Phase II study of buparlisib (BKM120) and trastuzumab in patients with HER2+ locally advanced or metastatic breast cancer resistant to trastuzumab-based therapy

B. Pistilli, T. Pluard, A. Urruticoechea, D. Farci, A. Kong, T. Bachelot, S. Chan, H. S. Han, G. Jerusalem, P. Urban, D. Robinson, S. L. Mouhaër, E. D. Tomaso, C. Massacesi, C. Saura

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    Résumé

    Purpose: A Phase Ib study in patients with trastuzumab-resistant, human epidermal growth factor receptor-2- (HER2)-positive advanced breast cancer defined the recommended Phase II dose of buparlisib as 100 mg/day in combination with 2 mg/kg weekly trastuzumab, and reported preliminary signs of clinical activity. Here we present results from the Phase II portion. Methods: Patients with trastuzumab-resistant, HER2-positive advanced breast cancer received buparlisib plus trastuzumab. Study endpoints included safety/tolerability and antitumour activity. The study was extended to include a Phase Ib dose-escalation phase, in which patients with progressive brain metastases also received capecitabine. Results: In the Phase II portion, of 50 patients treated with buparlisib and trastuzumab, the most common (≥ 30%) all-grade adverse events (AEs) were diarrhoea (54%), nausea (48%), decreased appetite, increased alanine aminotransferase (36% each), increased aspartate aminotransferase (34%), fatigue, rash (32% each), cough and hyperglycemia (30% each). One (2%) patient achieved complete response and four (8%) patients had confirmed partial responses [PR; including two patients with phosphatidylinositol 3-kinase (PI3 K) pathway-activated tumours]. Overall response rate (ORR) was 10%: the primary endpoint (ORR ≥ 25%) was therefore not met. In the Phase Ib portion, all patients with measurable brain lesions at baseline showed tumour shrinkage to some degree; due to low enrollment, maximum tolerated dose of buparlisib in combination with trastuzumab and capecitabine was not determined. Conclusion: Buparlisib plus trastuzumab, as a chemotherapy-free regimen, demonstrated an acceptable safety profile but limited efficacy in patients with heavily pretreated, trastuzumab-resistant HER2-positive breast cancer, and in patients with progressive brain metastases also receiving capecitabine.

    langue originaleAnglais
    Pages (de - à)357-364
    Nombre de pages8
    journalBreast Cancer Research and Treatment
    Volume168
    Numéro de publication2
    Les DOIs
    étatPublié - 1 avr. 2018

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