Sémiond, Dorothée

Abstract Introduction: IRAKLIA is an international, open-label, non-inferiority (NI) trial (NCT05405166) investigating isatuximab (Isa) subcutaneous (SC) vs intravenous (IV) administration, plus pomalidomide-dexamethasone (Pd) and the first Phase 3 multiple myeloma (MM) trial using an on-body injector (OBI). IRAKLIA demonstrated NI in its co-primary endpoints: overall response rate (ORR) and steady state trough concentration (Ctrough; Cycle(C) 6 Day(D) 1 predose). IsaOBI offers hands-free administration of flat-dose Isa, a small, hidden, retractable needle to prevent sharps injury and low-pressure delivery. Here, we examine the effect of body weight (BW) on pharmacokinetics (PK) as well as efficacy and safety outcomes with flat-dose IsaOBI vs IV + Pd in IRAKLIA. Methods: Patients (pts) with relapsed/refractory MM ≥18 years (yr) with ≥1 prior line of therapy (LOT) were randomized 1:1 to IsaOBI (1400mg; n=263) or IV (10mg/kg; n=264 weekly in C1, then every 2 weeks + P (4mg/day, D1–21) + d (40mg [20mg if ≥75yr] weekly) in 4-week cycles. This analysis is run by BW (≤65kg, >65–≤85kg, >85kg) which was a stratification factor, and extreme BW (≤50kg, >50–≤100kg, >100kg). Results: Number of pts per BW group were: ≤50kg [OBI n=16, IV n=14], ≤65kg [OBI n=84, IV n=85], >65–≤85kg [OBI n=117, IV n=118], >85kg [OBI n=62, IV n=65], and >100kg [OBI n=22, IV n=22]. Baseline (BL) demographic and disease characteristics were generally balanced across BW groups for IsaOBI vs IV, including age (median 66yr) and prior LOT (median 2). However, in the >100kg group, more IsaOBI vs IV pts exhibited poor prognostic characteristics including plasmacytoma, International Staging System Stage II/III disease, beta 2-microglobulin level ≥5.5mg/L, estimated glomerular filtration rate <60mL/min/1.73m2 and a lower very good partial response (VGPR) rate as best overall response at last regimen. Flat-dose IsaOBI showed adequate exposure (C2D1 Ctrough) for all BW groups, with geometric mean ratios (90% CI) vs IV >1: ≤65kg (1.628 [1.294–2.048]), >65–≤85kg (1.303 [1.089–1.560]) and >85kg (1.006 [0.817–1.239]). IsaOBI ORRs were comparable to IV across BW: ≤65kg, 66% vs 71% (relative risk [RR]: 0.928), >65–≤85kg, 70% vs 70% (RR: 1.009), and >85kg, 81% vs 72% (RR: 1.115). For extreme BW groups, ORRs (95% CI) were similar between IsaOBI and IV for ≤50kg group [56% vs 60%] and for >50–≤100kg [72(66–78)% vs 70(63–76)%] but lower [68% vs 86%] in >100kg group. An exposure-response (E-R) analysis showed the impact of BW on response: IsaOBI pts ≤50kg tended to respond less vs IsaOBI pts >50kg despite correct exposure because they were confounded by BL disease characteristicsincluding a higher proportion of high-risk cytogenetics and plasma cells in the bone marrow vs other BW group pts. For IsaOBI and IV, Grade (Gr)≥3 treatment-emergent adverse events (TEAEs) and Gr≥3 treatment-related TEAEs decreased with increasing BW. They were similar between arms in ≤65kg group (OBI vs IV, Gr≥3 TEAEs: 87% vs 88%; Gr≥3 treatment-related TEAEs: 73% vs 77%). A similar trend was observed in extreme BW groups along with similar incidences between arms in ≤50kg group. While TE serious AEs (TESAEs) and treatment-related TESAEs decreased with increasing BW for IsaIV, incidence was stable in the IsaOBI arm. OBI arm OBI Gr5 TEAEs were similar between groups and arms, except for higher incidence in ≤65kg group (12% vs 5%) with OBI vs IV that was not reflected in ≤50 or >50–≤100kg groups. Treatment discontinuation rates for all drugs with IsaOBI vs IV were 14% vs 6% (≤65kg), 8% vs 10% (>65–≤85kg), and 2% vs 10% (>85kg). Similar incidence of Gr≥3 laboratory (lab) neutropenia was observed across BW in IsaOBI: 86.9% (≤65kg), 83.5% (>65–≤85kg) and 83.9% (>85kg). Higher rates of Gr≥3 lab neutropenia were observed in ≤50kg group (93.8%, IsaOBI vs 71.4%, IsaIV), which did not translate into higher rates of neutropenic complications (18.8% vs 14.3%). The E-R analysis revealed no relationship between Isa PK exposure and safety for OBI and IV arms. Conclusions: No notable impact from IsaOBI flat dosing was observed across BW groups. Flat-dose Isa OBI showed consistent safety and efficacy across different BW groups, with differences likely linked to BL disease characteristics according to the E-R analysis. The IsaOBI C2D1 Ctrough, a time-independent predictor of efficacy, was similar to, or higher vs IsaIV in each BW group, supportive of a flat dose providing adequate exposure without need for adjustment.

