Real-world effectiveness and safety of multiple myeloma treatments based on thalidomide and bortezomib: A retrospective cohort study from 2009 to 2020 in a Brazilian metropolis.

Background: Multiple myeloma (MM) is an incurable cancer of plasma cells; the survival of which has improved over the years with the emergence of new treatments. In Brazil, the availability of treatment-regimens is different from developed countries. Real-world evidence with Brazilian patients is lacking.

Objectives: Our aim was to evaluate the effectiveness and the safety of MM treatments in a Brazilian metropolis.

Methods: This was a retrospective cohort study with MM patients, beginning MM treatment from 2009 to 2020 (i.e., before bortezomib became available in public health services). Patients' medical records were revised to obtain clinical variables. The primary outcomes were Overall Survival (OS) and Progression Free Survival (PFS, measured as time to next treatment), and the secondary outcomes were Adverse Events (AE). Kaplan-Meier curves were obtained and the Cox proportional hazards model was performed for univariate and multivariate analyses. The incidence of AE was estimated and the chi-squared test was performed to evaluate the association between AE and MM regimens.

Results: In total, 278 patients participated in the study with median age of 64 years; 50.4 % were females, 55.8 % attended a private clinic, 34.9 % received autologous stem cell transplantation (ASCT) and 32.4 % were on polypharmacy. Most patients from public services used thalidomide-based regimens (40.3 %) and at private clinics used bortezomib-based regimens (38.1 %) as first-line treatment. Patients had a median OS of 99 months. Patients had median PFS of 28 months in first-line treatment, which was significantly different for age (p = 0.0055), polypharmacy (p = 0.0094) and ASCT (p < 0.0001). PFS was independently associated to polypharmacy and ASCT. The incidence of peripheral neuropathy (39.6 %) was high. In contrast, the incidence of severe AE was low. We found significant difference between first-line T + B-based regimens and leukopenia (p = 0.012).

Conclusion: Our study showed that patients on polypharmacy and who did not receive ASCT had worse PFS. Similar to other Latin countries, most patients used thalidomide- and bortezomib-based regimens as first-line treatments having similar OS and PFS. Treatments were considered relatively safe, especially regarding serious AE.