forimtamig (RG6234)

Forimtamig is currently being evaluated in Phase 1 clinical trials in relapsed and refractory myeloma (RRMM) patients for monotherapy and in combination treatments. NCT04557150.

P1/2, N=316, Recruiting, Hoffmann-La Roche | Phase classification: P1 --> P1/2

P1, N=316, Recruiting, Hoffmann-La Roche | Not yet recruiting --> Recruiting

To evaluate if cereblon modulation represents a strategy to improve PFS, we combined fixed-duration forimtamig with either pomalidomide (pom) or iberdomide (iber) at C1 day 1 (C1D1). Taken together, our data suggest that combination with CELMoDs but not IMIDs can prevent relapse to forimtamig driven by GPRC5D negative tumor cells. We confirm timing of intervention with CELMoDs to have an significant impact on PFS and cytokine release and suggest a broad therapeutic window using low dose forimtamig and intermittent dosing of iberdomide or mezigdomide.

GPRC5D, FcRH5 and BCMA are highly prevalent across MM patient subgroups, including high-risk patients who may warrant targeted therapy approaches. Based on our data and previously published work for FcRH5- and BCMA-targeted T-cell bispecifics (Sumiyoshi et al. EHA 2021; Cortes-Selva et al.

P1, N=316, Not yet recruiting, Hoffmann-La Roche | Phase classification: P1/2 --> P1

Synergistic anti-tumoral and NK stimulatory effects suggest a benefit of daratumumab combination in patients with high tumor burden and high risk of developing CRS. Broad immunomodulatory effects of pomalidomide could help sustain T cell responses in patients but may increase the risk of CRS. Considering the importance of balancing CRS and efficacy, carfilzomib was identified as another promising combination partner for forimtamig.

Various T-cell redirecting BsAbs are in advanced stages of clinical development with promising activity and a manageable toxicity profile. Ongoing studies are evaluating combination strategies, fixed-duration treatment, and use of BsAbs in earlier lines of therapy. TsAbs hold great promise for the future.

P1, N=480, Recruiting, Hoffmann-La Roche | Trial completion date: Jun 2025 --> Aug 2026 | Trial primary completion date: Jun 2025 --> Aug 2026

These BsAb show impressive clinical activity for the relapsed/refractory population targeted and will likely become an essential part of MM treatment protocols in the future. In this podcast, the authors summarize and highlight some of the T cell-redirecting BsAb currently in development for the treatment of relapsed/refractory MM with a focus on the data reported at the oral session for BsAb at the American Society of Hematology's 2022 meeting from clinical phase 1 and 2 studies. The six presentations reported the latest safety and efficacy data for the BsAb: talquetamab, elranatamab, teclistamab, forimtamig, and alnuctamab.

P1, N=400, Recruiting, Hoffmann-La Roche | Trial completion date: Jan 2026 --> Jun 2025 | Trial primary completion date: Jan 2026 --> Jun 2025

This activity is supported by educational grants from AbbVie Inc, Genentech, a member of the Roche Group, Genmab US Inc, Karyopharm Therapeutics, Lilly, Regeneron Pharmaceuticals Inc, Sanofi, and Seagen Inc. Clinical and biological factors affecting the selection of up-front therapy for patients with MMLong-term findings with daratumumab-containing regimens for newly diagnosed MM; role for transplant-eligible and ineligible patientsPublished data with novel daratumumab-based quadruplet regimens for transplant-eligible patients with newly diagnosed MMSimilarities and differences between daratumumab and isatuximabKey findings from the Phase III GMMG HD7 trial comparing isatuximab with RVd to RVd alone for transplant-eligible patients with newly diagnosed MMOngoing Phase III studies of isatuximab as a part of induction therapy for transplant-eligible and ineligible patientsAvailable data with and current role of minimal residual disease assessment in therapeutic decision-makingOptimal maintenance approach for transplant-eligible and ineligible patientsResults from Phase III trials evaluating isatuximab-based combination regimens for relapsed/refractory (R/R) MMKey results from the Phase III BOSTON trial leading to the FDA approval of selinexor in combination with bortezomib/dexamethasone for R/R MM; available data with other selinexor-based combinationsStructural makeup and manufacturing of available B-cell maturation antigen (BCMA)-directed chimeric antigen receptor (CAR) T-cell platformsEfficacy and safety findings from the KarMMa (idecabtagene vicleucel) and CARTITUDE-1 (ciltacabtagene autoleucel) trials for R/R MMAvailable and emerging data with and ongoing studies of BCMA-targeted CAR T-cell therapies in earlier lines of treatmentSimilarities and differences in the cellular targets and mechanisms of action of bispecific antibodies in MMActivity and responses observed with available (teclistamab) and investigational (elranatamab, linvoseltamab, ABBV-383) BCMA-targeted bispecific antibodies in R/R MMBiological rationale for and available data with non-BCMA-targeted bispecific antibodies (eg, talquetamab, cevostamab, forimtamig); FDA breakthrough therapy designation for talquetamabSpectrum, incidence and severity of toxicities, including cytokine release syndrome and neurotoxicity, with bispecific antibodies in patients with MM; mitigation and management protocolsPublished data with and current role of venetoclax-based therapy for patients with MM and t(11;14) or Bcl-2 overexpressionOther promising novel strategies in clinical development for patients with MM

