Huang, Shang‐Yi

Abstract Background: Intravenous (IV) isatuximab plus pomalidomide and dexamethasone (Isa-Pd) is approved for treatment in patients with relapsed/refractory multiple myeloma (RRMM) based on the ICARIA-MM study. Subcutaneous (SC) administration of Isa offers potential advantages such as shorter administration duration and greater patient comfort compared with IV routes. Isa SC via an on-body injector (OBI), an investigational wearable bolus injector, demonstrated safety and efficacy in a Phase 1b study in patients with RRMM. The IRAKLIA trial (NCT05405166) was the first Phase 3 trial evaluating the non-inferiority of Isa-Pd SC via an OBI vs Isa-Pd IV in patients with RRMM. Here, we report the findings of the IRAKLIA trial in the East Asian subgroup with RRMM. Methods: This global, multicenter, open-label study enrolledpatients aged ≥18 years with RRMM who had received ≥1 prior line of therapy (LOT) including lenalidomide and a proteasome inhibitor (PI). Patients were randomized 1:1 to Isa SC (1400 mg) or Isa IV (10 mg/kg) weekly in Cycle (C)1, then every 2 weeks in addition to P (4 mg orally daily, Day [D]1-21) and d (40 mg orally [20 mg if age ≥75 years] weekly). Treatment was administered in 4-week cycles and continued until disease progression, unacceptable toxicity, or patient withdrawal. Co-primary endpoints included overall response rate (ORR) and observed Isa concentration before dosing (Ctrough) at steady state (predose at C6D1). Key secondary endpoints included rate of very good partial response or better (≥VGPR), Ctroughlevel Cycle 2 Day 1 (C2D1), infusion reaction incidence, and patient satisfaction rate based on the patient experience and satisfaction questionnaire (PESQ) at C5D15. Results: The East Asian subgroup consisted of 105 patients from China (Mainland, n=82 and Taiwan, n=1) and Japan(n=22) (SC, n=50; IV, n=55). Baseline characteristics of the East Asian subgroup were generally balanced between the two arms and generally comparable to the overall global population (median age 62 years; median 2 prior LOT; 29.5% high-risk cytogenetics; 82.9% refractory to lenalidomide; 7.6% prior exposure to daratumumab). After a median of 13.0 months follow-up, ORR in the SC and IV arm was 74.0% and 70.9%, respectively (relative risk [95% CI] = 1.044 [0.815 – 1.335]). The mean (SD) of Ctroughat C6D1 was 502 (232) µg/mL for SC arm and 282 (123) µg/mL for IV arm. The geometric mean ratio (90% CI) comparing SC to IV for Ctrough at steady state was 1.756 (1.346 – 2.290). The ≥VGPR rates were 58.0% for SC and 50.9% for IV (relative risk [95% CI] = 1.139 [0.798 – 1.631]). The mean(SD) of C2D1 Ctroughlevel was 420 (161) µg/mL for the SC arm and 262 (111) µg/mL for IV arm. The geometric mean ratio (90% CI) comparing SC to IV for Ctrough at C2D1 was 1.673 (1.321 to 2.120). The infusion reaction incidence was 0% and 21.8% for SC and IV, respectively. Grade ≥3treatment-emergent adverse events were observed in 82.0% and 87.3% of patients in the SC and IV arms, respectively. Treatment discontinuation rates were 6% for the SC arm and 12.7% for the IV arm. Injection site reactions (ISRs) occurred in 4% (2/50) of patients in the SC arm and in 0.21% (2/964) of SC injections (all Grade 1), with 99.3% of SC injections completed successfully. Isa SC patients expressed higher satisfaction with their injection method, with 64.0% of patients reporting “satisfied” or “very satisfied” vs 52.7% of Isa IV patients (odds ratio [95% CI] = 1.594 [0.728 – 3.489]). Conclusions: The efficacy, safety and pharmacokinetic results between Isa SC vs IV + Pd in the East Asian population from the IRAKLIA study were consistent with the results of the overall global population, in which non-inferiority of ORR, Ctrough at C6D1, ≥VGPR and Ctrough at C2D1 was demonstrated and statistically significantly fewer infusion reactions and higher patient satisfaction were also noted for SC vs IV. These results support the potential use of Isa SC delivered via OBI in East Asian patients and demonstrate the potential of this delivery method to improve patient experience and practice efficiency.

