Several novel therapies have been developed in recent years improving multiple myeloma (MM) treatment, although autologous hematopoietic stem cell transplantation (HSCT) remains a fundamental strategy in eligible patients. HSCT is even more important where access to drugs such as bortezomib is not available in Brazilian public health system.

To evaluate the outcomes after auto-HSCT in patients with MM treated at a public center in Brazil, identifying possible targets to improve assistance.

Between Jan-2010 and Oct-2018, 233 patients who underwent the first HSCT for MM were included. This was an observational, retrospective, and single-center study with data collected through medical records after approval by the local research ethics committee. The primary outcome was Progression-Free Survival (PFS) – defined as time between HSCT and death, date of last follow-up or disease progression according to current International Myeloma Working Group (IMWG) criteria. Secondary outcomes were: Overall Survival (OS), Transplant-Related Early Mortality (TRM) and HSCT toxicities (according to the Common Terminology Criteria for Adverse Events). Univariate analysis was performed followed by multiple Cox regression with regression elimination selection method, considering the following predictive variables: International Staging System (ISS), ECOG Performance Status, Charlson index, number of treatments and pre-HSCT response, lactic dehydrogenase at diagnosis, age and time between diagnosis and HSCT.

At the time of HSCT, the median patient's age was 57 years (27-70) and 30% of them were over 60. There was a predominance of advanced stages by Durie-Salmon (87% stage IIIA/IIIB), ISS II/III (58%) and ECOG ≤2 (74%). Charlson's comorbidity index was ≥4 in 50.6% of the sample and 80% had undergone only one previous treatment line. 23.8% of the patients were in complete response (CR) prior to HSCT and the procedure was able to increase this proportion to 46.7% at post-HSCT restaging. This increased depth of response was seen in all subgroups stratified by ISS. With a median follow-up after HSCT of 47.8 months, the 2-year PFS was calculated to be 52% (95%CI 45-58%). Multivariate analysis showed significant risk of reduced PFS for Charlson index ≥4 (HR 1.52 95%CI 1.10-2.09) and pre-HSCT depth of response (partial response [HR 1.52 95%CI 1.10- 2.09] and very good partial response [HR 1.52 95%CI 1.10-2.09], compared to CR). The 2-year OS was 82% (95%CI 77-87%). TRM was 4.3% and 41.8% of the patients had at least one toxicity classified as grade ≥3, the main ones being: oral mucositis, nausea and diarrhea.

With a median follow-up of 4 years, this study presents results of a Brazilian public center with similar rates of PFS and OS to those reported in the international literature prior to the advent of novel therapies for MM. HSCT proved to be safe and effective, with better outcomes in patients with fewer comorbidities and with deeper pre-HSCT responses, emphasizing the importance of incorporating new drugs to achieve even better results.