Rituximab-combined anthracycline-free chemotherapy in newly diagnosed paediatric and adolescent patients with non-high-risk aggressive mature B cell lymphoma: protocol for a single-arm, open-label, multicentre, phase II study (the Japan Children's Cancer Group Multicentre Trial, JPLSG B-NHL-20).

INTRODUCTION: Children and adolescents with mature B cell non-Hodgkin lymphoma (B-NHL) are treated with short-intensive chemotherapy. The burden of short-term and long-term toxicity is highly relative to its high cure rate in good-risk patients. Although the addition of rituximab to standard lymphome Malin B (LMB) chemotherapy markedly prolongs event-free survival and overall survival in high-risk patients, the benefit of rituximab in good-risk patients remains to be elucidated. This clinical trial will examine whether the addition of rituximab eliminates anthracyclines in good-risk patients without compromising treatment outcomes. METHODS AND ANALYSIS: We will perform a single-arm, open-label, multicentre phase II study. Low-risk (stage I - completely resected, stage II abdominal) and intermediate-risk (stages I and II - incompletely resected; stage II - resected, other than abdominal; stage III with LDH <2× upper limit of normal) patients with newly diagnosed B-NHL are eligible. Low-risk patients receive two courses of R-COM1P (rituximab, cyclophosphamide, vincristine, methotrexate, prednisolone and intrathecal methotrexate with hydrocortisone), and intermediate-risk patients receive COP (cyclophosphamide, vincristine, prednisolone and intrathecal methotrexate with hydrocortisone) followed by two courses each of R-COM3P and R-CYM (rituximab, cytarabine, methotrexate and intrathecal methotrexate with hydrocortisone). The primary endpoint is a 3-year event-free survival rate in paediatric patients (<18 years) with intermediate-risk disease. 100 patients (10 low-risk and 90 intermediate-risk) will enrol within a 4-year enrolment period and the follow-up period will be 3 years. 108 institutions are participating as of 1 January 2024 (64 university hospitals, 29 general hospitals, 12 children's hospitals and three cancer centres). ETHICS AND DISSEMINATION: This research was approved by the Certified Review Board at NHO Nagoya Medical Center (Nagoya, Japan) on 21 September 2021. Written informed consent is obtained from all patients and/or their guardians. The results of this study will be disseminated through peer-reviewed publications and conference presentations. STUDY REGISTRATION: Japan Registry of Clinical Trials, jRCTs041210104.

ADCT-602, a Novel PBD Dimer-containing Antibody-Drug Conjugate for Treating CD22-positive Hematologic Malignancies.

Relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) and lymphomas have poor patient outcomes; novel therapies are needed. CD22 is an attractive target for antibody-drug conjugates (ADCs), being highly expressed in R/R B-ALL with rapid internalization kinetics. ADCT-602 is a novel CD22-targeting ADC, consisting of humanized mAb hLL2-C220, site specifically conjugated to the pyrrolobenzodiazepine dimer-based payload tesirine. In preclinical studies, ADCT-602 demonstrated potent, specific cytotoxicity in CD22-positive lymphomas and leukemias. ADCT-602 was specifically bound, internalized, and trafficked to lysosomes in CD22-positive tumor cells; after cytotoxin release, DNA interstrand crosslink formation persisted for 48 hours. In the presence of CD22-positive tumor cells, ADCT-602 caused bystander killing of CD22-negative tumor cells. A single ADCT-602 dose led to potent, dose-dependent, in vivo antitumor activity in subcutaneous and disseminated human lymphoma/leukemia models. Pharmacokinetic analyses (rat and cynomolgus monkey) showed excellent stability and tolerability of ADCT-602. Cynomolgus monkey B cells were efficiently depleted from circulation after one dose. Gene signature association analysis revealed IRAK1 as a potential marker for ADCT-602 resistance. Combining ADCT-602 + pacritinib was beneficial in ADCT-602-resistant cells. Chidamide increased CD22 expression on B-cell tumor surfaces, increasing ADCT-602 activity. These data support clinical testing of ADCT-602 in R/R B-ALL (NCT03698552) and CD22-positive hematologic cancers.

