Assessments of prostate cancer cell functions highlight differences between a pan-PI3K/mTOR inhibitor, gedatolisib, and single-node inhibitors of the PI3K/AKT/mTOR pathway.

Metastatic castration-resistant prostate cancer (mCRPC) is characterized by loss of androgen receptor (AR) sensitivity and oncogenic activation of the PI3K/AKT/mTOR (PAM) pathway. Loss of the PI3K regulator PTEN is frequent during prostate cancer (PC) initiation, progression, and therapeutic resistance. Co-targeting the PAM/AR pathways is a promising mCRPC treatment strategy but is hampered by reciprocal negative feedback inhibition or feedback relief. Most PAM inhibitors selectively spare (or weakly inhibit) one or more key nodes of the PAM pathway, potentiating drug resistance depending on the PAM pathway mutation status of patients. We posited that gedatolisib, a uniformly potent inhibitor of all class I PI3K isoforms, as well as mTORC1 and mTORC2, would be more effective than inhibitors targeting single PAM pathway nodes in PC cells. Using a combination of functional and metabolic assays, we evaluated a panel of PC cell lines with different PTEN/PIK3CA status for their sensitivity to multi-node PAM inhibitors (PI3K/mTOR: gedatolisib, samotolisib) and single-node PAM inhibitors (PI3Kα: alpelisib; AKT: capivasertib; mTOR: everolimus). Gedatolisib induced anti-proliferative and cytotoxic effects with greater potency and efficacy relative to the other PAM inhibitors, independent of PTEN/PIK3CA status. The superior effects of gedatolisib were likely associated with more effective inhibition of critical PAM-controlled cell functions, including cell cycle, survival, protein synthesis, oxygen consumption rate, and glycolysis. Our results indicate that potent and simultaneous blockade of all class I PI3K isoforms, mTORC1, and mTORC2 could circumvent PTEN-dependent resistance. Gedatolisib, as a single agent and in combination with other therapies, reported promising preliminary efficacy and safety in various solid tumor types. Gedatolisib is currently being evaluated in a Phase 1/2 clinical trial in combination with darolutamide in patients with mCRPC previously treated with an AR inhibitor, and in a Phase 3 clinical trial in combination with palbociclib and fulvestrant in patients with HR+/HER2- advanced breast cancer.

Method development and validation for the estimation of gedatolisib in mouse plasma by tandem mass spectrometry and its application to pharmacokinetics studies.

A simple and a sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of gedatolisib in mouse plasma. The extraction technique involved a simple precipitation method to extract gedatolisib and idelalisib (internal standard) from mouse plasma. A clean chromatographic separation of gedatolisib and the internal standard was achieved on an Atlantis dC18 column using an isocratic mobile phase (10 mm ammonium formate and acetonitrile; 30:70% v/v, both supplemented with 0.1% formic acid) delivered at a flow rate of 0.7 ml/min. The total run time was 2.0 min, and gedatolisib and idelalisib were eluted at 0.80 and 0.95 min, respectively. Gedatolisib was monitored at m/z 616.40 → 488.20 and idelalisib at 416.05 → 176.10. All the required parameters for the method validation were performed as per US Food and Drug Administration guidelines, and the results were within the acceptance criteria. The method was accurate and proved to be precise at a linearity range of 1.33-2667 ng/ml. The accuracy for gedatolisib in mouse plasma was in the ranges 0.99-1.06% (intra-day) and 0.96-1.04% (inter-day). Gedatolisib appeared to be stable in a series of stability conditions. Gedatolisib showed a good intravenous profile when administered through a solution formulation.

Preclinical evaluation of the CDK4/6 inhibitor palbociclib in combination with a PI3K or MEK inhibitor in colorectal cancer.

