356 Characterization of TAS-117, a Novel, Highly Potent and Selective Inhibitor of AKT

A first-in-human phase I study of TAS-117, an allosteric AKT inhibitor, in patients with advanced solid tumors

PURPOSE

TAS-117 is a highly potent and selective, oral, allosteric pan-AKT inhibitor under development for advanced/metastatic solid tumors. The safety, clinical pharmacology, pharmacogenomics and efficacy were investigated.

METHODS

This phase I, open-label, non-randomized, dose-escalating, first-in-human study enrolled patients with advanced/metastatic solid tumors and comprised three phases (dose escalation phase [DEP], regimen modification phase [RMP], and safety assessment phase [SAP]). The SAP dose and regimen were determined in the DEP and RMP. Once-daily and intermittent dosing (4 days on/3 days off, 21-day cycles) were investigated. The primary endpoints were dose-limiting toxicities (DLTs) in Cycle 1 of the DEP and RMP and incidences of adverse events (AEs) and adverse drug reactions (ADRs) in the SAP. Secondary endpoints included pharmacokinetics, pharmacodynamics, pharmacogenomics, and antitumor activity.

RESULTS

Of 66 enrolled patients, 65 received TAS-117 (DEP, n = 12; RMP, n = 10; SAP, n = 43). No DLTs were reported with 24-mg/day intermittent dosing, which was selected as a recommended dose in SAP. In the SAP, 98.5% of patients experienced both AEs and ADRs (grade ≥ 3, 67.7% and 60.0%, respectively). In the dose range tested (8 to 32 mg/day), TAS-117 pharmacokinetics were dose proportional, and pharmacodynamic analysis showed a reduction of phosphorylated PRAS40, a direct substrate of AKT. Four patients in the SAP had confirmed partial response.

CONCLUSION

Oral doses of TAS-117 once daily up to 16 mg/day and intermittent dosing of 24 mg/day were well tolerated. TAS-117 pharmacokinetics were dose proportional at the doses evaluated. Antitumor activity may occur through AKT inhibition.

TRIAL REGISTRATION

jRCT2080222728 (January 29, 2015).

A phase II study of TAS-117 in patients with advanced solid tumors harboring germline PTEN-inactivating mutations

PTEN acts as a potent tumor suppressor within the PI3K/AKT/mTOR pathway. Germline mutations in the PTEN gene are a hallmark of PTEN hamartoma tumor syndrome, which includes Cowden syndrome, where they appear to elevate lifetime risk of cancer. Targeted AKT directed therapy has been proposed as an effective approach in cancer patients having germline PTEN mutations. The mechanism of action, safety and dosing regimen for the novel allosteric AKT inhibitor TAS-117 have been explored in a phase I study in Japan in which activity was observed against certain tumor types. Here we describe the study protocol of an international, two-part phase II study evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics and antitumor activity of TAS-117 in patients with advanced solid tumors harboring germline PTEN-inactivating mutations.

Targeting Akt/PKB in pediatric tumors: A review from preclinical to clinical trials

The serine/threonine kinase Akt is a major player in the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway, and its modulation impacts multiple cellular processes such as growth, proliferation, and survival. Several abnormalities in this pathway have been documented over the years, and these alterations were shown to have great implications in tumorigenesis and resistance to chemotherapy. Thus, multiple Akt inhibitors have been developed and tested in adult tumors, and some of them are currently undergoing phase I, II, and III clinical trials for distinct cancers that arise during adulthood. Despite that, the impact of these inhibitors is still not fully understood in pediatric tumors, and Akt-specific targeting seems to be a promising approach to treat children affected by cancers. This review summarizes recent available evidence of Akt inhibitors in pediatric cancers, from both preclinical and clinical studies. In short, we demonstrate the impact that Akt inhibition provides in tumorigenesis, and we suggest targeting the PI3K/Akt/mTOR signaling pathway, alone or in combination with other inhibitors, is a feasible tool to achieve better outcomes in pediatric tumors.

Phase 2 study of TAS-117, an allosteric akt inhibitor in advanced solid tumors harboring phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene homolog gene mutations

TAS-117 is a potent and selective allosteric pan-v-akt murine thymoma viral oncogene homolog (Akt) inhibitor. We conducted a single-arm single-center phase 2 study of TAS-117 in heavily treated patients with tumors refractory to systemic chemotherapy and harboring phosphatidylinositol 3-kinase (PI3K)/Akt mutations. Patients with gastrointestinal (GI) cancers were orally administered 16 mg TAS-117 daily, and those with non-GI tumors were administered 24 mg on a 4 days on/3 days off schedule. The primary endpoint was overall response rate (ORR). Secondary endpoints included disease control rate (DCR), progression-free survival (PFS), overall survival (OS), PFS ratio, safety, and tolerability. Thirteen patients were enrolled: eight with non-GI (breast, ovarian, endometrial, and non-small cell lung) and five with GI (colon, rectal, gastric, and gallbladder) cancers. Ten patients were treated with TAS-117 after ≥ 4 lines of therapy. Twelve patients showed PIK3 catalytic subunit alpha (PIK3CA) mutations; one harbored an Akt1E17K mutation. The median treatment duration was 1.4 months; the median number of treatment cycles was 2. The ORR was 8 %, and DCR was 23 %. The median PFS and OS were 1.4 and 4.8 months, respectively. Grade 3-4 treatment-related adverse events were anorexia (grade 3, 8 %) and hyperglycemia (grade 3, 8 %; grade 4, 8 %).Grade 3-4 treatment-related adverse events occurred in 27 % of grade 3 anorexia (9 %) and hyperglycemia (grade 3, 8 %; grade 4, 9\%). TAS-117 showed limited antitumor activity and manageable toxicity. Clinical efficacy was observed in patients with ovarian cancer harboring PIK3CA E545K mutations and in patients with breast cancer harboring PIK3CA H1047R and Akt1E17K mutations.Trial registration: This study was retrospectively registered with ClinicalTrial.gov (NCT03017521 on January 11, 2017).