Single agent subcutaneous blinatumomab for advanced acute lymphoblastic leukemia.

Blinatumomab is a BiTE® (bispecific T-cell engager) molecule that redirects CD3+ T-cells to engage and lyse CD19+ target cells. Here we demonstrate that subcutaneous (SC) blinatumomab can provide high efficacy and greater convenience of administration. In the expansion phase of a multi-institutional phase 1b trial (ClinicalTrials.gov, NCT04521231), heavily pretreated adults with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) received SC blinatumomab at two doses: (1) 250 µg once daily (QD) for week 1 and 500 µg three times weekly (TIW) thereafter (250 µg/500 µg) or (2) 500 µg QD for week 1 and 1000 µg TIW thereafter (500 µg/1000 µg). The primary endpoint was complete remission/complete remission with partial hematologic recovery (CR/CRh) within two cycles. At the data cutoff of September 15, 2023, 29 patients were treated: 14 at the 250 µg/500 µg dose and 13 at 500 µg/1000 µg dose. Data from two ineligible patients were excluded. At the end of two cycles, 12 of 14 patients (85.7%) from the 250 µg/500 µg dose achieved CR/CRh of which nine patients (75.0%) were negative for measurable residual disease (MRD; <10-4 leukemic blasts). At the 500 µg/1000 µg dose, 12 of 13 patients (92.3%) achieved CR/CRh; all 12 patients (100.0%) were MRD-negative. No treatment-related grade 4 cytokine release syndrome (CRS) or neurologic events (NEs) were reported. SC injections were well tolerated and all treatment-related grade 3 CRS and NEs responded to standard-of-care management, interruption, or discontinuation. Treatment with SC blinatumomab resulted in high efficacy, with high MRD-negativity rates and acceptable safety profile in heavily pretreated adults with R/R B-ALL.

Treatment of Double-Refractory Chronic Lymphocytic Leukemia-An Unmet Clinical Need.

Recent years have seen significant improvement in chronic lymphocytic leukemia (CLL) management. Targeting B-cell lymphoma (BCL-2) and Bruton's kinase (BTK) have become the main strategies to restrain CLL activity. These agents are generally well tolerated, but the discontinuation of these therapies happens due to resistance, adverse effects, and Richter's transformation. A growing population of patients who have previously used both BTK inhibitors and BCL2 suffer from the constriction of the following regimens. This review explores the resistance mechanisms for both ibrutinib and venetoclax. Moreover, we present innovative approaches evaluated for treating double-refractory CLL.

Update on the management of relapsed/refractory chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) predominantly affects older adults, characterized by a relapsing and remitting pattern with sequential treatments available for many patients. Identification of progressive/relapsed CLL should prompt close monitoring and early discussion about the next therapies when treatment indications are present. The intervening period represents an opportunity to optimize patient health, including establishing adequate vaccination and surveillance for second primary malignancies, and treating non-CLL-related comorbidities which may impact well-being and CLL therapy. We now see patients with relapsed/refractory (RR) CLL in the clinic who have been previously treated with chemoimmunotherapy (CIT) and/or one or more novel therapies. Continuous covalent inhibitors of Bruton's tyrosine kinase (cBTKi) and fixed-duration venetoclax (Ven)-anti-CD20 monoclonal antibody (mAb) are preferred over CIT given the survival advantages associated with these therapies, although have never been evaluated head-to-head. While both classes are effective for RR CLL, potential side effects and the logistics of administration differ. Few randomized data demonstrate the sequential use of cBTKi and fixed-duration Ven-anti-CD20 mAb; however, they may be used in either sequence. Newer non-covalent BTKi, active against BTK C481 resistance mutations emerging with continuous cBTKi exposure, and novel approaches such as BTK degraders, bispecific antibodies, and chimeric antigen receptor T-cell therapies demonstrate impressive efficacy. In this review of RR CLL we explore relevant investigations, consideration of broader CLL- and non-CLL-related health needs, and evidence for efficacy and safety of B-cell receptor inhibitors and Ven, including available data to support drug sequencing or switching. We describe novel approaches to RR CLL, including rechallenging with fixed-duration therapies, allogeneic stem cell transplant indications in the novel therapy era, and highlight early data supporting the use of T-cell directing therapies and novel drug targets.

