APG-2449抑制FAK可增强MAPK通路阻断在BRAF V600E突变肿瘤模型中的抗肿瘤活性

Background: BRAF mutations are present in approximately 4% to 8% of all cancers, predominantly in colorectal cancer (CRC), melanoma, and non-small-cell lung cancer. Among them, the V600E mutation is the most common and functionally activating form, leading to constitutive activation of the mitogen‑activated protein kinase (MAPK) signaling cascade. Combined BRAF and MEK inhibition has shown substantial clinical benefit in BRAF V600E-mutant melanoma and CRC. However, resistance frequently develops through feedback reactivation of ERK or compensatory activation of the PI3K‑AKT signaling pathway. Recent evidence indicates that focal adhesion kinase (FAK) signaling is also adaptively reactivated upon MAPK inhibition, contributing to therapeutic resistance. This study evaluated the effects of APG-2449, a potent and selective multikinase (FAK) inhibitor, on the antitumor activity of BRAF inhibitor dabrafenib and MEK inhibitor trametinib in BRAF V600E‑mutant CRC and melanoma preclinical models. Methods: Cell proliferation was measured by CellTiter-Glo ® assay or clonal formation assay. Apoptosis was assessed using flow cytometry. Protein expression levels were examined by western blot. Antitumor effects of APG‑2449, alone or combined with dabrafenib and trametinib, were evaluated in C32 and RKO xenograft models in vivo . Results: Cell proliferation assays across a panel of human cancer cell lines revealed that cell lines harboring BRAF V600E were more sensitive to APG-2449 than those without MAPK pathway alterations. APG-2449 synergistically enhanced the antiproliferative efficacy of dabrafenib and trametinib in both BRAF inhibitor-sensitive (C32 and Colo205) and -insensitive (RKO and LS411N) cells. The triple combination (APG-2449 + dabrafenib + trametinib) caused synergistic growth inhibition in C32 and RKO cells compared with BRAF/MEK dual blockade. Mechanistically, APG-2449 attenuated feedback reactivation of ERK signaling and bypass activation of the PI3K-AKT pathway induced by BRAF/MEK inhibition, resulting in sustained suppression of p-ERK and p-AKT expression, prolonged cell growth inhibition, and enhanced cell apoptosis. In in vivo studies, the triple combination (T/C: 4.55% for C32; 17.18% for RKO) outperformed APG-2449 alone (T/C: 106.09% for C32; 96.93% for RKO) or dabrafenib + trametinib (T/C: 35.39% for C32; 78.45% for RKO) in tumor growth inhibition. APG-2449 synergistically enhanced the antitumor activity of trametinib + dabrafenib in C32 and RKO xenograft models, with synergy ratios of 8.25 and 4.43, respectively. Conclusions: APG-2449 suppresses compensatory signaling activation induced by MAPK pathway blockade and synergistically enhances the antitumor activity of dabrafenib + trametinib. These results warrant clinical development of APG-2449 for patients with melanoma or CRC harboring BRAF V600E.