Carfilzomib, dexamethasone, and daratumumab in Asian patients with relapsed or refractory multiple myeloma: post hoc subgroup analysis of the phase 3 CANDOR trial

Isatuximab Plus Carfilzomib and Dexamethasone in East Asian Patients With Relapsed Multiple Myeloma: Updated IKEMA Subgroup Analysis

BACKGROUND

The Phase 3 IKEMA study (NCT03275285) demonstrated isatuximab (Isa) in combination with carfilzomib (K) and dexamethasone (d) significantly improved progression-free survival (PFS) in patients with relapsed multiple myeloma (MM) compared with Kd. A post-hoc analysis of East Asian patients in IKEMA evaluated the efficacy and safety of Isa-Kd versus Kd in this population and was previously published.

PATIENTS AND METHODS

Patients with relapsed MM who had received 1 to 3 prior lines of therapy were randomized 3:2 to receive Isa-Kd or Kd. The primary endpoint was PFS, and key secondary endpoints included rate of very good partial response or better (≥VGPR), complete response (CR) rate, and minimal residual disease (MRD) negativity. Of the IKEMA overall population, 46 patients were of East Asian descent. This is an updated analysis of the efficacy and safety of Isa-Kd in East Asian patients, including data through 14 January 2022.

RESULTS

Isa-Kd continued to demonstrate improved efficacy and safety versus Kd in East Asian patients with relapsed MM, with improved PFS, rate of ≥VGPR, CR rate, and MRD negativity, that was consistent with the overall IKEMA population. The rate of Grade ≥3 treatment-emergent adverse events was also consistent with the prior analysis and overall IKEMA population.

CONCLUSION

Based on the results of this analysis, Isa-Kd is a novel treatment option for East Asian patients with relapsed MM.

Clinical Pharmacokinetics and Pharmacodynamics of Daratumumab

Daratumumab is a fully human, monoclonal immunoglobulin G1 and a first-in-class CD38-targeting drug approved by the US Food and Drug Administration for the treatment of patients with relapsed/refractory and newly diagnosed multiple myeloma or newly diagnosed light-chain amyloidosis. CD38 is heavily expressed on malignant myeloma cells, and daratumumab exerts anti-myeloma activity via immune-mediated mechanisms, direct induction of apoptosis, and immunomodulation. Daratumumab is used as monotherapy or in combination with standard-of-care myeloma therapies, including proteasome inhibitors, immunomodulatory agents, DNA-alkylating agents, and corticosteroids. Following an intravenous infusion, daratumumab exhibits nonlinear pharmacokinetics (PK), as clearance decreases with higher doses and over time because of target-mediated effects. Dosing schedules vary depending on indications and co-administered drugs, but generally daratumumab is administered weekly for 6-9 weeks followed by a less frequent dosing regimen, once every 2-4 weeks. Daratumumab exposure is strongly correlated with efficacy, and the exposure-efficacy relationship follows a maximal effect model, whereas exposure is not correlated with safety endpoints. The approved dose of 16 mg/kg of daratumumab results in the saturation of 99% of the target at the end of weekly dosing in most patients, and high target saturation is maintained over time during the less frequent dosing schedule. Infusion-related reactions are frequently observed in patients given daratumumab, particularly with the first infusion, thus prompting long durations of infusion (~ 7 h) and splitting of the first dose across 2 days. This led to the development of a subcutaneous delivery formulation for daratumumab (Dara-SC). Dara-SC provides a similar efficacy and safety profile to intravenous daratumumab (Dara-IV) but has a much lower rate of infusion-related reactions and a shorter infusion time. Exposure-response relationships for efficacy and safety endpoints were similar between Dara-SC and Dara-IV, and co-administered drugs with either Dara-IV or Dara-SC do not significantly affect daratumumab PK. Except for baseline myeloma type and albumin level, none of the other investigated disease and patient characteristics (renal/hepatic function, age, sex, race, weight, Eastern Cooperative Oncology Group performance status) was identified to have clinically relevant effects on exposure to daratumumab monotherapy or combination therapy regimens. Dara-IV exposure was significantly lower in patients with immunoglobulin G myeloma compared with patients with non-immunoglobulin G myeloma (p < 0.0001) and in patients with a lower albumin level, whereas the overall response rate was similar regardless of the myeloma type and albumin level. Daratumumab dose adjustment is not currently recommended based on disease and patient characteristics.

Isatuximab plus carfilzomib and dexamethasone in East Asian patients with relapsed multiple myeloma: IKEMA subgroup analysis

In the phase 3 IKEMA study (NCT03275285), isatuximab (Isa) plus carfilzomib (K) and dexamethasone (d) significantly improved progression-free survival (PFS) in relapsed multiple myeloma (MM), compared with Kd. This IKEMA subgroup analysis evaluated efficacy and safety of Isa-Kd versus Kd among East Asian patients. Eligible patients had 1-3 prior lines of therapy and were stratified by number of prior lines and revised International Staging System. The primary endpoint was PFS. Key secondary endpoints included overall response, very good partial response or better (≥VGPR), minimal residual disease (MRD) negativity, and complete response (CR) rate. Forty-six East Asian patients (19 Japanese, 27 South Korean) were randomized to Isa-Kd (n = 25) or Kd (n = 21). Isa-Kd improved PFS (HR 0.64; 95% CI 0.23-1.76), ≥VGPR (80.0% vs 52.4%), MRD negativity rate (44.0% vs 9.5%), and CR (44.0% vs 23.8%). The rate of grade ≥ 3 treatment-emergent adverse events (TEAEs) was 79% for Isa-Kd versus 55% for Kd. The rate of serious TEAEs was 46% versus 50%, and the rate of TEAEs leading to treatment discontinuation was 4% versus 10%. Overall, Isa-Kd improved efficacy and safety versus Kd in East Asian patients with relapsed MM, consistent with the overall IKEMA population.