Cardiac Events in Real-World Multiple Myeloma Patients Treated with Carfilzomib: A Retrospective Claims Database Analysis

Introduction: Multiple myeloma (MM) is a hematologic cancer that mostly affects elderly patients who are at increased risk for development of cardiac-related comorbidities due to age-, disease-, and treatment-related factors. In real world data, approximately 25-30% of MM patients are hospitalized for a cardiac event after MM diagnosis (Kistler et al. American Society Hematology 2012 Annual Meeting, poster 2916). The proteasome inhibitor, carfilzomib, is approved for treatment of patients with relapsed or refractory MM. In carfilzomib clinical trials, grade 3 or higher cardiac failure was reported for ~4% of patients (Stewart et al. NEJM 2015;372:142-52, Dimopoulos et al. Lancet Oncol 2016;17:27-38). In this retrospective analysis, we sought to evaluate the incidence rate (IR) of cardiac events in MM patients treated with carfilzomib in a real-world setting in the US and to describe differences in baseline characteristics between carfilzomib-treated MM patients who do and do not have cardiac events.

Methods: Newly-diagnosed MM patients with symptomatic disease were identified in the Truven MarketScan claims database from 1/1/05 to 6/30/15 using an algorithm validated for ascertainment of MM patients in claims data (Princic et al. Blood 2015;126:4521). All carfilzomib-treated patients were included in the analysis. The first dose of carfilzomib was the index date. The baseline period was 12 months prior to the MM diagnosis date to the index date. Cardiac events (hypertension, heart failure, ischemic heart disease, arrhythmias and conduction disorders, and cardiomyopathy) were identified during baseline by inpatient (IP) or outpatient (OP) claims and after index date by primary diagnosis on IP claims (hospitalized events). Logistic regression was used to estimate baseline covariates associated with any cardiac event. Due to sample size constraints, multivariate regression was not performed. The incidence rate (IR) per 1000 patient-years (PYRs) and associated 95% confidence interval (CI) of hospitalized cardiac events during carfilzomib treatment which included 30 days after the last carfilzomib dose were calculated among patients without a history of the corresponding hospitalized event during the baseline period.

Results: The cohort included 498 MM patients treated with carfilzomib; 108 (22%) patients had ≥1 cardiac event identified by both IP and OP claims and 24 (5%) had ≥1 hospitalized cardiac event. Of the 24 hospitalized patients, 14 were hospitalized during carfilzomib treatment (median days to onset = 104) and 8 were hospitalized after carfilzomib treatment (>30 days post dosing; median days to onset = 284). The median age (range) of the 24 patients with hospitalized cardiac events and those with no hospitalized cardiac claims (n=474) was 62 (37, 79) and 61 (36, 96) years, respectively (Table). Baseline medical history of any cardiac event was evident for 92% of hospitalized patients and 84% of non-hospitalized patients. Among hospitalized patients, 25% were over 75 years as compared with 13% of non-hospitalized patients. In univariate analysis, patients with baseline amyloidosis, hypertensive chronic kidney disease, and chronic kidney disease had higher odds of having a hospitalized cardiac event. No significant differences were seen in the proportion of patients with or without a hospitalized cardiac event when evaluated by line of therapy or by carfilzomib treatment regimen (monotherapy or combination). Among patients aged 75+ years, 8.7% were hospitalized, while 2.5% and 4.9% of 65-74 and 18-64 year old patients were hospitalized, respectively (Table). IR per 1000 PYRs [95% CI] among the 14 carfilzomib-treated MM patients hospitalized for any cardiac event during the carfilzomib treatment period was 89.7 (49.0; 150.5) - see Figure for IRs of specific cardiac events.

Conclusions: Among carfilzomib-treated patients in a US claims database, hospitalization for a cardiac event was uncommon (~5%) and does not exceed what has been observed in MM patients. Patients at highest risk for cardiac hospitalizations had a history of amyloidosis or chronic renal failure. Additional analyses in much larger populations are needed to better understand risk factors for these events.

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