Hqp1351, A Novel Multikinase Inhibitor In Clinical Development, Overcomes Drug Resistance For The Treatment Of Gastrointestinal Stromal Tumors In Preclinical Models

Gastrointestinal stromal tumors (GIST) harbor driver mutations of signal transduction kinases such as KIT. Besides surgical resection for primary localized tumors, imatinib remains the first-line treatment for advanced and metastatic GISTs. Imatinib targets a few kinases including KIT that often carries the primary driver mutations commonly located on exon 11 and exon 9. Unfortunately, a large proportion of the patients ultimately develop progressive disease owing to the secondary resistance mutations in KIT gene. We have developed an orally bioavailable multikinase inhibitor HQP1351, which is currently in clinical trials for the treatment of T315I mutant CML. Here, we demonstrated that HQP1351 inhibited both wild type and mutant (i.e., KIT L576P , KIT V559D , and KIT V559D/T670I ) KIT in biochemical assays. Using a panel of imatinib-resistant and sensitive GIST cancer cell lines derived from patient samples, we showed that HQP1351 exhibited more potent anti-proliferative activities than ponatinib (range of IC 50 values: 0.027-0.133 µM vs. 0.021-0.730 µM), the latter of which is currently in clinical development in GIST to overcome the resistance to imatinib (NCT03171389). In addition, the treatment of GIST cancer cells with HQP1351 in vitro led to more profound inhibition of pharmacodynamic markers, including p-c-KIT, p-AKT, p-ERK1/2, and p-AKT, in comparison with ponatinib. Correspondingly, in multiple xenograft tumor models derived from these GIST cancer cell lines carrying the secondary mutations of KIT, HQP1351 exhibited superior antitumor activities to ponatinib. Collectively, considering that HQP1351 has already been in clinical trials, the above results suggest that therapeutic application of HQP1351 in imatinib-resistant GIST patients deserves further investigation in human. Citation Format: Guangfeng Wang, Haibo Qiu, Ping Min, Miaoyi Wu, Shuo Dang, Chunyang Yang, Fei Zhang, Wei Zhuang, Zhiwei Zhou, Douglas D. Fang, Dajun Yang, Yifan Zhai. HQP1351, a novel multikinase inhibitor in clinical development, overcomes drug resistance for the treatment of gastrointestinal stromal tumors in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1979.