Abstract 449: Discovery of novel MTA-cooperative PRMT5 inhibitors as targeted therapeutics for MTAP-deleted cancers

Homozygous deletions of p16/CDKN2a (cyclin dependent kinase inhibitor 2A) locus are prevalent in cancer and often involve co-deletion of adjacent genes. Metabolic gene MTAP (methylthioadenosine phosphorylase) is localized at the 9p21 chromosome in the close proximity to p16/CDKN2A tumor-suppressor locus. Co-deletion of MTAP may be observed in 80-90% of all tumors harboring homozygous deletion of CDKN2A, which represents 10 - 15% of all human tumors. Many of these tumor types, such as non-small cell lung cancer, pancreatic adenocarcinoma, glioblastoma or mesothelioma are associated with poor prognosis, representing a significant unmet medical need. MTAP deletion results in a massive accumulation of methylthioadenosine (MTA) in cells. MTA in high concentrations is a very selective inhibitor of PRMT5 methyltransferase, competitive for the substrate: S-adenosylmethionine (SAM). Accumulation of MTA in cells with MTAP deletion causes partial inhibition of the methylation activity of PRMT5, which in turn reduces the level of symmetric arginine dimethylation of the whole proteome, and thus an increased sensitivity of cells to modulation of methylosome activity. Therapeutic targeting of PRMT5 in homozygous MTAP-deleted cancers constitute a promising strategy of selective killing of genetically defined cancer cells. Ryvu has identified a series of MTA-cooperative PRMT5 inhibitors which have good drug-like physicochemical properties and block methyltransferase activity with nanomolar IC50 values. Structurally enabled hit generation and optimization allowed quick expansion and delivery of several generations of compounds with novel IP, high target engagement in cells and selective potency in MTAP-deleted cell lines. Ryvu compounds selectively inhibit growth of MTAP-deleted cancer cells in prolonged 3D culture, which strongly correlates with inhibition of PRMT5-dependent protein symmetric dimethylation (SDMA) in those cells. Selectivity between effects observed in MTAP-deleted and WT cells exceeds 100-fold both for SDMA and growth inhibition. The DMPK profile of these compounds allows for oral administration, which enables testing antitumor activity in MTAP null tumor xenograft-bearing mice. Efficacy studies with our lead compound resulted in demonstration of tumor growth inhibition in MTAP -/- model, accompanied by significant inhibition of target proximal PD biomarker.  Overall, these studies provide a rationale for further optimization of our chemical series of MTA-cooperative PRMT5 inhibitors towards a clinical candidate. 

Citation Format: Anna Bartosik, Adam Radzimierski, Aneta Bobowska, Oleksandr Levenets, Agata Stachowicz, Kamil Kuś, Kinga Michalik, Katarzyna Banaszak, Monika Madej, Marta Skoda, Kamila Kozłowska-Tomczyk, Igor Tomczyk, Karolina Pyziak, Dobrosława Krzemień, Mirosława Gładysz, Paulina Podkalicka, Aniela Gołas, Karolina Gluza, Grzegorz Satała, Andrzej Gondela, Marta Sowińska, Nicolas Boutard, Agata Chłopek, Aleksandra Więckowska, Daria Szukiel, Grzegorz Ćwiertnia, Iana Levenets, Karol Zuchowicz, Klara Korta-Piątek, Marcin Nowogródzki, Marek Wronowski, Marianna Girardi, Mateusz Świrski, Oleksandr Popika, Paulina Niedziejko-Ćwiertnia, Pierpaolo Cordone, Przemysław Wyrębek, Quỳnh Vũ, Sujit Sasmal, Svitlana Sukhomlinova, Magdalena Miodek, Jacek Faber, Anna Kowal-Chwast, Róża Starczak, Sanja Novak Ratajczak, Agnieszka Świrska, Dawid Gogola, Paweł Guzik, Martin Swarbrick, Mateusz Nowak. Discovery of novel MTA-cooperative PRMT5 inhibitors as targeted therapeutics for MTAP-deleted cancers  [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 449.

Abstract 1806: Discovery of novel MTA-cooperative PRMT5 inhibitors as a targeted therapeutics for MTAP deleted cancers

Targeting PRMT5 in MTAP-deleted tumors in a synthetic lethal approach represents a promising antitumor strategy across many tumor types. Metabolic gene MTAP is localized at the 9p21 chromosome in the close proximity to CDKN2A tumor-suppressor locus. Co-deletion of MTAP may be observed in 80-90% of all tumors harboring homozygous deletion of CDKN2A, which represents 10-15% of all human tumors. MTAP deletion results in a massive accumulation of methylotioadenosine (MTA) in cells. MTA in high concentrations is a selective inhibitor of PRMT5 type II methyltransferase. PRMT5 conjugated with WD-repeat containing protein (WDR77) builds methylosome, which regulates essential cellular functions via symmetric demethylation (SDMA) of target proteins involved in regulation of gene expression, RNA splicing, signal transduction, metabolism and other functions. Accumulation of MTA in cells with MTAP deletion causes a partial inhibition of the methylation activity of PRMT5, which in turn reduces the level of symmetric arginine dimethylation of the whole proteome, and thus an increased sensitivity of cells to modulation of the methylosome activity. Therapeutic targeting of PRMT5 in homozygous MTAP-deleted cancers constitute a promising strategy of selective killing of genetically defined cancer cells. Currently available clinical stage PRMT5 small molecule inhibitors are not MTA-cooperative and therefore are not selective in tumors harboring MTAP deletion. Here we present MTA-cooperative PRMT5 inhibitors, which selectively inhibit the growth of MTAP deleted cancer cells. Ryvu has identified a series of MTA-cooperative PRMT5 inhibitors which have good drug-like physicochemical properties and block methyltransferase activity with nanomolar IC50 values. Ryvu compounds selectively inhibit growth of MTAP deleted cancer cells in prolonged 3D culture, which strongly correlates with inhibition of PRMT5-dependent protein symmetric demethylation (SDMA) in those cells. Selectivity between effects observed in MTAP deleted and WT cells exceeds 100-fold both for SDMA and growth inhibition. The DMPK profile of these compounds allows for oral administration, which enables testing dose-dependent antitumor activity in MTAP null tumor xenograft-bearing mice. Overall, these studies provide rationale for further optimization of chemical series towards clinical candidate. 