BACKGROUND ELRA is a humanized, BCMA/CD3 bispecific antibody. In the phase 2 registrational MagnetisMM-3 (MM-3) trial, SC ELRA given as 2 step-up priming doses (12 mg on day 1 and 32 mg on day 4 of cycle 1) followed by 76 mg QW in patients (pts) with RRMM naive to BCMA-directed therapy resulted in an ORR of 61.0%. With a median follow-up of 28.4 mos, the median DOR, PFS, and OS were not reached (NR; 2-year rate, 66.9%), 17.2, and 24.6 mos, respectively. Overall, 56.3% of pts had CRS (grade 2, 14.3%; no grade ≥3). Most events occurred after doses 1 (44.5%), 2 (20.2%), and 3 (5.9%); 0.8% (1 pt) had CRS with doses ≥4. Recurrent CRS occurred in 15.1% of pts. The phase 1/2 MagnetisMM-9 (MM-9; NCT05014412) study is examining an alternative priming regimen and longer dosing intervals of ELRA. Here, we present updated MM-9 results. METHODS In MM-9, pts with RRMM and disease refractory to ≥1 IMiD drug, ≥1 PI, and ≥1 anti-CD38 antibody were given SC ELRA as step-up priming doses of 4 and 20 mg on Day 1 and Day 4 of Cycle 1, respectively. After the priming doses, ELRA 76 mg was given QW for the next 6 cycles (Part 1) or for 1 cycle followed by 116 (dose level 1 [DL1]) or 152 (dose level 2 [DL2]) mg Q2W for the next 5 cycles (Part 2A). After 6 cycles, the dosing frequency was decreased from QW to Q2W (Part 1) or from Q2W to Q4W (Part 2) in pts who achieved ≥PR lasting ≥2 months. The recommended phase 2 dose from Part 2A (152 mg, DL2) was evaluated in Part 2B (dose expansion). The primary endpoint for both parts is grade ≥2 CRS rate per ASTCT criteria during Cycle 1. Secondary endpoints include evaluation of efficacy and adverse events. Data cutoff: February 13, 2024. RESULTS Overall, 85 pts (median age, 64.0 y) were treated with ELRA. The majority (72.9%) of pts had R-ISS stage I/II disease (23.5% with R-ISS stage III); 31.8% had high-risk cytogenetics. Median number of prior lines of therapy was 5.0 (range, 1-12). The median treatment duration was 8.6, 2.9, 1.4, and 3.3 mos, in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, respectively. Median follow-up for pts overall (n=85), in Part 1 (n=33), Part 2A DL1 (n=12), Part 2A DL2 (n=11), and Part 2B (n=29) was 10.4, 23.3, 16.5, 15.2, and 9.3 mos, respectively. Overall, the ORR was 58.8%. For pts in Part 1, Part 2A DL1, Part 2A DL2, or Part 2B, ORR was 66.7%, 58.3%, 36.4%, and 58.6%, respectively; median DOR was NR (9-mo rate: 86.4%), 10.8 mos (9-mo rate: 80.0%), NR (9-mo rate: 100.0%), and NR (9-mo rate: 84.8%); median PFS was 17.1 (9-mo rate: 62.8%), 11.6 (9-mo rate: 50.9%), 1.6 mos (9-mo rate: 40.0%), and NR (9-mo rate: 57.1%); median OS was NR (9-mo rate: 75.8%), 17.4 mos (9-mo rate: 66.7%), NR (9-mo rate: 60.0%), and NR (9-mo rate: 72.4%), respectively. For pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, grade ≥2 CRS rates during Cycle 1 were 15.2%, 16.7%, 27.3%, and 6.9%, respectively. For pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, CRS rates were 30.3%, 33.3%, 36.4%, and 24.1% after dose 1, 27.3%, 