anti-CD20 Antibody Research Articles

Safety and biologic activity of a canine anti-CD20 monoclonal antibody in dogs with diffuse large B-cell lymphoma.

To explore the safety and utility of combining low dose single-agent doxorubicin with a canine specific anti-CD20 monoclonal antibody (1E4-cIgGB) in client owned dogs with untreated B-cell lymphoma. Forty-two client-owned dogs with untreated B-cell lymphoma. A prospective, single arm, open label clinical trial of dogs with B-cell lymphoma were enrolled to receive 1E4-cIgGB and doxorubicin in addition to 1 of 3 immunomodulatory regimens. B-cell depletion was monitored by flow cytometry performed on peripheral blood samples at each visit. Dogs demonstrated a statistically significant depletion in CD21+ B-cells 7 days following the first antibody infusion (median fraction of baseline at 7 days = 0.04, P < .01) that persisted throughout treatment (median fraction of baseline at 21 days = 0.01, P < .01) whereas CD5+ T-cells remained unchanged (median fraction of baseline at 7 days = 1.05, P = .88; median fraction of baselie at 7 days = 0.79, P = .42; Figure 1; Supplemental Table 3). Recovery of B-cells was delayed, with at Day 196, only 6/17 dogs (35%) remaining on the study had CD21+ counts >0.5 of baseline, indicating sustained B cell depletion at 4+ months after the final treatment. 1E4-cIgGB was well tolerated with only 1 dog exhibiting a hypersensitivity event within minutes of the last antibody infusion. The canine 1E4-cIgGB anti-CD20 monoclonal antibody is apparently safe when administered with doxorubicin and effectively depletes B-cells in dogs with DLBCL.

Effect of Immunotherapy on C-peptide Levels in Patients With Type I Diabetes Mellitus: A Systematic Review of Randomized Controlled Trials.

Type 1 diabetes mellitus is an autoimmune condition characterized by insulin deficiency resulting from loss of function of beta cells in the pancreas, leading to hyperglycemia and associated long-term systemic complications and even death. Immunotherapy demonstrates beta cell function-preserving potential; however, its impact on C-peptide levels, a definitive biomarker of beta cell function, and endogenous insulin secretion remain unclear. A systematic review of various immunotherapeutic interventions is hence needed for a comprehensive assessment of their effectiveness as well as identifying research gaps and influencing future research and clinical decisions. An extensive literature search was done in PubMed, Scopus, and Cochrane Library databases using precise keywords and filters to identify relevant studies. Three independent reviewers assessed eligibility according to predetermined eligibility criteria, and data was extracted. The Cochrane risk of bias assessment tool (RoB 2.0) was used to evaluate the quality and validity of the included studies. A senior reviewer resolved discrepancies and differences of opinion between independent reviewers. A total of 11 studies were included, with 1464 study participants. Both Phase II and III trials were included. Within the included studies, four studies assessed the anti-CD3 monoclonal antibody otelixizumab as an intervention. Another anti-CD3 monoclonal antibody, teplizumab, was assessed as an intervention in four studies, whereas two studies assessed the anti-CD20 antibody rituximab and one study assessed abatacept as its interventional drug. Otelixizumab demonstrated benefits at higher doses but was associated with adverse effects like Ebstein-Barr virus reactivation and cytomegalovirus infection, while at lower doses it failed to show a significant difference in C-peptide levels or glycosylated hemoglobin (HbA1c). Teplizumab, on the other hand, showed promise in reducing C-peptide loss and exogenous insulin requirements and was associated with adverse events such as rash, lymphopenia, urinary tract infection, and cytokine release syndrome. However, these reactions were only associated with therapy initiation, and they subsided on their own. Rituximab improved C-peptide responses, and abatacept therapy demonstrated reduced loss of C-peptide, improved C-peptide levels, and lowered HbA1c. Teplizumab, rituximab, otelixizumab, and abatacept show potential for preserving beta cell function by reducing C-peptide loss in patients with type I diabetes mellitus. However, careful monitoring of adverse reactions, particularly viral infections and cytokine release syndrome, is necessary for the safe implementation of these therapies.

E018 Prophylactic co-trimoxazole prescribing practice in patients who received rituximab therapy: comparison across indications and specialties

