Owen, Scott

Abstract Oncogenic translocations involving the MET gene have been reported in several cancer types, but detailed clinicogenomic characterization of these cancers is not well defined. In addition, prospective clinical trials evaluating the antitumor activity of MET inhibitors in MET rearrangement–positive cancers are limited. In this study, in a pan-cancer analysis of >46,000 solid tumors with comprehensive genomic profiling, we identified oncogenic MET rearrangements in ∼0.04% of cancers. Preliminary analysis from a phase II clinical trial of the type I MET tyrosine kinase inhibitor (TKI) vebreltinib in MET fusion–positive solid tumors demonstrated an objective response rate of 50% and disease control rate of 79%, with antitumor activity seen in diverse cancer types, including lung adenocarcinoma and intrahepatic cholangiocarcinoma, among others. Similar to MET exon 14–altered lung cancer, secondary mutations in the kinase domain can confer resistance to MET TKIs in MET fusion–positive cancers. Overall, these data categorize MET rearrangements as actionable targets in solid tumors. Significance: MET rearrangement–positive cancers are not well-characterized, and optimal treatment strategies are yet to be defined. Through comprehensive genomic analysis, preclinical modeling, and preliminary results of a phase II clinical trial, we demonstrate that MET fusions are a unique molecular subtype of cancers targetable with vebreltinib, a TKI in development.

Abstract GBM AGILE(NCT03970447) is a phase 2/3 Bayesian adaptive registration platform trial testing multiple therapies against a common control. Paxalisib, a PI3K/mTOR inhibitor, is the 3rd arm in the trial to conclude evaluation. METHODS Paxalisib was open to patients with newly diagnosed unmethylated (NDU) and recurrent (RD) glioblastoma, with three possible signatures: NDU, RD, and All(NDU+RD). Arm enrollment occurred Dec2020 through May2022. Control patients were enrolled from study initiation (July2019) and were treated with temozolomide(NDU) or lomustine(RD). GBM AGILE investigational arms have 1 or 2 stages, with adaptive randomization in stage 1 and fixed randomization if arms continue to stage 2. Efficacy is based on OS hazard ratio(HR) of Arm/Control. Efficacy goal is final Bayesian probability ≥ 98% for HR<1.00 in combined Stages. An Arm continues to Stage 2 if Bayesian predictive power (PP) ≥ 0.8. An Arm stops accruing in Stage 1 if it reaches maximal sample size(N) or does not meet a minimum efficacy threshold (PP<0.25 for all signatures when N>50). Clinical cut-off is 12 months after accrual stops. The maximum N for paxalisib was approximately 150(Stage 1) and 50(Stage 2). RESULTS After paxalisib reached >150 patients in Stage 1, accrual stopped [Paxalisib/control N 54/75(NDU), 100/188(RD)]. Neither PP thresholds for moving to Stage 2 nor stopping for minimum efficacy were met. Following an unplanned public disclosure that the arm did not continue to stage 2, clinical cut-off for final analysis (planned May2023) was updated to public disclosure date (August2022). At final analysis mean HRs were 0.89(NDU), 1.25(RD), 1.05(All), probabilities of HR<1.00 of 0.72(NDU), 0.076(RD), 0.398(All). Model estimated median OS paxalisib/control (months) were 14.77/13.84(NDU) and 8.58/10.06(RD). CONCLUSION Paxalisib did not show survival benefit over cumulative control in final primary analysis; additional secondary analyses are being considered. GBM AGILE continues to rapidly and efficiently assess therapies in ND and RD glioblastoma.