High-grade B-cell lymphoma, not otherwise specified, presenting as primary peritoneal lymphomatosis and successfully treated with dose-adjusted EPOCH-R.

Peritoneal lymphomatosis (PL) is a rare lymphoma-associated condition defined as the dissemination of lymphoma cells in the peritoneum. An 82-year-old man presented with abdominal pain, heartburn, and high fever. Radiological findings, including positron emission tomography-computed tomography (PET-CT), and gastrointestinal fiberscopy, showed diffuse thickening of the peritoneum, omentum, and mesentery; however, no lymphadenopathy, hepatosplenomegaly, or gastrointestinal lesions were observed. Under suspicion of peritonitis carcinomatosa of unknown origin, exploratory laparoscopy was performed that revealed multiple white nodules and masses on the surfaces of the peritoneum, mesentery, and intestinal serosa. The histopathological and cytogenetic findings of the peritoneum revealed high-grade B-cell lymphoma, not otherwise specified, and a gain of MYC by fluorescence in-situ hybridization. The patient was treated with two cycles of R-CHOP therapy, followed by six cycles of dose-adjusted EPOCH-R therapy, and a complete metabolic response was confirmed by PET-CT. Since there are no specific radiological findings to confirm the diagnosis of PL, a histopathological diagnosis is usually required. Most PL exhibit an aggressive lymphoma phenotype and can be cured by appropriate chemotherapy. Therefore, early diagnosis and treatment are desirable.

[Pharmacological characteristics and clinical outcomes of Epcoritamab (recombinant) (Epkinly® subcutaneous injection ) for malignant lymphoma].

The prognosis of patients with B-cell non-Hodgkin lymphoma (B-NHL) has improved with the use of anti-CD20 based immunochemotherapy. However, management of relapsed or refractory disease remains a challenge, indicating a high unmet need for novel treatments. Epcoritamab (recombinant) is a humanized immunoglobulin G1 (IgG1) bispecific antibody that simultaneously binds to CD3 on T cells and CD20 on B cells or tumor cells inducing T-cell mediated cytotoxicity against CD20-positive B cells. It demonstrated consistent cytotoxic effects in B-cell lymphoma cell line-derived xenograft models, patient-derived xenograft models, and cynomolgus monkey studies. Pharmacological studies in cynomolgus monkeys showed peak plasma concentrations of cytokines were lower with subcutaneous versus intravenous administration. To reduce the risk of cytokine release syndrome (CRS) and improve convenience, Epcoritamab has been developed as a subcutaneous formulation.To further reduce the risk of CRS, clinical trials utilized a priming dose and incremental dose increases. In Phase I/II overseas trials with relapsed, progressive, or refractory B-NHL patients, the recommended Phase II trial dose was determined based on safety, efficacy, and pharmacokinetic model simulation results. The Phase II dose-expansion part demonstrated the efficacy and high tolerability of epcoritamab monotherapy at the recommended dose. Similar efficacy and tolerability were observed in Japanese Phase I/II trials in relapsed or refractory B-NHL patients. Based on these results, epcoritamab received the approval in September 2023 for the treatment of "relapsed or refractory large B-cell lymphoma (DLBCL, HGBCL, PMBCL)" and "relapsed or refractory follicular lymphoma (Grade 3B)" in Japan.

Ofatumumab as part of reduced intensity conditioning in high risk B-cell lymphoma patients: final long-term analysis from a prospective multicenter Phase-II Trial.

