bimiralisib (PQR309)

Mechanistically, PQR309 sensitized NPC to gemcitabine by increasing caspase pathway-dependent apoptosis, blocking GSK-3β and STAT3/HSP60 signaling, and ablating epithelial-mesenchyme transition. Thus, targeting PI3K/mTOR using PQR309 might represent a treatment option to promote the response to gemcitabine in NPC, and provides a theoretical foundation for the study of targeted drugs combined with chemotherapy for NPC.

We further tested the PLK1-specific inhibitor onvansertib (0-100nM) combined with pan-PI3K inhibitor copanlisib (0-200nM) or dual inhibitor bimiralisib (0-1μM). We will further validate this combination in vivo to determine the effect of combined PI3K and PLK1 inhibition on tumor growth and survival. These novel findings may lead to the development of a better therapeutic approach for NOTCH1MUT HNSCC and for patients who develop acquired resistance to targeted therapies.

In this study, the BCL-XL inhibitor A1331852, MCL1-inhibitor S63845, dual PI3K-mTOR inhibitor bimiralisib (PQR309), BMI-1 inhibitor unesbulin (PTC596), MEK-inhibitor trametinib (GSK1120212), and STAT3 inhibitor C-188-9 were assessed as single agents and in combination with venetoclax, for their ability to induce apoptosis and cell death in leukemic cells grown in the absence or presence of bone marrow stroma. For the venetoclax and bimiralisib combination treatment, responders were enriched for IDH2 and FLT3 mutations, whereas non-responders were associated with PTPN11 mutations. The combination of PI3K/mTOR dual pathway inhibition with bimiralisib and BCL2 inhibition with venetoclax has emerged as a candidate treatment in IDH2- and FLT3-mutated AML.

Although the trial was small, outcomes with bimiralisib were better than the historical standard of care; Results will need to be confirmed in a larger trial. The lack of cl-NOTCH1 was consistent with loss-of-function mutations and validated our mutation function algorithm. The ability to detect NOTCH1 mutations in blood will help future studies. (ClinicalTrials.gov Identifier: NCT03740100).

Using high-throughput screening of 157 inhibitors targeting the PI3K/AKT/mTOR pathways in vitro, we identified a dozen inhibitors (such as BEZ235, LY2090314, and AZD8055) with significant growth-suppressive effects...Furthermore, we demonstrated two orally bioavailable inhibitors AZD8055 and PQR309 suppressed NF2-associated schwannoma growth both in vitro and in vivo...Furthermore, we demonstrated two orally bioavailable inhibitors AZD8055 and PQR309 suppressed NF2-associated schwannoma growth both in vitro and in vivo. In conclusion, our novel patient-derived models of NF2-associated schwannoma closely mimic the phenotypes and genotypes of patient tumors, making them reliable preclinical tools for testing novel personalized therapies.

Dual PI3K/mTOR (LY3023414, bimiralisib) and AKT inhibitors (ipatasertib, afuresertib) induced dose-dependent reductions in cell growth. However, mTOR-selective inhibitors (everolimus, rapamycin) alone did not exert cytotoxic effects. The MEK1/2 inhibitor trametinib did not impact proliferation even at the highest doses tested. Our data suggest that molecularly targeted strategies may be effective in PI3K/AKT/mTOR-activated ssRMS. Taken together, these data highlight the importance of utilizing patient-derived models to assess molecularly targetable treatments and their potential as future treatment options.

mtp53 silence enhanced PQR309-inhibited cell viability, spheroid formation, and the expressions of p-Akt, c-Myc, and CDK6. This is the first study to reveal the novel finding of the PI3K/mTOR dual inhibitor in lowering cell viability by abolishing the PI3K/Akt/mTOR/c-Myc/mtp53 positive feedback loop in endometrial cancer cell lines.

In particular, we observed the upregulation of a lncRNA, lncTNK2-2:1, which correlated with the stabilization of transcripts involved in the regulation of translation and DNA damage after bimiralisib treatment. We identified miR-21-3p as miRNA likely sponged by lncTNK2-2:1, with consequent stabilization of the mRNA of p53, which is a master regulator of cell growth in response to DNA damage.

We combined the resulting 74 drugs with PI3K inhibitors, bimiralisib (0-1µM) or copanlisib (FDA approved, 0-100nM), for 72 h. Synergistic effects from these combinations were assessed using Bliss, HAS, Zip, and Loewe models. Trametinib (MEK inhibitor) and copanlisib were synergistic with the combination leading to 0.90 fraction of cells affected at concentrations of 30nM and 100nM respectively...Likewise, low concentrations of inhibitors of EGFR (10nM afatinib, 50nM AZ5104), HER2 (25nM sapitinib, 10nM poziotinib), and PLK1 (50nM BI2536, 50nM volasertib) were both effective and additive to synergistic with PI3K inhibitors...The identified pathways may give us insight into mechanisms of resistance. If validated, these combinations may lead to the first biomarker-specific, targeted therapy for HNSCC.

These results indicated that PQR309 exerts an antitumor effect by inhibiting proliferation, inducing apoptosis, inducing G1 cell cycle arrest, and inhibiting invasion and migration in human glioma cells. The present study provides evidence supportive of further development of PQR309 for adjuvant therapy of GBM.

In the second stage, IHC and WES may be performed on pre- and post- treatment (day 15 and progression) tissue to examine pharmacodynamics and mechanisms of resistance. Research Funding: PIQUR