PURPOSE To report the results of the multicenter, open-label IRAKLIA trial (ClinicalTrials.gov identifier: NCT05405166 ) of isatuximab subcutaneous (SC) versus intravenous (IV), plus pomalidomide and dexamethasone, in relapsed/refractory multiple myeloma (MM), to our knowledge, the first phase III MM trial using an on-body injector (OBI). METHODS Patients with ≥1 prior line of therapy were randomly assigned 1:1 to Isa OBI (1,400 mg) or IV (10 mg/kg) once weekly in cycle (C)1 and then every 2 weeks, plus pomalidomide (4 mg once daily, day [D]1-21) and dexamethasone (40 mg once weekly [age ≥75: 20 mg]) and treated until progression, unacceptable toxicity, or patient request. Coprimary end points were overall response rate (ORR; noninferiority margin, 0.839) and Isa C trough (C6D1 predose; noninferiority margin, 0.8). Noninferiority of OBI versus IV was demonstrated if both coprimary end points achieved noninferiority. RESULTS IRAKLIA randomly assigned 531 patients (OBI, n=263; IV, n=268). After 12-month median follow-up, the ORR was 71.1% (OBI) and 70.5% (IV; relative risk, 1.008 [95% CI, 0.903 to 1.126]; lower CI exceeded noninferiority margin). The mean (standard deviation) C6D1 C trough was 499 (259) μg/mL (OBI) and 340 (169) μg/mL (IV). The C trough geometric mean ratio (90% CI) was 1.532 (1.316 to 1.784); lower CI exceeded noninferiority margin. Grade ≥3 treatment-emergent adverse event incidences were 81.7% (OBI) and 76.1% (IV); infusion reaction incidences were 1.5% and 25.0%. Injection site reactions occurred in 0.4% of OBI injections (all grade 1-2); 99.9% of injections completed without interruption. CONCLUSION IRAKLIA demonstrated efficacy and pharmacokinetic noninferiority between Isa OBI and IV. No unexpected safety signal was observed, with excellent local tolerability of Isa OBI. Efficacy and safety were comparable with Isa IV in ICARIA-MM, except the lower OBI infusion reaction rate. These results support potential use of the OBI, designed to improve practice efficiency.

7506 Background: IV Isa-Pd is approved to treat RRMM patients (pts) based on the ICARIA-MM study. A Phase 1b study showed safety and efficacy of Isa SC via an OBDS, an investigational wearable bolus injector, plus Pd, in RRMM pts. Isa SC offers shorter duration, fixed dose and smaller administration volume. Here, we report results of the IRAKLIA trial (NCT05405166); Isa SC vs IV + Pd in RRMM pts, the first Phase 3 myeloma trial reporting the use of an OBDS. Methods: This multicenter, open-label study enrolled pts aged ≥18 years with ≥1 prior line of therapy (LOT). Pts were randomized 1:1 to Isa SC (1400 mg) or Isa IV (10 mg/kg) weekly in Cycle (C)1, then every 2 weeks + P (4 mg/day, Day [D]1–21) + d (40 mg [20 mg if age ≥75 years] weekly). Pts had 4-week cycles until progression, unacceptable toxicity or patient request. Co-primary endpoints were overall response rate (ORR; non-inferiority [NI] margin of 0.839) and Isa trough level (C trough ) at steady state (predose at C6D1; NI if lower limit of 90% CI of geometric mean ratio ≥0.8). Results: 531 pts (SC n=263; IV n=268 [4 not treated]) were randomized. Baseline characteristics were balanced (median age 66 years; median 2 prior LOT). After median 12 months follow-up, ORR was 71% (SC arm) and 71% (IV arm; relative risk [95% CI] = 1.008 [0.903–1.126]; lower CI > NI margin). Mean (SD) C trough at C6D1 was 499 (259) μg/mL for SC and 340 (169) μg/mL for IV. C trough geometric mean ratio (90% CI) was 1.532 (1.316–1.784); lower CI > NI margin. Co-primary and all 4 key secondary endpoints including pt experience are in the Table. Grade ≥3 treatment-emergent adverse events occurred in 82% (SC) and 76% (IV) of pts; with treatment discontinuation rates of 8% and 9%. Injection site reactions (ISRs) occurred in 4% (11/263) of the SC arm and in 19 (0.4%) of 5145 SC injections (all Grade 1–2). 