The efficacy of WEE1 inhibition in KRAS-mutant colorectal cancer
In over 40% of colorectal cancer (CRC) cases, patients present with a KRAS mutation, an alteration associated with aggressive disease, therapeutic resistance, and poor prognosis. Despite the prevalence of tumors with KRAS mutations, there exists a significant unmet clinical need for targeted therapeutics in this context. A potential treatment strategy for KRAS mutant CRCs is G2/M checkpoint abrogation, which enables cells with DNA damage to divide, which can lead to mitotic catastrophe and cell death. This can be achieved using AZD1775, a drug that inhibits WEE1 kinase, which regulates the G2/M checkpoint and has shown promise in phase 1 clinical trials. We hypothesized that KRAS mutant CRC cell lines with concomitant p53 mutation will be most sensitive to AZD1775 in combination with DNA damaging agents as compared to KRAS wild type cell lines. The sensitivity of CRC cell lines (± mutant KRAS and ± mutant TP53) was determined using a cell viability assay after treatment with AZD1775. It was observed that LOVO, which has mutant KRAS and wild-type p53, was the most sensitive to the WEE1 drug. Other CRC cell lines responded similarly to the drug independent of KRAS and p53 status. One confounding factor could be the presence of BRAF mutations that activate similar signaling to mutant KRAS. It was confirmed that AZD1775 was inhibiting WEE1 using immunoblot analysis to detect phospho-CDC2, a WEE1 target. DNA damage was detected in cells treated with AZD1775, as indicated by an increase in phospho-H2AX. In all CRC cell lines (SW620, HCT116, LOVO, HT-29, and COLO205) combination treatment of AZD1775 and cisplatin lowered cell viability between 21-78% compared to cisplatin alone. Future investigations will determine the role of mutant KRAS in the sensitivity of CRC to AZD1775 and the most effective combinational strategies. This research will provide important insight into the viability of AZD1775 as a therapeutic option in CRC patients with mutant KRAS, who currently have no effective therapeutic regimens.