Response and Dynamics of Renal Function in Transplantation-Eligible Multiple Myeloma Patients Treated with a Novel Agent: The CAREMM-2201 Study

Newly diagnosed multiple myeloma (NDMM) frequently results in renal impairment (RI), and its natural course has not been fully elucidated in the era of novel agents. We aimed to identify the dynamics of renal function after autologous stem cell transplantation (ASCT) following induction treatment using a novel agent in transplantation-eligible NDMM patients with RI (estimated glomerular filtration rate [eGFR] ≤50 mL/min/1.73 m²) at diagnosis. The factors associated with achieving a renal response based on the term renal benefit regardless of baseline eGFR were investigated as well. In a multicenter registry database including 1795 patients with plasma cell disorder, 140 transplantation-eligible NDMM patients who developed RI at the time of initiation of treatment for NDMM were identified. They received protocol-based treatment (PBT) consisting of induction treatment using proteasome inhibitors and/or immunomodulatory drugs followed by ASCT. MM and renal responses were evaluated using the International Myeloma Working Group response criteria. To evaluate the standardized improvement of renal function irrespective of baseline eGFR, renal benefit was defined as a sustained (for at least 3 months) increase in eGFR >15 mL/min/1.73 m². The mean patient age was 54.7 ± 7.4 years. With a mean baseline eGFR of 24.8 ± 13.9, the renal complete response (renalCR) and renal benefit rates were 49.3% and 67.9%, respectively. In a multivariable analysis, the 3 factors significantly associated with reduced likelihood of achieving both renalCR and renal benefit were age ≥55 years, light chain type NDMM, and failure to improve eGFR by 5 mL/min/1.73 m² with supportive care when measured 3 days prior to induction therapy and at the initiation of chemotherapy. Hypertension and advanced eGFR also were associated with poor renalCR achievement. The mean eGFR improved until the time of ASCT and then decreased gradually over time. The mean eGFR improved significantly until 4 months post-PBT compared with each eGFR at previous time points, but this significant improvement disappeared by 5 months post-PBT. In a subgroup of patients who developed RI after undergoing ASCT (n = 55), the eGFR increased temporarily at 1 month post-ASCT; however, this improvement reverted to baseline at 2 months post-ASCT. Among another subgroup of 27 patients who were dialysis-dependent at the time of initial treatment, 18 (66.7%) were no longer dialysis-dependent after a median of 60 days. The best renal response was acquired early during the PBT period, and ASCT did not have a robust impact on the renal outcome. Patients who failed to achieve a renal benefit should be provided with the best supportive care for chronic kidney disease, and this simplified criterion for evaluating the renal response needs to be validated in larger studies before it can be recommended.