Response After Auto-HSCT Predicts PFS, OS in Younger Patients With MM

Patients younger than 40 years with multiple myeloma (MM) had durable survival after autologous hematopoietic stem cell transplant (auto-HSCT), which further improved with the availability of novel antimyeloma drugs in the years after 2010. These findings were reported in the British Journal of Haematology.

Fewer than 2% of patients with MM are younger than 40 years at diagnosis, and data on outcomes for these patients are lacking, especially for those treated with upfront auto-HSCT. Therefore, researchers at the University of Texas MD Anderson Cancer Center investigated the long-term outcomes in this patient population.

For this retrospective, single-center study, the researchers searched the institution’s database for patients with MM who underwent auto-HSCT between 1989 and 2023. Primary endpoints included progression-free survival (PFS) and overall survival (OS).

A total of 117 patients were included. The median age was 37 years (range, 22 to 40), and 15% had high-risk cytogenetic abnormalities. Most patients had revised International Staging System (R-ISS) stage I or II disease. However, no R-ISS staging data were available for 55% of the patients.

Induction regimens utilized for patients in this study were bortezomib, lenalidomide, and dexamethasone (VRD; 23 patients); conventional chemotherapy (22 patients); other proteosome inhibitor (PI)-based regimens (21 patients); immunomodulatory drug (IMiD)-based doublets (15 patients); bortezomib/dexamethasone (VD; 13 patients); and other regimens (23 patients).

A total of 74 patients received single-agent melphalan conditioning, 96% of whom received melphalan dosed at 200 mg/m². Posttransplant maintenance was mostly lenalidomide-based and administered to 61 patients (52%) for a median duration of 26.6 months (range, 1.7 to 111.6).

Following induction and prior to transplant, 10% of patients achieved a complete response (CR) or better, and 44% achieved a very good partial response (VGPR) or better. Additionally, 22% of patients achieved minimal residual disease (MRD)-negative status.

At day 100, 32% and 62% of patients achieved CR or better and VGPR or better, respectively, and the best posttransplant responses were 56% and 77%.

The median follow-up for survivors was 72.6 months (range, 0.9-238.0). The median PFS was 43.1 months (95% CI, 31.2-65.0), and the median OS was 146.6 months (95% CI, 100.0-208.1).

The median PFS and OS were better in patients who underwent auto-HSCT after 2010 (56 patients) compared with those who underwent auto-HSCT prior to 2010 (61 patients). The median PFS was 84.9 months after 2010 and 28.2 months prior to 2010 (P <.001). The median OS was not reached (NR) and 91.8 months, respectively (P <.001).

Induction therapy also influenced PFS and OS. The median PFS was NR with VRD, 87.8 months with other PI-based regimens, 57.8 months with VD, 32.1 months with IMiD-based doublets, and 23.4 months with chemotherapy. The median OS was NR with VRD, other PI-based regimens, and VD; 105.6 months with IMiD-based doublets, and 56.0 months with conventional chemotherapy.

A multivariate analysis revealed that achieving a CR or better as best posttransplant response was associated with improved PFS (hazard ratio [HR], 0.55; 95% CI, 0.32-0.95; P =.032). Achieving a VGPR or better was associated with superior OS (HR, 0.32; 95% CI, 0.16-0.62; P <.001).

A second primary malignancy developed in 3% of patients (1 case each of colon cancer, bladder cancer, and melanoma).

These findings show that patients with MM who are younger than 40 years at diagnosis tend to have a different cancer experience compared with older adults. However, the researchers reported that depth of response after auto-HSCT remains a key predictor of survival.

Reference

Pasvolsky O, Marcoux C, Milton DR, et al. Outcomes of young adults (aged ≤40 years) with newly diagnosed multiple myeloma after up-front autologous stem cell transplant. Br J Haematol. Published online June 27, 2023. doi:10.1111/bjh.18944