Survival Analysis of Newly Diagnosed Transplant-Eligible Multiple Myeloma Patients in Czech Republic

Introduction: Although highly effective agents and novel therapeutic strategies are being developed, high-dose chemotherapy followed by autologous stem cell transplantation (HDT/ASCT) has not been overcome in the first-line treatment for fit patients (pts) with multiple myeloma. The objective of this work is to retrospectively analyze the use of this procedure in newly diagnosed Czech patients.

Methods: Data were derived using the Czech Myeloma Group Registry of Monoclonal Gammopathies. By February 2 ^nd 2021, a total of 2154 newly diagnosed multiple myeloma patients who underwent HDT/ASCT were identified.

Results: At the time of multiple myeloma diagnosis, the median age was 59 years; 24%/56%/14%/5%/1% pts were ECOG 0/1/2/3/4; 44%/32%/24% pts were ISS stage I/II/III; 14.5%/17.5%/68% and 84%/16% pts were Durie-Salmon stage I/II/III and subclassification A/B, respectively. The combinations of agents used in the induction regimen were proteasome inhibitor (PI), immunomodulatory drug (IMiD) and glucocorticoid (GC) in 28.5% (613/2154) pts; PI, GC and chemotherapy (CHT) in 24.8% (534/2154) pts; GC and CHT in 22,5% and IMiD, GC and CHT in 16.1% (346/2154). Other combination of drugs was used in 8.2% (177/2154) pts. It was registered that 3.7% (79/2154) induction regimens were switched to a different combination because of toxicity, patient's choice, poor peripheral venous access or other reasons. Single HDT/ASCT was performed in 77.3% (1665/2154) cases whereas tandem HDT/ASCT was given to 11.8% (254/2154) patients. In 10% (215/2154) cases, the transplantation technique was not specified. Nine percent (193/2154) patients were treated within a clinical study. The median progression free survival (mPFS) and the median overall survival (mOS) of the whole cohort was 28.9 and 92.1 months, respectively. Information about response to treatment before and after the high-dose therapy were available for 75.7% (1627/2154) and 92.2% (1987/2154) patients, respectively. Disease status at the time of HDT/ASCT was defined as stringent complete response (sCR) at 2.2% (36/1627), complete response (CR) at 11.9% (194/1627), very good partial response (VGPR) at 38.2% (621/1627), partial response (PR) at 40.9% (666/1627), minimal response (MR) at 3.6%, (58/1627), stable disease (SD) at 2.2% (36/1627), progressive disease (PD) at 1% (16/1627) patients. The overall response rate (ORR) on day 100 was 92.8% (sCR: 10.5% [209/1987], CR: 22.4% [446/1987], VGPR: 35% [696/1987], PR: 24.8% [493/1987], MR: 2.7% [54/1987], SD: 1.4% [27/1987], PD: 3.1% [62/1987]). We also performed a survival analysis of patients progressing up to 18 months after HDT/ASCT (n=1219) versus patients progressing in more than 18 months (n=935). The median OS was 41.5 versus 124.9 months, respectively. An analysis of the role of tandem HDT/ASCT in this real-world cohort will be presented at the conference.

Conclusion: Globally as well as in the Czech Republic, HDT/ASCT is an important therapeutic approach in the first-line treatment of multiple myeloma. Our analysis of 2154 newly diagnosed transplant-eligible patients confirms high effectiveness - ORR of 92.8%, mPFS of 28.9 months, and long-term survival reaching mOS of 92.1 months.