99.9% of OBDS injections were completed without interruption. Conclusions: IRAKLIA met its co-primary endpoints, showing efficacy and pharmacokinetic NI between Isa SC vs IV + Pd. No new safety signal besides a low ISR incidence was observed, showing excellent Isa SC tolerability. Far fewer infusion reactions and higher pt satisfaction were also noted for SC vs IV. Efficacy and safety are comparable to Isa IV in ICARIA-MM. These results support potential use of Isa SC delivered via the OBDS, designed to improve pt experience and practice efficiency. Clinical trial information: NCT05405166 . Isa SC + Pd Isa IV + Pd Efficacy, % N=263 N=268 ORR 71 71 ≥VGPR 46 46 PK*, µg/mL N=131/121 N=126/121 Geometric mean Isa C trough at C2D1 / C6D1 360/426 277/278 Safety, % N=263 N=264 All grade IR 2 25 Pt satisfaction with injection method at C5D15, % 70 53 *PK was analyzed at C6D1 with PP PK population and at C2D1 with PP CT4W population. CT4W, C trough at 4 weeks; IR, infusion reaction; PK, pharmacokinetics; PP, per protocol; VGPR, very good partial response.

Significance Statement There is no standardized desensitization regimen for kidney transplant candidates. CD38, expressed by plasma cells, could be targeted for desensitization to deplete plasma cells producing alloantibodies and donor-specific antibodies. Few studies and case reports are available regarding the use of CD38 antibodies for desensitization in patients awaiting kidney transplant. This study shows that isatuximab, a CD38-targeting therapy, was well tolerated in kidney transplant candidates, with a durable decrease in anti-HLA antibodies and partial desensitization activity. The short treatment period and long follow-up of this study allowed for the understanding of the mechanism and timing for any antibody rebound. Isatuximab could be further investigated as an option for adjunct therapy to existing desensitization for patients on the kidney transplant waitlist. Background Patients with calculated panel reactive antibody (cPRA) ≥80.00%, particularly those with cPRA ≥99.90%, are considered highly sensitized and underserved by the Kidney Allocation System. Desensitization removes circulating reactive antibodies and/or suppresses antibody production to increase the chances of a negative crossmatch. CD38 is expressed highly on plasma cells, thus is a potential target for desensitization. Methods This was an open-label single-arm phase 1/2 study investigating the safety, pharmacokinetics, and preliminary efficacy of isatuximab in patients awaiting kidney transplantation. There were two cohorts, cohorts A and B, which enrolled cPRA ≥99.90% and 80.00% to <99.90%, respectively. Results Twenty-three patients (12 cohort A, 11 cohort B) received isatuximab 10 mg/kg weekly for 4 weeks then every 2 weeks for 8 weeks. Isatuximab was well tolerated with pharmacokinetic and pharmacodynamic profiles that indicated similar exposure to multiple myeloma trials. It resulted in decreases in CD38 + plasmablasts, plasma cells, and NK cells and significant reductions in HLA-specific IgG-producing memory B cells. Overall response rate, on the basis of a predefined composite desensitization end point, was 83.3% and 81.8% in cohorts A and B. Most responders had decreases in anti-HLA antibodies that were maintained for 26 weeks after the last dose. Overall, cPRA values were minimally affected, however, with only 9/23 patients (39%) having cPRA decreases to target levels. By study cutoff (median follow-up of 68 weeks), six patients received transplant offers, of which four were accepted. Conclusions In this open-label trial, isatuximab was well tolerated and resulted in a durable decrease in anti-HLA antibodies with partial desensitization activity. Clinical Trial registration number NCT04294459.