Abstract Background/Aims Rituximab is a chimeric anti-CD20 monoclonal antibody targeting B-cells used as part of treatment algorithms for malignancy and autoimmune diseases. As is the case of other immunosuppressive agents, rituximab increases the risk of infections. Primary prophylaxis with co-trimoxazole may be considered in high-risk cohort of patients to prevent opportunistic infection, particuarly Pneumocystis jerovecii pneumonia (PJP). To investigate the prescribing practice for prophylactic co-trimoxazole in patients who received rituximab infusion in a large tertiary referral centre. To compare practices between rheumatology and nephrology department. To compare the incidence of hospitalisation for infection (particularly PJP) between those prescribed prophylactic co-trimoxazole and those who did not. Methods This was a single centre retrospective observational study over a 3 year period assessing prophylactic co-trimoxazole prescribing practice in 185 patients attending rheumatology or renal services in Cork University Hospital (CUH) and receiving rituximab. Co-trimoxazole prophylactic treatment was defined as prophylaxis dose of co-trimoxazole (either 480mg daily or 960mg three times per week) received during rituximab treatment and at least 6 months post completion of treatment. Results 185 patients’ medical charts were reviewed. Only 28 patients received prophylaxis with co-trimoxazole. The majority of patients (n = 24, 85%) who received prophylaxis with co-trimoxazole had an underlying diagnosis of small vessel vasculitis (SVV). Co-trimoxazole was more commonly prescribed by nephrologists (n = 17, 71% primarily for SVV) as compared to rheumatologist (n = 7, 29% primarily for SVV). 156 patients were not prescribed prophylactic co-trimoxazole. The primary indication for rituximab in these patients was inflammatory arthropathy (IA) (n = 72,46%), SVV (n = 26, 16%), systemic lupus erythematosus (n = 19, 12%), with the remainder accounted for by scleroderma, undifferentiated connective tissue disease, membranous nephropathy (MN), myositis, focal segmental glomerulosclerosis and amyloid renal disease. No patient was admitted over the course of the study period with PJP. 59 patients required hospital admissions due to other infections, most commonly patients with SVV. The most common infections were respiratory tract and urinary tract infections. Overall infections requiring hospitalization were more common in the group receiving prophylaxis, perhaps highlighting the vulnerable nature and greater prednisolone prescribing in the SVV cohort. No difference was seen between groups in the prevalence of UTIs. Conclusion In this cohort co-trimoxazole prophylaxis was more commonly prescribed for patient with small vessel vasculitis and differences in prescribing patterns were seen between nephrologists and rheumatologists. With greater awareness of the heightened risk of PJP in patents receiving rituximab consideration should be given to use of antibiotic prophylaxis for other indications. Disclosure S. Tio: None. J. Morrow: None. S. Cowley: None. M. Clarkson: None. G. Murphy: None.

Brentuximab vedotin for skin involvement in refractory diffuse cutaneous systemic sclerosis, an open-label trial.

We explored the efficacy and safety of brentuximab vedotin, a chimeric anti-CD30 antibody drug conjugate, in patients with severe active diffuse cutaneous systemic sclerosis (dcSSc). This phase II proof-of-concept, single center, open-label, single arm, investigator-initiated trial included patients ≥18 years, with dcSSc, modified Rodnan skin score (mRSS) ≥15 with <5 years since the first non-Raynaud's symptom and/or skin worsening despite immunosuppression who were treated with intravenous brentuximab vedotin 0.6 mg/Kg q3 weeks for 45 weeks. The primary end point was a decrease in mRSS of ≥ 8 points at 48 weeks. Eleven patients were treated with brentuximab vedotin, with 9 completing the study. The mean mRSS reduction at week 48 was 11.3 (95% CI 6.9, 15.8; p= 0.001), meeting the primary end point in the intention to treat analysis (7/11 had a decrease in mRSS ≥8). The % forced vital capacity increased by 7.8% (12.5). The Composite Response Index in dcSSc (CRISS) suggested a beneficial treatment effect (86% ≥0.6). Most adverse events were mild. No SAEs were attributed to brentuximab vedotin. In dcSSc, brentuximab vedotin improved skin and FVC; without safety concerns. A placebo-controlled trial is warranted to corroborate these initial findings.

ENSEMBLE PLUS: final results of shorter ocrelizumab infusion from a randomized controlled trial

IntroductionOcrelizumab is an approved intravenously administered anti-CD20 antibody for multiple sclerosis (MS). The safety profile and patient preference for conventional versus shorter ocrelizumab infusions were investigated in the ENSEMBLE PLUS study.MethodsENSEMBLE PLUS was a randomized, double-blind substudy to the single-arm ENSEMBLE study (NCT03085810), comparing outcomes in patients with early-stage relapsing–remitting MS receiving ocrelizumab 600 mg over the approved 3.5-h (conventional) versus 2-h (shorter) infusion. The primary endpoint was the proportion of patients with infusion-related reactions (IRRs) following the first randomized dose (RD); the secondary endpoint included IRR frequency at subsequent RDs.ResultsAt first RD, the number of patients with an IRR in the conventional (101/373; 27.1%) versus shorter (107/372; 28.8%) infusion group was similar (difference, stratified estimates [95% CI]: 1.9% [− 4.4, 8.2]). Most IRRs (conventional: 99.4%; shorter: 97.7%) were mild/moderate. IRR frequency decreased over the course of RDs; three patients discontinued from the shorter infusion arm but continued with conventional infusion. Overall, > 98% of IRRs resolved without sequelae in both groups. Pre-randomization throat irritation was predictive of future throat irritation as an IRR symptom. Adverse events (AEs) and serious AEs were consistent with the known ocrelizumab safety profile. On completion of ENSEMBLE PLUS, most patients chose to remain on (95%) or switch to (80%) shorter infusion.ConclusionENSEMBLE PLUS demonstrates the safety and tolerability of shorter ocrelizumab infusions. Most patients remained on/switched to shorter infusion after unblinding; IRRs did not strongly influence patient decisions.Clinical Trials Registration: Substudy of ENSEMBLE (NCT03085810). Registration: March 21, 2017.

Disrupting B and T-cell collaboration in autoimmune disease: T-cell engagers versus CAR T-cell therapy?