BACKGROUND: Studies have demonstrated the efficacy of Palbociclib (CDK 4/6 inhibitor), Gedatolisib (PI3K/mTOR dual inhibitor) and PD0325901 (MEK1/2 inhibitor) in colorectal cancer (CRC), however single agent therapeutics are often limited by the development of resistance. METHODS: We compared the anti-proliferative effects of the combination of Gedatolisib and Palbociclib and Gedatolisib and PD0325901 in five CRC cell lines with varying mutational background and tested their combinations on total and phosphoprotein levels of signaling pathway proteins. RESULTS: The combination of Palbociclib and Gedatolisib was superior to the combination of Palbociclib and PD0325901. The combination of Palbociclib and Gedatolisib had synergistic anti-proliferative effects in all cell lines tested [CI range: 0.11-0.69] and resulted in the suppression of S6rp (S240/244), without AKT reactivation. The combination of Palbociclib and Gedatolisib increased BAX and Bcl-2 levels in PIK3CA mutated cell lines. The combination of Palbociclib and Gedatolisib caused MAPK/ERK reactivation, as seen by an increase in expression of total EGFR, regardless of the mutational status of the cells. CONCLUSION: This study shows that the combination of Palbociclib and Gedatolisib has synergistic anti-proliferative effects in both wild-type and mutated CRC cell lines. Separately, the phosphorylation of S6rp may be a promising biomarker of responsiveness to this combination.

Design, Synthesis and Phenotypic Profiling of Simplified Gedatolisib Analogues.

Targeted antitumour therapy has revolutionized the treatment of several types of tumours. Among the validated targets, phosphatidylinositol-3 kinase (PI3K) deserves to be highlighted. Several PI3K inhibitors have been developed for the treatment of cancer, including gedatolisib (4). This inhibitor was elected as a prototype and molecular modifications were planned to design a new series of simplified gedatolisib analogues (5a-f). The analogues were synthesised, and the comparative cytotoxic activity profile was studied in phenotypic models employing solid and nonadherent tumour cell lines. Compound 5f (LASSBio-2252) stood out as the most promising of the series, showing good aqueous solubility (42.38 µM (pH = 7.4); 39.33 µM (pH = 5.8)), good partition coefficient (cLogP = 2.96), cytotoxic activity on human leukemia cell lines (CCRF-CEM, K562 and MOLT-4) and an excellent metabolic stability profile in rat liver microsomes (t1/2 = 462 min; Clapp = 0.058 mL/min/g). The ability of 5f to exert its cytotoxic effect through modulation of the PI3K pathway was demonstrated by flow cytometry analysis in a comparative manner to gedatolisib.

Antitumor activity of the dual PI3K/mTOR inhibitor gedatolisib and the involvement of ABCB1 in gedatolisib resistance in canine tumor cells.

The phosphatidylinositol 3­kinase/mammalian target of rapamycin (PI3K/mTOR) signaling pathway is a therapeutic target for various types of human tumors, and dual PI3K/mTOR inhibitors demonstrate antitumor activities in both preclinical and clinical studies. However, resistance mechanisms limit their abilities. As the molecular mechanisms involved in the cellular resistance are not clear in any canine tumors, an understanding of resistance mechanisms would support the potential use of dual PI3K/mTOR inhibitors in canine tumors. The antitumor activity of gedatolisib on cell viability, protein phosphorylation, and cell cycle distribution was assessed using 12 canine tumor cell lines from 6 types of tumors. In addition, the molecular determinants involved in the cellular sensitivity to gedatolisib were explored by investigating the involvement of serum­and­glucocorticoid­induced kinase 1 (SGK1), PIK3CA, and ATP­binding cassette, subfamily B, member 1 (ABCB1). The results demonstrated that gedatolisib decreased cell viability in all cell lines, with IC50 values <1 µM in 10 of the 12 lines. Gedatolisib inhibited Akt and mTOR complex 1 substrate phosphorylation and induced G0/G1 cell cycle arrest. However, certain cell lines with higher IC50 values were more resistant to these effects. These cell lines exhibited higher ABCB1 activity and the ABCB1 inhibitor cyclosporin A enhanced the decrease of cell viability caused by gedatolisib. SGK1 overexpression did not confer resistance to gedatolisib. The mutations of E545K and H1047R in PIK3CA were not observed. The present results indicated that gedatolisib decreased cell viability in canine tumor cell lines and ABCB1 played an important role in gedatolisib resistance, supporting the potential use of gedatolisib for canine tumors.

