A dynamic portrait of adverse events for breast cancer patients: results from a phase II clinical trial of eribulin in advanced HER2-negative breast cancer

Purpose Adverse events (AE) during oncology clinical trials are typically reported using the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), which provides information about the frequency and severity of AEs from the provider’s perspective. Instruments that track patient-reported outcomes (PRO) complement the CTCAE and provide additional patient-centered information about the toxicity profile of an anti-cancer drug. Methods We conducted a single-arm, open-label phase II study of eribulin as first- or second-line therapy for metastatic hormone receptor-positive/HER2-negative (HR+/HER2−) or triple-negative breast cancer (TNBC). Patients were recruited simultaneously into each cohort by tumor subtype. The primary endpoint was overall response rate (ORR). Secondary endpoints included evaluation of toxicity by CTCAE and PRO instruments and agreement between CTCAE and PRO. The study also investigated single-nucleotide polymorphisms (SNPs) associated with treatment-induced neurotoxicity. Results 83 patients were enrolled: 45 into the HR+/HER2− cohort and 38 into the TNBC cohort. The ORR was 35.6% (90% CI 24–39%) in the HR+/HER2− cohort and 13.2% (90% CI 5–26%) in the TNBC cohort. Stable disease as the best response was recorded in 55.1% of patients with HR+/HER2− disease and 60.5% with TNBC. Toxicity analysis revealed a discordance between CTCAE and PRO assessment in many patients, with a focus on fatigue, alopecia, and neuropathy. Pharmacogenomic analysis identified SNPs associated with treatment-induced peripheral neuropathy. Conclusions Eribulin is active in HER2− breast cancer. This study reveals that provider-assessed AEs can vary greatly from patient experiences. Future studies should incorporate CTCAE and PRO instruments to improve reporting of treatment-related AEs. ClinicalTrials.gov Registration: NCT01827787