B and T cells collaborate to drive autoimmune disease (AID). Historically, B- and T-cell (B-T cell) co-interaction was targeted through different pathways such as alemtuzumab, abatacept, and dapirolizumab with variable impact on B-cell depletion (BCD), whereas the majority of patients with AID including rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, and organ transplantation benefit from targeted BCD with anti-CD20 monoclonal antibodies such as rituximab, ocrelizumab, or ofatumumab. Refractory AID is a significant problem for patients with incomplete BCD with a greater frequency of IgD-CD27+ switched memory B cells, CD19+CD20- B cells, and plasma cells that are not directly targeted by anti-CD20 antibodies, whereas most lymphoid tissue plasma cells express CD19. Furthermore, B-T-cell collaboration is predominant in lymphoid tissues and at sites of inflammation such as the joint and kidney, where BCD may be inefficient, due to limited access to key effector cells. In the treatment of cancer, chimeric antigen receptor (CAR) T-cell therapy and T-cell engagers (TCE) that recruit T cells to induce B-cell cytotoxicity have delivered promising results for anti-CD19 CAR T-cell therapies, the CD19 TCE blinatumomab and CD20 TCE such as mosunetuzumab, glofitamab, or epcoritamab. Limited evidence suggests that anti-CD19 CAR T-cell therapy may be effective in managing refractory AID whereas we await evaluation of TCE for use in non-oncological indications. Therefore, here, we discuss the potential mechanistic advantages of novel therapies that rely on T cells as effector cells to disrupt B-T-cell collaboration toward overcoming rituximab-resistant AID.

Switching from natalizumab to an anti-CD20 monoclonal antibody in relapsing remitting multiple sclerosis: A systematic review

BackgroundUse of natalizumab (NTZ) is precluded in many Multiple Sclerosis (MS) patients by the risk of progressive multifocal leukoencephalopathy (PML). Regardless, some patients may commence natalizumab for short term disease control in spite of being seropositive, and others may seroconvert whilst on treatment. In these circumstances, discontinuation of NTZ should not occur until a clear exit strategy is established to prevent post-NTZ disease reactivation, which often exceeds the severity of disease activity prior to NTZ treatment. The objective of this systematic review was to summarise the available evidence for CD20-monoclonal antibodies (CD20mAb) as a suitable NTZ exit strategy, and to identify whether a superior switch protocol can be established. MethodsIn accordance with PRISMA guidelines, a total of 2393 references were extracted from a search of three online databases (PubMed, Scopus, MEDLINE). Following the application of inclusion/exclusion criteria, a total of 5 studies representing 331 patients were included. ResultsThe overall incidence of clinical relapse during washout periods ranging from 4.4–10.7 weeks was 0 %. The incidence of clinical relapse during two-year follow-up ranged from 1.8 % to 10 % for switches to all types of CD20 monoclonal antibody. The weighted mean for clinical relapse at 12 months was 8.8 %. Three studies reported an annualised relapse rate (ARR) ranging from 0.02–0.12 with a weighted mean ARR of 0.07. The overall incidence of PML during washout was 0 % and the overall incidence of PML within 6 months follow-up was 0.6 %. ConclusionsThis systematic review provides the first attempt at identifying a superior switch protocol in patients at risk of PML transitioning from NTZ to a CD20mAb. Our results indicate that CD20mAb's are a suitable transitional option for patients who discontinue NTZ, with our cohort demonstrating very low rates of carryover PML and low rates of clinical relapse. The most appropriate washout period is unclear due to confounding factors but is likely between 4 and 12 weeks.

Fcγ-Receptor-Independent Controlled Activation of CD40 Canonical Signaling by Novel Therapeutic Antibodies for Cancer Therapy.

The activation of CD40-mediated signaling in antigen-presenting cells is a promising therapeutic strategy to promote immune responses against tumors. Most agonistic anti-CD40 antibodies currently in development require the Fcγ-receptor (FcγR)-mediated crosslinking of CD40 molecules for a meaningful activation of CD40 signaling but have limitations due to dose-limiting toxicities. Here we describe the identification of CD40 antibodies which strongly stimulate antigen-presenting cells in an entirely FcγR-independent manner. These Fc-silenced anti-CD40 antibodies induce an efficient upregulation of costimulatory receptors and cytokine release by dendritic cells. Finally, the most active identified anti-CD40 antibody shows activity in humanized mice. More importantly, there are no signs of obvious toxicities. These studies thus demonstrate the potent activation of antigen-presenting cells with anti-CD40 antibodies lacking FcγR-binding activity and open the possibility for an efficacious and safe combination therapy for cancer patients.

Crystal structures of human CD40 in complex with monoclonal antibodies dacetuzumab and bleselumab

CD40 is a member of the tumor necrosis factor receptor superfamily, and it is widely expressed on immune and non-immune cell types. The interaction between CD40 and the CD40 ligand (CD40L) plays an essential function in signaling, and the CD40/CD40L complex works as an immune checkpoint molecule. CD40 has become a therapeutic target, and a variety of agonistic/antagonistic anti-CD40 monoclonal antibodies (mAbs) have been developed. To better understand the mode of action of anti-CD40 mAbs, we determined the X-ray crystal structures of dacetuzumab (agonist) and bleselumab (antagonist) in complex with the extracellular domain of human CD40, respectively. The structure reveals that dacetuzumab binds to CD40 on the top of cysteine-rich domain 1 (CRD1), which is the domain most distant from the cell surface, and it does not compete with CD40L binding. The binding interface of bleselumab spread between CRD2 and CRD1, overlapping with the binding surface of the ligand. Our results offer important insights for future structural and functional studies of CD40 and provide clues to understanding the mechanism of biological response. These data can be applied to developing new strategies for designing antibodies with more therapeutic efficacy.

