Subcutaneous daratumumab in Chinese patients with relapsed or refractory multiple myeloma: an open-label, multicenter, phase 1 study (MMY1010).

Despite recent progress in multiple myeloma (MM) treatments, most patients will relapse and require additional treatment. Intravenous daratumumab, a human IgGκ monoclonal antibody targeting CD38, has shown good efficacy in the treatment of MM. A subcutaneous version of daratumumab was formulated to reduce the burden of intravenous infusions. We aimed to investigate the efficacy and safety of subcutaneous daratumumab in Chinese patients with relapsed/refractory MM based on the demonstrated noninferiority of subcutaneous daratumumab to intravenous daratumumab, with a shorter administration time and reduced infusion-related reaction rate in global studies. This phase 1, multicenter study (MMY1010; ClinicalTrials.gov Identifier: NCT04121260) evaluated subcutaneous daratumumab in Chinese patients with relapsed/refractory MM after 1 prior line (n = 1) or ≥2 prior lines (n = 20) of therapy, including a proteasome inhibitor and an immunomodulatory drug. Primary endpoints were pharmacokinetics and safety. Mean (standard deviation) maximum trough concentration of daratumumab was 826 (335) µg/mL, which was consistent with prior studies of subcutaneous daratumumab and intravenous daratumumab. Safety was consistent with safety profiles observed in other daratumumab studies, with no new safety concerns identified. Incidences of infusion-related reactions and injection-site reactions were low and consistent with other subcutaneous daratumumab studies. At a median follow-up of 7.5 months, the overall response rate was 57.1%, with a very good partial response or better rate of 38.1% and complete response or better rate of 19.0%. Our results demonstrate a favorable benefit/risk profile of subcutaneous daratumumab in Chinese patients with relapsed/refractory MM, potentially impacting clinical administration of daratumumab in this population.

Consensus guidelines and recommendations for the management and response assessment of chimeric antigen receptor T-cell therapy in clinical practice for relapsed and refractory multiple myeloma: a report from the International Myeloma Working Group Immunotherapy Committee.

Chimeric antigen receptor (CAR) T-cell therapy has shown promise in patients with late-line refractory multiple myeloma, with response rates ranging from 73 to 98%. To date, three products have been approved: Idecabtagene vicleucel (ide-cel) and ciltacabtagene autoleucel (cilta-cel), which are approved by the US Food and Drug Administration, the European Medicines Agency, Health Canada (ide-cel only), and Brazil ANVISA (cilta-cel only); and equecabtagene autoleucel (eque-cel), which was approved by the Chinese National Medical Products Administration. CAR T-cell therapy is different from previous anti-myeloma therapeutics with unique toxic effects that require distinct mitigation strategies. Thus, a panel of experts from the International Myeloma Working Group was assembled to provide guidance for clinical use of CAR T-cell therapy in myeloma. This consensus opinion is from experts in the field of haematopoietic cell transplantation, cell therapy, and multiple myeloma therapeutics.

LILRB4 represents a promising target for immunotherapy by dual targeting tumor cells and myeloid-derived suppressive cells in multiple myeloma.

Multiple myeloma (MM) remains an incurable hematological malignancy. Despite tremendous advances in the treatment, about 10% of patients still have very poor outcomes with median overall survival less than 24 months. Our study aimed to underscore the critical mechanisms pertaining to the rapid disease progression and provide novel therapeutic selection for these ultra-high-risk patients. We utilized single-cell transcriptomic sequencing to dissect the characteristic bone marrow niche of patients with survival of less than two years (EM24). Notably, an enrichment of LILRB4high pre-matured plasma-cell cluster was observed in the patients in EM24 compared to patients with durable remission. This cluster exhibited aggressive proliferation and drug-resistance phenotype. High-level LILRB4 promoted MM clonogenicity and progression. Clinically, high expression of LILRB4 was correlated with poor prognosis in both newly diagnosed MM patients and relapsed/refractory MM patients. The ATAC-seq analysis identified that high chromosomal accessibility caused the elevation of LILRB4 on MM cells. CRISPR-Cas9 deletion of LILRB4 alleviated the growth of MM cells, inhibited the immunosuppressive function of MDSCs, and further rescued T cell dysfunction in MM microenvironment. The more infiltration of myeloid-derived suppressive cells (MDSCs) was observed in EM24 patients as well. Therefore, we innovatively generated a TCR-based chimeric antigen receptor (CAR) T cell, LILRB4-STAR-T. Cytotoxicity experiment demonstrated that LILRB4-STAR-T cells efficaciously eliminated tumor cells and impeded MDSCs function. In conclusion, our study elucidates that LILRB4 is an ideal biomarker and promising immunotherapy target for high-risk MM. LILRB4-STAR-T cell immunotherapy is promising against tumor cells and immunosuppressive tumor microenvironment in MM.

