anti-CD20 mAb Research Articles

Abstract CT262: Durable responses following anti-TIGIT (BMS-986207) and anti-LAG3 (BMS-980616) in combination with pomalidomide in relapsed myeloma: MMRF MyCheckpoint trial

Abstract Background: T cell redirection with agents such as Chimeric Antigen Receptor T cells or bispecific T cell engagers is remarkably effective in relapsed multiple myeloma (MM), however, they are not curative. Translational studies suggest that T cell exhaustion, characterized by upregulation of immune checkpoints LAG-3 and TIGIT, is a potential resistance mechanism to T cell redirection. These findings support the hypothesis that checkpoint inhibition with anti-LAG-3 or anti-TIGIT mAbs may restore anti-myeloma T cell activity. There is an unmet need to assess the feasibility and safety of checkpoint blockade in this malignancy. Patients and Methods: MyCheckpoint (NCT04150965) is a phase 1/2 platform trial for relapsed MM patients who have received ≥3 lines of therapy, including a proteasome inhibitor, immunomodulatory drug, and anti-CD38 mAb. Primary objectives were safety and tolerability of the investigational agents alone and in combination with pomalidomide (Pom) and dexamethasone (Dex) and overall response rates in each arm. In the phase 1 portion subjects were randomized to Arm B (anti-LAG-3) or Arm C (anti-TIGIT mAb). Subjects received one cycle (C1) of mAb therapy alone, with the addition of Pom and Dex starting with cycle 2 (C2) onward. Bone marrow aspirates and peripheral blood were obtained at screening, C2D1, C3D1, and end of study for correlative analysis. Results: Fourteen (14) eligible subjects were enrolled (seven subjects in Arm B dose level (DL) 1, one not evaluable; six subjects in Arm C DL1, and 1 subject Arm C DL2 not evaluable). The most common adverse events (AE) were anemia and dyspnea. Grade 3-4 AEs related to therapy in the anti-LAG-3 arm were dyspnea and neutropenia; those in anti-TIGIT arm were neutropenia, thrombocytopenia, and anemia. There was 1 death due to progression of disease unrelated to the study treatment. There was 1 death due to a serious adverse event of pneumonia (unrelated). There was one adverse event of special interest in Arm B DL1 (grade 1 AST elevation). No autoimmune AEs were reported. Best overall responses for Arm B DL1 were 1 very good partial response (VGPR), 1 partial response (PR), 4 stable disease (SD); for Arm C DL1, 1 VGPR, 2 PR, and 3 SD. Eight subjects withdrew from treatment for disease progression, 2 for AE, and 2 for patient decision. Two subjects continue in Arm C DL1 as of December 2022, 1 PR as of C16D1 and 1 VGPR (C23D1). Conclusion: Anti-LAG-3 and anti-TIGIT mAb alone and in combination with Pom are safe, feasible and clinically active in relapsed MM after Pom and anti-CD38 mAb. These data provide the first evidence of clinical activity of TIGIT and LAG-3 blockade in MM. Translational results utilizing serial analyses with mass cytometry suggest evidence of immune activation following combination therapy. Citation Format: Hearn J. Cho, Shambavi Richard, Alex Lesokhin, Noa Biran, Barry Paul, Ravi Vij, Matthew Pianko, Deon Doxie, Mercedes Martillo, Katie Wozniak, Kavita Dhodapkar, Madhav Dhodapkar. Durable responses following anti-TIGIT (BMS-986207) and anti-LAG3 (BMS-980616) in combination with pomalidomide in relapsed myeloma: MMRF MyCheckpoint trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT262.

Abstract CT011: A phase 1 multicenter study (TRAVERSE) evaluating the safety and efficacy of ALLO-316 following conditioning regimen in pts with advanced or metastatic clear cell renal cell carcinoma (ccRCC)

Abstract Background: While doublet therapies provide important first-line treatment options in metastatic renal cell carcinoma (mRCC), novel and mechanistically distinct agents are needed for pts who are not cured by/intolerant of such therapies. Due to the high incidence (~80%) of CD70 antigen expression in primary and mRCC, yet limited expression in normal tissue, ccRCC is an attractive proof-of-concept tumor for CD70 directed allogeneic CAR T. TRAVERSE (NCT04696731), a first-in-human trial, seeks to identify a maximum tolerated dose (MTD) of ALLO-316 after conditioning with fludarabine/cyclophosphamide with/without ALLO-647 in pts with advanced or metastatic ccRCC. ALLO-316 is an anti-CD70 allogeneic CAR T cell product that utilizes TALEN® gene editing to knock out TCRα constant gene to reduce the risk of graft-versus-host disease (GvHD) and knock out CD52 gene to permit use of ALLO-647 (a humanized anti-CD52 mAb) to selectively deplete host T cells without affecting allogeneic CAR T cells. Methods: This multicenter, single-arm, open-label, 3+3 dose-escalation trial enrolls adults with advanced or metastatic ccRCC and ≥1 measurable lesion and ECOG Performance Status 0 or 1. Prior treatment with an immune checkpoint inhibitor and a vascular endothelial growth-factor targeted therapy was required, with evidence of progression on/after treatment or discontinuation due to toxicity. ALLO-316 is administered at escalating doses (40 - 240 × 106 allogeneic CAR+ cells IV) on Day 0 after conditioning. The primary endpoint is a target incidence rate for dose-limiting toxicities (DLTs) <33% in the first 28 days after infusion of ALLO-316. Results: By 12/3/2022, 18 pts with ccRCC (median age: 63 yrs; 82% male) were enrolled; all (100%) 17 pts who received ALLO-316, had metastatic disease with 3 lines (median) of prior therapy. Eleven (65%) of these pts experienced CRS, all low Gr except one (6%) Gr 3. No ICANS or GVHD was observed. One (6%) DLT (elevated LFT) was observed and required dose expansion. MTD has not yet been reached. Three pts achieved best overall response of PR at all time points with two PRs confirmed at subsequent visits; ORR = 12% and disease control rate (DCR) = 71%. In pts with confirmed CD70+ tumors (n=9), confirmed ORR = 22% (unconfirmed ORR = 33%) and DCR = 100%. High CAR T cell expansion was observed in peripheral blood (median Cmax > 35,000 copies/μg) and high VCN in available tumor aspirates (n=3). Conclusions: ALLO-316, an allogeneic CAR T cell product targeting CD70 in advanced mRCC, is demonstrating encouraging antitumor activity and a manageable safety profile. A single administration of ALLO-316 could be an effective treatment for pts with CD70+ solid tumors, including RCC, and hematologic malignancies. The MTD for ALLO-316 in TRAVERSE will support Phase 2 trial design. Enrollment of pts with CD70+ tumors is ongoing. Citation Format: Samer Srour, Ritesh Kotecha, Brendan Curti, Jad Chahoud, Alexandra Drakaki, Lily Tang, Lovely Goyal, Sacha Prashad, Victoria Szenes, Kevin Norwood, Sumanta Pal. A phase 1 multicenter study (TRAVERSE) evaluating the safety and efficacy of ALLO-316 following conditioning regimen in pts with advanced or metastatic clear cell renal cell carcinoma (ccRCC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT011.

