|The following article features coverage from the American Society of Clinical Oncology (ASCO) 2018 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.|
CHICAGO—Bosutinib may lead to improved 2-year major molecular response (MMR) among patients with newly diagnosed chronic phase chronic myeloid leukemia (CP-CML) compared with imatinib, according to a presentation at the American Society of Clinical Oncology 2018 Annual Meeting on Saturday, June 2.1
The ongoing phase 3 BFORE study (ClinicalTrials.gov Identifier: NCT02130557) assessed the efficacy of first-line bosutinib 400 mg once daily — a dual Src/Abl tyrosine kinase inhibitor approved for newly diagnosed CP-CML and relapsed/refractory CML — versus imatinib 400 mg once daily. Researchers randomly assigned 536 patients to bosutinib or imatinib treatment arms, with a planned follow-up period of 5 years. The authors presented findings from the 24-month follow up.
Results showed that patients treated with bosutinib had a higher MMR compared with imatinib after 12 months (46.6% vs 37.0%; P = .013). This effect persisted after 18 months (57.0% vs 47%; P = .0198), and even after 24 months (61.2% vs 50.7%; P = .015). The cumulative complete cytogenetic response rate (CCyR) was improved among patients in the bosutinib arm compared with imatinib at both 48 weeks (78% vs 66%, respectively) and 96 weeks (82% vs 76%, respectively).
The cumulative incidence of MR4 in the bosutinib arm was 17% versus 10% in the imatinib arm after 48 weeks and was 34% versus 27% after 96 weeks (P = .0249). The cumulative incidence of MR4.5 in the bosutinib arm was 6% versus 3% in the imatinib arm after 48 weeks, and was 20% versus 15% after 96 weeks (P = .0542).
The time to MMR and CCyR were longer in the imatinib arm compared with bosutinib at 24 months, which were consistent with findings reported at 12 months. There were 6 and 7 transformations to accelerated and blast phase CML among patients in the bosutinib and imatinib arms, respectively.
Seventy-one percent of patients remained on bosutinib therapy after 24 months, and 66% of patients remained on imatinib therapy.
Both study arms reported encouraging rates of overall survival, with 99.6% and 98.1% at 12 months in the bosutinib and imatinib arms, respectively, and 99.2% and 97.0% at 24 months, respectively.
The authors concluded that “at 24 [months], a higher MMR rate was maintained with bosutinib vs imatinib. The results support the use of bosutinib as first-line therapy for CP-CML.”
Read more of Cancer Therapy Advisor‘s coverage of the American Society of Clinical Oncology (ASCO) 2018 meeting by visiting the conference page.
- Cortes JE, Mauro MJ, Deininger MWN, et al. Bosutinib vs imatinib for newly diagnosed chronic myeloid leukemia in the BFORE trial: 24-month follow-up. Oral presentation at: 2018 ASCO Annual Meeting; June 1-5, 2018; Chicago, IL.