared with that of the radiologists on the testing set. The mAP of the model was 96.4% at the 50% intersection-over-union threshold. The accuracy values of it were 0.962 for benign lymph nodes, 0.982 for lymphomas, and 0.960 for metastatic lymph nodes. The precision values of it were 0.928 for benign lymph nodes, 0.975 for lymphomas, and 0.927 for metastatic lymph nodes. The accuracy values of radiologists were 0.659 for benign lymph nodes, 0.836 for lymphomas, and 0.580 for metastatic lymph nodes. The precision values of radiologists were 0.478 for benign lymph nodes, 0.329 for lymphomas, and 0.596 for metastatic lymph nodes. The model effectively classifies lymphadenopathies from ultrasound images and outperforms qualitative visual evaluation by experienced radiologists in differential diagnosis.

Successful ovarian tissue cryopreservation with transvaginal natural orifice transluminal endoscopic surgery: A case report.

Chemotherapy and radiation therapy can cause gonadal dysfunction in women of reproductive age. Ovarian tissue cryopreservation is performed to restore fertility by allowing transplantation of the patient's frozen-thawed ovarian tissue or through future in vitro maturation and in vitro fertilization of frozen-thawed oocytes. Herein, we describe our initial experience with vaginal natural orifice transluminal endoscopic surgery for ovarian tissue preservation in a young woman with malignant tumor. A 23-year-old woman with anaplastic lymphoma kinase-positive malignant lymphoma was scheduled for hematopoietic stem cell transplantation after experiencing relapse following R-cyclophosphamide, doxorubicin, vincristine, and prednisolone therapy. Ovarian tissue cryopreservation was selected as only MII2 oocytes were collected. Vaginal natural orifice transluminal endoscopic surgery was performed to excise the left ovary. Ovarian tissues were frozen using the vitrification method. The operative time was 37 min, and blood loss was minimal. Pathological examination revealed no metastatic findings of malignant lymphoma and no thermal damage to the ovarian tissue due to bipolar disorder. The patient was discharged on the first day postoperatively, and her postoperative course was uneventful. The vaginal natural orifice transluminal endoscopic surgery technique can provide a safe and effective alternative to laparoscopy or laparotomy for the cryopreservation of ovarian tissue in young patients with cancer. We believe this method has potential application in sexually mature female cancer survivors.

Ovarian tissue cryopreservation with vaginal natural orifice transluminal endoscopic surgeryChemotherapy and radiotherapy can affect a woman's ability to have children by reducing ovarian function. This can make it hard to conceive even with fertility treatments. Freezing healthy ovaries before these treatments can help restore fertility. This can be done by freezing and later transplanting ovarian tissue or by fertilizing frozen eggs in a lab. Traditional surgery to remove ovaries can cause cosmetic issues and pain. But now, a new method called vaginal spontaneous opening transperitoneal endoscopic surgery is becoming more common. This surgery is less invasive, quicker, and causes less bleeding. We recently used this method to preserve ovarian tissue in young women with cancer. The surgery was successful with minimal complications. This new approach could offer a safer option for preserving fertility in female cancer survivors.

Resection or Biopsy: The Efficacy of Different Surgical Approaches for Primary Central Nervous System Lymphoma.

AIM: To analyze the efficacy of surgical resection versus brain biopsy combined with postoperative chemotherapy for primary central nervous system lymphoma (PCNSL) and to discuss a clinically standardized treatment protocol. MATERIAL AND METHODS: Patients with a pathological diagnosis of PCNSL and subsequent chemotherapy between 2016 and 2021 at Northern Jiangsu People?s Hospital were selected and divided into groups according to whether they underwent microsurgical resection or stereotactic needle biopsy. Statistical analyses were performed to compare efficacy and safety in the two groups. RESULTS: A total of 21 patients with PCNSL were identified, of whom 12 underwent resection and 9 underwent diagnostic stereotactic biopsy only. Compared with the resection group, the biopsy group had a higher proportion of deep tumors (55.6% vs. 8.3%, p=0.016), and the mean intraoperative bleeding was significantly reduced (13.33 ± 6.61 mL vs. 170.83 ± 101.04 ml, p < 0.001). In addition, the mean survival time of patients who died during the postoperative follow-up period was shorter (6.83 ± 1.60 vs. 18.56 ± 10.20 months, p=0.016), and the one-year survival rate was lower (33.3% vs. 83.3%, p=0.032). There was no significant difference between the two groups in terms of the mean progression-free survival time or new functional impairment after surgery. CONCLUSION: For PCNSL, patients who undergo surgical resection have a better outcome than those who undergo biopsy only, suggesting that when the tumor is located at a surgically resectable site, surgical resection should be actively chosen; when the tumor is located at a deep and unresectable site, brain biopsy should be chosen.