Combinational therapy of CAR T-cell and HDT/ASCT demonstrates impressive clinical efficacy and improved CAR T-cell behavior in relapsed/refractory large B-cell lymphoma.

BACKGROUND: Approximately two-thirds of patients with relapsed or refractory large B-cell lymphoma (R/R LBCL) do not respond to or relapse after anti-CD19 chimeric antigen receptor T (CAR T)-cell therapy, leading to poor outcomes. Previous studies have suggested that intensified lymphodepletion and hematological stem cell infusion can promote adoptively transferred T-cell expansion, enhancing antitumor effects. Therefore, we conducted a phase I/II clinical trial in which CNCT19 (an anti-CD19 CAR T-cell) was administered after myeloablative high-dose chemotherapy and autologous stem cell transplantation (HDT/ASCT) in patients with R/R LBCL. METHODS: Transplant-eligible patients with LBCL who were refractory to first-line immunochemotherapy or experiencing R/R status after salvage chemotherapy were enrolled. The study aimed to evaluate the safety and efficacy of this combinational therapy. Additionally, frozen peripheral blood mononuclear cell samples from this trial and CNCT19 monotherapy studies for R/R LBCL were used to evaluate the impact of the combination therapy on the in vivo behavior of CNCT19 cells. RESULTS: A total of 25 patients with R/R LBCL were enrolled in this study. The overall response and complete response rates were 92.0% and 72.0%, respectively. The 2-year progression-free survival rate was 62.3%, and the overall survival was 68.5% after a median follow-up of 27.0 months. No unexpected toxicities were observed. All cases of cytokine release syndrome were of low grade. Two cases (8%) experienced grade 3 or higher CAR T-cell-related encephalopathy syndrome. The comparison of CNCT19 in vivo behavior showed that patients in the combinational therapy group exhibited enhanced in vivo expansion of CNCT19 cells and reduced long-term exhaustion formation, as opposed to those receiving CNCT19 monotherapy. CONCLUSIONS: The combinational therapy of HDT/ASCT and CNCT19 demonstrates impressive efficacy, improved CNCT19 behavior, and a favorable safety profile. TRIAL REGISTRATION NUMBERS: ChiCTR1900025419 and NCT04690192.

[The Optimal Storage Condition and Storage Time of Umbilical Cord Blood from Collection to Preparation].

OBJECTIVE: To explore the optimal storage condition and time of umbilical cord blood from collection to preparation. METHODS: Collect cord blood samples from 30 healthy newborns, with each new born's umbilical cord blood was divided into two parts on average. One part was stored in cold storage (4 ℃) and the other was stored at room temperature (20-24 ℃). Samples were taken at 24, 36, 48, 60 and 72 h, respectively, total nucleated cells (TNC) count and TNC viability was analyzed. Flow cytometry was used to detect the ratio of viable CD34+ cells to viable CD45+ cells and viability of CD34+ cells, and colony-forming unit-granulocyte-macrophage (CFU-GM) count was performed by hematopoietic progenitor cell colony culture. The change trend of each index over time was observed, and the differences in each index was compared between cold storage and room temperature storage under the same storage time. RESULTS: The TNC count (r 4 ℃=-0.9588， r 20-24 ℃=-0.9790), TNC viability (r 4 ℃=-0.9941， r 20-24 ℃=-0.9970), CD34+ cells viability (r 4 ℃=-0.9932， r 20-24 ℃=-0.9828) of cord blood stored in cold storage (4 ℃) and room temperature storage (20-24 ℃) showed a consistent downward trend with the prolongation of storage time. The percentage of viable CD34+ cells (r 4 ℃=0.9169， r 20-24 ℃=0.7470) and CFU-GM count (r 4 ℃=-0.2537， r 20-24 ℃=-0.8098) did not show consistent trends. When the storage time was the same, the TNC count, TNC viability, CD34+ cells viability and CFU-GM count of cord blood stored in cold storage were higher than those stored at room temperature. Under the same storage time (24, 36, 48, 60 or 72 h), TNC viability in room temperature storage was significantly lower than that in cold storage (P <0.001), but TNC count, percentage of viable CD34+ cells and CFU-GM count were not significantly different between room temperature storage and cold storage. When stored at room temperature for 24 h and 36 h, the viability of CD34+ cells was significantly lower than that in cold storage (P <0.001, P <0.01), when the storage time for 48, 60 and 72 h, there was no significant difference in the CD34+ cells viability between room temperature storage and cold storage. CONCLUSION: It is recommended that cord blood be stored in cold storage (4 ℃) from collection to preparation, and processed as soon as possible.