Daratumumab-lenalidomide and daratumumab-pomalidomide in relapsed lenalidomide-exposed or refractory multiple myeloma.

Daratumumab is an anti-CD38 mAb, used frequently in combination with lenalidomide and pomalidomide. No studies compared daratumumab plus lenalidomide and dexamethasone (DRd) to daratumumab plus pomalidomide and dexamethasone (DPd) in lenalidomide-exposed multiple myeloma. We identified 504 consecutive multiple myeloma patients who received daratumumab at Mayo Clinic between January 2015 and April 2019. We excluded patients who received daratumumab in the first line, received more than four lines of therapy prior to daratumumab use, did not receive lenalidomide prior to daratumumab, or had an unknown status of lenalidomide exposure, and patients who received daratumumab combinations other than DRd or DPd. We examined the impact of using DRd compared to DPd on progression-free survival (PFS) and overall survival (OS) in patients with relapsed/refractory multiple myeloma. Out of 504 patients, 162 received DRd or DPd and were included; 67 were lenalidomide-exposed and 95 were lenalidomide-refractory. DRd was used in 76 (47%) and DPd in 86 (53%) patients. In lenalidomide-exposed multiple myeloma, there was no difference in median PFS; 34.2 months [95% confidence interval (CI), 22.8-44.6] for DRd compared to 25.2 months (95% CI, 4.9-35.3) for DPd, P = 0.2. In lenalidomide-refractory multiple myeloma, there was no difference in median PFS; 18.6 months (95% CI, 13-32) for DRd compared to 9 months (95% CI, 5.2-14.6) for DPd, P = 0.09. No difference in median OS was observed in DRd compared to DPd. Our study shows combining daratumumab with lenalidomide in patients with prior lenalidomide use is a viable and effective treatment option.

Abstract 4139: Functional human myeloid cells in BRGSF-HIS humanized mice enables myeloid-directed therapy assessment

Abstract Translational preclinical assessment of myeloid-targeting therapies is considered challenging due to the reduced availability of humanized mouse models expressing both lymphoid and myeloid compartments. Most of the humanized models harboring myeloid compartment overexpress human cytokines, leading to body weight loss, anemia and a short life span. Recent report described the BRGSF-HIS as an alternative model displaying all major human hematopoietic cell subsets, such as B, T, natural killer (NK), dendritic cells (DCs), plasmacytoid cells (pDCs) and monocytes/macrophages. Human myeloid cells developed in the BRGSF-HIS mice without side effects and human immune system engraftment is stable for over a year (Labarthe et al., 2019), favoring long terms studies with agents requiring a wide therapeutic window. Here we report that myeloid compartment developed in BRGSF-HIS mice is recruited in the tumor microenvironment of tumor bearing mice, and are also capable of triggering effector mechanisms such as ADCP and ADCC. Myeloid cells developed in the BRGSF-HIS mice are functional as, ex vivo stimulation with TLR and STING agonists induce CD83 expression and pro-inflammatory cytokine secretion (TNF-α, IL-1β, CCL2, ⋯) by monocytes and bone marrow derived macrophages (BMDM). In vivo, myeloid cells are activated through LPS challenge, leading to increased CD83-expressing cDCs frequency and CD83 and CD86 expression levels. Furthermore, BMDM are efficiently skewed toward M1 and M2-like profiles in response to LPS and IL-4, respectively. Analyses of TME from MDA-MB-231, show the recruitment of human immune cells, including T cells, NK cells, cDC and activated M2 macrophages (expressing both CD86 and CD206). Expression of FcγR, essential for antibody dependent cellular cytotoxicity (ADCC) and antibody dependent cellular phagocytosis (ADCP) activities, is found on human peritoneal macrophages and BMDM from BRGSF-HIS. ADCP activity mediated by macrophages was established as tumor cells are specifically phagocyted ex vivo in presence of a bispecific antibody (anti-human CD47 x tumor-associated antigen). Such findings were corroborated by B cell depletion in vivo induced by Rituximab (anti-CD20 mAb - hIgG1), which has been described to trigger CDC, ADCC and ADCP via FcγR (Teige et al., 2019). Finally, OKT3 induces cytokine release syndrome in these mice, evidenced by cytokine release, body weight and temperature drop. Treatment with Infliximab reduced these symptoms, suggesting that BRGSF-HIS mice enable assessment of safety and its clinical management. In summary, BRGSF-HIS mice develop myeloid cells without side effects and has a wide therapeutic window, enabling the assessment of effector mechanisms such as ADCP and ADCC, triggered by of myeloid-targeted therapies. Citation Format: Florence Renart-Depontieu, Gaëlle Martin, Valery Moine, Coline Burnet-Merlin, Florent Creusat, Alexis Gonon, Perrine Martin-Jeantet, Fabiane Sônego, Lise Nouveau, Yacine Cherifi, Kader Thiam. Functional human myeloid cells in BRGSF-HIS humanized mice enables myeloid-directed therapy assessment. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4139.

Abstract 6329: Preclinical study of CD19 detection methods using monoclonal antibodies post tafasitamab treatment

Abstract Introduction Tafasitamab (TAFA), an Fc-enhanced antibody immunotherapy against CD19 received accelerated/conditional approval in relapsed or refractory diffuse large B cell lymphoma (R/R DLBCL) in combination with lenalidomide. Several other CD19 targeting therapies including CAR Ts are now available for R/R DLBCL treatment warranting evaluation of potential therapeutic sequencing strategies. In this context, CD19 expression status may be assessed on patient samples post TAFA treatment. However, methods for detecting CD19 using monoclonal antibodies (mAbs) following TAFA treatment are not standardized which may lead to data misinterpretations including confusion of CD19 epitope masking with CD19 loss or downregulation. Aim This study evaluated various CD19 detection methods following TAFA treatment using comprehensive panels of available flow cytometry (FC) and immunohistochemistry (IHC) anti-CD19 mAbs, routinely used in laboratory practice. Methods FC and IHC competition assays were used on TAFA pre-treated CD19+ cell lines to differentiate non-competing from competing mAbs, the latter resulting in epitope masking by TAFA. Bound TAFA was removed from CD19+ cells using an acidic dissociation protocol. Antibody affinities for CD19 were determined using Surface Plasmon Resonance (SPR) or Bio-Layer Interferometry (BLI). Results All but one of the 8 mAbs tested in FC competed with TAFA and their affinities for CD19 were shown to be lower than that of TAFA. The non-competing clone OTI3B10, reported to recognize a linear epitope of CD19 (1), bound to only one of three tested CD19+ cell lines, which rendered it unsuitable for reliable FC detection of CD19. In contrast, several clones could detect CD19 on TAFA pre-treated samples using IHC. To circumvent TAFA masking in FC, we successfully unmasked CD19 via acidic dissociation and similar CD19 levels on TAFA pre-treated as on untreated cells could be subsequently detected by a competing CD19 antibody (HIB19). Conclusion Our study provides an overview of commonly used mAb tools for CD19 detection post TAFA treatment, some of which may be used in routine clinical practice. Our findings reveal that CD19 expression post TAFA could be detected by IHC but lack of TAFA non-competing anti-CD19 antibodies for FC poses a risk of mistaking CD19 masking by TAFA with CD19 loss or downregulation. Prior acidic dissociation is critical in the staining protocol to avoid data misinterpretations. 1. Klesmith et al, 2019, Biochem. Citation Format: Kristina M. Ilieva, Markus Eberl, Jan Jaehrling, Carmen Ginzel, Britta Voland, Michaela Zankl, Andrea Polzer, Derek Blair, Rainer Boxhammer, Liang-Chuan Wang, Diana Alvarez Arias, Christina Heitmüller. Preclinical study of CD19 detection methods using monoclonal antibodies post tafasitamab treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6329.