Despite promising efficacy in MM, BsAbs may come with substantial infection risk, warranting more detailed analysis of infections and immune phenotyping to guide targeted supportive care. Table – Summary of included studiesAgent Target Source Phase Enrolment (mm/yy) N Median prior lines All- Grade Infection N (%) Grade ≥3 Infection N (%) Alnuctamab (CC-93269) BCMA Wong 2022 I 03/18- 68 4 23 (34) 6 (9) ABBV-383 BCMA Voorhees 2022 I 10/22- 174 5 61/124 (50) 39/124 (22) Elranatamab BCMA Raje 2022 I 10/21- 123 5 82 (67) 43 (35) Linvoseltamab (REGN545) BCMA Bumma 2022 Ib/II 1/19- 252 5 136 (54) 73 (29) Pacanalotamab (AMG-420) BCMA Topp 2020 I 3/19 – 4/22 42 5 14 (33) 10 (24) Teclistamab BCMA Moreau 2022 I/II 09/20- 165 5 126 (77) 57 (45) Teclistamab + daratumumab BCMA + CD38 Rodriguez- Otero 2022 II 03/21- 46 5 29 (63) 8 (17) Forimtamig (RG6234) GPRC5D Carlo- Stella 2022 I 11/20- IV: 51 SC: 57 IV: 5 SC: 4 IV: 31 (61) SC: 26 (46) IV:11 (22) SC:15 (27) Talquetamab GPRC5D Chari 2022 I/II 02/21- 288 5 153 (53) 46 (16) Talquetamab + daratumumab GPRC5D + CD38 Van de Donk 2022 II 09/21- 46 5 23 (50) 6 (13) Cevostamab (BFCR4350A) FcRH5 Trudel 2021 I 07/21- 161 6 68 (43) 18 (11) Bispecific, Multiple myeloma, Cellular therapy

The mechanistic model is able to simulate RG6234-induced T-cell mediated tumor cell killing and can be utilized to predict response and CRS in virtual populations after IV administrations at different dosing regimens. A model validation is planned with data from the expansion cohort of the study.

Biomarker analysis indicates that RG6234 leads to T-cell engagement in the BM of patients with RRMM and demonstrates rapid and effective T-cell mediated anti-myeloma activity irrespective of the route of administration. Cytokine release, T-cell activation followed by BM infiltration, and MM cell depletion are early PD changes after IV and SC administration and precede clinical responses. Compared with IV dosing, SC administration reduces peak cytokine levels in Cycle 1, suggesting a more subtle immune activation and a potential safety benefit for patients.

We next evaluated the therapeutic capacity of RG6234 in combination with daratumumab (Dara) and/or pomalidomide (Pom) in total BM aspirate samples from 10 MM patients with variable frequency of GPRC5D positive MM plasma cells (range 74-98%)...To validate synergistic combination activity upon repetitive dosing huNSG mice were engrafted s.c. with RPMI-8226 or OMP-2 tumors and treated with RG6234 in combination with Dara or Lenalidomide (Len), respectively...Improved efficacy in combination with Len was found to correlate with significant expansion of intratumoral T cells 48h after second injection. In summary, we demonstrate preclinical evidence for best in class potential of the RG6234 antibody format for the treatment of multiple myeloma.

Conclusion Cytokine release, T-cell activation, BM infiltration, and MM cell depletion are early PD changes seen after treatment with RG6234 and precede clinical responses. These PD changes indicate that RG6234 leads to T-cell engagement in the BM of pts with RRMM and clearly demonstrate rapid and effective T-cell mediated anti-MM activity.