Identification of Wee1 as a target in combination with avapritinib for gastrointestinal stromal tumor treatment

Abstract

Management of gastrointestinal stromal tumors (GISTs) has been revolutionized by the identification of activating mutations in KIT and PDGFRA and clinical application of RTK inhibitors in advanced disease. Stratification of GISTs into molecularly defined subsets provides insight into clinical behavior and response to approved targeted therapies. Although these RTK inhibitors are effective in most GISTs, resistance remains a significant clinical problem. Development of effective treatment strategies for refractory GISTs requires identification of novel targets to provide additional therapeutic options. Global kinome profiling has the potential to identify critical signaling networks and reveal protein kinases essential in GISTs. Using multiplexed inhibitor beads and mass spectrometry, we explored the majority of the kinome in GIST specimens from the 3 most common molecular subtypes ( KIT mutant, PDGFRA mutant, and succinate dehydrogenase deficient) to identify kinase targets. Kinome profiling with loss-of-function assays identified an important role for G 2 /M tyrosine kinase, Wee1, in GIST cell survival. In vitro and in vivo studies revealed significant efficacy of MK-1775 (Wee1 inhibitor) in combination with avapritinib in KIT mutant and PDGFRA mutant GIST cell lines as well as notable efficacy of MK-1775 as a monotherapy in the engineered PDGFRA mutant line. These studies provide strong preclinical justification for the use of MK-1775 in GIST.

Antitumor effect of WEE1 blockade as monotherapy or in combination with cisplatin in urothelial cancer

“…Recent studies have shown that WEE1 is implicated in multidrug resistance, particularly to drugs related to cell cycle modulators, DNA‐damaging agents, or DNA‐repair inhibitors. Consistently, the drug resistance of tumors is associated with increased expression of WEE1 or activation of WEE1 signaling pathways 11,20 . Indeed, several reports have shown the synergistic effect of the WEE1 inhibitor with various anticancer agents in a variety of malignant diseases, such as the AURKA inhibitor alisertib (MLN8237) in HNSCC, 14 an ATR inhibitor in diffuse large B‐cell lymphoma, 15 a BET inhibitor in non‐small‐cell lung cancer, 35 trastuzumab in HER2‐positive breast cancer, 36 and avapritinib in gastrointestinal stromal tumors 20 .…”

“…Consistently, the drug resistance of tumors is associated with increased expression of WEE1 or activation of WEE1 signaling pathways 11,20 . Indeed, several reports have shown the synergistic effect of the WEE1 inhibitor with various anticancer agents in a variety of malignant diseases, such as the AURKA inhibitor alisertib (MLN8237) in HNSCC, 14 an ATR inhibitor in diffuse large B‐cell lymphoma, 15 a BET inhibitor in non‐small‐cell lung cancer, 35 trastuzumab in HER2‐positive breast cancer, 36 and avapritinib in gastrointestinal stromal tumors 20 . These findings suggest that WEE1 is induced by drug treatment as a process toward resistance.…”

Combined Inhibition of AKT and KIT Restores Expression of Programmed Cell Death 4 (PDCD4) in Gastrointestinal Stromal Tumor

“…Wells were then treated with varying doses of MK-4440 and/or IM. Cell proliferation and viability were measured at 72 h post treatment using the CellTiter Blue Viability Assay (Promega, Fitchburg, WI, USA) as described previously [24]. Assays were performed as three independent biological replicates, with a minimum of six technical replicates in each treatment arm.…”

“…Assays were performed as three independent biological replicates, with a minimum of six technical replicates in each treatment arm. Combination indexes of CI LD50 (GIST-T1) and CI LD30 (GIST430, GIST-T1/829) were quantified using the previously described approach [24].…”

“…BrdU incorporation assay was used to measure cell proliferation. GIST-T1 cells were labeled with BrdU for 4 h, and GIST430 cells were labeled for 20 h and GIST-T1/829 for 1.5 h and then analyzed with BrdU-APC Flow Kit (BD Biosciences, San Jose, CA, USA), as described previously [24].…”