Abstract 2256: Cancer stem cells and exosomal PD-L1 suppress anti-tumor B cells

Abstract We have conducted clinical trials for cancer immunotherapy using vaccine-primed lymph node (VPLN) T calls based on our animal studies with tumor-draining lymph node (TDLN) T cells. More recently we have identified antitumor effector TDLN B cells which demonstrated significant tumor reactivity in vitro and therapeutic efficacy in vivo upon adoptive transfer which can be enhanced by anti-PD-L1 administration. It is unknown whether tumor cells, particularly cancer stem cells (CSCs) could suppress the antitumor effector B cells. We found that depletion of B cells with anti-CD20 mAb prior to anti-PD-L1 administration resulted in more aggressive tumor growth, and the anti-tumor efficacy of anti-PD-L1 was significantly reduced in both 4T1 and CT26 murine tumor-bearing hosts, suggesting the involvement of host B cells in the anti-tumor effect of anti-PD-L1. In addition, administration of anti-PD-L1 partially recovered the humoral immune response, confirming the PD-L1/PD-1 pathway involvement in B cell suppression. We detected elevated expression of PD-1 on activated B cells, and higher PD-L1 expression on ALDHhigh CSCs than on ALDHlow non-CSCs. Co-culturing ALDHhigh CSCs with purified B cells significantly reduced IgG secretion, and such CSC-mediated B cell suppression was rescued by adding anti-PD-L1 mAb in a dose-dependent manner to the CSC-B cell co-culture. These experiments thus indicate that CSCs suppress the IgG production by B cells via the PD-L1/PD-1 axis. Tumor cells were recently recognized to suppress T cell function via secretion of exosomes that express PD-L1. To investigate if exosomal PD-L1 contributes to B cell immunosuppression, we generated Rab27ako D5 cells to delete exosomes as well as PD-L1ko D5 cells by CRISPR/Cas9 gene editing. D5-derived exosomes suppressed B cell proliferation and IgG production in vitro, and administration of these exosomes promoted tumor growth and reduced animal survival, revealing the role of tumor-derived exosomes in B cell immunosuppression. Tumor-derived exosomes expressed PD-L1, but PD-L1 was absent in the exosomes isolated from the PD-L1ko tumor cells as evident by western blot and flow cytometry. Deletion of Rab27a or PD-L1 did not affect the proliferation of the tumor cells in vitro. However, Rab27ako or PD-L1ko resulted in significantly enhanced host anti-tumor immunity evident by reduced 4T1 tumor growth in vivo compared with the WT tumor. Importantly, anti-PD-L1 therapy significantly reduced Rab27ako or PD-L1ko 4T1 tumor growth and prolonged animal survival vs. the WT tumor control. We conclude that PD-L1-expresing CSCs and PD-L1-expresing exosomes suppress antitumor effector B cells via the PD-L1/PD-1 axis. To characterize the suppression of CSC-derived exosomes on host B cells as well as T cells, isolation of Rab27ako ALDHhigh CSCs warranties further investigation. Citation Format: Ying Xin, Jiayu Liu, You Qin, Kexing Lyu, Sifei Yu, Ming Lin, Max Wicha, Alfred E. Chang, Qiao Li. Cancer stem cells and exosomal PD-L1 suppress anti-tumor B cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2256.

Obinutuzumab Can Be Administered as a 90-minute Short Duration Infusion in Patients With Previously Untreated Follicular Lymphoma: GAZELLE End of Induction Analysis.

Obinutuzumab Can Be Administered as a 90-minute Short Duration Infusion in Patients With Previously Untreated Follicular Lymphoma: GAZELLE End of Induction Analysis.

30 Years of Improved Survival in Non-Transplant-Eligible Newly Diagnosed Multiple Myeloma.

The treatment of multiple myeloma (MM) has greatly evolved these past few years. Recent advances in therapeutics have largely benefited elderly patients now renamed "non-transplant-eligible" (NTE) patients. Since the 1960s, and for several decades, chemotherapy was the only treatment for MM. Then, the field was marked by the emergence of targeted therapies in the 2000s, such as immunomodulating agents (thalidomide, lenalidomide, and pomalidomide) and proteasome inhibitors (bortezomib, carfilzomib, and ixazomib), which were the first steps towards an increase in survival. Thereafter, the apparition of monoclonal antibodies (mAbs) was considered a milestone in the treatment of MM for both transplant-eligible and NTE patients. Anti-CD38 mAbs can be safely administered to older patients with an impressive efficacy leading to a never-achieved-before survival rate with the triple association of anti-CD38 mAbs, lenalidomide, and dexamethasone. However, progress is still expected with the introduction in the armamentarium for NTE patients of the most recent innovative immunotherapy-based treatments newly introduced in MM, e.g., CAR-T cells and bispecific antibodies. These "improved versions" of immune-based treatments will probably also benefit NTE patients, although further studies will be needed to better understand their role in this population.

Clearance as an Early Indicator of Efficacy for Therapeutic Monoclonal Antibodies: Circumventing Dose Selection Challenges in Oncology.

The designs of first-in-human (FIH) studies in oncology (e.g., 3+3 dose escalation design) usually do not provide a sufficient sample size to determine the dose-response relationship for efficacy. This study aimed to assess the feasibility of using monoclonal antibody (mAb) clearance as a biomarker for efficacy to facilitate the identification of potentially efficacious doses across cancer types and drug targets. We performed electronic searches of the Drugs@FDA website, the European Medicines Agency website, and PubMed to identify reports of FIH trials of approved mAbs in oncology. The clearance, half-life, and overall response rate (ORR) data for the mAbs at different dose levels were extracted. Twenty-five approved mAbs were included in this study. As expected, due to the small sample sizes in FIH studies, there was no clear dose-response for ORR. However, we found a clear negative association between mAb clearance and ORR across tumors/drug targets, and a clear negative dose-clearance relationship, with clearance decreasing and saturated at high dose levels. The approved mAb doses (1-25 mg/kg) are approximately 2-fold the saturation doses (1-10 mg/kg). The associated clearance values at the approved doses vary across different cancers and drug targets (0.17-1.56 L/day), while tend to be similar within a disease/drug target. Anti-CD20 mAbs for B-cell lymphomas show a higher clearance (~ 1 L/day) than other cancers and targets (e.g., ~0.3 L/day for anti-PD-1). Clearance of mAbs can be a tumor/drug target-agnostic biomarker for potential anti-tumor activity as clearance decreases with increasing ORR. Our findings shed important insights into target clearance values that may lead to desired efficacy for different cancers and drug targets, which can be used to guide dose selection for the future development of mAbs during FIH oncology studies.

