Phase IB Study of Vemurafenib in Combination with Irinotecan and Cetuximab in Patients with Metastatic Colorectal Cancer with BRAFV600E Mutation.

In vitro, EGFR inhibition, combined with the BRAF inhibitor vemurafenib, causes synergistic cytotoxicity for BRAFV600E metastatic colorectal cancer, further augmented by irinotecan. The safety and efficacy of vemurafenib, irinotecan, and cetuximab in BRAF-mutated malignancies are not defined. In this 3+3 phase I study, patients with BRAFV600E-advanced solid cancers received cetuximab and irinotecan with escalating doses of vemurafenib. Nineteen patients (18 with metastatic colorectal cancer and 1 with appendiceal cancer) were enrolled. Three patients experienced dose-limiting toxicities. The MTD of vemurafenib was 960 mg twice daily. Six of 17 evaluable patients (35%) achieved a radiographic response by Response Evaluation Criteria in Solid Tumors 1.1 criteria, consistent with in vivo models demonstrating tumor regressions with the triplet regimen. Median progression-free survival was 7.7 months. BRAFV600E circulating cell-free DNA (cfDNA) trends correlated with radiographic changes, and acquired mutations from cfDNA in genes reactivating MAPK signaling were observed at progression. SIGNIFICANCE: Vemurafenib, in combination with irinotecan and cetuximab, was well tolerated in patients with refractory, BRAF-mutated metastatic colorectal cancer, and both survival outcomes and response rates exceeded prior reports for vemurafenib and for irinotecan plus cetuximab in BRAFV600E metastatic colorectal cancer. In vivo models demonstrated regressions with the triplet, in contrast with vemurafenib and cetuximab alone. cfDNA predicted radiographic response and identified mutations reactivating the MAPK pathway upon progression. Cancer Discov; 6(12); 1352-65. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 1293.

Phase I combination of pazopanib and everolimus in PIK3CA mutation positive/PTEN loss patients with advanced solid tumors refractory to standard therapy.

PURPOSE: Combining agents that block both the VEGF and PI3K/AKT/mTOR pathways may be synergistic. We explored a novel dosing schedule to assess safety, toxicity and activity in patients with advanced solid tumors. PATIENTS AND METHODS: Patients with refractory solid tumors were enrolled in a modified 3 + 3 Phase I dose escalation study to determine dose limiting toxicities (DLTs) and the maximum tolerated dose (MTD) of a combination of everolimus (mTOR inhibitor) and pazopanib (tyrosine kinase inhibitor with anti-VEGF activity). An expansion cohort selected for patients with molecular alterations in the PI3K/AKT/mTOR pathway. RESULTS: Sixty-two patients were enrolled; median age was 60 years; 29 were women. The MTD was pazopanib 600 mg every other day (QOD) alternating with everolimus 10 mg PO QOD. DLTs were grade 3 thrombocytopenia and creatinine elevation. Most common toxicities of any grade were thrombocytopenia, transaminitis, leukopenia/neutropenia and lipid abnormalities. Among 52 patients evaluable for response, the clinical benefit rate (CBR) was 27 % (14/52) including four partial responses (PR), and 10 stable disease (SD) ≥6 months. 26 of 45 patients evaluated for molecular alterations had at least one alteration in the PI3K/AKT/mTOR pathway. CBR in patients with a matched alteration was 27 % (7/26) versus 26 % (5/19) for patients without an alteration (p = 0.764). However, 64% of those with CBR and molecular testing done for alteration in the PI3K/AKT/mTOR pathway were positive. CONCLUSION: Combination treatment with pazopanib and everolimus was well tolerated and demonstrated activity in solid tumors. Further exploration of this combination and molecular correlation with treatment outcomes is warranted.