Descontinuação da primeira linha de tratamento de pacientes com mieloma múltiplo: coorte histórica.

Abstract

Multiple myeloma (MM) is a hematologic malignancy of plasma cells and presents variable signs and symptoms. The treatment is recommended for symptomatic patients in order to control the disease, promote remission, and increase survival and quality of life. However, discontinuation of treatment regimens often occurs due to several factors, such as ineffectiveness of treatment, problems in access to drugs, and the occurrence of adverse events. The aim of the study is to evaluate the discontinuation of antineoplastic treatment of MM patients initiating treatment. This is a historical cohort study conducted in onco-hematology outpatient clinics from 2009 to 2020. Study endpoints were first-line treatment discontinuation defined as transient discontinuation for termination of first-line and receipt of second-line treatment and permanent discontinuation for discontinuation of first-line antineoplastic therapy regimen in which patients did not receive subsequent lines of treatment within the study period. Selected exposure variables comprised sociodemographic, clinical, and pharmacotherapy variables. Data were collected from medical records and laboratory tests. Absolute and relative frequencies, measures of central tendency and dispersion of the study variables were calculated. The cumulative incidence of transient discontinuation, with a 95% confidence interval (CI), was estimated by nonparametric analysis of competitive risks in the presence of competitive events (reasons for permanent discontinuation - response to treatment, stable disease, limiting events, deaths, and discontinuations with no recorded reason - censoring). Transient discontinuation was compared according to exposure variables using Gray's test, considering a significance level of 5%. A total of 260 patients were selected for the study. Approximately half of the participants were younger than 65 years of age (mean 63.3 years; standard deviation - SD=11.9), 50.7% were female, 56.2% were linked to the private institution, and 27.3% and 72.7% started treatment in the periods 2009-2014 and 2015-2020, respectively. Thalidomide-based treatment regimens accounted for 47.7%, bortezomib-based 40.3%, thalidomide + bortezomib-based 6.2%, and other therapeutic regimens 5.8%. Polypharmacy use was identified for 68.5% of participants and 97.3% had comorbidities. The mean treatment time in first-line treatment was 7.4 months (SD=4.9). Of the participants, 125 (48%) experienced transient discontinuation and 135 patients (52%) experienced permanent discontinuation of first-line treatment. The main reason for transient discontinuation was the occurrence of a limiting event with AEs predominating, while achieving a response to treatment was the main reason for permanent discontinuation. The cumulative incidence of transient discontinuation was significantly different between the 2009-2014 and 2015-2020 treatment initiation periods (p<0.0001). Prevention and management of discontinuation for modifiable reasons should contribute to better MM treatment outcomes.