Computational and Experimental Evaluation of Linker Peptides and Thioredoxin Fusion Tag in CD20-rituximab Specific Interactions.

Overexpression of CD20 protein on the surface of B cells in lymphoma can be targeted by several anti-CD20 molecules. The development of accessible interactive epitopes is more favorable than the full-length transmembrane CD20 in the affinity assessment of anti-CD20 monoclonal antibodies (mAbs). The sequence of these epitopes was extracted, and the effects of different linker peptides and the location of histidine (His)-tag were computationally analyzed. The impact of thioredoxin (Trx)-tag on the folding of the selected construct and its interaction with rituximab was further investigated. The two final expression cassettes were expressed in Escherichia coli after optimization of culture conditions for incubation temperature, post-induction time, optical density at the induction time, and concentration of the inducer. ELISA evaluated the binding affinity of rituximab towards the recombinant proteins. By homology modeling studies, C-terminal His-tagged structures represented more desirable folded structures. Validation of the models revealed that CD20 extracellular domain linked by the G4S polypeptide had better stereochemical quality and structural compatibility. It was selected due to its more effective interaction with rituximab showing the highest dissociation constant of 5.8E-09M, which improved after the fusion of Trx-tag (7.1E-10M). The most influential parameters in the expression of the two selected proteins were post-induction temperature and optical density at the induction time. Homemade ELISA assays revealed a slightly higher affinity of rituximab towards the Trx-CD20 protein than the CD20/G4S molecule. Experimental in vitro studies confirmed the computationally calculated affinity of rituximab towards the two designed CD20 constructs. Also, the cell-based binding assessment of anti-CD20 mAbs could be substituted by the engineered extracellular domain of human CD20 protein.

The case report of AQP4 and MOG IgG double positive NMOSD treated with subcutaneous Ofatumumab

Neuromyelitis optica spectrum disorders (NMOSD) is an autoimmune demyelinating disease with IgG against aquaporin 4 (AQP4) in more than two thirds of patients. Anti-myelin-oligodendrocyte glycoprotein (MOG) antibody is found in some AQP4-negative NMOSD patients and MOG antibody-associated disease (MOGAD) is thought to be distinct from NMOSD. Due to the high disabling nature of NMOSD, treatment strategy on first attack is crucial for good prognosis. Rituximab (RTX), an anti-CD20 monoclonal antibody (mAb), is the first-line treatment for NMOSD. However, RTX can be limited by the relatively high rate of systemic allergic reaction. Herein, we reported a rare case of AQP4 and MOG-IgG double positive NMOSD patient effectively and safely treated with ofatumumab (OFA), a novel fully humanized anti-CD20 mAb.

CAR-T Cell-Mediated B-Cell Depletion in Central Nervous System Autoimmunity.

Anti-CD20 monoclonal antibody (mAb) B-cell depletion is a remarkably successful multiple sclerosis (MS) treatment. Chimeric antigen receptor (CAR)-T cells, which target antigens in a non-major histocompatibility complex (MHC)-restricted manner, can penetrate tissues more thoroughly than mAbs. However, a previous study indicated that anti-CD19 CAR-T cells can paradoxically exacerbate experimental autoimmune encephalomyelitis (EAE) disease. We tested anti-CD19 CAR-T cells in a B-cell-dependent EAE model that is responsive to anti-CD20 B-cell depletion similar to the clinical benefit of anti-CD20 mAb treatment in MS. Anti-CD19 CAR-T cells or control cells that overexpressed green fluorescent protein were transferred into C57BL/6 mice pretreated with cyclophosphamide (Cy). Mice were immunized with recombinant human (rh) myelin oligodendrocyte protein (MOG), which causes EAE in a B-cell-dependent manner. Mice were evaluated for B-cell depletion, clinical and histologic signs of EAE, and immune modulation. Clinical scores and lymphocyte infiltration were reduced in mice treated with either anti-CD19 CAR-T cells with Cy or control cells with Cy, but not with Cy alone. B-cell depletion was observed in peripheral lymphoid tissue and in the CNS of mice treated with anti-CD19 CAR-T cells with Cy pretreatment. Th1 or Th17 populations did not differ in anti-CD19 CAR-T cell, control cell-treated animals, or Cy alone. In contrast to previous data showing that anti-CD19 CAR-T cell treatment exacerbated EAE, we observed that anti-CD19 CAR-T cells ameliorated EAE. In addition, anti-CD19 CAR-T cells thoroughly depleted B cells in peripheral tissues and in the CNS. However, the clinical benefit occurred independently of antigen specificity or B-cell depletion.

Prolonged B-Lymphocyte-Mediated Immune and Inflammatory Responses to Tuberculosis Infection in the Lungs of TB-Resistant Mice.

During tuberculosis (TB) infection, B-lymphocytes migrate to the lungs and form B-cell follicles (BCFs) in the vicinity of TB granulomata. B-cell-lacking mice display enhanced susceptibility to TB infection, and early B-cell depletion in infected non-human primates alters T-lymphocyte cytokine responses and increases bacterial burdens in the lungs. However, the role of B cells during late TB stages remained unaddressed. Here, we demonstrate that B cells and BCFs persist up to weeks 25-45 post-challenge in the lungs of TB-resistant C57BL/6 (B6) mice. In hyper-susceptible I/St mice, B-cell content markedly drops between weeks 12-16 post-infection, paralleled by diffuse lung tissue inflammation and elevated gene expression levels for pro-inflammatory cytokines IL-1, IL-11, IL-17a, and TNF-α. To check whether B-cells/BCFs control TB infection at advanced stages, we specifically depleted B-cells from B6 mice by administrating anti-CD20 mAbs at week 16 post-infection. This resulted in more rapid cachexia, a shortened lifespan of the infected animals, an increase in (i) lung-infiltrating CD8+ T cells, (ii) IL-6 production by F4/80+ macrophages, (iii) expression levels of genes for neutrophil-attracting factors CXCL1 and IL-17, and tissue-damaging factors MMP8, MMP9, and S100A8. Taken together, our results suggest that lung B cells and BCFs are moderately protective against chronic TB infection.