The PI3K/mTOR inhibitor Gedatolisib eliminates dormant breast cancer cells in organotypic culture, but fails to prevent metastasis in preclinical settings.

Dormant, disseminated tumor cells (DTCs) are thought to be the source of breast cancer metastases several years or even decades after initial treatment. To date, a selective therapy that leads to their elimination has not been discovered. While dormant DTCs resist chemotherapy, evidence suggests that this resistance is driven not by their lack of proliferation, but by their engagement of the surrounding microenvironment, via integrin-ß1-mediated interactions. Because integrin-ß1-targeted agents have not been translated readily to the clinic, signaling nodes downstream of integrin-ß1 could serve as attractive therapeutic targets in order to sensitize dormant DTCs to therapy. By probing a number of kinases downstream of integrin-ß1, we determined that PI3K inhibition with either a tool compounds or a compound (PF-05212384; aka Gedatolisib) in clinical trials robustly sensitizes quiescent breast tumor cells seeded in organotypic bone marrow cultures to chemotherapy. These results motivated the preclinical study of whether Gedatolisib-with or without genotoxic therapy-would reduce DTC burden and prevent metastases. Despite promising results in organotypic culture, Gedatolisib failed to reduce DTC burden or delay, reduce or prevent metastasis in murine models of either triple-negative or estrogen receptor-positive breast cancer dissemination and metastasis. This result held true whether analyzing Gedatolisib on its own (vs. vehicle-treated animals) or in combination with dose-dense doxorubicin and cyclophosphamide (vs. animals treated only with dose-dense chemotherapies). These data suggest that PI3K is not the node downstream of integrin-ß1 that confers chemotherapeutic resistance to DTCs. More broadly, they cast doubt on the strategy to target PI3K in order to eliminate DTCs and prevent breast cancer metastasis.

ABCB1 and ABCG2 restricts the efficacy of gedatolisib (PF-05212384), a PI3K inhibitor in colorectal cancer cells.

BACKGROUND: Overexpression of ABC transporters is a big challenge on cancer therapy which will lead cancer cells resistance to a series of anticancer drugs. Gedatolisib is a dual PI3K and mTOR inhibitor which is under clinical evaluation for multiple types of malignancies, including colorectal cancer. The growth inhibitory effects of gedatolisib on colorectal cancer cells have been specifically studied. However, the role of ABC transporters on gedatolisib resistance remained unclear. In present study, we illustrated the role of ABC transporters on gedatolisib resistance in colorectal cancer cells. METHODS: Cell viability investigations of gedatolisib on colorectal cancer cells were determined by MTT assays. The verapamil and Ko143 reversal studies were determined by MTT assays as well. ABCB1 and/or ABCG2 siRNA interference assays were conducted to verify the role of ABCB1- and ABCG2-overexpression on gedatolisib resistance. The accumulation assays of gedatolisib were conducted using tritium-labeled paclitaxel and mitoxantrone. The effects of gedatolisib on ATPase activity of ABCB1 or ABCG2 were conducted using PREDEASY ATPase Kits. The expression level of ABCB1 and ABCG2 after gedatolisib treatment were conducted by Western blotting and immunofluorescence assays. The well-docked position of gedatolisib with crystal structure of ABCB1 and ABCG2 were simulated by Autodock vina software. One-way ANOVA was used for the statistics analysis. RESULTS: Gedatolisib competitively increased the accumulation of tritium-labeled substrate-drugs in both ABCB1- and ABCG2-overexpression colorectal cancer cells. Moreover, gedatolisib significantly increased the protein expression level of ABCB1 and ABCG2 in colorectal cancer cells. In addition, gedatolisib remarkably simulated the ATPase activity of both ABCB1 and ABCG2, suggesting that gedatolisib is a substrate drug of both ABCB1 and ABCG2 transporters. Furthermore, a gedatolisib-resistance colorectal cancer cell line, SW620/GEDA, was selected by increasingly treatment with gedatolisib to SW620 cells. The SW620/GEDA cell line was proved to resistant to gedatolisib and a series of chemotherapeutic drugs, except cisplatin. The ABCB1 and ABCG2 were observed overexpression in SW620/GEDA cell line. CONCLUSIONS: These findings suggest that overexpression of ABCB1 and ABCG2 may restrict the efficacy of gedatolisib in colorectal cancer cells, while co-administration with ABC transporter inhibitors may improve the potency of gedatolisib.