Stage Migration in Canine Multicentric Lymphoma: Impact of Diagnostic Techniques on Assessing Disease Extent.

BACKGROUND/AIM: Stage migration, a phenomenon triggered by technological advancements allowing more sensitive tumor spread detection, results in alterations in the distribution of cancer stages within a population. Canine multicentric lymphoma is staged I to V based on the affected anatomic site(s) and substage a or b depending on the presence of tumor-related clinical signs. The primary objective of this study was to assess the influence of various diagnostic techniques on staging accuracy and determine whether multiple staging methods lead to significant stage migration, impacting the reliability of disease stage assignments. MATERIALS AND METHODS: Dogs cytologically diagnosed with multicentric lymphoma were staged using four different staging methods (A-D): A (physical examination, hemogram, blood smear), B (A plus thoracic X-ray, abdominal ultrasound), C (B plus liver and spleen cytology) and D (C plus bone marrow cytology). RESULTS: Twenty-three dogs were enrolled: 16 females (70%) and seven males (30%). Regarding immunophenotype, 21 dogs (91.3%) were B-cell and two dogs (8.7%) were T-cell. Stage migration was observed between all staging methods. Between A and B, 12 animals migrated from stage III to stage IV. Between B and C, four animals migrated, three to a higher stage (stage III to IV) and one to a lower stage (stage IV to III). Between C and D, one animal migrated from stage IV to V. The differences between staging methods A and B were statistically significant (p≤0.001). CONCLUSION: Stage migration in canine multicentric lymphoma depends on the diagnostic methods used and reinforces the need to use standardized staging methods to avoid it.

High yield killing of lymphoma cells by anti-CD22 CAR-NK cell therapy.

Chimeric antigen receptors (CARs) offer a promising new approach for targeting B cell malignancies through the immune system. Despite the proven effectiveness of CAR T cells targeting CD19 and CD22 in hematological malignancies, it is imperative to note that their production remains a highly complex process. Unlike T cells, NK cells eliminate targets in a non-antigen-specific manner while avoiding graft vs. host disease (GvHD). CAR-NK cells are considered safer than CAR-T cells because they have a shorter lifespan and produce less toxic cytokines. Due to their unlimited ability to proliferate in vitro, NK-92 cells can be used as a source for CAR-engineered NK cells. We found that CARs created from the m971 anti-CD22 mAb, which specifically targets a proximal CD22 epitope, were more effective at anti-leukemic activity compared to those made with other binding domains. To further enhance the anti-leukemic capacity of NK cells, we used lentiviral transduction to generate the m971-CD28-CD3ζ NK-92. CD22 is highly expressed in B cell lymphoma. To evaluate the potential of targeting CD22, Raji cells were selected as CD22-positive cells. Our study aimed to investigate CD22 as a potential target for CAR-NK-92 therapy in the treatment of B cell lymphoma. We first generated m971-CD28-CD3ζ NK-92 that expressed a CAR for binding CD22 in vitro. Flow cytometric analysis was used to evaluate the expression of CAR. The 7AAD determined the cytotoxicity of the m971-CD28-CD3ζ NK-92 towards target lymphoma cell lines by flow cytometry assay. The ELISA assay evaluated cytokine production in CAR NK-92 cells in response to target cells. The m971-CD28-CD3ζ NK-92 cells have successfully expressed the CD22-specific CAR. m971-CD28-CD3ζ NK-92 cells efficiently lysed CD22-expressing lymphoma cell lines and produced large amounts of cytokines such as IFN-γ and GM-CSF but a lower level of IL-6 after coculturing with target cells. Based on our results, it is evident that transferring m971-CD28-CD3ζ NK-92 cells could be a promising immunotherapy for B cell lymphoma.

Recent advances in liquid biopsy of central nervous system lymphomas: case presentations and review of the literature.

