ADMET you should know regarding PRMT5 inhibitor TNG462

1. Background

Tango Therapeutics is a clinical-stage biotechnology company dedicated to discovering novel drug targets and delivering the next generation of precision medicine for the treatment of cancer. Using an approach that starts and ends with patients, Tango leverages the genetic principle of synthetic lethality to discover and develop therapies that take aim at critical targets in cancer. This includes expanding the universe of precision oncology targets into novel areas such as tumor suppressor gene loss and their contribution to the ability of cancer cells to evade immune cell killing.

Tango Therapeutics, formerly Tango Therapeutics is investigating TNG908, a synthetic lethal small molecule inhibitor of protein arginine methyltransferase 5 (PRMT5) against methylthioadenosine phosphorylase (MTAP) deleted cancers. It is also developing drugs for BRCA1-mutant breast, ovarian and prostate cancer, lung cancer, and solid tumors. Tango Therapeutics utilizes CRISPR (clustered regularly interspaced short palindromic repeats) based functional genomics target discovery platform to detect novel synthetic lethal targets for loss or deactivation of multiple tumor suppressor genes. It works in collaboration with Gilead Sciences to discover, develop, and commercialize cancer therapies. Tango Therapeutics is headquartered in Boston, Massachusetts, the US.

MTAP deletions occur in 10-15% of all human cancers, which provides one of the largest precision oncology patient populations. MTA-cooperative PRMT5 inhibitors leverage the well-characterized synthetic lethal relationship between PRMT5 inhibition and MTAP deletion. TNG908 is a clinical-stage MTA-cooperative PRMT5 inhibitor for the treatment of MTAP-deleted solid tumors. TNG462 is an investigational-stage MTA-cooperative PRMT5 inhibitor with significantly enhanced potency, selectivity, and extended target coverage designed to be a best-in-class treatment for patients with MTAP-deleted cancer. In vitro, TNG462 is 45X selective for MTAP-deleted cancer cell lines over isogenic MTAP WT cell lines and has marked selectivity for MTAP-deleted cancer cell lines independent of lineage in a large, diverse cell line panel. Oral administration of TNG462 drives dose-dependent antitumor activity including durable tumor regressions and complete responses in cell line- and patient-derived xenograft models representative of clinically relevant histologies. Preclinical data suggest a low risk for drug-drug interactions, supporting clinical combination strategies. With enhanced potency and selectivity for MTAP-deleted cancer cells and improved pharmacokinetic properties to extend target coverage, TNG462 has the potential for broader and deeper clinical activity in MTAP-deleted solid tumors than the MTA-cooperative PRMT5 currently being evaluated in clinical trials.

Cancer Res (2023) 83 (7_Supplement): 497.;https://doi.org/10.1158/1538-7445.AM2023-4970

2. Chemistry Structure of TNG462

a) structure

b) synthesis route

1. Route 1 for TNG908

2. Route 1 for TNG462

3. Route 2 for TNG462

c) Intermediates of TNG462

d) Patents and related literature

US20220127256A1
US20230113778A1
US20230192679A1
WO2022026892A1

3. Activity of TNG462

a) Model of action

MTA-cooperative PRMT5 inhibitors work by locking PRMT5 into the MTA-bound inactive state, induce cytotoxicity in MTAP deleted cells at much lower concentrations than in normal Cells.

Differentiating strategy between non-MTA-cooperative PRMT5 inhibitors and TNG462.

b) Percentage of MTAP deletions in all human cancers

c) Selectivity of TNG462 and TNG908 in MTAP deletion cancer cells

7-day viability assay Same cell lines represented in all panels
TNG462 has an optimized PK profile for enhanced target coverage
Enhanced potency and MTAP selectivity has the potential for broader and deeper clinical activity

d) TNG462 efficacy in vitro is on-target

TNG462 PD modulation is on-target and is selective for MTAP-deleted cells in vitro. (A) TNG462 pharmacodynamic activity to inhibit PRMT5 in the HAP1 MTAP-isogenic cell line pair. The data are normalized to a DMSO control for each cell line and presented as mean ± SD. (B) Pharmacodynamic activity of TNG462 to inhibit Type I PRMTs in the HAP1 MTAP-isogenic cell line pair. The data are normalized to a DMSO control for each cell line and presented as mean ± SD. (C) Antiproliferative activity of TNG462 in MTAP-isogenic cell lines engineered by either CRISPR-mediated MTAP gene knockout (HC T116) or by reconstituting exogenous MTAP in an endogenous MTAP-deleted cell line (LN18). Data are presented as mean ±SD

e) TNG462 antiproliferative activity is selective for MTAP-null models across histologies