CAR-T Cell-Mediated B Cell Depletion in Central Nervous System Autoimmunity

Objective Evaluate chimeric antigen receptor (CAR)-T cell mediated B cell depletion in experimental autoimmune encephalomyelitis (EAE). Background CAR-T cells are autologous T cells expressing a non-MHC target antigen specific receptor. We tested whether anti-CD19 CAR-T cells, which more thoroughly deplete human B cell populations than monoclonal antibodies (mAbs), recapitulated the beneficial effects of B cell depletion in EAE. Design/Methods Anti-CD19 CAR-T cells or control T cells that overexpressed green fluorescent protein were transferred into female wild-type C57BL/6 mice that had been pretreated with cyclophosphamide. EAE was induced by immunization with either recombinant human (rh) myelin oligodendrocyte protein (MOG) (B cell-dependent) or MOG peptide (p) 35-55 (B cell-independent). Mice were evaluated daily for clinical signs of EAE and weekly for peripheral B and T cell counts. B cell levels, T cell immune modulation and histology were assessed at peak disease and at termination. Results In rhMOG-induced EAE, clinical scores and histologic lymphocyte infiltration were reduced in mice treated with cyclophosphamide and either anti-CD19 CAR-T cells or control T cells. B cell depletion was observed in peripheral lymphoid tissue and in the central nervous system (CNS) of mice treated with anti-CD19 CAR T cells, similar to effects of anti-CD20 mAbs. There was no difference in T cell modulation including Th1 or Th17 populations, but there was a trend towards increase in Treg populations in the periphery and CNS in the anti-CD19 CAR-T cell and control T cell treated animals. Clinical scores and histology did not differ among treatment groups in p35-55-induced disease. Conclusions Anti-CD19 CAR-T cells thoroughly deplete B cells peripherally and within the CNS. Treatment also results in less severe rhMOG-induced disease, but it was independent of B cell depletion. Our results are consistent with human data indicating that anti-CD19 CAR-T cells deplete B cells across compartments, suggesting that they may hold promise for progressive MS.

IPSC-Derived CD38-Null NK Cells in Combination with CD38-Targeted Antibody: A Dual Therapeutic Strategy to Enable ADCC and Eliminate Host Immune Cells in Multiple Myeloma

Anti-CD38 therapeutic monoclonal antibodies (mAbs) such as daratumumab (dara) have shown wide application and therapeutic benefit for Multiple Myeloma (MM) patients. However, antibody-dependent cell-mediated cytotoxicity (ADCC), a critical mechanism of action associated with many mAbs, is not realized for anti-CD38 mAbs as the effector cells with the potential to elicit ADCC, namely natural killer (NK) cells, are also positive for CD38 surface expression and succumb to anti-CD38 mAb-mediated fratricide. To develop a therapeutic strategy that captures the full breadth of the anti-tumor capacity of dara and other anti-CD38 mAbs, we utilized our induced pluripotent stem cell (iPSC) platform, where the generation of precisely engineered master iPSC lines serve as the starting material for the manufacture of uniformly engineered immune cells for off-the-shelf cell therapies. To generate an iPSC-derived NK (iNK) cell capable of maximizing ADCC in combination with dara, a master iPSC line (termed FT538) was created containing three unique edits; a high-affinity, non-cleavable CD16 (hnCD16) to potentiate ADCC in combination with mAb, a recombinant IL-15 receptor fusion (IL-15RF) for cytokine-autonomous persistence and importantly, deletion of CD38 expression to prevent anti-CD38 mAb mediated fratricide and to enhance NK cell fitness. In addition to previous studies, we show here in a variety of preclinical models, FT538 has the unique ability to exhibit potent ADCC when combined with dara by avoiding anti-CD38 mAb-mediated fratricide (MM1s tumor remaining after FT538 + dara = 16%, after primary NK cell + dara = 61%). Similar results were seen in xenograft tumor models of MM, where established MM1S cells were controlled for growth when dara was combined with FT538 compared to dara alone (p<0.001) or FT538 alone (p<0.001). Having established the unique ability of FT538 to avoid fratricide in the presence of dara, we next investigated whether anti-CD38 mAb could also deplete alloreactive CD38+ lymphocytes to reduce or eliminate the need to administer the unfavorable lymphodepleting conditioning (LDC) currently used in cellular immunotherapy. To evaluate the effect of anti-CD38 mAb on host lymphocyte reconstitution we used flow cytometry to characterize PBMCs or marrow collected from MM patients after LDC with cytoxan 300 mg/m2 and fludarabine 30 mg/m2 x 3 days either as monotherapy (N = 4) or in combination with dara 16 mg/kg 1 week prior to LDC (Day -11) and weekly thereafter (n = 3) (NCT05182073). Prior to LDC the NK cell population in patients without dara treatment was highly CD38+ (80-90%). However, after 1 dose of dara patient NK cells expressed reduced CD38 (all <20%). In monotherapy patients CD8+ T cells reconstituting after LDC were predominantly CD38+ by Day 8 (80-90%) and remained so through Day 29 (Figure 1). In contrast, in dara treated patients reconstituting NK and T cells were significantly reduced in number with low CD38 expression. The same pattern was observed in bone marrow lymphocytes. To fully eliminate the dependency on LDC, FT538 was further engineered with the knockout of beta-2 macroglobulin and class II major histocompatibility complex transactivator (B2M/CIITA-null) to render it undetectable by CD8+ cytotoxic and CD4+ T cells, respectively. B2M/CIITA-null FT538 showed complete loss of HLA class I and class II expression, became unrecognizable by CD8+ and CD4+ T cells and in combination with dara, displayed persistence in various allogeneic models consisting of co-culture with allogeneic NK and T cells. In an in vivo allogeneic model, B2M/CIITA-null FT538 and allogeneic NK cells were co-infused into NOG-IL15 mice with or without anti-CD38 mAb. In the presence of anti-CD38 mAb treatment, B2M/CIITA-null FT538 continued to persist while allogeneic NK cells were not detected, while in the study arm that lacked anti-CD38 mAb, B2M/CIITA-null FT538 was eliminated by the persisting allogeneic NK cells (p<0.001). In summary, these data demonstrate the potential to combine off-the-shelf iPSC-derived CD38-null NK cells with anti-CD38 mAb as a novel therapeutic strategy, uniquely demonstrating the potentiating of ADCC while reducing or eliminating the need for LDC in cell therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Pre-Clinical Efficacy of AB-101, an Allogeneic Cord-Blood Derived Natural Killer (NK) Cell Therapeutic Candidate, in Combination with Anti-CD38 Antibodies in Models of Multiple Myeloma