Surgical biopsy is the gold standard for diagnosing central nervous system (CNS) lymphomas. However, reliable liquid biopsy methods for diagnosing CNS lymphomas have quickly developed and have been implicated in clinical decision-making. In the current report, we introduce two patients for whom liquid biopsy was essential for diagnosing CNS lymphomas and discuss the rapidly growing applications of this technology.

Impact of the COVID-19 pandemic on lymphoma incidence and short-term survival - a Swedish Lymphoma Register Study.

BACKGROUND & PURPOSE: The COVID-19 pandemic posed a large challenge for healthcare systems across the world. Comprehensive data on the impact of the COVID-19 pandemic on incidence and mortality in lymphoma are lacking. PATIENTS/METHODS: Using data from the Swedish lymphoma register, we compare incidence and 1-year survival of lymphoma patients in Sweden before (2017-2019) and during the pandemic (2020 and 2021). RESULTS: Fewer patients were diagnosed with lymphomas during March-June 2020, but the annual incidence rates for 2020 and 2021 were similar to those of 2017-2019. A larger proportion of patients presented with stage IV disease during 2021. There were no differences in other base-line characteristics nor application of active treatment in pre-pandemic and pandemic years. One-year overall survival was not inferior among lymphoma patients during the pandemic years compared to pre-pandemic years i.e., 2017-2019. INTERPRETATION: The COVID-19 pandemic had limited impact on the incidence and mortality of lymphoma in Sweden.

Should paediatric tonsillar asymmetry be an indication for tonsillectomy? A single centre experience.

BACKGROUND: Paediatric tonsillar lymphoma (TL) is a rare diagnosis. Historically, the presence of clinical features such as tonsillar asymmetry, grossly abnormal tonsil appearance and cervical lymphadenopathy raise concern for this diagnosis. Tonsillar asymmetry is considered to be the most concerning clinical feature; however, asymmetry is often apparent due to differences in depth or shape of tonsillar fossa and tonsillar pillars, rather than a true difference in volume. There is debate whether a tonsillectomy is required in all cases of tonsil asymmetry to exclude lymphoma, and what clinical features should raise concern. The aim of this study was to establish whether the presence of clinical asymmetry can be deemed a reliable marker for genuine tonsil size discrepancies. We also sought to evaluate the clinical and examination characteristics that are concerning for lymphoma. METHODS: Retrospective review of clinical records for paediatric tonsil specimens sent for histological evaluation between 1 January 2012 and 1 January 2023 driven by a clinical suspicion of lymphoma at Starship Children's Hospital, New Zealand. Patient demographics and clinical data were recorded. A comparison was made between tonsil size asymmetry on clinical examination (Brodsky criteria) and tonsil volume difference based on dimensions given in pathology reports. RESULTS: One hundred and forty-three patients had tonsillectomies between 2012 and 2022 at Starship Children's Hospital due to concern for lymphoma. Of these, three were positive for lymphoma. Presence of pain and abnormal tonsil appearance were predictors for lymphoma (p<0.02). Interrater reliability agreement between clinical size difference and tonsil volume was poor, Kappa= -0.13 p<0.05. CONCLUSION: Clinical size difference is a poor predictor for true tonsil volume difference. We advise that assessment of tonsil size should be performed in conjunction with the examination of gross visual abnormalities and lymphadenopathy to guide clinical decision making.

Update on FDG-PET in pediatric lymphoma.

Lymphoma represent the third most common malignant disease in childhood and adolescence. They are divided into pediatric Hodgkin lymphoma (P-HL) and pediatric non-Hodgkin lymphoma (P-NHL). In P-HL, excellent cure rates are achieved through combined modality treatment using chemotherapy and radiotherapy. For more than 20 years, FDG-PET has been an integral part of the treatment and guides its intensity through improved staging and precise assessment of chemotherapy response. In P-NHL, good cure rates are achieved with chemotherapy alone. At present FDG-PET plays only a subordinate role in the treatment setting. Its potential to contribute to treatment management is far from being fully utilised. In this article, the current status of FDG-PET in pediatric lymphoma is presented in detail. The core elements are the sections on staging and response assessment. In addition, challenges and pitfalls are discussed and future developments are outlined.

Distinguishing Kikuchi-Fujimoto disease from lymphoma in patients by clinical and PET/CT features.