Novel nanococktail of a dual PI3K/mTOR inhibitor and cabazitaxel for castration-resistant prostate cancer.

Prognosis of castration-resistant prostate cancer (CRPC) carries is poor, and no effective therapeutic regimen is yet known. The phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway played a predominant role and may be a promising molecular target for CRPC. However, the toxicity of the dual PI3K inhibitors in clinical trials limits their clinical efficacy for CRPC. To solve this problem, we employed a highly integrated precision nanomedicine strategy to molecularly and physically target CRPC through synergistic effects, enhanced targeted drug delivery efficiency, and reduced unwanted side-effects. Gedatolisib (Ge), a potent inhibitor of PI3K/mTOR, was formulated into our disulfied-crosslinked micelle plateform (NanoGe), which exhibits excellent water solubility, small size (23.25±2 nm), excellent stability with redox stimulus-responsive disintegration, and preferential uptake at tumor sites. NanoGe improved the anti-neoplastic effect of free Ge by 53 times in PC-3M cells and 13 times in C4-2B cells though its enhanced uptake via caveolae- and clathrin-mediated endocytic pathways and the subsequent inhibition of the PI3K/mTOR pathway, resulting in Bax/Bcl-2 dependent apoptosis. In an animal xenograft model, NanoGe showed superior efficacy than free Ge, and synergized with nanoformulated cabazitaxel (NanoCa) as a nanococktail format to achieve a cure rate of 83%. Taken together, our results demonstrate the potency of NanoGe in combination with NanoCa is potent against prostate cancer.

Study on the Stability of Antitumor Candidate Gedatolisib in Plasma in vitro and Simulated Gastric/intestinal Fluid and Its Catabolites Analysis / 中国药房

