Abstract 4928: Gedatolisib, a well-tolerated pan-PI3K/mTOR inhibitor, exhibits potent therapeutic effects on endometrial cancer models regardless of their PI3K pathway mutational status

Background: The PI3K, AKT, and mTOR (PAM) pathway is one of the most commonly activated oncogenic pathways in gynecological cancers. Loss of PTEN function and PIK3CA activating mutations are especially frequent in endometrial cancer (EC). Targeting the PAM pathway, in combination with other cooperative oncogenic pathways (e.g., the estrogen pathway), is a promising EC treatment strategy. Currently, everolimus, an mTORC1 inhibitor, in combination with letrozole, an aromatase inhibitor, is one of the available hormonal therapy options for patients with advanced endometrioid EC. Most PAM inhibitors (PAM-i) selectively spare (or weakly inhibit) one or more key PAM pathway components, which can lead to drug resistance. To minimize drug resistance, a more comprehensive inhibition of the PI3K isoforms and downstream mTOR complexes may be required. We hypothesized that gedatolisib, which potently inhibits all Class I PI3K isoforms, mTORC1, and mTORC2, can potentially be an effective and well tolerated therapy for patients with EC. Methods: A panel of endometrial, ovarian and cervical cancer cell lines with different PI3K pathway mutational status were assayed for their sensitivity to gedatolisib and other PAM inhibitors (PI3K-α: alpelisib, pan-PI3K: copanlisib; AKT: capivasertib; mTORC1: everolimus; pan-PI3K/mTOR: gedatolisib). Cell viability, cell proliferation, and flow cytometry analytical assays were conducted. Xenograft studies evaluating gedatolisib in EC cell lines were also performed. Results: Gedatolisib strongly inhibited PAM pathway activation, and reduced cell cycle progression and cell viability in the endometrial, ovarian, and cervical cancer cell lines. Compared to the other PAM-i, Gedatolisib exhibited superior anti-proliferative potency and efficacy in almost all the cell lines tested, regardless of the PI3K pathway mutational status or cancer type. In EC xenografts, gedatolisib substantively inhibited tumor growth irrespective of the cell line models’ PI3K pathway mutational status. Conclusions: We demonstrated that, gedatolisib induces superior anti-proliferative activity compared to the other PAM pathway inhibitors, regardless of the PI3K pathway mutational status of the cancer cell lines evaluated. Gedatolisib as a single agent and in combination with other therapies has previously reported promising preliminary clinical efficacy and safety in various solid tumor types, including EC. In summary, nonclinical and preliminary clinical data suppor