Fluorescence in situ hybridization reveals the evolutionary biology of minor clone of gain/amp(1q) in multiple myeloma.

Growing evidence suggests that gain or amplification [gain/amp(1q)] accumulates during disease progression of multiple myeloma (MM). Previous investigations have indicated that small gain/amp(1q) subclones present at the time of diagnosis may evolve into dominant clones upon MM relapse. However, the influence of a minor clone of gain/amp(1q) on MM survival, as well as the correlation between different clonal sizes of gain/amp(1q) and the chromosomal instability (CIN) of MM, remains poorly understood. In this study, we analyzed fluorescence in situ hybridization (FISH) results of 998 newly diagnosed MM (NDMM) patients. 513 patients were detected with gain/amp(1q) at diagnosis. Among these 513 patients, 55 had a minor clone (≤20%) of gain/amp(1q). Patients with a minor clone of gain/amp(1q) displayed similar survival outcomes compared to those without gain/amp(1q). Further analysis demonstrated patients with a minor clone of gain/amp(1q) exhibited a clonal architecture similar to those without gain/amp(1q). Lastly, our results showed a significant increase in the clonal size of the minor clone of gain/amp(1q), frequently observed in MM. These findings suggested that a minor clone of gain/amp(1q) might represent an earlier stage in the pathogenesis of gain/amp(1q) and propose a "two-step" process in the clonal size changes of gain/amp(1q) in MM.

Dynamic monitoring of circulating tumor DNA reveals outcomes and genomic alterations in patients with relapsed or refractory large B-cell lymphoma undergoing CAR T-cell therapy.

BACKGROUND: Over 50% of patients with relapsed or refractory large B-cell lymphoma (r/r LBCL) receiving CD19-targeted chimeric antigen receptor (CAR19) T-cell therapy fail to achieve durable remission. Early identification of relapse or progression remains a significant challenge. In this study, we prospectively investigate the prognostic value of dynamic circulating tumor DNA (ctDNA) and track genetic evolution non-invasively, for the first time in an Asian population of r/r patients undergoing CAR19 T-cell therapy. METHODS: Longitudinal plasma samples were prospectively collected both before lymphodepletion and at multiple timepoints after CAR19 T-cell infusion. ctDNA was detected using a capture-based next-generation sequencing which has been validated in untreated LBCL. RESULTS: The study enrolled 23 patients with r/r LBCL and collected a total of 101 ctDNA samples. Higher pretreatment ctDNA levels were associated with inferior progression-free survival (PFS) (p=0.031) and overall survival (OS) (p=0.023). Patients with undetectable ctDNA negative (ctDNA-) at day 14 (D14) achieved an impressive 3-month complete response rate of 77.8% vs 22.2% (p=0.015) in patients with detectable ctDNA positive (ctDNA+), similar results observed for D28. CtDNA- at D28 predicted significantly longer 1-year PFS (90.9% vs 27.3%; p=0.004) and OS (90.9% vs 49.1%; p=0.003) compared with patients who remained ctDNA+. Notably, it is the first time to report that shorter ctDNA fragments (<170 base pairs) were significantly associated with poorer PFS (p=0.031 for D14; p=0.002 for D28) and OS (p=0.013 for D14; p=0.008 for D28) in patients with LBCL receiving CAR T-cell therapy. Multiple mutated genes exhibited an elevated prevalence among patients with progressive disease, including TP53, IGLL5, PIM1, BTG1, CD79B, GNA13, and P2RY8. Notably, we observed a significant correlation between IGLL5 mutation and inferior PFS (p=0.008) and OS (p=0.014). CONCLUSIONS: Our study highlights that dynamic ctDNA monitoring during CAR T-cell therapy can be a promising non-invasive method for early predicting treatment response and survival outcomes. Additionally, the ctDNA mutational profile provides novel insights into the mechanisms of tumor-intrinsic resistance to CAR19 T-cell therapy.

