Chemotherapy is the mainstay treatment stragety for triple negative breast cancer (TNBC). However resistance to chemotherapy is common, leading to disease progression and death. Strategies that improve chemotherapy efficacy has the potential to reduce TNBC mortality. In this research, we demonstrated that the pan-PI3K inhibitor copanlisib, which is already in clinic to treat hematologic malignancies, enhanced the cytotoxicity of eribulin, a common chemotherapy used to treat taxane-resistant TNBC, in a panel of TNBC patient-derived xenograft (PDX) models. The improved tumor growth inhibition was irrespective of PI3K pathway alteration and was corroborated by the enhanced apoptotic induction observed in PDX tumors post combination therapy compared to each drug alone. The combination therapy inhibited eribulin-induced PI3K pathway activation, providing an underlying mechanism of action for its enhanced anti-tumor effect. Based on these results, a Phase I/II trial of this combination in patients with metastatic TNBC was initiated and is ongoing.
Overall design
27 mRNA microarray experiments were analyzed for 8 different HIM lines. 5 of these lines had data from a patient biospy as well as multiple passages from a mouse xenograft. 3 tumors had data from mouse xenograft passages but no data from the patient biopsy. Each representative patient tumor sample and mouse xenograft passage was amplified, labeled, and co-hybridized with a reference sample.
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