Curative potential of allogeneic transplantation (AlloSCT) in high-risk non-Hodgkin lymphoma (NHL) could be enhanced by the integration of Ofatumumab (OFA), a 2nd generation anti-CD20 moAb, due to an antitumor effect and a role over graft-versus-host disease (GVHD). In this phase II trial (NCT01613300), we investigated safety and effectiveness of OFA-based reduced intensity conditioning (RIC). High-risk B-cell NHL patients with chemorrefractory disease or post-autologous SCT relapse were eligible. OFA was added to a standard RIC regimen. Primary endpoint was grade 3-4 aGVHD rate, while secondary endpoints included CR and survival rates. Thirty-three patients were included (median age 51; diffuse large B-cell:68%, HLA-identical donor: 74%). No grade >2 OFA toxicity was observed. Acute GVHD affected 77% of patients (16% grade 3-4). Remarkably, GVHD achieved CR in 75% of patients after first-line treatment. Chronic GVHD, primarily mild or moderate, occurred in 54% of patients. NHL CR rate at day +100 was 81%. Relapses occurred in 7 patients after a median of 3 months. Causes of death were lymphoma progression (5), infections (10), and GVHD (2). At 24 months, progression-free and overall survival rates were 50.1 and 51.6% respectively. OFA-RIC regimen is safe and effective, though acute GVHD remains a significant complication. However, data suggest that OFA could mitigate its severity.

Bi- and Tri-specific antibodies in non-Hodgkin lymphoma: current data and perspectives.

Bispecific antibodies (BsAbs) are a new group of targeted therapies that are revolutionizing the treatment landscape of B-cell non-Hodgkin's lymphoma (B-NHL). In the relapsed/refractory setting, salvage chemotherapy and autologous stem cell transplantation are capable of curing 50% of patients, whereas the other half will have a dismal outcome with a median overall survival of less than 12 months. This unmet need reinforced the importance of innovative therapies like the BsAbs and CAR-T cell therapies. In this review, we delve into BsAbs in B-NHL from the preclinical development to clinical data in both refractory and frontline settings, and then discuss future perspectives.

Rising Star in Immunotherapy: Development and Therapeutic Potential of Small-Molecule Inhibitors Targeting Casitas B Cell Lymphoma-b (Cbl-b).

Casitas B cell lymphoma-b (Cbl-b) is a vital negative regulator of TCR and BCR signaling pathways, playing a significant role in setting an appropriate threshold for the activation of T cells and controlling the tolerance of peripheral T cells via a variety of mechanisms. Overexpression of Cbl-b leads to immune hyporesponsiveness of T cells. Conversely, the deficiency of Cbl-b in T cells results in markedly increased production of IL-2, even in the lack of CD28 costimulation in vitro. And Cbl-b-/- mice spontaneously reject multifarious cancers. Therefore, Cbl-b may be associated with immune-mediated diseases, and blocking Cbl-b could be considered as a new antitumor immunotherapy strategy. In this review, the possible regulatory mechanisms and biological potential of Cbl-b for antitumor immunotherapy are summarized. Besides, the potential roles of Cbl-b in immune-mediated diseases are comprehensively discussed, with emphasis on Cbl-b immune-oncology agents in the preclinical stage and clinical trials.

A Systematic Review of Clinical Applications of Anti-CD20 Radioimmunotherapy for Lymphoma.