Novel Insights into the Initiation, Evolution, and Progression of Multiple Myeloma by Multi-Omics Investigation.

The evolutionary history of multiple myeloma (MM) includes malignant transformation, followed by progression to pre-malignant stages and overt malignancy, ultimately leading to more aggressive and resistant forms. Over the past decade, large effort has been made to identify the potential therapeutic targets in MM. However, MM remains largely incurable. Most patients experience multiple relapses and inevitably become refractory to treatment. Tumor-initiating cell populations are the postulated population, leading to the recurrent relapses in many hematological malignancies. Clonal evolution of tumor cells in MM has been identified along with the disease progression. As a consequence of different responses to the treatment of heterogeneous MM cell clones, the more aggressive populations survive and evolve. In addition, the tumor microenvironment is a complex ecosystem which plays multifaceted roles in supporting tumor cell evolution. Emerging multi-omics research at single-cell resolution permits an integrative and comprehensive profiling of the tumor cells and microenvironment, deepening the understanding of biological features of MM. In this review, we intend to discuss the novel insights into tumor cell initiation, clonal evolution, drug resistance, and tumor microenvironment in MM, as revealed by emerging multi-omics investigations. These data suggest a promising strategy to unravel the pivotal mechanisms of MM progression and enable the improvement in treatment, both holistically and precisely.

Gemcitabine-based conditioning compared to BEAM/BEAC conditioning prior to autologous stem cell transplantation for non-Hodgkin lymphoma: No difference in outcomes.

BACKGROUND: High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) remains an effective treatment for non-Hodgkin lymphoma (NHL). The limited availability of carmustine has prompted the exploration of novel alternative conditioning regimens. This study aimed to compare the efficacy and safety profile of GBM/GBC (gemcitabine, busulfan, and melphalan or cyclophosphamide) conditioning compared with the standard BEAM/BEAC regimens (carmustine, etoposide, cytarabine, and melphalan or cyclophosphamide) for ASCT in patients with NHL. METHODS: A retrospective analysis was conducted on 231 NHL patients, who underwent ASCT from October 2010 to October 2021 at the Institute of Hematology & Blood Disease Hospital, including both first-line and salvage settings. This resulted in the inclusion of 112 patients in the GBM/GBC arm and 92 in the BEAM/BEAC arm. Propensity score matching was employed to validate the results. RESULTS: Disease subtype distribution was similar between the GBM/GBC and BEAM/BEAC groups, with diffuse large B-cell lymphoma being the most common (58.9% vs. 58.7%), followed by PTCL (17.0% vs. 18.5%) and MCL (14.3% vs. 14.1%). At 3 months post-ASCT, complete response (CR) rates were comparable (GBM/GBC 93.5% vs. BEAM/BEAC 91.1%; p = 0.607). The 4-year progression-free survival (78.4% vs. 82.3%; p = 0.455) and 4-year overall survival (88.1% vs. 87.7%; p = 0.575) were also similar. Both groups exhibited low non-relapse mortality at 4 years (GBM/GBC 1.8% vs. BEAM/BEAC 3.5%; p = 0.790) with no transplant-related mortalities reported. The GBM/GBC cohort demonstrated a higher incidence of grade 3/4 oral mucositis and hepatic toxicity, whereas the BEAM/BEAC group had more frequent cases of bacteremia or sepsis (13 cases vs. 5 in GBM/GBC). CONCLUSIONS: The GBM/GBC regimen is effective and well-tolerated, offering outcomes that are highly comparable to those in NHL patients conditioned with BEAM/BEAC, as demonstrated in a prognostically matched cohort.

Development and validation of an individualized and weighted Myeloma Prognostic Score System (MPSS) in patients with newly diagnosed multiple myeloma.