TNG462 antiproliferative activity is selective for MTAP-deleted cells in vitro. 180 cancer cell lines representing multiple cancer lineages including NSCLC, PDAC, bladder, CNS, and heme malignancies were profiled with either TNG462 or GSK3326595, a non-MTA-cooperative PRMT5 inhibitor, in a 7-day CellTiter-Glo assay. For each cell line, the maximum effect at a concentration equal to 10X the HAP1 MTAP-null GI50 is reported for each compound, and the cell lines are colored by MTAP status. TNG462 is >20x more potent than GSK3326595 in MTAP-null cell lines in vitro

f) TNG462 efficacy in vivo is on-target

TNG462 antitumor activity is on-target in an MTAP-null cell line-derived xenograft model. (A) 7-day PK/PD study using the LU99 MTAP-deleted xenograft model. TNG462 was dosed as indicated, and PK and tumor samples were harvested at the indicated timepoints. n=4 tumors per group, and data are presented as mean ± SEM. (B) Antitumor activity in the LU99 MTAPnull CDX model with TNG462 or TNG908 dosed as indicated. In the efficacy study, 40 mpk BID and 100 mpk QD TNG462 were dosed in an acidified water formulation that provided similar exposure 60 mpk BID or 120 mpk QD dosed in 5% DMA/20% Captisol, which was used in the PK/PD. n=8 mice per group. Data are presented as mean ± SEM. Regression is defined as final mean tumor volume < 30% initial mean tumor volume.

g) TNG462 drives strong responses across histologies in MTAP deleted PDX models

TNG462 antitumor activity is histology-agnostic in MTAP-deleted patient-derived xenograft models. (A) Waterfall plot demonstrating activity of TNG462 in PDX models representing the indicated tumor histologies. TNG462 was dosed as either one of two formulations: 40 mpk BID in acidified water or 60 mpk BID in 5% DMA/20% Captisol. Each formulation gave equivalent TNG462 exposure. n=3 mice per group for all of the PDX models, except one bladder and one cholangiocarcinoma model which had n=6 mice per group. -%TGI is reported for tumors with Tumor Volumefinal ≥ Tumor Volumeinitial (values -100 to 0). %Tumor Volumeinitial -100 is reported for models with Tumor Volumefinal < Tumor Volumeinitial (values -200 to -100) “Stasis” is defined as 100% TGI and ”completely response” is defined as %Volumeinitial equal to -100%.

h) TNG462 drives dose-dependent antitumor activity and deep regressions in MTAP-deleted xenograft models

TNG462 antitumor activity is dose-dependent in xenograft models. Antitumor activity in the LN18 MTAP-null CDX model, the OCI-LY19 MTAP-null DLBCL CDX model, or MTAP-null PDX models representing the indicated histologies. TNG462 dosed as indicated. n=3-8 mice per group. Data are presented as mean ± SEM. TNG462 was dosed in acidified ddH20 for LN18 and the mesothelioma PDX model, and in 5% DMA/20% Captisol for the remaining models. For the NSCLC (squamous) PDX model, the mice were either dosed, or monitored after discontinuation of dosing, for the indicated time periods.

i) TNG462 re-sensitizes tumors with incomplete response to TNG908

TNG462 overcomes incomplete response to an MTA-cooperative PRMT5 inhibitor in a DLBCL CDX model. (A) The MTAP-null OCI-LY19 DLBCL model was either dosed continuously with 120 mpk BID TNG908 or 40 mpk BID TNG462, or switched from 120 mpk BID TNG908 to 40 mpk BID TNG462 when mean tumor volume recovered to an approximate mean starting tumor volume (Day 36). (B) Same data as (A) with broken y-axis to highlight region of interest. Arrow denotes time of compound switch. n=8 mice Vehicle group, n=10 mice for continuous TNG462 treatment group, n=12 mice for continuous TNG908 treatment group “TNG908 to TNG462” group. Data presented as mean ± SEM. Regression is defined as final mean tumor volume < 30% initial mean tumor volume.

j) PRMT5 inhibitors synergize with targeted therapeutics in vivo

MTA-cooperative PRMT5 inhibitors synergize with targeted therapeutics in MTAP-null xenograft models. (A) Prevalence of co-occurring mutations and deletions in MTAP-deleted tumors across histologies in TCGA PanCancer Atlas (Cerami et al 2012 and Gao et al 2013). (B) TNG908 + abemaciclib (CDK4/6 inhibitor) combination in the MTAP-deleted U87MG CDX model. (C) TNG908 + sotorasib (KRAS G12C inhibitor) combination in the MTAP-deleted, KRASmut LU99 CDX model. The sotorasib dose was adjusted in combination to provide an equivalent exposure to single agent. (D) TNG462 + osimertinib (EGFR inhibitor) in the MTAP-deleted, EGFRmut NCI-H1650 CDX model. This study was on-going at the time of poster preparation. (E) TNG462 + AGI-41998 (MAT2A inhibitor) in the MTAP-deleted NCI-H838 CDX model. TNG908 and TNG462 were both dosed sub-therapeutically in these studies

4. DMPK of TNG462

a) Superior TNG462 PK properties support QD clinical dosing

Free plasma exposures following 3 mg/kg oral gavage of TNG462 in cynomolgus monkeys. The HAP1 MTAP-null and MTAP WT GI50s from a 7-day viability assay are indicated for TNG462. n=3 per group. Data are presented as mean ± SD

b) Predicted human properties

Table content summarizes human PK predictions based on preclinical in vitro and in vivo studies.