Kinase experiment:

The selectivity and inhibitory potential of LY3023414 are assessed against a panel of 192 kinases in PC-3 cell lysates using the KiNativ platform and a panel of 102 kinases as purified enzymes from Cerep. Together, the 2 kinase panels covered approximately 266 unique kinases. These kinases are tested with three concentrations of LY3023414 to measure inhibition and calculate approximate IC50 values. The IC50 of LY3023414 for PI3Kα is measured using 5 nM recombinant human PI3Kα, 0.01 mM ATP with a 1.76 mM Triton X 100/0.04 mM PIP2/0.2 mM PS mixed micelle as the lipid substrate in a scintillation proximity assay (SPA) with neomycin-linked beads. The IC50 of LY3023414 for PI3Kβ is measured using a mixed micelle SPA format with 0.04 mM ATP with a 0.27 mM Triton X 100/0.05 mM PIP2/0.04 mM PA mixed micelle as the lipid substrate. The IC50s of PI3Kδ and PI3Kγand of DNA-PK are measured. The IC50 for mTOR is measured[1].

Cell experiment:

The CellTiter-Glo luminescent cell viability assay system is used to measure the antiproliferative effects of LY3023414 after 2 cell doublings on cells plated on plastic or incubated for 2 weeks in soft agar with a collection of standard cell lines and human patient–derived tumor xenografts passaged in nude mice. For the soft-agar assay, RKO and SK-OV-3 cells; MOLT-4 and L-363 cells; DLD-1, HCT-116, HCT-15, and NCI-H460 cells are used. These standard cell lines are genotyped by STR and matched to existing STR reference genotypes. Oncotest PDX models (including model MX1 originally derived at NCI) are characterized using the Affymetrix genome-wide human SNP Array 6.0 as well as whole-exome sequencing. Genetic identity analysis confirm that all PDX models are derived from independent patient samples. Combination studies are conducted in which LY3023414 is mixed with other therapeutic agents in fixed ratios of concentrations corresponding to the IC50 equivalents of each single agent. The combination index at 50% inhibition (CI50) is calculated[1].

Animal experiment:

Mice[1] Xenograft tumors are implanted subcutaneously in athymic nude, CD-1 nude mice, and NMRI athymic nude mice. B6.Cg-Tg(IghMyc)22Bri/J mice and C57BL/6NTac mice are used in the Eμ-myc transgenic orthotopic mutant PI3Kα E545K-driven leukemia model similar to the Akt1 E17K cancer model. LY3023414 is formulated in 1% HEC in distilled water containing 0.25% polysorbate 80 and 0.05% Dow-Corning Antifoam 1510-US and administered by oral gavage (final volume 0.2 mL) at the indicated doses and schedules. Efficacy and in vivo target inhibition studies are carried out after tumor volumes reach 150 to 200 mm3. Target inhibition studies are conducted at various time points after administration of a single dose of LY3023414 to mice harboring tumors. Tumors are harvested, flash frozen, lysed in MSD buffer, and then analyzed using the MSD-ELISA multiplex method.

IC50: 64.9, 42.1, 10.6, and 19.1 nM for Akt1(pT308), Akt1 (pS473), P70S6(pT389), and S6RP(pS240/242), respectively.

LY3023414 is an ATP competitive inhibitor of the class I PI3K isoforms, mTOR and DNA-PK.

The phosphoinositide-3 kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway is one of the most frequently altered pathways in cancer cell growth and survival.

In vitro: In biochemical testing against approximately 266 kinases, LY3023414 was found to potently and selectively inhibit class I PI3K isoforms, mTORC1/2, as well as DNA-PK at low concentrations. In addition, inhibition of PI3K/AKT/mTOR signaling by LY3023414 led to G1 cell-cycle arrest and resulted in broad antiproliferative activity in cancer cell panel [1].

In vivo: LY3023414 showed high bioavailability and dose-dependent dephosphorylation of PI3K/AKT/mTOR pathway downstream substrates for 4 to 6 hours, indicating LY3023414's half-life of 2 hours. Moreover, equivalent total daily doses of LY3023414 given either once or twice daily could inhibit tumor growth to the similar extents in multiple xenograft models, demonstrating intermittent target inhibition was sufficient for antitumor activity [1].

Clinical trial: LY3023414 appears to be safe when administered as single agent up to 325 mg QD or 200 mg BID. Currently, LY3023414 is investigated in tumor-specific expansion cohorts for breast cancer, mesothelioma, Non-Hodgkin Lymphoma as well as NSCLC (Clinical trial information: NCT01655225).

Reference:
[1] Smith MC,Mader MM,Cook JA,et al.  Characterization of LY3023414, a Novel PI3K/mTOR Dual Inhibitor Eliciting Transient Target Modulation to Impede Tumor Growth. Mol Cancer Ther.2016 Oct;15(10):2344-2356.