Monitoring Humoral Response Following BNT162b2 mRNA Vaccination against SARS-CoV-2 in Hematopoietic Stem-Cell Transplantation Patients: A Single-Center Prospective Study along with a Brief Review of Current Literature.

Data on antibody response (AR) after vaccination against SARS-CoV2 in hematopoietic stem-cell transplantation setting (HSCT) were initially scarce, mainly due to the exclusion of such patients from approval studies. Shortly after the worldwide application of vaccination against SARS-CoV-2 in vulnerable populations such as patients with hematologic malignancies, limited single-center trials, including HSCT patients, were published. However, there was a great heterogeneity between them regarding the type of underlying malignancy, co-current treatment, type of vaccine, method of AR measurement, and time point of AR measurement. Herein, we present the results of a prospective study on AR after vaccination for SARS-CoV-2 using the BNT162b2 vaccine in a cohort of 54 HSCT recipients-mostly autologous from a single Unit-along with a broad review of the current literature. In our cohort, the AR positivity rate at 1 month was 80.8% and remained positive in 85.7% of patients at 3 months after vaccination. There were only nine non-responders, who were more heavily pretreated and more frequently hypogammaglobulinemic compared to responders. High antibody titers (AT), [AT ≥ 1000 U/mL], were detected in 38.5% and 30.6% of the patients at m1 and m3, respectively. A significant decline in AT between m1 and m3 was demonstrated-p < 0.0001; median AT1 and AT3 were 480.5 and 293 U/mL, respectively. A novel finding of our study was the negative impact of IgA hypogammaglobulinemia on response to vaccination. Other negative significant factors were treatment with anti-CD20 antibody at vaccination and vaccination within 18 months from HSCT. Our data indicate that HSCT recipients elicit a positive response to the BNT162b2 vaccine against SARS-CoV-2 when vaccinated at 6 months post-transplant, and vaccination should be offered to this patient population even within the post-pandemic COVID-19 era.

Extracellular Vesicles from Highly Metastatic Osteosarcoma Cells Induce Pro-Tumorigenic Macrophage Phenotypes.

Metastasis is the principal factor in poor prognosis for individuals with osteosarcoma (OS). Understanding the events that lead to metastasis is critical to develop better interventions for this disease. Alveolar macrophages are potentially involved in priming the lung microenvironment for OS metastasis, yet the mechanisms involved in this process remain unclear. Since extracellular vesicles (EVs) are a known actor in primary tumor development, their potential role in OS metastagenesis through macrophage modulationis explored here. The interaction of EVs isolated from highly metastatic (K7M2) and less metastatic (K12) osteosarcoma cell lines is compared with a peritoneal macrophage cell line. An EV concentration that reproducibly induced macrophage migration is identified first, then used for later experiments. By confocal microscopy, both EV types associated with M0 or M1 macrophages; however, only K7M2-EVs are associated with M2 macrophages, an interaction that is abrogated by EV pre-treatment with anti-CD47 antibody. Interestingly, all interactions appeared to be surface binding, not internalized. In functional studies, K7M2-EVs polarized fewer macrophages to M1. Together, these data suggest that K7M2-EVs have unique interactions with macrophages that can contribute to the production of a higher proportion of pro-tumor type macrophages, thereby accelerating metastasis.

Immunoglobulin Level Changes in Patients with Multiple Sclerosis Treated with Anti-CD20 Monoclonal Antibodies (P9-6.011)

Immunoglobulin Level Changes in Patients with Multiple Sclerosis Treated with Anti-CD20 Monoclonal Antibodies (P9-6.011)

Bone marrow stromal cells dictate lanosterol biosynthesis and ferroptosis of multiple myeloma

Ferroptosis has been demonstrated a promising way to counteract chemoresistance of multiple myeloma (MM), however, roles and mechanism of bone marrow stromal cells (BMSCs) in regulating ferroptosis of MM cells remain elusive. Here, we uncovered that MM cells were more susceptible to ferroptotic induction under the interaction of BMSCs using in vitro and in vivo models. Mechanistically, BMSCs elevated the iron level in MM cells, thereby activating the steroid biosynthesis pathway, especially the production of lanosterol, a major source of reactive oxygen species (ROS) in MM cells. We discovered that direct coupling of CD40 ligand and CD40 receptor constituted the key signaling pathway governing lanosterol biosynthesis, and disruption of CD40/CD40L interaction using an anti-CD40 neutralizing antibody or conditional depletion of Cd40l in BMSCs successfully eliminated the iron level and lanosterol production of MM cells localized in the Vk*MYC Vk12653 or NSG mouse models. Our study deciphers the mechanism of BMSCs dictating ferroptosis of MM cells and highlights the therapeutic potential of non-apoptosis strategies for managing refractory or relapsed MM patients.

Proinflammatory polarization strongly reduces human macrophage in vitro phagocytosis of tumor cells in response to CD47 blockade.