Introduction: AB-101 is a non-engineered, allogeneic, off-the-shelf, cryopreserved cord blood-derived natural killer (NK)-cell therapy in development as a cancer therapeutic. A highly scaled manufacturing process enables production of 1000s of doses of AB-101 from a single donor cord blood unit (CBU). AB-101 is derived from CBUs selected for KIR-B haplotype and natural high-affinity variant of CD16 (158V/V), which are associated with improved anti-tumor activity and ADCC enhancement, resulting in a highly active NK cell product without the requirement for additional engineering. We are developing AB-101 for combination with monoclonal antibodies (mAbs) to enhance antibody dependent cellular cytotoxicity (ADCC) in patients, initially in an ongoing Phase I clinical trial for NHL. To further develop AB-101 as an ADCC enhancer, we assessed anti-tumor activity in combination with CD38 mAb, against multiple myeloma (MM) cell lines. CD38 is a transmembrane glycoprotein that is uniformly and highly upregulated on MM cells. Anti-CD38 mAbs exert anti-tumor activity against MM through ADCC and other mechanisms. NK cells play a key role in ADCC responses through CD16 receptor signaling. However, the majority of NK cells express CD38 and are depleted by therapeutic CD38 mAbs which could limit their therapeutic efficacy. Combining NK cell therapies with anti-CD38 mAbs, thus necessitates CD38 knockout to prevent fratricide. AB-101 has a naturally low percent and intensity of CD38 expression. Here we present data demonstrating that AB-101 are resistant to anti-CD38 mAb-induced fratricide and can elicit significant ADCC against MM cell lines both in vitro and in vivo. Since anti-CD38 mAbs are combined with glucocorticoids in the clinic, we assessed the impact of dexamethasone and methylprednisolone on ADCC by AB-101. Here we report robust ADCC following treatment of AB-101 with glucocorticoids. Methods: AB-101 was screened for CD38 expression and incubated with anti-CD38 mAb - daratumumab or hIgG1 control (300 - 0.41 µg/ml) for 4 hours to assess fratricide. In vitro ADCC assays were performed at various effector to target ratios against control (Daudi and K562) and MM cell lines (NCI-H929, RPMI 8226, MM.1S and MM.1R) using 2 µg/ml of daratumumab or hIgG1. To study the effect of glucocorticoids, AB-101 was cultured in various concentrations of dexamethasone and methylprednisolone for 48 hours in the presence of 50 or 500 IU/ml of IL-2, prior to ADCC assay. In vivo efficacy of AB-101 in combination with daratumumab was assessed in the intraperitoneal (IP) MM.1S-Luc xenograft model in NSG mice (Figure 1A). Daratumumab and AB-101 were administered by IP injection. Tumor burden was assessed by bioluminescent imaging (BLI). Results: AB-101 was over 98% CD56+/CD3- with 87% CD56+/CD16+ population. Only 22% of GMP drug product were CD38+ with low intensity of expression compared to peripheral blood NK cells (~88%). In the presence of daratumumab AB-101 viability was unaltered compared to hIgG1 control demonstrating resistance to fratricide. Daratumumab enhanced ADCC potential of AB-101 against MM cell lines and Daudi in in vitro. ADCC against MM lines and Daudi did not decrease on exposure to glucocorticoids compared to no treatment group. In vivo anti-tumor efficacy, as evidenced by reduction in BLI signal, was observed in the MM.1S model in AB-101 + daratumumab groups compared to daratumumab and AB-101 alone (Figure 1B). AB-101 + daratumumab (1 and 3mpk) led to 98 and 99% tumor growth inhibition (TGI), respectively, relative to no treatment. Daratumumab monotherapy at 1 and 3mpk showed 21% and 87% TGI respectively, and AB-101 showed 16% TGI relative to no treatment. Conclusions: AB-101 has high and consistent expression of CD16 and low CD38 expression and is resistant to daratumumab induced fratricide and hence can be combined with daratumumab without additional engineering such as CD38 knockout. Daratumumab is combined in the clinic with glucocorticoids, immunomodulatory drugs (IMiDs) and proteosome inhibitors (PI). While IMiDs and PIs are reported to enhance NK cell function, glucocorticoids have been shown to diminish NK cell cytotoxicity. Data presented here suggests that ADCC potential of AB-101 is not negatively impacted by glucocorticoids. Taken together, the in vitro and in vivo data supports further clinical development of AB-101 in combination with daratumumab to treat MM patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Real-World Treatment (Tx) Patterns and Clinical Outcomes Among Patients (Pts) with Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL) Who Received at Least 2 Prior Lines of Therapy Including Bruton Tyrosine Kinase Inhibitor (BTKi) and/or B-Cell Lymphoma 2 Inhibitor (BCL2i)

Background: Real-world evidence highlighting the tx landscape and outcomes among pts with CLL/SLL who have received ≥3 lines (3L+) of systemic therapy that include a prior BTKi and/or BCL2i are limited. The objective of this study was to describe pt characteristics, tx patterns, and overall survival (OS) among these pts. Methods: This was a retrospective study using de-identified, electronic health records from the Flatiron Health database from 01/01/2011 to 02/28/2022. The study population included US pts aged ≥ 18 years with CLL/SLL who received ≥ 2 prior lines of therapy (LOT) including a BTKi (cohort 1) or both a BTKi and a BCL2i (cohort 2) and who initiated a subsequent LOT. For cohorts 1 and 2, respectively, the index date was defined as the start of 3L+ therapy after discontinuation of a BTKi and discontinuation of a BTKi and a BCL2i. Pts with any other primary cancers (except nonmelanoma skin cancer) within 12 months before the index date or during the follow-up period were excluded from the analytic cohorts. Descriptive analyses were conducted to examine pt characteristics and tx patterns. Time to discontinuation (TTD), time to next tx (TTNT), and OS for the index LOT were assessed using Kaplan-Meier (KM) method. TTD was defined as the time between index therapy start date and end date. TTNT was defined as the time between start of index therapy and start of subsequent LOT. Results: The study sample included 405 pts in cohort 1 and 57 pts in cohort 2, with a median follow-up of 18 and 11 months, respectively. The majority of pts (percent in cohort 1 and cohort 2) were aged ≥ 65 years (80.2% and 78.9%), male (60.2% and 50.9%), White (76% and 78.9%), and treated in the community setting (93.6% and 94.7%). Approximately 70% of pts in cohort 1 began their index LOT in 2018 or later, whereas 79% of pts in cohort 2 began their index LOT in 2019 or later. Pts in both cohorts were largely well functioning, with ECOG PS score ≤ 1 in 83.7% of cohort 1 and 68.0% of cohort 2. Disease transformation was reported among 8.9% of pts in cohort 1 and 14.0% of pts in cohort 2. Pts in cohort 1 received a median of 2 prior LOTs, whereas those in cohort 2 received a median of 3 prior LOTs. The most common txs observed in cohort 1 in the index LOT were BTKi monotherapy (20.0%), chemotherapy + anti-CD20 mAb (19.0%), BCL2i monotherapy (13.3%), and BCL2i + anti-CD20 mAb (13.1%). The most common txs observed in cohort 2 in the index LOT were BCL2i + anti-CD20 mAb (19.3%), phosphatidylinositol-3-kinase inhibitor monotherapy (17.5%), chemotherapy + anti-CD20 mAb (14.0%), and BCL2i monotherapy (12.3%). Median (95% CI) KM estimate of TTD for index therapy was 13.2 (11.1‒17.5) months and 7.1 (5.0‒11.8) months for cohorts 1 and 2, respectively. For pts who received a subsequent LOT after index therapy, the median (95% CI) KM estimate of TTNT was 11.3 (9.1‒12.6) months for cohort 1 and 6.6 (3.6‒10.1) months for cohort 2. The median (95% CI) OS was 33.1 (28.3‒40.0) months (Figure 1) and 16.6 (11.0‒27.5) months (Figure 2), and the 12-month OS estimate was 76.5% and 57.5%, for cohorts 1 and 2, respectively. Conclusions: The study findings highlight a significant unmet need in pts with 3L+ CLL/SLL. Real-world tx patterns observed in this study are reflective of a heterogenous tx landscape without the presence of a standard of care. The results indicate that pts receive similar txs as used in earlier LOTs. This rechallenging results in suboptimal disease control as indicated by short TTNT, TTD, and estimated OS. Study findings suggest that disease prognosis worsens among pts who were heavily pretreated (i.e., cohort 2, which received prior BTKi and BCL2i), despite the relatively small sample size. Although response and disease progression data were not captured in the Flatiron database, this study sufficiently demonstrates the need for newer and more effective options in the CLL/SLL tx landscape, which can delay disease progression while ensuring better disease control. Overall, these findings are generalizable to pts with CLL/SLL treated in the community setting in the US. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Rapid Tumor Debulking of Relapsed/Refractory CLL Patients By PI3Kδ Inhibition and Anti-CD20 Monoclonal Antibody Treatment