Citation Format: Oleksandr Levenets, Anna Bartosik, Marta Sowińska, Karol Zuchowicz, Sujit Sasmal, Klara Korta-Piątek, Adam Radzimierski, Paulina Niedziejko, Oleksandr Popika, Mateusz Świrski, Agata Stachowicz, Maciej Mikulski, Magdalena Sieprawska-Lupa, Katarzyna Banaszak, Kinga Michalik, Kamil Kuś, Monika Madej, Adrian Podkowa, Karolina Gluza, Grzegorz Satała, Ewelina Cieluch, Dobrosława Krzemień, Andrzej Gondela, Grzegorz Ćwiertnia, Marek Wronowski, Nicolas Boutard, Aleksandra Więckowska, Joanna Zezula, Justyna Jabłońska, Mirosława Gładysz, Igor Tomczyk, Jacek Faber, Marcin Serocki, Eliza Drwal, Kamila Kozłowska-Tomczyk, Marta Skoda, Martin Swarbrick, Krzysztof Brzózka, Mateusz Nowak. Discovery of novel MTA-cooperative PRMT5 inhibitors as a targeted therapeutics for MTAP deleted cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1806.

752 Novel, orally administered HPK1 inhibitors demonstrate anti-tumor efficacy and enhanced immune response

Background

Hematopoietic progenitor kinase 1 (HPK1, MAP4K1) is emerging as a well-renowned, druggable target for T cell-based immunotherapies. HPK1 is a member of the serine/threonine MAP4K family, predominantly expressed in hematopoietic cell lineages and shown to be a negative regulator of the T cell receptor (TCR) signaling pathway. Upon TCR activation, HPK1 is recruited to the proximity of the cell membrane and phosphorylates an adaptor protein SLP-76 at the Ser376 residue which, in turn, abrogates TCR signaling. Other studies point to a potential role of HPK1 in T cell exhaustion as well as in functional re-programming of regulatory T cells. Moreover, mounting evidence suggest that HPK1 kinase activity suppresses the immune functions of a wide range of other immune cell subsets like B cells and dendritic cells. Taken together, these observations support small-molecule HPK1 inhibitors as an attractive modality in cancer immunotherapy either as single agents or in combination with immune checkpoint inhibitors.

Methods

Activity of compounds against HPK1 and selected off- and anti-targets was assessed in biochemical assays. Phosphorylation of SLP-76 was measured either by flow cytometry or TR-FRET. Jurkat and primary T cells were activated and cultured in the presence of tested compounds and immunosuppressive agents. Impact on TCR selectivity and T cell function was measured by AlphaLISA and flow cytometry. Target engagement was measured in splenocytes of mice administered orally with tested compounds followed by IP injection of aCD3 antibody. Anti-tumor efficacy of HPK1 inhibitors was assessed in a syngeneic tumor model.

Results

Ryvu's proprietary small molecule HPK1 inhibitors exhibit sub-nanomolar activity against human and mouse HPK1 proteins and good selectivity against other TCR pathway kinases. Tested compounds efficiently block phosphorylation of SLP-76 upon TCR engagement. TCR selectivity of Ryvu's inhibitors, measured as a ratio between CD69 and pSer376 SLP-76 inhibition, is on par or superior to reference molecules. Tested compounds are not only able to overcome PGE-2 induced resistance following TCR activation in human PBMCs, inducing elevated IL-2 release but also affect T cell function in co-culture assay. Developed molecules have favorable PK profiles, allowing for sustained target coverage in proposed dosing regimens and demonstrate efficacy in a mammary carcinoma syngeneic model.

Conclusions

Ryvu has developed potent and selective HPK1 inhibitors with favorable PK and PD profiles, whose activity in vitro translates to in vivo efficacy. Further preclinical work is warranted to select a lead candidate for IND-enabling studies and subsequently clinical studies across a variety of solid tumors.

Discovery of a series of ester-substituted NLRP3 inflammasome inhibitors

The NLRP3 inflammasome is a component of the innate immune system involved in the production of proinflammatory cytokines. Aberrant activation by a wide range of exogenous and endogenous signals can lead to chronic, low-grade inflammation. It has attracted a great deal of interest as a drug target due to the association with diseases of large unmet medical need such as Alzheimer's disease, Parkinson's disease, arthritis, and cancer. To date, no drugs specifically targeting inhibition of the NLRP3 inflammasome have been approved. In this work, we used the known NLRP3 inflammasome inhibitor CP-456,773 (aka CRID3 or MCC 950) as our starting point and undertook a Structure-Activity Relationship (SAR) analysis and subsequent scaffold-hopping exercise. This resulted in the rational design of a series of novel ester-substituted urea compounds that are highly potent and selective NLRP3 inflammasome inhibitors, as exemplified by compounds 44 and 45. It is hypothesized that the ester moiety acts as a highly permeable delivery vehicle and is subsequently hydrolyzed to the carboxylic acid active species by carboxylesterase enzymes. These molecules are greatly differentiated from the state-of-the-art and offer potential in the treatment of NLRP3-driven diseases, particularly where tissue penetration is required.