Antibody-based CD47 blockade aims to activate macrophage phagocytosis of tumor cells. However, macrophages possess a high degree of phenotype heterogeneity that likely influences phagocytic capacity. In murine models, proinflammatory (M1) activation increases macrophage phagocytosis of tumor cells, but in human models, results have been conflicting. Here, we investigated the effects of proinflammatory polarization on the phagocytic response of human monocyte-derived macrophages in an in vitro model. Using both flow cytometry-based and fluorescence live-cell imaging-based phagocytosis assays, we observed that mouse monoclonal anti-CD47 antibody (B6H12) induced monocyte-derived macrophage phagocytosis of cancer cells in vitro. Proinflammatory (M1) macrophage polarization with IFN-γ+LPS resulted in a severe reduction in phagocytic response to CD47 blockade. This reduction coincided with increased expression of the antiphagocytic membrane proteins LILRB1 and Siglec-10 but was not rescued by combination blockade of the corresponding ligands. However, matrix metalloproteinase inhibitors (TAPI-0 or GM6001) partly restored response to CD47 blockade in a dose-dependent manner. In summary, these data suggest that proinflammatory (M1) activation reduces phagocytic response to CD47 blockade in human monocyte-derived macrophages.

Complete response to front-line therapies is associated with long-term survival in HIV-related lymphomas in Taiwan

BackgroundThe prognosis for people living with HIV (PLWH) who develop lymphomas has been greatly improved by combination antiretroviral therapy (cART) and anti-CD20 monoclonal antibodies. However, real-world clinical data on this patient group in Asia are limited. MethodsTreatment outcomes were retrospectively examined for 104 PLWH with lymphomas between 2000 and 2019. The cohort comprised five PLWH with Hodgkin lymphoma (HL) and 99 with non-Hodgkin lymphomas, including 61 with diffuse large B-cell lymphoma (DLBCL), 19 with Burkitt lymphoma (BL), nine with primary central nervous system lymphoma (PCNSL) and ten with other subtypes. ResultsThe 5-year overall survival (OS) rates were as follows: HL (100%), PCNSL (76.2%), other subtypes (60.0%), BL (57.4%), and DLBCL (55.6%). Individuals who achieved complete response (CR) to front-line therapies had a significantly better 5-year OS rate than those without (96.2% vs. 17.8%, p < 0.001). PLWH who received cART for ≤6 months had significantly lower CD4+ T-cell counts at lymphoma diagnosis than those who received cART for longer periods (p = 0.048). Additionally, the 5-year OS rate was better for PLWH who received cART for ≤6 months before lymphomas diagnosis than those who received cART for longer periods (64.5% vs. 51.9%, p = 0.114). ConclusionsPLWH with DLBCL or BL had OS rates compatible to patients without HIV infection. Better outcomes for patients achieving CR to front-line therapy and those with shorter cART duration before lymphoma diagnosis suggest an underlying biological distinction in the lymphomas and the involvement of immunity, which warrants further studies.

Abstract CT086: Phase I study of intravesical Fc-optimized anti-CD40 agonist antibody 2141-V11 for non-muscle invasive bladder cancer (NMIBC) unresponsive to Bacillus Calmette-Guerin (BCG) therapy

Abstract Introduction: The CD40-CD40L pathway is crucial for activating antigen-presenting cells and initiating tumor-specific T cell responses across various malignancies. However, prior agonistic anti-CD40 antibodies have encountered limited clinical success and significant toxicity. Our previous studies demonstrate that interactions between the antibody Fc domain and the inhibitory Fc-gamma receptor FcγRIIB are critical for efficient CD40 multimerization and enhanced antitumor activity. To optimize this interaction, we developed 2141-V11, a novel anti-CD40 antibody Fc-engineered to increase binding affinity for FcγRIIB, resulting in effective antitumor activity in both in vivo and in a recent first-in-human phase I trial (NCT04059588). Non-muscle invasive bladder cancer (NMIBC) is the most common presentation of bladder cancer, with a high risk of recurrence and progression despite optimal surgical interventions and standard therapies. Bacillus Calmette-Guerin (BCG) intravesical treatment has been the standard of care for NMIBC over the last five decades. However, 75% of patients ultimately become unresponsive to this therapy, leaving limited curative options aside from complete radical cystectomy. Using several preclinical bladder cancer models, including BCG-unresponsive disease, we found that intravesical administration of 2141-V11 induces durable anti-tumor immunity without systemic toxicity. Based on these findings, we initiated a Phase I study of intravesical 2141-V11 for the treatment of BCG-unresponsive NMIBC. Methods: This is an investigator-initiated Phase I, open-label, dose-escalation study to evaluate the safety and tolerability of intravesical 2141-V11 in patients with BCG-unresponsive NMIBC (N=25) who are ineligible for or decline radical cystectomy (NCT05126472). Following complete transurethral resection, intravesical 2141-V11 is administered once weekly for three doses, with re-treatment eligibility at week 13 and 25, based on disease status determined by on-treatment biopsies. The study follows an MCRM dose escalation design with five dose levels (0.7, 2.0, 7.0, 21.0 and 70.0 mg). Primary endpoints include safety and dose tolerability to determine maximal tolerated dose (MTD) and/or recommended phase 2 dose (RP2D). Secondary endpoints involve pharmacokinetic profiling and preliminary evaluation of clinical activity. Exploratory objectives include investigation of biological markers of drug activity in pre- and post-treatment tissue biopsies and urine biospecimens. As of the data cutoff on 12/20/23, 80% of the planned patients (n=20) have been enrolled, with no dose-limiting toxicities observed. Accrual completion is expected by the first quarter of 2024, with ongoing analysis of urine immune profiling, cytokine analysis, as well as single-cell spatial phenotyping in pre- and post-treatment samples. Citation Format: Juan C. Osorio, Muneeb Alam, Jeffrey Wong, David Knorr, Lucas Blanchard, Juan C. Angulo-Lozano, Karissa Whiting, Venkatraman E. Seshan, Timothy F. Donahue, Eugene K. Cha, Alvin C. Goh, Robert Smith, Guido Dalbagni, Christian Hernandez, Melissa McCarter, Eugene J. Pietzak, Jonathan E. Rosenberg, Jeffrey V. Ravetch, Bernard H. Bochner. Phase I study of intravesical Fc-optimized anti-CD40 agonist antibody 2141-V11 for non-muscle invasive bladder cancer (NMIBC) unresponsive to Bacillus Calmette-Guerin (BCG) therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT086.