Introduction Effective multi-targeted drug combinations could rapidly achieve deep remissions in CLL allowing for defined duration treatment. The combination of a novel highly-specific phosphoinositide 3-kinase delta (PI3Kδ) inhibitor and casein kinase 1 epsilon (CSK1ε) inhibitor, umbralisib (UMB), and a glycoengineered chimeric monoclonal antibody (mAb) targeting a unique epitope on CD20, ublituximab (UBL), with the BCL2 inhibitor venetoclax (VEN) may decrease drug resistance, reduce risk of tumor lysis syndrome (TLS) and achieve higher levels of undetectable minimal residual disease (MRD). This triple agent therapy is being evaluated in relapsed or refractory CLL patients (U2-VEN, ClinicalTrials.gov NCT03379051). Patients received oral 800 mg UMB once-daily. For Cycle 1, UBL was given via IV on Day 1 (150 mg), Day 2 (750 mg), Day 8 (900 mg), Day 15 (900 mg), and then on Day 1 in Cycles 2 and 3 (900 mg); for 3 cycles of 28 days, followed by consolidation with UMB and VEN for cycles 4 to 24. Patient (n = 25) blood samples were collected Pre- and Post-treatment on days of UBL administration during cycles 1-3. Our studies focused on UMB and UBL treatment effects on: 1) The decrease in the circulating CLL tumor burden and thus the subsequent risk of TLS from the addition of VEN to the regimen; and 2) CD20 antigen loss on CLL cells, a major mechanism of anti-CD20 mAb resistance. Methods Blood was analyzed by clinical laboratory automated cell counter and then stained with antibodies against CD3, CD5, CD19, and CD20 for flow cytometry analysis. CLL cell counts were calculated from flow cytometry and clinical laboratory results. To quantitate CD20 surface molecules, peripheral blood mononuclear cells were isolated and stained for flow cytometry analysis with the addition of a Molecules of Equivalent Soluble Fluorochrome standard curve. All human specimen collection and usage was conducted with written informed consent after approval of our Institutional Research Subjects Review Board according to the ethical guidelines of the Declaration of Helsinki. Results Average CLL cell counts (47 x 109/L) decreased rapidly after administration of the first dose of UMB and UBL (C1D1 Post, 26 x 109/L), which rebounded the next day (C1D2 Pre, 43 x 109/L) and then decreased after the second treatment (C1D2 Post, 24 x 109/L). By Day 15, the average CLL cell count had dropped to 9 x 109/L, which decreased further to 5 x 109/L by the start of cycle 3 (Fig. 1). Notably, the variation in CLL cell counts (error bars) decreases over treatment time, suggesting that most CLL patients' tumor burdens are decreasing to a similar low level independent of starting CLL cell count. The change in average CLL cell count between Pre and Post measurements is initially very high (45% decrease C1D1) with decreasing effectiveness over treatment time (8% decrease C3D1). This change could be due to the loss of CLL cell membrane CD20 levels leading to mAb resistance. Pre-treatment (C1D1 Pre) average CLL cell membrane CD20 levels (n=18) were 29,000 CD20 molecules/cell. This decreased to 9,000 molecules/cell after the first treatment (C1D1 Post), stabilized at 9,100 molecules/cell on the next day (C1D2 Pre) and then decreased further after the second treatment (C1D2 Post) to 1600 molecules/cell. After day 8 treatment, CD20 levels remained at 1,000 molecules/cell or less until the end of this study (C3D1). Discussion UMB and UBL rapidly decrease circulating CLL counts over three cycles of treatment, reducing most CLL patient tumor burden to similar low levels. This clinical response could facilitate addition of VEN in the 4thcycle of therapy by decreasing the risk of TLS. The rapid loss of surface CD20 from CLL cells to 1,000 CD20 molecules/cell or less by C1D8 Post has the potential to cause acquired resistance to anti-CD20 mAb therapy. This rapid and sustained loss of CD20 levels is consistent with that reported at standard doses for other anti-CD20 mAbs. However, an effect of concomitant UMB on CD20 levels cannot be ruled out. Previous work suggests that lower anti-CD20 mAb doses can prevent these large decreases in CD20 levels and increase UBL efficacy. In conclusion, our initial data show that treatment with a selective PI3Kδ and CSK1ε inhibitor (UMB) combined with an anti-CD20 mAb (UBL) is effective in decreasing CLL cell counts in all patients assessed in the U2-VEN clinical trial. However, treatment efficacy could be limited by large decreases in the CLL surface CD20 levels. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Mezigdomide (CC-92480), a Potent, Novel Cereblon E3 Ligase Modulator (CELMoD), Combined with Dexamethasone (DEX) in Patients (pts) with Relapsed/Refractory Multiple Myeloma (RRMM): Preliminary Results from the Dose-Expansion Phase of the CC-92480-MM-001 Trial

