As of April 15, 2022, 38 pts had received IBER + DEX in the anti-BCMA-exposed cohort. Median age was 65 (range 50–78) years and median time since initial diagnosis was 7.8 (0.6–24.8) years. High-risk cytogenetics were present in 31.6% of pts (52.6% pts were not evaluable), and 23.7% of pts had extramedullary plasmacytomas. Median number of prior regimens was 7 (4–15). All pts were triple-class exposed. Prior anti-BCMA therapies included CAR T cell therapy (36.8%), antibody-drug conjugates (34.2%), and T-cell engagers (TCEs; 23.7%) (Table); 78.9% of pts were refractory to the last antimyeloma regimen and 84.2% were triple-class refractory. Median follow-up was 8.1 (range 1.5–24.2) months, with a median number of 3.5 (1–19) cycles received and 21.1% of pts continuing treatment. Discontinuation was due mainly to PD, reported in 68.4% of pts.

ORR (≥ partial response) was 36.8%, with 2 (5.3%) complete responses, 5 (13.2%) very good partial responses, and 7 (18.4%) partial responses. Clinical benefit rate (≥ minimal response) was 39.5%. Responses were observed regardless of prior anti-BCMA therapy (Figure; updated data will be presented at the congress). Median duration of response was 7.5 (95% confidence interval [CI] 3.2–not reached) months, median progression-free survival was 2.4 (95% CI 2.1–4.2) months, and median time to response was 1.4 (range 0.9–5.4) months.

Grade (Gr) 3/4 treatment-emergent adverse events (TEAEs) occurred in 30 (78.9%) pts and were mostly hematologic; most frequent (≥ 20% pts) were neutropenia (50.0%, with 5.3% cases of febrile neutropenia), anemia (28.9%), leukopenia (23.7%), and thrombocytopenia (21.1%). Gr 3/4 infections occurred in 23.7% of pts and included pneumonia (21.1%); the occurrence of other Gr 3/4 non-hematologic TEAEs was low and included hypokalemia, hypertension, and mood alterations (all 5.3%). Two (5.3%) deaths were reported (due to sepsis and PD) which were not considered related to study treatment. IBER dose interruptions and reductions occurred in 24 (63.2%) and 7 (18.4%) pts, respectively. No pts discontinued IBER due to TEAEs.