Efficacy of vemurafenib based regimens in colorectal cancer: A systematic review of clinical trials

e15566 Background: Colorectal cancer (CRC) is the 3 rd most common cancer worldwide, and BRAF gene mutation is present in almost 10% of these cancers. It results in constitutive activation of the mitogen-activated protein kinase pathway (MAPKP). Abnormal activation of MAPKP leads to uncontrolled mitotic activity and inhibition of apoptosis. In this systematic review, we will assess the efficacy of vemurafenib (BRAF inhibitor) based regimens in CRC. Methods: We followed PRISMA guidelines to conduct this systematic review. A literature search was performed on PubMed, Clinicaltirals.gov, and Embase with mesh terms, ‘’Colorectal Neoplasms’’ and “Proto-Oncogene Proteins B-raf” from the inception of data till 01/05/2023. We screened 4572 articles and included 1 randomized clinical trial (RCT, N = 100), and 4 non-randomized trials (nRCTs, N = 85), measuring the efficacy of vemurafenib (V) based regimens in BRAF V600E-mutated CRC. Results: In 5 clinical trials (N = 185), 90 patients were treated with triple therapy, 45 with dual therapy, and 50 were in the control arm. In triple therapy, 69 patients were treated with V plus irinotecan (I) and cetuximab (C), overall response rate (ORR) was 17% and 35%, and progression-free survival (PFS) was 4.2 and 7.7 months in the randomized and the non-randomized study, respectively. PFS was improved significantly with a hazard ratio (HR) of 0.50 (95% CI, 0.32 to 0.76, P = .001) in favor of V+I+C compared to C+I. Among combinations of V+C, adding 5-fluorouracil/leucovorin/irinotecan (FOLFIRI) as third combination showed the highest ORR of 81% and overall survival (OS) and PFS of 15.4 and 9.7 months, respectively. In two drug regimens, V was combined with Cobimetinib (Co) and Panitumumab (P) in two non-randomized studies, and partial response (PR) was 26% and 13%, respectively. (Table 1). Conclusions: BRAF + EGFR inhibitor combination is showing promising antitumor effects, and the addition of the FOLFIRI regimen was more effective than adding irinotecan alone while comparing treatment regimens in BRAF V600E-mutated CRC patients with metastasis. V+Co showed antitumor effects in CRC BRAF mutated patients who were heavily pre-treated. More randomized trials needed. [Table: see text]