25.0%, 36.4%, and 24.1% after dose 2, 15.2%, 33.3%, 27.3%, and 20.7% after dose 3, 6.1%, 8.3%, 0%, and 3.4% after dose 4, and 6.1%, 16.7%, 9.1%, and 0% after doses ≥5. Recurrent CRS occurred in 18.2%, 33.3%, 18.2%, and 17.2% of pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B. The most common (>60%) TEAEs (any grade/grade ≥3) were hematologic TEAEs (Part 1, 75.8%/75.8%; Part 2A DL1, 83.3%/83.3%; Part 2A DL2, 81.8%/81.8%; Part 2B, 79.3%/69.0%), infections (Part 1, 78.8%/48.5%; Part 2A DL1, 83.3%/66.7%; Part 2A DL2, 72.7%/63.6%; Part 2B, 62.1%/37.9%), and CRS (Part 1, 60.6%/0%; Part 2A DL1, 83.3%/0%; Part 2A DL2, 90.9%/9.1%; Part 2B, 48.3%/0%). Grade 5 TEAEs not including PD were infection (n=4), fall (n=1), subdural hematoma (n=1), and food poisoning (n=1). CONCLUSIONS The 4/20 mg step-up priming regimen and alternative dosing schedules in MM-9 resulted in similar efficacy vs the step-up regimen used in the registrational MM-3 study (12/32 mg). Responses were durable with encouraging PFS and OS with the alternative step up and longer dosing schedule. While the overall safety signals with the alternative step up regimen are similar to those seen with MM-3, the CRS profile differed with more CRS events after each subsequent dose and a higher prevalence of recurrent CRS. Thus, the optimal ELRA step-up regimen remains 12/32 mg from the original regimen in the MM-3 study. In addition, these early results suggest that reducing the dose frequency of ELRA may not compromise efficacy.

AbstractObjectivesCluster of differentiation 38 (CD38) is a key target on multiple myeloma (MM) cells. This multi‐centre, Phase 1, single‐agent study (NCT04000282) investigated SAR442085, a novel fragment crystallisable (Fc)‐modified anti‐CD38 monoclonal antibody (mAb), with enhanced affinity towards Fc‐gamma receptor on effector cells in patients with relapsed and/or refractory (RR) MM.MethodsThis study comprised two parts: Part‐A (dose‐escalation involving anti‐CD38 mAb pre‐treated and naïve patients) and Part‐B (dose expansion). Primary endpoints were maximum tolerated dose and recommended Phase 2 dose (RP2D).ResultsThirty‐seven heavily pre‐treated patients were treated in Part A. Part‐B (dose‐expansion) was not studied. Seven dose‐limiting toxicities were reported at DL3, DL5, DL6, and DL7. RP2D was determined to be 5–7·5 mg/kg. Most common treatment‐emergent adverse events were infusion‐related reactions in 70·3% (26/37) patients. Grade ≥3 thrombocytopenia was reported in 48·6% (18/37). Overall response rate was 70% in anti‐CD38 mAb naïve and 4% in anti‐CD38 pre‐treated patients, with a median progression‐free survival of 7·62 (95%CI: 2·858; not calculable) months and 2·79 (95%CI: 1·150; 4·172) months and, respectively.ConclusionsThe efficacy of SAR442085 was promising in anti‐CD38 mAb naïve patients but did not extend to the larger cohort of anti‐CD38 mAb pre‐treated patients. This observation, along with transient high‐grade thrombocytopenia, could potentially limit its clinical use.