PURPOSE: The clinical efficacy of anti-CD20 radioimmunotherapy (RIT) is due to a combination of extracellular mechanisms involving immune-mediated cytotoxicity, and intracellular mechanisms related to inhibition of CD20 signaling and DNA damage from ionizing radiation. In 2002, the first RIT was approved by the U.S. Food and Drug Administration for the treatment of patients with indolent B-cell follicular non-Hodgkin lymphoma (NHL). The 2 approved agents, 90 Y-ibritumomab tiuxetan (90Y-IT, Zevalin, Acrotech Biopharma) and 131 I-tositumomab (131-IT, Bexxar, GlaxoSmithKline) both target CD20. The aim of this study was to review the clinical applications and supporting clinical trial data of anti-CD20 RIT for lymphoma. METHODS: A review of published articles and abstracts on the clinical efficacy and safety of 90Y-IT and iodine I 131 tositumomab was performed. RESULTS: The clinical efficacy and safety of anti-CD20 RIT have been demonstrated in numerous clinical trials and case series. Agents have produced significant responses in patients with follicular NHLs and in off-label applications. Importantly, RIT has demonstrated promising findings in high-risk lymphomas and heavily pretreated and refractory patient populations. Associated toxicity profiles are noted as tolerable, acceptable, and most often reversible. CONCLUSIONS: In the 2 decades since its approval, anti-CD20 RIT continues to demonstrate efficacy, particularly with a proportion of patients maintaining long-term remissions. The combination of prolonged efficacy, tolerability, and treatment convenience makes RIT a reasonable alternative to other systemic therapies. It is recommended that further research on RIT should focus on biomarkers of long-term response, pretargeting, and sequencing of RIT in the treatment course.

Recent advances and future perspectives of T-cell engagers in lymphoid malignancies.

Bispecific antibodies (BsAbs) are monoclonal antibodies that simultaneously bind to a specific antigen on tumors and CD3 on T cells, leading to T cell activation and subsequent tumor cell lysis. Several CD20 × CD3 BsAbs are being developed for B-cell lymphomas. Furthermore, multiple clinical trials to evaluate BsAbs for the treatment of multiple myeloma, with targets including BCMA, GPRC5D and FcRH5, are ongoing. Emerging evidence suggests promising efficacy in heavily pretreated patients with relapsed or refractory lymphoid malignancies, showing an overall response rate of 50-60%, with complete response rates of 30-40% for relapsed or refractory large B-cell lymphoma and 60-70% for relapsed or refractory multiple myeloma. Their toxicity profiles are generally consistent with other T-cell redirecting therapies, including cytokine release syndrome, which may be mitigated with several strategies, such as step-up dosing, pre-mediation with glucocorticoids and a subcutaneous route of administration, and very rare neurotoxicity. Several clinical trials evaluated BsAbs in combination with other agents or in earlier lines of treatment, including in front-line settings. BsAbs have the potential to change the treatment paradigm of lymphoid malignancies in the coming years; however, longer follow-ups are required to assess the durability of responses to these agents. We herein provide an overview of the findings of recent clinical trials on BsAbs, including mechanisms of action, safety profiles, and efficacy, and discuss the role of BsAbs in the treatment of B-cell lymphomas and multiple myeloma.

Hypofractionated radiotherapy for refractory or relapsed aggressive B-cell lymphoma in the rituximab era.

BACKGROUND: Radiotherapy (RT) is an effective and available local treatment for patients with refractory or relapsed (R/R) aggressive B-cell lymphomas. However, the value of hypofractionated RT in this setting has not been confirmed. METHODS: We retrospectively analyzed patients with R/R aggressive B-cell lymphoma who received hypofractionated RT between January 2020 and August 2022 at a single institution. The objective response rate (ORR), overall survival (OS), progression-free survival (PFS) and acute side effects were analyzed. RESULTS: A total of 30 patients were included. The median dose for residual disease was 36 Gy, at a dose per fraction of 2.3-5 Gy. After RT, the ORR and complete response (CR) rates were 90% and 80%, respectively. With a median follow-up of 10 months (range, 2-27 months), 10 patients (33.3%) experienced disease progression and three died. The 1-year OS and PFS rates for all patients were 81.8% and 66.3%, respectively. The majority (8/10) of post-RT progressions involved out-of-field relapses. Patients with relapsed diseases, no response to systemic therapy, multiple lesions at the time of RT, and no response to RT were associated with out-of-field relapses. PFS was associated with response to RT (P = 0.001) and numbers of residual sites (P < 0.001). No serious non-hematological adverse effects (≥ grade 3) associated with RT were reported. CONCLUSION: These data suggest that hypofractionated RT was effective and tolerable for patients with R/R aggressive B-cell lymphoma, especially for those that exhibited localized residual disease.

