Voxtalisib (XL765) in patients with relapsed or refractory non-Hodgkin lymphoma or chronic lymphocytic leukaemia: an open-label, phase 2 trial

Background Patients with relapsed or refractory lymphoma or chronic lymphocytic leukaemia have a poor prognosis. Therapies targeting more than one isoform of PI3K, as well as mTOR, might increase antitumour activity. We aimed to investigate the efficacy and safety of voxtalisib (also known as XL765 or SAR245409), a pan-PI3K/mTOR inhibitor, in patients with relapsed or refractory lymphoma, or chronic lymphocytic leukaemia/small lymphocytic lymphoma. Methods We did a non-randomised, open-label, phase 2 trial at 30 oncology clinics in the USA, Belgium, Germany, France, the Netherlands, and Australia. Patients aged 18 years or older with Eastern Cooperative Oncology Group (EGOG) performance status score of 2 or lower and relapsed or refractory mantle cell lymphoma, follicular lymphoma, diffuse large B-cell lymphoma, or chronic lymphocytic leukaemia/small lymphocytic lymphoma were enrolled and treated with voxtalisib 50 mg orally twice daily in 28-day continuous dosing cycles until progression or unacceptable toxicity. The primary endpoint was the proportion of patients in each disease-specific cohort who achieved an overall response, defined as a complete response or partial response. All patients who received more than 4 weeks of treatment and who completed a baseline and at least one post-baseline tumour assessment were analysed for efficacy and all patients were analysed for safety. This study is registered with ClinicalTrials.gov, number NCT01403636, and has been completed. Findings Between Oct 19, 2011, and July 24, 2013, 167 patients were enrolled (42 with mantle cell lymphoma, 47 with follicular lymphoma, 42 with diffuse large B-cell lymphoma, and 36 with chronic lymphocytic leukaemia/small lymphocytic lymphoma. The median number of previous anticancer regimens was three (IQR 2-4) for patients with lymphoma and four (2-5) for patients with chronic lymphocytic leukaemia/small lymphocytic lymphoma. Of 164 patients evaluable for efficacy, 30 (18.3%) achieved an overall response (partial, n=22; complete, n=8); 19 (41.3%) of 46 with follicular lymphoma, five (11.9%) of 42 with mantle cell lymphoma, two (4.9%) of 41 with diffuse large B-cell lymphoma, and four (11.4%) of 35 with chronic lymphocytic leukaemia/small lymphocytic lymphoma. The safety profile was consistent with that of previous studies of voxtalisib. The most frequently reported adverse events were diarrhoea (in 59 [35%] of 167 patients), fatigue (in 53 [32%]), nausea (in 45 [27%]), pyrexia (in 44 [26%,]), cough (in 40 [24%]), and decreased appetite (in 35 [21%]). The most frequently reported grade 3 or worse adverse events were anaemia (in 20 [12%] of 167 patients), pneumonia (in 14 [8%]), and thrombocytopenia (in 13 [8%]). Serious adverse events occurred in 97 (58.1%) of 167 patients. Interpretation Voxtalisib 50 mg given orally twice daily had an acceptable safety profile, with promising efficacy in patients with follicular lymphoma but limited efficacy in patients with mantle cell lymphoma, diffuse large B-cell lymphoma, or chronic lymphocytic leukaemia/small lymphocytic lymphoma.