Abstract CT037: A phase I investigator-initiated trial of evorpacept (ALX148), lenalidomide and rituximab for patients with relapsed or refractory B-cell non-Hodgkin lymphoma

Abstract Introduction. We have recently demonstrated that pro-tumoral SIRPα+ macrophages may mediate resistance to lenalidomide and rituximab (R2) in patients (pts) with relapsed or refractory (RR) B-cell non-Hodgkin lymphoma (B-NHL). Evorpacept (ALX148) is a novel high-affinity CD47 blocker that abrogates the ‘do-not-eat-me signal’ provided to SIRPα+ macrophages. In a phase I trial including 33 pts with RR B-NHL it was well tolerated in combination with rituximab. We hypothesized that evorpacept and R2 will be synergistic, and the combination will be safe and effective for the treatment of pts with RR B-NHL. Methods. This single arm phase I study (NCT05025800) was conducted between 11/2021 and 9/2023 (data cut-off 12/2023). Adult pts with RR B-NHL who had received at least 2 prior lines of systemic therapy (1 in case of indolent B-NHL [iNHL]) were included. Evorpacept was administered intravenously (IV), in a 28-day cycle, for 12 cycles, at two dose levels (DL): 30 mg/Kg on day (D) 1 and D15 (DL1), or 60 mg/Kg on day 1 (DL2); rituximab IV was given weekly during cycle 1, and on D1 during cycles 2-6; lenalidomide was given orally on D1-21 during cycles 1-6. Dose limiting toxicity (DLT) was evaluated according to CTCAE v5 during cycle 1 and a Bayesian Optimal Interval design was used, with a target DLT rate of 0.3. Response was assessed according to Lugano 2014 criteria. Results. Twenty pts were included in the study. Median age was 61 (27-85), 10 (50%) were male, and 7 (35%) were non-white; 15 (75%) had follicular lymphoma, 3 (15%) marginal zone lymphoma, 1 (5%) mantle cell lymphoma, and 1 (5%) Richter Syndrome; 20 (100%) had previously received an anti-CD20 monoclonal antibody, 13 (72%) chemoimmunotherapy, and 15/18 (83%) iNHL pts had intermediate-high FLIPI. Three pts were treated at DL1, 17 at DL2, and no DLT was observed. The most common grade 3-4 adverse events included: neutropenia (55%), infections (30%), ALT increase (15%), AST increase (10%), skin rash (10%), and anemia (10%). Eight (40%) pts experienced a cycle delay, mainly due to grade (G) 1 AST/ALT elevation; 6 (30%) required a dose reduction for lenalidomide, none for evorpacept; 1 pt discontinued treatment after 1 cycle due to G3 lenalidomide-associated myocarditis. Sixteen (80%) pts achieved CR and best overall response rate was 90%. After a median follow-up of 16 months (95% CI, 12-20 months), 1-year PFS rate was 70% and 1-year OS rate was 90%. Conclusions. The combination of evorpacept and R2 is well tolerated in pts with RR B-NHL, with similar toxicity and promising anti-tumoral activity as compared to historical CR rates with R2 alone (34%). Bulk RNA sequencing and multiplex immunofluorescence are being performed on tissue biopsies collected before and during treatment, to characterize its effects on the tumor immune microenvironment. A phase 2 study investigating its efficacy in pts with previously untreated iNHL is now enrolling. Citation Format: Paolo Strati, Lei Feng, Dai Chihara, Jason Westin, Sairah Ahmed, Luis Fayad, Jared Henderson, Jeffrey Davidson, Elizabeth McChesney, Loretta Nastoupil, Sattva Neelapu, Christopher Flowers. A phase I investigator-initiated trial of evorpacept (ALX148), lenalidomide and rituximab for patients with relapsed or refractory B-cell non-Hodgkin lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT037.

