Characteristics and outcome of relapsed myeloma after single autologous stem cell transplant: 20-year experience

Abstract

Relapse following autologous stem cell transplantation (ASCT) for multiple myeloma (MM) remains a major cause of treatment failure. We analyzed case records of 327 consecutive MM patients who underwent ASCT between 1995 and 2016 at our centre. Patient's median age was 52 years ranging from 29 to 68 years; 226 (68.9%) were males, 33.4% had ISS stage III disease, 80(24.9%) patients had light chain myeloma. 240 (73.2%) patients had received novel agents for induction, 34.3% of patients had received more than one induction regimen prior to transplant. Median interval from diagnosis to transplant was 10 months, ranging from 2 to 128 months. Median follow up for study population is 86 months (95% CI 74.70-97.30). The cumulative incidence of relapse at 1 year and 2 years is 9.8 % and 22%, respectively. Median time to progression (TTP) was 8.5 months (95% CI 5.0-11.96) for those with very early relapse (<12 months), 18.0 months (95% CI 17.6-18.4) and 45.50 months (95% CI 39.8-51.2) for those relapsing between 12 to 24 months and >24 months post ASCT, respectively, p<0.0001. Clinical (symptomatic), biochemical (asymptomatic), localized plasmacytoma and relapse into plasma cell leukemia (PCL) was seen in 72.5% (n=140), 18.7% (n=36), 1.6% (n=3), and 7.3% (n=14) patients, respectively. Median TTP was 37.50 months (95% CI 33.83-41.2) for biochemical relapse compared to 21 months (95% CI 18.8-23.2) for clinical relapse and 18 months (95% CI 15.6-20.4) for PCL, p<0.0001. Median overall survival (OS) for all patients is 100 months (95% CI 83.24-116.76) from date of transplant. Corresponding figures for those with biochemical, clinical and PCL relapse are 174 months, 51 months (41.1-60.9) and 26 months (0-57.2), respectively (p<0.0001). 12 patients have died of unrelated causes (second malignancy-5, cardiac-2, stroke-1, dementia-1, accident-1, viral infection-2). Currently, 122 (37.3%) patients are alive without relapse. On comparison of three relapse groups (<12, 12-24 and >24 months) - presence of extramedullary disease (p<0.003), >one line of induction therapy (p<0.008),