Results from a Phase 1 Study of ACTR707 in Combination with Rituximab in Patients with Relapsed or Refractory CD20+ B Cell Lymphoma.

The antibody-coupled T cell receptor (ACTR) platform is an autologous engineered T cell therapy combining the cell-killing ability of T cells and the tumor-targeting ability of coadministered antibodies. Activation of the T cell product ACTR707 is dependent on the engagement of antibody bound to target cells via the CD16 domain of the chimeric receptor (CD16V-CD28-CD3ζ). ACTR707 in combination with the anti-CD20 monoclonal antibody rituximab was evaluated in the ATTCK-20-03 study, a multisite, single-arm, open-label phase I trial in B cell non-Hodgkin lymphoma (NHL). The primary objectives of this study were to evaluate the safety of the combination of ACTR707 and rituximab and to determine a recommended phase 2 dose (RP2D). Secondary objectives included evaluation of antitumor activity and ACTR T cell persistence. The study design included an ACTR707 cell dose escalation phase and an expansion phase at the RP2D. Escalating dose levels of ACTR707 in combination with rituximab were explored in 5 dose cohorts, with 25 subjects receiving study treatment. Subjects received lymphodepleting chemotherapy (cyclophosphamide 400 mg/m2/day and fludarabine 30 mg/m2/day) for 3 days, followed by rituximab 375 mg/m2 and, 24 to 48 hours later, a single dose of ACTR707. Additional doses of rituximab were administered every 3 weeks until disease progression, unacceptable toxicity, or investigator decision. Blood samples were collected at various time points to assess levels of rituximab, cytokines, inflammatory markers, and ACTR707 T cells. The overall response rate of ACTR707 plus rituximab was 56% (14 of 25) across all dose levels. Ten subjects (40.0%) achieved a complete response, with the longest duration of 586 days (range, 85 to 586 days), and 4 subjects (16.0%) experienced a partial response, with the longest duration of 130 days (range, 44 to 130 days). Only 1 case of cytokine release syndrome (grade 2) and no events of neurotoxicity were reported. There were no dose-limiting toxicities or events leading to death. ACTR707 plus rituximab resulted in only 1 adverse event (neutropenia), leading to study discontinuation of rituximab. The ATTCK-20-03 trial serves as proof of principle regarding the ACTR approach that potentially could be used with other antibodies targeting other markers in other malignancies. Although the ACTR707 program has been discontinued, these results may support other programs in the use of similar novel approaches of antibody-coupled T cell activation.

Ex Vivo Expanded Cord Blood Natural Killer Cells Combined with Rituximab and High-Dose Chemotherapy and Autologous Stem Cell Transplantation for B Cell Non-Hodgkin Lymphoma.

Relapse is the major cause of failure of high-dose chemotherapy (HDC) with autologous stem cell transplantation (ASCT) for B cell non-Hodgkin lymphomas (B-NHL). Improvement strategies include use in combination with effective immunotherapies. We hypothesized that the combination of rituximab/HDC/ASCT with expanded cord blood (CB)-derived natural killer (NK) cells is safe and active in B-NHL. Patients with B-NHL age 15 to 70 years and appropriate ASCT candidates were eligible for the study. The CB units were selected without considering HLA match with the recipient. The CB NK cells were expanded from day -19 to day -5. Treatment included rituximab on days -13 and -7, BEAM (carmustine/etoposide/cytarabine/melphalan) on days -13 to -7, lenalidomide on days -7 to -2, CB NK infusion (108/kg) on day -5, and ASCT (day 0). The primary endpoint was 30-day treatment-related mortality (TRM); secondary endpoints included relapse-free survival (RFS), overall survival (OS), and persistence of CB NK cells. We enrolled 20 patients. CB NK cells were expanded a median of 1552-fold with >98% purity and >96% viability. We saw no adverse events attributable to the CB NK cells and 0% 30-day TRM. At median follow-up of 47 months, the RFS and OS rates were 53% and 74%, respectively. CB NK cells were detectable in blood for 2 weeks, independent of HLA-mismatch status. CD16 expression in donor NK cells was correlated favorably with outcome, and homozygosity for the high-affinity CD16 variant (158 V/V) in CB, but not recipient, NK cells was correlated with better outcomes. Our data indicate that the combination of expanded and highly purified CB-derived NK cells with HDC/ASCT for B-NHL is safe. CD16 expression in donor NK cells, particularly if homozygous for the high-affinity CD16 variant, was correlated with better outcomes.

