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Neuro Oncol. 2015 Sep;17(9):1270-4. doi: 10.1093/neuonc/nou365. Epub 2015 Jan 20.

Phase II study of PX-866 in recurrent glioblastoma.

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CancerCare Manitoba, Winnipeg, Canada (M.W.P., S.B.); Queen's University, Department of Oncology, Kingston, Canada (E.A.E.); Dalhousie University,Halifax, Canada (M.V.M.); BritishColumbia Cancer Agency, Vancouver, Canada (B.T.); Tom Baker Cancer Centre, Calgary, Canada (J.C.E.); London Regional Cancer Program, London, Canada (D.R.M.); University of Alberta, Edmonton, Canada (D.D.E.); Allan Blair Cancer Center, Regina, Canada (A.S.K., M.S., H.C.); Department of Pathology and Molecular Medicine, Queen's University, Kingston, Canada (J.S.); Department of Pathology, University Health Network, University of Toronto, Toronto, Canada (M.S.T., S.K.-R.); NCIC Clinical Trials Group, Queen's University, Kingston, Canada (D.T., J.P.); Oncothyreon, Inc., Seattle, Washington (D.F.H.); Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada (W.P.M.).



Glioblastoma (GBM) is the most aggressive malignancy of the central nervous system in adults. Increased activity of the phosphatidylinositol-3-OH kinase (PI3K) signal transduction pathway is common. We performed a phase II study using PX-866, an oral PI3K inhibitor, in participants with recurrent GBM.


Patients with histologically confirmed GBM at first recurrence were given oral PX-866 at a dose of 8 mg daily. An MRI and clinical exam were done every 8 weeks. Tissue was analyzed for potential predictive markers.


Thirty-three participants (12 female) were enrolled. Median age was 56 years (range 35-78y). Eastern Cooperative Oncology Group performance status was 0-1 in 29 participants and 2 in the remainder. Median number of cycles was 1 (range 1-8). All participants have discontinued therapy: 27 for disease progression and 6 for toxicity (5 liver enzymes and 1 allergic reaction). Four participants had treatment-related serious adverse events (1 liver enzyme, 1 diarrhea, 2 venous thromboembolism). Other adverse effects included fatigue, diarrhea, nausea, vomiting, and lymphopenia. Twenty-four participants had a response of progression (73%), 1 had partial response (3%, and 8 (24%) had stable disease (median, 6.3 months; range, 3.1-16.8 months). Median 6-month progression-free survival was 17%. None of the associations between stable disease and PTEN, PIK3CA, PIK3R1, or EGFRvIII status were statistically significant.


PX-866 was relatively well tolerated. Overall response rate was low, and the study did not meet its primary endpoint; however, 21% of participants obtained durable stable disease. This study also failed to identify a statistically significant association between clinical outcome and relevant biomarkers in patients with available tissue.


PI3K; clinical trial; glioblastoma

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