|The following article features coverage from the American Society of Clinical Oncology 2019 meeting. Click here to read more of Hematology Advisor’s conference coverage.|
Bosutinib may be a safe and efficacious treatment option for patients with Philadelphia-positive (Ph+) chronic-phase (CP) chronic myeloid leukemia (CML), according to results from the phase 4 BYOND study (ClinicalTrials.gov Identifier: NCT02228382) presented at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois.
In total, 163 patients received bosutinib, 156 of whom had Ph+ CP CML and had been pretreated with 1, 2, or 3 other tyrosine kinase inhibitors (TKIs). Bosutinib dosage started at 500 mg/day and was adjusted as needed due to adverse events. Cumulative confirmed major cytogenetic response was the primary endpoint. Cumulative rates of molecular response and adverse events were also assessed.
After a median follow-up of 20.4 months, 56.4% of patients remained on bosutinib. Adverse events led to discontinuation in 25.0% of patients, while 5.1% of patients discontinued treatment due to insufficient response. Median duration of treatment was 23.7 months, and median dosage was 313 mg/day.
Overall survival at 1 year was 98.0%. Of 144 evaluable patients who had valid baseline assessments, 71.5% achieved confirmed major cytogenetic response within 1 year of starting treatment, and 81.3% of experienced complete cytogenetic response at some point during treatment.
Major molecular response was achieved by 56.3% of patients with 3 prior TKIs, 76.4% of patients with 2 prior TKIs, and 82.6% of patients with 1 prior TKI. Deep molecular response was achieved by 39.6% of patients with 3 prior TKIs, 61.8% of patients with 2 prior TKIs, and 69.6% of patients with 1 prior TKI.
Diarrhea and nausea were the most common treatment-emergent adverse events, occurring in 87.8% and 41.0% of patients, respectively. Diarrhea and increased alanine aminotransferase (ALT) were the only grade 3 or 4 adverse events with incidence greater than 10%, and increased ALT was the only adverse event that resulted in treatment discontinuation in more than 5% of patients.
“[These] results further support bosutinib use for Ph+ CP CML resistant or intolerant to prior TKIs,” the researchers wrote.
1. Gambacorti-Passerini C, Abboud CN, Gjertsen BT, et al. Primary results of the phase 4 BYOND study of bosutinib (BOS) for pretreated chronic phase (CP) chronic myeloid leukemia (CML). Poster presentation at: 2019 ASCO Annual Meeting; June 3, 2019; Chicago, IL. Abstract 7012.