To develop a scheme for distinguishing Kikuchi-Fujimoto disease (KFD) from lymphoma in patients presenting enlarged lymph nodes (LNs) predominantly on the upper side of the diaphragm. From November 2015 to August 2023, 32 KFD patients and 38 lymphoma patients were pathologically confirmed and enrolled in this retrospectively study. Clinical and 18F-fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT) features were collected. When comparing those PET/CT parameters, we set 5 models with different research objects: (1) all affected LNs; (2) the 5 largest affected LNs in terms of maximum diameter; (3) the 5 largest affected LNs in terms of maximum standard uptake values (SUVmax); (4) the largest affected LNs in terms of maximum diameter; (5) the largest affected LNs in terms of SUVmax. Compared to lymphoma patients, KFD patients were younger; and with higher incidence of fever, arthralgia, abnormal serum white blood cell, lactate dehydrogenase (LDH) and splenomegaly; lower incidence of affected LNs perinodal infiltration, necrosis and conglomeration; more affected LNs in Head and Neck nodes (particularly in level II) and Axillary in KFD (P ˂ .05). PET/CT parameters presented as various difference in each model. Finally, 11 clinical and PET/CT features (age ≤ 34, with fever, arthralgia, abnormal white blood cell, abnormal LDH, and without node necrosis and node conglomeration have a score of 2 each; splenomegaly, perinodal infiltration, median maximum diameter ≤ 20.5 and median SUVmax ≤ 7.1 of affected LNs in model 2 have score of 1 each) were selected as scheme items for distinguishing KFD from lymphoma. Individuals who have a total score > 8, meet the criteria for KFD. Sensitivity and specificity were high: 86.8% (95% CI: 71.9%, 95.5%) and 96.9% (95% CI: 83.7%, 99.5%), AUC = 0.975 (95% CI: 90.5%, 99.6%), respectively. It can effectively distinguish KFD from lymphoma by clinical and PET/CT parameters.

Jaundice caused by primary common bile duct lymphoma of a cat.

A 10-year-old American Shorthair cat presented with anorexia and jaundice, and echogenic evaluation revealed diffuse thickening of the common bile duct (CBD) wall. An exploratory laparotomy was conducted, the lesion was evaluated as difficult to remove, and the cat was euthanized and autopsied. Histologically, round neoplastic cells proliferated in the mucosa of the CBD and infiltrated the hepatic lobe, pancreas, and duodenum. Immunohistochemistry revealed that the neoplastic cells were positive for cytoplasmic-CD3 and granzyme B, and TCR-gamma clonal rearrangement was detected. Based on these findings, the neoplasia was diagnosed as a primary CBD lymphoma originating from cytotoxic T or natural killer cells. To the best of our knowledge, this is the first reported case of feline primary CBD lymphoma. Although rare, lymphoma of the CBD should be considered in cats with jaundice and thickening of the CBD.

T-cell help in the tumor microenvironment enhances rituximab-mediated NK-cell ADCC.

ABSTRACT: Rituximab (RTX) and other monoclonal antibodies (mAbs) that bind directly to malignant cells are of great clinical value but are not effective for all patients. A major mechanism of action of RTX is antibody-dependent cellular cytotoxicity (ADCC) mediated by natural killer (NK) cells. Prior in vitro studies in our laboratory demonstrated that T cells contribute to maintaining the viability and cytotoxic potential of NK cells activated by anti-CD20-coated target B cells. Here, we conducted studies using a novel mouse model and clinical correlative analysis to assess whether T-cell help contribute to RTX-mediated NK-cell ADCC in the tumor microenvironment (TME) in vivo. A humanized mouse model was developed using Raji lymphoma cells and normal donor peripheral blood mononuclear cells that allows for control of T-cell numbers in the lymphoma TME. In this model, NK-cell viability and CD16 and CD25 expression dropped after RTX in the absence of T cells but increased in the presence of T cells. RTX therapy was more effective when T cells were present and was ineffective when NK cells were depleted. In patients with indolent lymphoma, fine needle aspirates were obtained before and ∼1 week after treatment with a RTX-containing regimen. There was a strong correlation between CD4+ T cells as well as total T cells in the pretherapy TME and an increase in NK-cell CD16 and CD25 expression after RTX. We conclude that T-cell help in the TME enhances RTX-mediated NK-cell viability and ADCC.