Loss of CD20 expression as a mechanism of resistance to mosunetuzumab in relapsed/refractory B-cell lymphomas.

ABSTRACT: CD20 is an established therapeutic target in B-cell malignancies. The CD20 × CD3 bispecific antibody mosunetuzumab has significant efficacy in B-cell non-Hodgkin lymphomas (NHLs). Because target antigen loss is a recognized mechanism of resistance, we evaluated CD20 expression relative to clinical response in patients with relapsed and/or refractory NHL in the phase 1/2 GO29781 trial investigating mosunetuzumab monotherapy. CD20 was studied using immunohistochemistry (IHC), RNA sequencing, and whole-exome sequencing performed centrally in biopsy specimens collected before treatment at predose, during treatment, or upon progression. Before treatment, most patients exhibited a high proportion of tumor cells expressing CD20; however, in 16 of 293 patients (5.5%) the proportion was <10%. Analyses of paired biopsy specimens from patients on treatment revealed that CD20 levels were maintained in 29 of 30 patients (97%) vs at progression, where CD20 loss was observed in 11 of 32 patients (34%). Reduced transcription or acquisition of truncating mutations explained most but not all cases of CD20 loss. In vitro modeling confirmed the effects of CD20 variants identified in clinical samples on reduction of CD20 expression and missense mutations in the extracellular domain that could block mosunetuzumab binding. This study expands the knowledge about the occurrence of target antigen loss after anti-CD20 therapeutics to include CD20-targeting bispecific antibodies and elucidates mechanisms of reduced CD20 expression at disease progression that may be generalizable to other anti-CD20 targeting agents. These results also confirm the utility of readily available IHC staining for CD20 as a tool to inform clinical decisions. This trial was registered at www.ClinicalTrials.gov as #NCT02500407.

Gene expression profiles associated with early relapse during first remission induction in canine multicentric high-grade B-cell lymphoma.

Although chemotherapy using CHOP-based protocol induces remission in most cases of canine multicentric high-grade B-cell lymphoma (mhBCL), some cases develop early relapse during the first induction protocol. In this study, we examined the gene expression profiles of canine mhBCL before chemotherapy and investigated their associations with early relapse during the first whole CHOP-based protocol. Twenty-five cases of mhBCL treated with CHOP-based protocol as first induction chemotherapy were included in this study. Sixteen cases completed the first whole CHOP-based protocol without relapse (S-group), and nine developed relapse during the chemotherapy (R-group). RNA-seq was performed on samples from neoplastic lymph nodes. Differentially expressed genes (DEGs) were extracted by the comparison of gene expression profiles between S- and R-groups, and the differences in the expression levels of these genes were validated by RT-qPCR. Extracted 179 DEGs included the genes related to chemokine CC motif ligand, T-cell receptor signaling pathway, and PD-L1 expression and PD-1 checkpoint pathway. We focused on chemokine CC motif ligand, and CCL4 was confirmed to be significantly downregulated in the R-group (P=0.039). We also focused on the genes related to T-cell signaling pathway, and CD3E (P=0.039), ITK (P=0.023), and LAT (P=0.023) genes were confirmed to be significantly upregulated in the R-group. The current results suggest that both changes in tumor cells and the interactions between tumor cells and immune cells are associated with the efficacy of the chemotherapy for first remission induction.

