A phase I safety and pharmacokinetic study of XL765 (SAR245409), a novel PI3K/TORC1/TORC2 inhibitor, in combination with temozolomide (TMZ) in patients (pts) with newly diagnosed malignant glioma.
2010 ASCO Annual Meeting
Background: PI3K pathway dysregulation has been implicated in resistance to TMZ in preclinical glioma models. XL765, a potent and selective inhibitor of class I PI3K isoforms and TORC1 and TORC2, has demonstrated dose-dependent target modulation in both tumor xenograft models and in normal brain tissue in preclinical studies. Methods: Pts with WHO grade III and IV astrocytic tumors who have received standard chemoradiation with TMZ followed by at least one cycle of maintenance TMZ (200 mg/m2/day × 5 q 28 days) are eligible. XL765 is dose escalated following a standard 3 + 3 design and administered in combination with a fixed dose of TMZ. Results: 18 pts have been treated with XL765 in combination with TMZ across 4 dose levels of XL765 (30, 40, 50, and 60 mg qd). The maximum administered dose (MAD) of XL765 is 60 mg for the qd schedule; 2 of 6 pts experienced DLTs. The most common (≥ 10%) treatment-related AEs were nausea, hyperglycemia, constipation, fatigue, thrombocytopenia, and skin disorders. Grade ≥ 3 treatment related AEs were observed in four pts: grade 3 brain edema and grade 4 thrombocytopenia (one pt, also reported as a DLT), grade 3 rash (one pt, also reported as a DLT), grade 3 thrombocytopenia (one pt), and grade 4 increased transaminases (one pt). Based on comparison with single agent data, no major PK interaction between XL765 and TMZ is evident. At the 30 and 40 mg qd XL765 dose levels, inhibition of PI3K pathway (pAKT-T308, pAKT-S473, and p4EBP1) signaling has been demonstrated in skin. Based on assessment of archival tumor material, the most common molecular alterations detected include MGMT promoter methylation, PTEN point mutations, and EGFR gene amplification. Of the first 18 pts enrolled, seven pts have remained on study for > 16 weeks, one of whom continued on study for 62 weeks. Conclusions: XL765 in combination with TMZ is generally well tolerated at doses up to 40 mg qd. There is no apparent PK interaction between XL765 and TMZ. MTD determinations for qd and bid schedules are ongoing.
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