Current standard predictive models of disease risk do not adequately account for the heterogeneity of survival outcomes in patients with new-diagnosed multiple myeloma (NDMM). In this retrospective, multicohort study, we collected clinical and genetic data from 1792 NDMM patients and identified the prognostic impact of all features. Using the top-ranked predictive features, a weighted Myeloma Prognostic Score System (MPSS) risk model was formulated and validated to predict overall survival (OS). In the training cohort, elevated lactate dehydrogenase level (LDH), International Staging System (ISS) Stage III, thrombocytopenia, and cumulative high-risk cytogenetic aberration (HRA) numbers were found to have independent prognostic significance. Each risk factor was defined as its weighted value respectively according to their hazard ratio for OS (thrombocytopenia 2, elevated LDH 1, ISS III 2, one HRA 1, and ≥2 HRA 2, points). Patients were further stratified into four risk groups: MPSS I (22.5%, 0 points), II (17.6%, 1 points), III (38.6%, 2-3 points), and IV (21.3%, 4-7 points). MPSS risk stratification showed optimal discrimination, as well as calibration, of four risk groups with median OS of 91.0, 69.8, 45.0, and 28.0 months, for patients in MPSS I to IV groups (p < .001), respectively. Importantly, the MPSS model retained its prognostic value in the internal validation cohort and an independent external validation cohort, and exhibited significant risk distribution compared with conventional prognostic models (R-ISS, R2-ISS, and MASS). Utilization of the MPSS model in clinical practice could improve risk estimation in NDMM patients, thus prompting individualized treatment strategies.

CRIP1 involves the pathogenesis of multiple myeloma via dual-regulation of proteasome and autophagy.

BACKGROUND: Multiple myeloma (MM) is an incurable hematological malignancy of the plasma cells. The maintenance of protein homeostasis is critical for MM cell survival. Elevated levels of paraproteins in MM cells are cleared by proteasomes or lysosomes, which are independent but inter-connected with each other. Proteasome inhibitors (PIs) work as a backbone agent and successfully improved the outcome of patients; however, the increasing activity of autophagy suppresses the sensitivity to PIs treatment. METHODS: The transcription levels of CRIP1 were explored in plasma cells obtained from healthy donors, patients with newly diagnosed multiple myeloma (NDMM), and relapsed/refractory multiple myeloma (RRMM) using Gene expression omnibus datasets. Doxycycline-inducible CRIP1-shRNA and CRIP1 overexpressed MM cell lines were constructed to explore the role of CRIP1 in MM pathogenesis. Proliferation, invasion, migration, proteasome activity and autophagy were examined in MM cells with different CRIP1 levels. Co-immunoprecipitation (Co-IP) with Tandem affinity purification/Mass spectrum (TAP/MS) was performed to identify the binding proteins of CRIP1. The mouse xenograft model was used to determine the role of CRIP1 in the proliferation and drug-resistance of MM cells. FINDINGS: High CRIP1 expression was associated with unfavorable clinical outcomes in patients with MM and served as a biomarker for RRMM with shorter overall survival. In vitro and in vivo studies showed that CRIP1 plays a critical role in protein homeostasis via the dual regulation of the activities of proteasome and autophagy in MM cells. A combined analysis of RNA-seq, Co-IP and TAP/MS demonstrated that CRIP1 promotes proteasome inhibitors resistance in MM cells by simultaneously binding to de-ubiquitinase USP7 and proteasome coactivator PA200. CRIP1 promoted proteasome activity and autophagosome maturation by facilitating the dequbiquitination and stabilization of PA200. INTERPRETATION: Our findings clarified the pivotal roles of the CRIP1/USP7/PA200 complex in ubiquitin-dependent proteasome degradation and autophagy maturation involved in the pathogenesis of MM. FUNDING: A full list of funding sources can be found in the acknowledgements section.

Monitoring Minimal Residual Disease in Patients with Multiple Myeloma by Targeted Tracking Serum M-Protein Using Mass Spectrometry (EasyM).

PURPOSE: We investigated both the clinical utilities and the prognostic impacts of the clonotypic peptide mass spectrometry (MS)-EasyM, a blood-based minimal residual disease (MRD) monitoring protocol in multiple myeloma. EXPERIMENTAL DESIGN: A total of 447 sequential serum samples from 56 patients with multiple myeloma were analyzed using EasyM. Patient-specific M-protein peptides were sequenced from diagnostic samples; sequential samples were quantified by EasyM to monitor the M-protein. The performance of EasyM was compared with serum immunofixation electrophoresis (IFE), bone marrow multiparameter flow cytometry (MFC), and next-generation flow cytometry (NGF) detection. The optimal balance of EasyM sensitivity/specificity versus NGF (10-5 sensitivity) was determined and the prognostic impact of MS-MRD status was investigated. RESULTS: Of the 447 serum samples detected and measured by EasyM, 397, 126, and 92 had time-matching results for comparison with serum IFE, MFC-MRD, and NGF-MRD, respectively. Using a dotp >0.9 as the MS-MRD positive, sensitivity was 99.6% versus IFE and 100.0% versus MFC and NGF. Using an MS negative cutoff informed by ROC analysis (<1.86% of that at diagnosis), EasyM sensitivity remained high versus IFE (88.3%), MFC (85.1%), and NGF (93.2%), whereas specificity increased to 90.4%, 55.8%, and 93.2%, respectively. In the multivariate analysis, older diagnostic age was an independent predictor for progression-free survival [PFS; high risk (HR), 3.15; 1.26-7.86], the best MS-MRD status (MS-MRD negative) was independent predictor for both PFS (HR, 0.25; 0.12-0.52) and overall survival (HR, 0.16; 0.06-0.40). CONCLUSIONS: EasyM is a highly sensitive and minimal invasive method of MRD monitoring in multiple myeloma; MS-MRD had significant predictive ability for survival outcomes.