OBJECTIVE：To investigate th e stabilities of antitumor candid ate Gedatolisib in plasma in vitro and simulated gastric/intestinal fluids ，and to analyze the possible catabolites in plasma. METHODS ：HPLC method was adopted. Using indometacin as internal standard ，the contents of Gedatolisib incubated in plasma of SD rats （male）for 0，0.5，1.0，1.5，2.0，3.0 h and blank simulated gastric fluid （pH 1.3，no enzyme ），blank simulated intestinal fluid （pH 6.8，no enzyme ），simulated gastric fluid（pH 1.3，containing pepsin ）and simulated intestinal fluid （pH 6.8，containing trypsin ）for 0，0.5，1.0，2.0，3.0，4.0，6.0 h were determined. The remaining percentage of Gedatolisib was calculated. UPLC-Q-TOF/MS was used to analyze the TIC of blank plasma and incubated samples. The differential peaks were compared， and catabolites were inferred by MS 1Z073）.gzwjkj2019-1- chromatograms. RESULTS ： The remaining percentage in plasma of rats for 2.0 h was about 63％，and there was nosignificant change after continued incubation. The remaining percentage of Gedatolisib incubated in blank simulated intestinal fluid for different time ranged （99.18 ± 2.15）％ -（103.20 ± 3.41）％ . The remaining percentage in simulated com intestinal fluids for 2.0 h ranged （88.76 ± 1.53）％ . The remaining percentage in blank simulated gastric fluids for 2.0 h was ranged （85.63±1.55）％，and there was no significant change after continued incubation. The remaining percentage in simulated gastric fluid was from （94.94±3.52）％（0 h）to（16.19±1.17）％ （6.0 h）. TIC of UPLC-Q-TOF/MS showed that the differential peaks of incubated samples and blank plasma was 6.42 min under positive mode scanning ，molecular ion peak of m/z 616.335 1，simulated 632.327 7，630.317 0，602.278 6 [M+H]+ could be found in scanning channel. It was speculated that Gedatolisib could generate 1-（4-（3-（4，6-dimorpholino-1，3，5-triazin-2-yl）phenyl）urea） benzoyl）-N，N-dimethylpiperidin-4-amine oxide ，1-（4-（4-（dimethylamino）piperidine-1-carbonyl）phenyl）-3-（4-（4-morpholino-6- （3-oxomorpholino）-1，3，5-triazin-2-yl）phenyl）urea and 1-（4-（3-（4-（4，6-dimorpholino-1，3，5-triazin-2-yl）phenyl）urea） benzoyl）-N-methylpiperidine. CONCLUSIONS ：Gedatolisib is not stable in rat plasma ，and it may undergo terminal N oxidation， morpholine ring oxidation and terminal N demethylation. Gedatolisib is stable in artificial intestinal fluid and blank artificial gastric/ intestinal fluid ，and degrades obviously in the presence of pepsin.

Distribution, Metabolism, and Excretion of Gedatolisib in Healthy Male Volunteers After a Single Intravenous Infusion.

In this open-label study (NCT02142920), we investigated the distribution, pharmacokinetics, and metabolism of the pan-class-I isoform phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor gedatolisib (PF-05212384), following a single intravenous administration in healthy male subjects. A single, 89-mg, intravenous dose of gedatolisib was associated with a favorable safety profile in the 6 healthy subjects evaluated. Peak plasma concentrations for unchanged gedatolisib and total radioactivity were observed at the end of the 30-minute infusion. The only observed drug-related material in plasma was the parent drug, gedatolisib. Terminal half-life for plasma gedatolisib was ∼37 hours. Following the dose, 66%-73% of drug-related material was recovered in the feces. Metabolism of gedatolisib was trace; only 1 oxidative metabolite, M5, was identified in feces (<1% of total dose). Identification of gedatolisib in feces suggests that biliary and/or intestinal secretion of unchanged parent drug significantly contributes to gedatolisib clearance.

The dual specificity PI3K/mTOR inhibitor PKI-587 displays efficacy against T-cell acute lymphoblastic leukemia (T-ALL).

Although significant improvements have been made in the treatment of acute lymphoblastic leukemia (ALL), there is a substantial subset of high-risk T-cell ALL (T-ALL) patients with relatively poor prognosis. Like in other leukemia types, alterations of the PI3K/mTOR pathway are predominant in ALL which is also responsible for treatment failure and relapse. In this study, we show that relapsed T-ALL patients display an enrichment of the PI3K/mTOR pathway. Using a panel of inhibitors targeting multiple components of the PI3K/mTOR pathway, we observed that the dual-specific PI3K/mTOR inhibitor PKI-587 was the most selective inhibitor for T-ALL cells dependent on the PI3K/mTOR pathway. Furthermore, we observed that PKI-587 blocked proliferation and colony formation of T-ALL cell lines. Additionally, PKI-587 selectively abrogated PI3K/mTOR signaling without affecting MAPK signaling both in in vitro and in vivo. Inhibition of the PI3K/mTOR pathway using PKI-587 delayed tumor progression, reduced tumor load and enhanced the survival rate in immune-deficient mouse xenograft models without inducing weight loss in the inhibitor treated mice. This preclinical study shows beneficial effects of PKI-587 on T-ALL that warrants further investigation in the clinical setting.