First-in-Human Study with Preclinical Data of BCL-2/BCL-xL Inhibitor Pelcitoclax in Locally Advanced or Metastatic Solid Tumors.

PURPOSE: B-cell lymphoma-extra-large (BCL-xL) regulates apoptosis and is an attractive anticancer therapeutic target. However, BCL-xL inhibition also kills mature platelets, hampering clinical development. Using an innovative prodrug strategy, we have developed pelcitoclax (APG-1252), a potent, dual BCL-2 and BCL-xL inhibitor. Aims of this study were to characterize the antitumor activity and safety of pelcitoclax and explore its underlying mechanisms of action (MOA). PATIENTS AND METHODS: Cell line-derived xenograft and patient-derived xenograft (PDX) models were tested to evaluate antitumor activity and elucidate MOA. Subjects (N = 50) with metastatic small-cell lung cancer and other solid tumors received intravenous pelcitoclax once or twice weekly. Primary outcome measures were safety and tolerability; preliminary efficacy (responses every 2 cycles per RECIST version 1.1) represented a secondary endpoint. RESULTS: Pelcitoclax exhibited strong BAX/BAK‒dependent and caspase-mediated antiproliferative and apoptogenic activity in various cancer cell lines. Consistent with cell-based apoptogenic activity, pelcitoclax disrupted BCL-xL:BIM and BCL-xL:PUMA complexes in lung and gastric cancer PDX models. Levels of BCL-xL complexes correlated with tumor growth inhibition by pelcitoclax. Combined with taxanes, pelcitoclax enhanced antitumor activity by downregulating antiapoptotic protein myeloid cell leukemia-1 (MCL-1). Importantly, pelcitoclax was well tolerated and demonstrated preliminary therapeutic efficacy, with overall response and disease control rates of 6.5% and 30.4%, respectively. Most common treatment-related adverse events included transaminase elevations and reduced platelets that were less frequent with a once-weekly schedule. CONCLUSIONS: Our data demonstrate that pelcitoclax has antitumor activity and is well tolerated, supporting its further clinical development for human solid tumors, particularly combined with agents that downregulate MCL-1.

Response-adapted, time-limited venetoclax, umbralisib, and ublituximab for relapsed/refractory chronic lymphocytic leukemia.

ABSTRACT: Many patients with chronic lymphocytic leukemia (CLL) will develop treatment resistance to Bruton tyrosine kinase (BTK) inhibitors. Phosphatidylinositol-3-kinase (PI3K) inhibitors, including umbralisib, have significant clinical activity in relapsed/refractory CLL, but prolonged exposure is associated with potential toxicities. Owing to the synergistic antitumor effects of combined PI3K and BCL-2 inhibition, we sought to explore the feasibility of response-adapted, time-limited therapy to optimize disease control while mitigating the risks of prolonged treatment. We conducted a phase 1/2 clinical trial to determine the safety and efficacy of venetoclax in combination with umbralisib and the anti-CD20 monoclonal antibody, ublituximab, (U2-VeN) in patients with relapsed/refractory CLL (N = 46) and Richter transformation (N = 5). After 12 cycles, treatment was stopped for patients with CLL who achieved undetectable minimal residual disease (uMRD). Adverse events of special interest included diarrhea in 50% of patients (11% grade 3/4), and aspartate aminotransferase and/or alanine aminotransferase elevation in 15 patients (33%), with 3 (7%) grade 3/4. There were no cases of tumor lysis syndrome related to venetoclax, with outpatient initiation in 96% of patients. The intent-to-treat overall response rate for CLL was 98% with best response of 100% in evaluable patients (42% complete responses). The end-of-treatment rate of uMRD at 10-4 in bone marrow was 77% (30/39), including a 71% uMRD rate among 14 patients refractory to prior BTK inhibitor. Time-limited venetoclax and U2 is safe and highly effective combination therapy for patients with relapsed/refractory CLL including those who have been previously treated with covalent BTK inhibitors. This trial was registered on www.clinicaltrials.gov as #NCT03379051.