Sequential treatment escalation improves survival in patients with Waldenstrom macroglobulinemia.

Waldenstrom macroglobulinemia (WM) is a type of incurable, indolent B-cell lymphoma that is prone to relapse. Over time, treatment strategies have progressed from cytotoxic drugs to rituximab (R)- or bortezomib (V)-based regimens, and have now entered into an era of Bruton tyrosine kinase inhibitor (BTKi)-based regimens. However, the optimal treatment for the relapsed patients is still unclear. Herein, we analyzed the outcomes of the first- and second-line therapies in 377 patients with WM to illustrate the optimal choices for second-line therapy. After a median follow-up of 45.4 months, 89 patients received second-line therapy, and 53 patients were evaluated for response. The major response rates (MRR) of first- and second-line treatment were 65.1% and 67.9% (P = 0.678). The median progression-free survival (PFS) for the second-line therapy (PFS2) was shorter than that for the first-line therapy (PFS1) (56.3 vs 40.7 months, P = 0.03). However, PFS2 in targeted drugs group (R-/V-/BTKi-based regimens) was comparable to PFS1 (60.7 months vs 44.7 months, respectively, P = 0.21). Regarding second-line therapy, patients who underwent sequential treatment escalation-such as transitioning from cytotoxic drugs to R-/V-/BTKi-based regimens or from R-/V-based to BTKi-based regimens (escalation group) -had higher MRR (80.6% vs 47.1%, respectively, P = 0.023) and longer PFS2 (50.4 vs 23.5 months, respectively, P < 0.001) compared to the non-escalation group. Patients in the escalation group also had longer post-relapse overall survival compared with the non-escalation group (median, 50.4 vs 23.5 months, respectively, P = 0.039). Our findings indicate that sequential treatment escalation may improve the survival of patients with WM.

Phase I study of the Syk inhibitor sovleplenib in relapsed or refractory mature B-cell tumors.

Sovleplenib (HMPL-523) is a selective spleen tyrosine kinase (Syk) inhibitor with antitumor activity in preclinical models of B-cell malignancy. We conducted a dose-escalation and dose-expansion phase I study of sovleplenib in patients with relapsed/refractory mature Bcell tumors. Dose escalation followed a 3+3 design; patients received oral sovleplenib (200-800 mg once daily [q.d.] or 200 mg twice daily [b.i.d.], 28-day cycles). During dose expansion, patients were enrolled into four cohorts per lymphoma classification and treated at the recommended phase 2 dose (RP2D). Overall, 134 Chinese patients were enrolled (dose escalation, n=27; dose expansion, n=107). Five patients experienced dose-limiting toxicities: one each of amylase increased (200 mg q.d.), febrile neutropenia (800 mg q.d), renal failure (800 mg q.d.), hyperuricemia and blood creatine phosphokinase increased (200 mg b.i.d.) and blood bilirubin increased and pneumonia (200 mg b.i.d.). RP2D was determined as 600 mg (>65 kg) or 400 mg (≤65 kg) q.d. The primary efficacy end point of independent review committee-assessed objective response rate in indolent B-cell lymphoma was 50.8% (95% CI, 37.5-64.1) in 59 evaluable patients at RP2D (follicular lymphoma: 60.5%, marginal zone lymphoma: 28.6%, lymphoplasmacytic lymphoma/Waldenström macroglobulinemia, 0%). The most common (≥10% patients) grade ≥3 treatment-related adverse events in the doseexpansion phase were decreased neutrophil count (29.9%), pneumonia (12.1%) and decreased white blood cell count (11.2%). Pharmacokinetic exposures increased doseproportionally with ascending dose levels from 200-800 mg, without observed saturation. Sovleplenib showed antitumor activity in relapsed/refractory B-cell lymphoma with acceptable safety. Further studies are warranted.