Safety results from the phase 3 MajesTEC-7 study in patients (pts) with transplant ineligible/not intended newly diagnosed multiple myeloma (NDMM).

7506 Background: Despite recent advances in the treatment (tx) of transplant ineligible/not intended NDMM, most pts still relapse and require alternative txs, highlighting a need for new frontline tx options with new mechanisms of action to improve pt outcomes. Teclistamab (tec) demonstrated rapid, deep, and durable responses in the MajesTEC-1 trial (NCT03145181/NCT04557098). Preliminary data from the MajesTEC-2 trial (NCT04722146) demonstrated that tec, daratumumab (dara), and lenalidomide (len) combination (tec + DR) is tolerable, with promising efficacy in pts with relapsed/refractory MM and NDMM. The phase 3 MajesTEC-7 (NCT05552222) study will compare tec + DR vs DR + dexamethasone (dex) in pts with NDMM who are ineligible/not intended for ASCT as initial tx. We report the results of the first safety run-in (SRI) from MajesTEC-7. Methods: Eligible patients were aged ≥18 yrs with NDMM and ineligible/not intended for ASCT as initial tx, with measurable disease and an ECOG performance status (PS) score 0–2. Pts in the SRI received tec (step-up dose cycle 1, QW cycle 2, Q2W cycle 3–6, and Q4W cycle 7+) + DR (as SOC) until progression, unacceptable toxicity, or death. Response assessments were based on IMWG criteria. Adverse events (AEs) were graded per CTCAE v5.0; cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded per ASTCT criteria. Prophylactic immunoglobulin replacement was highly recommended. Results: As of Nov 27, 2023, 26 pts had received tec + DR (median, 11 cycles; range, 2–14) and 24 pts (92.3%) remained on tx. Median follow-up was 10.2 mo (range, 2–12). At baseline, median age was 72.5 yrs, 11.5% had an ECOG PS score of 2, and 15.4% had ≥1 soft-tissue plasmacytoma. 4 pts (15.4%) deferred transplant. Treatment-emergent AEs (TEAEs) occurred in 100% of pts (grade gr 3/4, 22 pts 84.6%). Infections occurred in 25 pts (96.2%; gr 3/4, 8 pts 30.8%). CRS occurred in 16 pts (61.5%; all gr 1). ICANS occurred in 1 pt (gr 1). Gr 3/4 TEAEs occurring in ≥3 pts were neutropenia (13 50%), febrile neutropenia (5 19.2%), thrombocytopenia (4 15.4%), COVID-19 (3 11.5%), maculo-papular rash (3 11.5%), and hypertension (3 11.5%). 1 pt discontinued tec + DR due to withdrawal of consent. 2 discontinued len due to TEAEs (gr 3 maculo-papular rash and gr 4 neutropenia). There was 1 death due to a TEAE in cycle 3 (pneumonia influenza). Overall response rate was 92.3% (complete response or better, 73.1%; very good partial response or better, 92.3%). Conclusions: These results from the first SRI of MajesTEC-7 demonstrate a manageable safety profile with early efficacy of tec + DR in NDMM. Two additional SRIs are ongoing investigating tec (less frequent dosing) + DR and talquetamab + DR. Clinical trial information: NCT05552222 .