Introduction: Mezigdomide (MEZI), a novel oral CELMoD® agent with enhanced tumoricidal and immune-stimulatory effects compared to immunomodulatory drugs (IMiDs®), induces maximal degradation of Ikaros and Aiolos, leading to increased apoptosis in myeloma cells. Preclinically, MEZI demonstrated potent synergy with DEX, proteasome inhibitors (PIs), and anti-CD38 monoclonal antibodies (mAbs). CC-92480-MM-001 (NCT03374085) is an ongoing phase 1/2 trial evaluating MEZI alone or in combination with DEX in pts with RRMM; in phase 1, the recommended phase 2 dose (RP2D) of MEZI in combination with DEX was selected at 1 mg once daily for 21/28 days (Richardson PG, et al. J Clin Oncol 2020;30[15 suppl]:8500). Here we report results from the dose-expansion cohort of MEZI + DEX in pts with heavily pretreated RRMM. Methods: Eligible pts had: RRMM; ≥ 3 prior lines of therapy; disease progression on or within 60 days of last myeloma therapy; refractoriness to LEN/POM, a PI, a glucocorticoid, and an anti-CD38 mAb. MEZI 1 mg was given orally on days 1-21 of each 28-day cycle, plus weekly DEX (40 mg; 20 mg if > 75 years of age). Primary objective was to determine efficacy by overall response rate (ORR); secondary objectives included safety/tolerability and additional efficacy assessments. Efficacy was also assessed in pts with plasmacytomas and in pts with prior anti-B-cell maturation antigen (BCMA) therapy. Pharmacodynamics was an exploratory objective. Results: As of May 24, 2022, 101 pts had received MEZI + DEX at the RP2D. Median age was 67 (range 42-85) years, median time since initial diagnosis was 7.4 (1.1-37.0) years, and 20.8% of pts had ISS stage III at study entry. Plasmacytomas were present in 38.6% of pts and 36/101 pts had high-risk cytogenetics (55/101 pts were not evaluable). Median number of prior regimens was 6 (range 3-15). Prior therapies included stem cell transplantation (77.2%) and anti-BCMA therapy (29.7%) (Table 1). All pts were refractory to last myeloma regimen and triple-class refractory (refractory to an IMiD agent [LEN/POM], a PI, and an anti-CD38 mAb), and 39.6% of pts were refractory to LEN, POM, ≥ 2 PIs, and an anti-CD38 mAb. Median follow-up was 5.8 (range 0.5-19.0) months, with a median number of 4 (1-18) cycles received and 23 (22.8%) pts continued on treatment. The main reason for discontinuation was progressive disease (50.5%). ORR was 39.6%, with 2 (2.0%) stringent complete responses, 3 (3.0%) complete responses, 18 (17.8%) very good partial responses, and 17 (16.8%) partial responses (Table 2). While data are not yet mature, the preliminary median duration of response was 8.3 (95% confidence interval [CI] 5.4-not reached) months and median progression-free survival was 4.6 (95% CI 3.2-6.3) months. ORR was 30.8% in pts with plasmacytomas (N = 39) and 50.0% in pts with prior anti-BCMA therapy (N = 30). Grade (Gr) 3/4 treatment-emergent adverse events (TEAEs) were reported in 90 (89.1%) pts. Most frequent (≥ 20% pts) hematologic Gr 3/4 TEAEs were neutropenia (74.3%, with 14.9% febrile neutropenia), anemia (32.7%), and thrombocytopenia (25.7%). Gr 3/4 infections were observed in 32.7% of pts; Gr 3/4 pneumonia and COVID-19 were present in 9.9% and 5.0% of pts, respectively. The occurrence of other Gr 3/4 non-hematologic TEAEs was generally low, including gastrointestinal disorders (5.9%), fatigue (4.0%), and rash (1.0%). Seventy-two (71.3%) pts and 29 (28.7%) had MEZI dose interruptions and reductions due to TEAEs, respectively; 6 (5.9%) pts discontinued MEZI due to TEAEs, with 1 pt due to hematological TEAEs. MEZI induced potent pharmacodynamic effects in this cohort, including substrate degradation and increases in activated and proliferating T cells in all pts, as well as in pts directly refractory to POM-based therapies demonstrating the mechanism of MEZI action is still functioning in this heavily pretreated population. Conclusions: MEZI + DEX had a manageable safety profile and demonstrated promising efficacy in pts with triple-class refractory RRMM, including pts with prior BCMA-targeted therapies, with an ORR of 40% and 50% respectively. These results support the development of MEZI in pts with MM. MEZI is currently being evaluated in combination with standard therapies in MM as part of a large, ongoing phase 1/2 trial (NCT03989414) and phase 3 trials in combination with PIs are planned. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Multicenter Open Label Phase 3 Study of Isatuximab Plus Lenalidomide and Dexamethasone with/without Bortezomib in the Treatment of Newly Diagnosed Non-Frail Transplant Ineligible Multiple Myeloma Elderly Patients (≥ 65; < 80 Years). IFM2020-05/Benefit

Background. The addition of the anti-CD38 monoclonal antibody (mAb) daratumumab to lenalidomide-dexamethasone (Rd) (MAIA) as part of the upfront treatment regimen for non-transplant eligible (NTE) newly diagnosed multiple myeloma (NDMM) has considerably increased survival. Interestingly, while median PFS reached 5 years, the sustained minimal residual disease (MRD) negativity rate was lower than 15%. To continue improving the treatment of NTE NDMM and allow most patients to survive with only one line of treatment, sustained MRD negativity rates need to further increase. Two randomized phase III studies are investigating the quadruplet combination of anti-CD38 mAb + bortezomib + Rd in the same NTE NDMM population, IMROZ (NCT03319667) and CEPHEUS (NCT03652064), with isatuximab and daratumumab, respectively, and VRd as the comparator arm. The design of these studies is expected to demonstrate the added value of an anti-CD38 mAb to VRd. However, VRd might be considered suboptimal SOC in NTE NDMM compared to the triplet-based regimen Dara-Rd until progression, given the results of the median PFS in the MAIA trial, with an unprecedented 5-year median PFS. We hypothesized that adding a proteasome inhibitor (PI) to the anti-CD38 mAb + Rd combination would significantly increase the sustained MRD negativity rate compared to the anti-CD38 mAb + Rd combination, the optimal standard of care (SOC) today in the NTE NDMM. We therefore have conducted the present study of Isa-VRd compared to Isa-Rd (IFM2020-05/Benefit). Benefit has fully enrolled as of August 2022, and there has been no safety warnings from the safety committee with the prolonged use of bortezomib on a weekly basis in combination to Isa-Rd. Study Design and Methods. 270 NTE NDMM patients, aged 65-79 years old and non-frail, were randomized and assigned in a 1:1 ratio to either the anti-CD38 mAb isatuximab + Rd (Isa-Rd) or isatuximab + VRd (Isa-VRd lite) (NCT04751877). Stratification across arms was done according to high-risk MM, age cutoff of 75 years and study centers. Patients receive isatuximab IV 10 mg/kg on days 1, 8, 15, and 22 of cycle 1, days 1 and 15 from cycle 2 to 12 and day 1 from cycle 13 onward, 28-day cycles. Lenalidomide and dexamethasone were given orally as approved. Bortezomib was administered weekly and subcutaneously on days 1, 8, 15 at 1.3 mg/m² from cycle 1 to 12 and on days 1, 15 from cycle 13 to 18, and then stopped. All patients will discontinue dexamethasone after cycle 12. Patients will then continue receiving Isa-Rd until progression in both arms. The primary objective is to evaluate the MRD negativity rate at 10-5 at 18 months in both arms. The study will be considered positive if the MRD negativity rate at 10-5 at 18 months is >30% in the Isa-VRd arm, and twice as much at the same time point in the Isa-Rd arm. Key secondary objectives include the survival analysis (OS, PFS, EFS, TTNT), response rates, duration of response, and safety. The study is estimated to read out December 2023, 18 months after the last patient enrolls.