Highlights from

ASH 2020

62nd Annual Meeting & Exposition of the American Society of Hematology

Virtual 5 - 8 December 2020

Bosutinib demonstrates efficacy superior to imatinib

Results from a phase 3 trial showed superior efficacy of first-line bosutinib when compared with imatinib. Patients treated with bosutinib achieved both an earlier and a deeper molecular response, with an acceptable safety profile [1].

The FDA approved bosutinib as a first-line therapy for Philadelphia chromosome-positive chronic myeloid leukaemia (CML) in 2017. At that time, patients had been followed for just over 12 months. At ASH 2020, Dr Tim Brümmendorf (Center for Integrated Oncology, Germany) shared the results of 5 years’ follow-up (BFORE trial, NCT02130557).

The BFORE trial, which started in July 2014, randomised 536 patients with Philadelphia chromosome-positive CML to receive an oral 400 mg dose of either bosutinib or imatinib once daily for a 12 month treatment period. Long-term secondary endpoints of the BFORE trial included duration of response (DOR), on-treatment event-free survival (EFS), and overall survival (OS).

Upon study completion (April 2020), 59.7% of patients in the bosutinib treatment arm and 57.4% of patients in the imatinib treatment arm continued to receive treatment. The median duration of treatment and time in the study was 55.2 months. In those who were not continuing to receive treatment, adverse reasons were the most common reason given for treatment discontinuation. In the bosutinib arm, diarrhoea, nausea, thrombocytopenia, and increased alanine aminotransferase comprised the most common adverse events. In the imatinib arm, the most common adverse effects were diarrhoea, nausea, and muscle spasms.

Cumulative major molecular response (MMR) rate at 5-year follow-up was higher with bosutinib than with imatinib (73.9% vs 64.6%). Cumulative molecular response and molecular response rates were also higher in the bosutinib treatment arm (58.2% vs 48.1%, and 47.4% vs 36.6%, respectively). While patients in the bosutinib arm showed earlier responses, MMR duration was similar between groups. There were no differences in EFS between treatment arms, and 60-month OS rates were similar (94.5% in the bosutinib arm and 94.6% in the imatinib arm).

Researchers assert that their findings confirm the use of bosutinib as a standard of care in those with newly diagnosed Philadelphia chromosome-positive CML.

  1. Brümmendorf T, et al. Bosutinib (BOS) Versus Imatinib for Newly Diagnosed Chronic Phase (CP) Chronic Myeloid Leukemia (CML): Final 5-Year Results from the Bfore Trial. 62nd ASH Annual Meeting, December 5-8, 2020. Abstract 46.

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