Inhibition of mTOR's Catalytic Site by PKI-587 Is a Promising Therapeutic Option for Gastroenteropancreatic Neuroendocrine Tumor Disease.

BACKGROUND: The characteristic clinical heterogeneity and mostly slow-growing behavior of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) cause problems in finding appropriate treatments. Thus, the current therapy options are not satisfactory. PKI-587 is a highly potent, novel dual inhibitor of PI3K and mTORC1/C2. AIM: We assessed the effects of PKI-587 in different GEP-NEN tumor models, including the poorly differentiated cell line LCC-18, and compared them with those of the established mTORC1 inhibitor everolimus. METHODS: We treated BON, QGP-1, KRJ-I, and LCC-18 cell lines with increasing concentrations of the inhibitor PKI-587, and compared the results with those of everolimus and DMSO. We assessed the impact of the treatments on viability (WST-1 assay), on apoptotic processes (caspase 3/7 assay, JC-1), and on cell cycle regulation (flow cytometry). We determined alterations in signaling mediators by phosphor-specific Western blot analysis and conducted multiplexed gene expression analysis (nCounter® technology). RESULTS: In all cell lines, PKI-587 dose-dependently inhibited proliferation, whereas everolimus was less effective. Treatment with PKI-587 led to cell cycle arrest and induction of apoptosis and successfully suppressed activity of the direct mTORC1 target 4E-BP1, a crucial factor for tumor genesis only partially inhibited by everolimus. Gene expression analyses revealed relevant changes of RAS, MAPK, STAT, and PI3K pathway genes after treatment. Treatment-dependent and cell line-characteristic effects on AKT/Rb/E2F signaling regarding cell cycle control and apoptosis are extensively discussed in this paper. CONCLUSION: PI3K/mTOR dual targeting is a promising new therapeutic approach in neuroendocrine tumor disease that should be evaluated in further clinical trials.

A randomized phase II non-comparative study of PF-04691502 and gedatolisib (PF-05212384) in patients with recurrent endometrial cancer.

OBJECTIVE: PF-04691502 and gedatolisib (PF-05212384) are potent, dual PI3K/mTOR inhibitors. This phase II study (B1271004) was conducted in patients with recurrent endometrial cancer following platinum-containing chemotherapy. The primary endpoint was to assess clinical benefit response (complete or partial response, or stable disease for ≥16weeks) following treatment with PF-04691502 or gedatolisib. METHODS: The main study consisted of four independent arms based on a Simon two-stage design. Patients were assigned to putative PI3K-basal (PF-04691502 or gedatolisib) or PI3K-activated (PF-04691502 or gedatolisib) arms based on stathmin-low or stathmin-high tumor expression, respectively. Japanese patients were also enrolled in a separate lead-in cohort. RESULTS: In stage 1 (main study), eighteen patients were randomized to PF-04691502 and 40 to gedatolisib. The two PF-04691502 arms were discontinued early due to unacceptable toxicity, including pneumonia and pneumonitis. The most common treatment-related adverse events associated with gedatolisib were nausea (53%), mucosal inflammation (50%), decreased appetite (40%), diarrhea (38%), fatigue (35%), and dysgeusia and vomiting (each 30%). Clinical benefit response rate was 53% (10/19) in the gedatolisib/stathmin-low arm and 26% (5/19) in the gedatolisib/stathmin-high arm. Safety profile and pharmacokinetic characteristics of both drugs in the Japanese lead-in cohort were comparable to the Western population. CONCLUSIONS: Gedatolisib administered by weekly intravenous infusion demonstrated acceptable tolerability and moderate activity in patients with recurrent endometrial cancer. PF-04691502 daily oral dosing was not well tolerated. Clinical benefit response criteria for proceeding to stage 2 were only met in the gedatolisib/stathmin-low arm. Stathmin-high expression did not correlate with greater treatment efficacy. ClinicalTrials.gov registration ID: NCT01420081.