Subgroup analysis based on cytogenetic risk in patients with relapsed or refractory multiple myeloma in the CANDOR study

Difficult-to-treat patients with relapsed/refractory multiple myeloma: A review of clinical trial results

Overall outcomes for multiple myeloma have improved due to the availability of new therapies, but patients with relapsed/refractory multiple myeloma harbouring certain factors continue to pose a therapeutic challenge. These challenging features include high-risk cytogenetics, renal impairment, patient characteristics such as age and frailty, and extramedullary disease. Prior refractory status and number of prior lines add further complexity to the treatment of these patients. While newer regimens are available and have suggested efficacy in these patient populations through subgroup analyses, differences in trial definitions and cut-offs make meaningful comparisons difficult. This review aims to examine the available clinical trial data for patients with high-risk cytogenetics, renal impairment, age and frailty and extramedullary disease.

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.

Daratumumab with lenalidomide and dexamethasone in relapsed or refractory multiple myeloma patients - real world evidence analysis

We performed real world evidence (RWE) analysis of daratumumab, lenalidomide and dexamethasone (Dara-Rd) versus lenalidomide and dexamethasone (Rd) treatment in relapsed/refractory multiple myeloma patients (RRMM). In total, 240 RRMM patients were treated with Dara-Rd from 2016 to 2022 outside of clinical trials in all major Czech hematology centers. As a reference, 531 RRMM patients treated with Rd were evaluated. Patients' data were recorded in the Czech Registry of Monoclonal Gammopathies (RMG). Partial response (PR) or better response (ORR) was achieved in significantly more patients in Dara-Rd than in Rd group (91.2% vs. 69.9%; p < 0.001). The median progression free survival (PFS) was 26.9 months in the Dara-Rd and 12.8 months in the Rd group (p < 0.001). Median overall survival (OS) was not reached in the Dara-Rd compared to 27.2 months in the Rd group (p = 0.023). In patients with 1-3 previous treatment lines, there was significant PFS benefit of Dara-Rd compared to Rd (median PFS not reached vs. 13.2 months; p < 0.001). In patients with > 3 previous treatment lines, there was no significant PFS benefit of Dara-Rd treatment (7.8 months vs. 9.9 months; p = 0.874), similarly in patients refractory to PI + IMIDs (11.5 months vs. 9.2 months; p = 0.376). In RWE conditions, the median PFS in RRMM patients treated with Dara-Rd is shorter when compared to clinical trials. In heavily pretreated RRMM patients, efficacy of Dara-Rd treatment is limited; best possible outcomes of Dara-Rd are achieved in minimally pretreated patients.

A Clinical and Correlative Study of Elotuzumab, Carfilzomib, Lenalidomide, and Dexamethasone (Elo-KRd) for Lenalidomide Refractory Multiple Myeloma in First Relapse

INTRODUCTION

Treatment of patients with multiple myeloma (MM) in first relapse remains a challenge. This phase II study combined elotuzumab (Elo) with carfilzomib, lenalidomide, and dexamethasone (KRd) for treatment of MM in first relapse with the aim of improving efficacy.

METHODS

Enrolled patients received Elo-KRd induction for 4 cycles, and Elo-lenalidomide maintenance until progression. The primary endpoint was VGPR or better (≥VGPR) postinduction. Secondary endpoints were MRD by flow cytometry, OS, PFS, and safety. Correlatives included characterization of the impact of Elo-KRd on NK and T cell subsets via flow cytometry. Target accrual of 40 patients was not met due to COVID-19 pandemic.

RESULTS

Of 15 patients enrolled, 10 (67%) had high-risk features (del17p, t[4;14], t[14;16], 1q gain/amplification, plasma cell leukemia, extramedullary MM, or functional high risk), 12 (80%) were lenalidomide-refractory, and 5 (33.3%) bortezomib-refractory. Postinduction ≥VGPR was 7/15 (46.7%) and MRD-negative (10^-5) rate 20%. Overall response during study was 80%, including ≥VGPR as best response of 53.3%. At median follow-up of 28.2 (range, 3.8 to 44.2) months, the median PFS was 11.5 months (95% CI 1.9, 18), and median OS not reached (95% CI 10.1, NA). No new safety concerns were reported. Elo-KRd treatment did not augment NK cell distribution or activity in blood or bone marrow. Effector CD4+ and CD8+ T cells significantly decreased postinduction, with concomitant acquisition of T central memory phenotype, particularly at a high rate in ≥VGPR group.

CONCLUSION

A short course of Elo-KRd induction followed by Elo-lenalidomide maintenance demonstrated activity in predominantly lenalidomide-refractory and / or high-risk MM. The results with this well-tolerated combination are comparable to other contemporary approved triplet combinations.