SummaryBackground Poly(ADP-ribose) polymerase (PARP) inhibitors have activity in ovarian carcinomas with homologous recombination defi ciency. Along with BRCA1 and BRCA2 (BRCA) mutations genomic loss of heterozygosity (LOH) might also represent homologous recombination defi ciency. In ARIEL2, we assessed the ability of tumour genomic LOH, quantifi ed with a next-generation sequencing assay, to predict response to rucaparib, an oral PARP inhibitor.
Purpose: This first-in-human dose-escalation trial evaluated the safety, tolerability, maximal-tolerated dose (MTD), doselimiting toxicities (DLT), pharmacokinetics, pharmacodynamics, and preliminary clinical activity of pictilisib (GDC-0941), an oral, potent, and selective inhibitor of the class I phosphatidylinositol-3-kinases (PI3K).Patients and Methods: Sixty patients with solid tumors received pictilisib at 14 dose levels from 15 to 450 mg once-daily, initially on days 1 to 21 every 28 days and later, using continuous dosing for selected dose levels. Pharmacodynamic studies incorporated 18 F-FDG-PET, and assessment of phosphorylated AKT and S6 ribosomal protein in platelet-rich plasma (PRP) and tumor tissue.Results: Pictilisib was well tolerated. The most common toxicities were grade 1-2 nausea, rash, and fatigue, whereas the DLT was grade 3 maculopapular rash (450 mg, 2 of 3 patients; 330 mg, 1 of 7 patients). The pharmacokinetic profile was dose-proportional and supported once-daily dosing. Levels of phosphorylated serine-473 AKT were suppressed >90% in PRP at 3 hours after dose at the MTD and in tumor at pictilisib doses associated with AUC >20 hÁmmol/L. Significant increase in plasma insulin and glucose levels, and >25% decrease in 18 F-FDG uptake by PET in 7 of 32 evaluable patients confirmed target modulation. A patient with V600E BRAF-mutant melanoma and another with platinumrefractory epithelial ovarian cancer exhibiting PTEN loss and PIK3CA amplification demonstrated partial response by RECIST and GCIG-CA125 criteria, respectively.Conclusion: Pictilisib was safely administered with a doseproportional pharmacokinetic profile, on-target pharmacodynamic activity at dose levels !100 mg and signs of antitumor activity. The recommended phase II dose was continuous dosing at 330 mg once-daily.
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