Abstract CT065: Modakafusp alfa shows intratumoral immune pharmacodynamics (PD) in a subset of patients (pts) in a phase 1b study in advanced/metastatic solid tumors

Abstract Background: Modakafusp alfa (moda), a novel immunocytokine, is an innate immune enhancer comprising an anti-CD38 IgG4 antibody fused to 2 attenuated interferon (IFN) α2b molecules. Moda is being evaluated in phase 1/2 trials for multiple myeloma and in a phase 1/2 trial in solid tumors. Here, we present PD data in tumor biopsies and peripheral blood (PB) from the phase 1/2 study of moda as monotherapy in pts with advanced/metastatic solid tumors (NCT04157517). Methods: A total of 21 pts were treated with moda 0.1-1.5 mg/kg every 3 weeks. Tumor biopsy samples were collected at screening and on cycle 2, day 2 (C2D2). Biopsies were evaluated by multiplex immunofluorescence (using a Multiomyx platform) and RNASeq. PB samples were collected pre-dose on C1D1 and at timepoints after treatment. PB samples were evaluated by CyTOF to assess PD changes in immune cells. Results: No clinical tumor responses (partial or better) were observed in the 21 pts. Analysis of tumor biopsies revealed two subgroups defined by differences in upregulation of CD38 expression after moda treatment, with differential intratumoral PD changes. The CD38 gene has IFN response elements within its promoter region. Thus, correlation of tumor PD with changes in CD38 expression is of interest because, along with being a target of moda, an increase in CD38 expression may indicate drug activity in the tumor microenvironment. Interestingly, in the subset of pts in whom an increase in the percentage of CD38+ lymphocytes in response to moda was reported, there were also increases in CD8 and CD4 T cell activation, (%CD69) as well as CD8 T cell cytotoxic function (%GzB). Additionally, moda led to increase in CD14+CD16+ intermediate monocytes, indicating an enhanced myeloid response in several pts, and minimal changes in FoxP3+ Tregs regardless of changes in CD38 expression. Moda treatment led to an increase in activated and cytolytic natural killer (NK) and CD8 T cells in all pts. This was accompanied by increased NK and CD8 T cell proliferation (%Ki67) in PB, without sustained increase in exhaustion markers. CD4 T cells were also activated in response to moda and there was no increase in circulating FoxP3+ Tregs. Enhanced myeloid cell response, measured by increased proliferation of monocytes and dendritic cells, along with upregulation of costimulatory molecules, were also seen. Importantly, immune PD changes in the PB were seen in most pts and there were no immune PD differences identified between the two patient subsets defined in the biopsy analysis. Conclusion: PD biomarker data from this phase 1/2 trial in pts with advanced solid tumors demonstrated that moda enhances innate and adaptive immune activation in PB and within tumors. The presence of a differential intratumoral PD response in a subset of pts with elevated CD38+ cells highlights that tumor intrinsic factors may play a role in driving moda’s activity in tumors. Citation Format: Gurpanna Saggu, Janet L. Markman, Min Young Lee, Faith Dunbar, Adarsh Joshi, Shining Wang, Sabrina Collins. Modakafusp alfa shows intratumoral immune pharmacodynamics (PD) in a subset of patients (pts) in a phase 1b study in advanced/metastatic solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT065.

Abstract CT243: Primary analysis of the Phase 2 ELM-2 study: Odronextamab in patients (pts) with relapsed/refractory follicular lymphoma (R/R FL)

Abstract Background: R/R FL is an incurable disease and outcomes worsen with successive relapses. A high unmet need remains for therapies that improve tumor control and extend survival after relapse. Odronextamab, an off-the-shelf CD20×CD3 bispecific antibody, demonstrated compelling efficacy, generally manageable safety, and maintenance of pt-reported overall quality of life scores from baseline in an interim analysis of the ELM-2 study (NCT03888105) in heavily pretreated pts with R/R FL (Villasboas et al. ASH 2023). Here, for the first time, we present the primary analysis of R/R FL in ELM-2. Methods: IV odronextamab was administered in 21-day cycles (C) until disease progression/unacceptable toxicity. Steroid prophylaxis and step-up dosing (0.7/4/20 mg) were used in C1 to mitigate the risk of cytokine release syndrome (CRS), followed by 80 mg on Days (D) 1, 8, and 15 of C2-4. Maintenance dosing continued at 160 mg Q2W, or Q4W if complete response (CR) was durable for 9 months (mo). Primary endpoint was objective response rate (ORR) per Lugano criteria by independent central review (ICR). Secondary endpoints included CR rate, duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Primary analysis was performed when 128 pts had ≥52 weeks’ follow-up. Results: At data cutoff (Oct 20, 2023), 128 pts with FL Grade (Gr) 1-3a were evaluable for efficacy and safety: median age 61 yrs (range 22-84); FLIPI risk score 3-5 57.8%; POD24 49.2%; median 3 prior lines of therapy (2-13); 71.9% refractory to last treatment (Tx); 74.2% refractory to an anti-CD20 antibody. The median no. of Tx cycles was 19.4 (0.1-95.9); 95.3% and 85.2% of pts completed C1 and C4, respectively.Median efficacy follow-up was 20.1 mo; ORR was 80.5% and CR rate was 73.4% confirmed by ICR. Responses were durable (median DOR 22.6 mo; median DOCR 25.1 mo). Median PFS was 20.7 mo and 24-mo PFS was 46.1%. Median OS was not reached and 24-mo OS was 70.1%.The odronextamab safety profile was generally manageable and consistent with previous reports. Tx-emergent adverse events (AEs) occurred in all pts (Gr ≥3 85.9%); 15.6% had AEs leading to Tx discontinuation. With 0.7/4/20 mg step up (n=60), CRS events were mostly low grade (Gr 1 45.0%; Gr 2 10.0%; Gr 3 in 1 pt), occurred mostly in C1, and resolved in a median of 2 days; ICANS was reported in 1 pt (Gr 2). Infection rates were consistent with heavily pretreated, immunosuppressed pts (Leonard et al. JCO 2019; Hayne et al. BBMT 2020), occurring in 79.7% (102/128) of pts (Gr 4/5 14.0%; COVID-19 36.7% [Gr 5 6.3%]).Conclusion: Odronextamab demonstrated deep and durable responses in heavily pretreated pts with R/R FL; 91% of responders achieved CR, correlating with favorable PFS and OS at 24 mo. Odronextamab had a generally manageable safety profile and a low incidence of Gr 3 CRS/ICANS. Odronextamab could offer an important off-the-shelf Tx option for pts with heavily pretreated R/R FL. Citation Format: Geoffrey Chong, Michal Taszner, Silvana Novelli, Seok-Goo Cho, Jose C. Villasboas, Ana Jiménez Ubieto, Benoît Tessoulin, Michelle Poon, David Tucker, Jan Walewski, Yuqin Song, Emmanuel Bachy, Stephanie Guidez, Aranzazu Alonso, Deepa Jagadeesh, Stefano Luminari, Laura Magnano Mayer, Elżbieta Iskierka-Jażdżewska, Monica Tani, Jingxian Cai, Amulya Uppala, Saleem Shariff, Jurriaan Brouwer-Visser, Aafia Chaudhry, Hesham Mohamed, Srikanth Ambati, Tae Min Kim. Primary analysis of the Phase 2 ELM-2 study: Odronextamab in patients (pts) with relapsed/refractory follicular lymphoma (R/R FL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT243.

Abstract LB129: Preclinical development of a bispecific antibody-trap selectively targeting CD38 and CD47 for treating hematologic malignancies

Abstract CD38 and CD47 are co-expressed in various hematologic malignancies including multiple myeloma (MM), B-cell non-Hodgkin lymphoma (NHL), B-cell acute lymphoblastic leukemia (ALL), T-cell ALL and B-cell chronic lymphocytic leukemia (CLL). We present, herein, several CD38 antibody - CD47 ligand trap bispecific antibodies (BsAbs) in an ADCC-enhanced IgG1 form that harbor high CD38 binding affinity, low CD47 binding affinity, along with negligible affinity to red blood cells (RBCs) and no induction of RBCs agglutination. Using flow cytometry and Biolayer interferometry (BLI), we confirmed that our BsAbs can simultaneously bind to both CD38 and CD47, and that binding to either antigen first does not prevent binding to the other antigen subsequently. On CD47+/CD38low Jurkat (T leukemic) cells, our BsAbs reveal less blocking effect on the CD47/SIRPα interaction than a monospecific CD47 ligand trap molecule based on which our BsAbs were designed; conversely, on CD38/CD47 double-positive Reh (pro-B ALL) cells, our BsAbs reveal 200-500-fold greater blocking effect on the CD47/SIRPα interaction than the same monospecific CD47 ligand trap molecule, indicating that the inhibition of CD47/SIRPα by our BsAbs is depended on the engagement of CD38 on tumor cells. On CD47+/CD38+ Daudi (B NHL) lymphoma cells and L-1236 (B Hodgkin) lymphoma cells, four of our BsAbs inhibited CD38 enzymatic activity, which is responsible for immune-suppressive adenosine production in tumor microenvironment. Our BsAbs presented potent dose-dependent antibody-dependent cellular cytotoxicity (ADCC) against CD47+/CD38+ Raji (B NHL) and NCI-H929 (B plasmacytoma myeloma) cells, while revealing negligible ADCC activity against CD47+/CD38− cells, indicating low off-tumor toxicity. Likewise, our BsAbs also harbor potent antibody-dependent cellular phagocytosis (ADCP) activity against Raji NHL cells, varied degree of complement-dependent cytotoxicity (CDC) activity and direct apoptosis induction against Daudi NHL cells. In a mouse xenograft model harboring NCI-H929 multiple myeloma, our BsAbs produced more potent tumor growth inhibition, than monospecific anti-CD47 ligand trap, anti-CD38 (isatuximab) or combination of isatuximab and anti-CD47 ligand trap, at the same molecular dose per body weight. Notably, clone IMM5605-12C10 eradicated all tumors and achieved 100% complete response rate in a group of six mice. In summary, simultaneous targeting CD38 and CD47 using our CD38 antibody - CD47 ligand trap bispecific design in an ADCC-enhanced IgG1 form presents a novel multimodal approach for treating hematologic malignancies that are resistant to anti-CD38 antibodies. Citation Format: Wenzhi Tian, Song Li, Dianze Chen, Yanan Yang, Huiqin Guo, Dandan Liu, Ruliang Zhang, Fan Zhang. Preclinical development of a bispecific antibody-trap selectively targeting CD38 and CD47 for treating hematologic malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB129.