Abstract 463: GRC 54276, a novel small molecule inhibitor of HPK1 has entered phase 1/2 clinical trial insolid malignancies and Hodgkin’s/non Hodgkin’s lymphoma

Background: Pre-clinical profile of GRC 54276, a clinical candidate with Phase 1/2 clinical trial ongoing, is presented here. GRC 54276 is a novel small molecule inhibitor of Hematopoietic progenitor kinase 1 (HPK1), a serine/threonine kinase1,2 that negatively regulates T and B cell receptor signaling3. Inhibition of HPK1 is an attractive therapeutic strategy for immuno-oncology based treatment of solid tumors3.

Methods: GRC 54276 was designed and developed using SAR based medicinal chemistry design supported by computational approaches. In vitro profiling was done using a battery of biochemical assays, functional read-outs and primary human in vitro T-cell activation assays. In vivo efficacy was demonstrated in mouse colon tumor models of CT26 and MC38-hPD-L1. In vivo inhibition of biomarker pSLP76 Ser(376) by GRC 54276 was determined using CT26 tumor model. Detailed ADME-PK studies have been performed along with safety tolerability studies conducted in mice and monkeys.

Results: GRC 54276, demonstrated excellent in vitro immune profile of target engagement and anti-tumor immune response activity in both human and mouse systems. As a single agent, GRC 54276 demonstrated strong inhibition of tumor growth and biomarker pSLP76 Ser(376) in the CT26 tumor model. Enhanced efficacy was demonstrated by combining GRC 54276 with check-point blocking antibodies anti-CTLA4 and Atezolizumab in the CT26 and MC38-hPD-L1 models, respectively. GRC 54276 robustly enhanced complete tumor rejections when combined with Atezolizumab in the MC38-hPD-L1 model, correlating with increased immune effector memory T cells. Pharmacokinetic profile of GRC 54276 is characterized by high permeability, rapid absorption and moderate oral bioavailable across species. GRC 54276 is non-gentoxic with no observed adverse effects in mice and no treatment related cardiovascular or respiratory effects in repeat dose toxicity study in monkeys.

Conclusions: GRC 54276 is a novel HPK1 inhibtitor with acceptable pre-clincial profile and is currently undergoing a Phase 1/2 clinical trial.

Acknowledgements: We thank Pooja S, Shital M, Rahul B, Ajit J, Sanjay G, Somesh K, Pramod S for their contributions to the project

References: 1. F.Kiefer et al., The EMBO Journal 1996 2. Hu et al., Genes and Development 1996 3. Sawasdikosol and Burakoff. eLife 2020;9:e55122

Citation Format: Sravan Mandadi, Sanjib Das, Malini Bajpai, Jagmohan Saini, Murugan Chinnapattu, Sanjay Patale, Sandip Patil, Nanasaheb Kadlag, Nayan Waghmare, Balasaheb Gavhane, Ameya Deshpande, Dnyaneshwar Dahale, Vidya Kattige, Priyanka Pangre, Namrata Singh, Ekta Kashyap, Megha Marathe, Jiju Mani, Atul Akarte, Chandrasekhar Misra, Subhadip Das, Anuj Singh, Pandurang Lambade, Avratanu Das, Chaitanya Tirumalasetty, Raju Patole, Nilanjana Biswas, Vikas Karande, Heta Shah, Dayanidhi Behera, Pankaj Jain, Pavankumar Sancheti, Pramod Pawar, Vinod KR, Venkatesha Udupa, Sachin S. Chaudhari, Nagaraj Gowda, Pravin S. Iyer. GRC 54276, a novel small molecule inhibitor of HPK1 has entered phase 1/2 clinical trial insolid malignancies and Hodgkin’s/non Hodgkin’s lymphoma [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 463.

Abstract 462: A novel and potent Cblb inhibitor demonstrates robust immunological profile and anti-tumor efficacy

Background: Casitas B-lineage lymphoma b (Cbl-b), a RING finger E3 ligase, is a negative regulator of immune cell activation1. Genetic deletion or pharmacological inhibition of Cbl-b resulted in hyper-reactive and co-stimulation independent T cell activation and cytokine production1. In syngeneic tumor models, CD8 T-cell and NK-cell mediated rejection of tumours were observed1. These findings point to Cbl-b as a therapeutic target in cancer immunotherapy. Inhibition of Cbl-b also demonstrated the potential to enhance the efficacy of check-point blockers like anti-PD-1 antibody, an unmet need in the clinic.

Methods: Using intuitive medicinal chemistry design supported by computational approaches, we identified a lead Cbl-b inhibitor. SAR was developed using a battery of biochemical assays, functional read-outs and primary human in vitro T-cell activation and exhaustion assays. In vivo efficacy was demonstrated in syngeneic mouse colon tumor model.

Results: Our lead Cbl-b inhibitor demonstrated potent binding to Cbl-b, robust anti-tumor cytokine secretion in human and mouse T cells, whole blood and potent reversal of T cell exhaustion. A strong tumor growth inhibition was demonstrated by the lead compound in a mouse colon tumor model. Compared to single agent, a combination of the lead compound with anti-PD-1 antibody induced enhanced complete tumor rejections.

Conclusions: We have identified a novel, potent and orally bioavailable Cbl-b inhibitor that demonstrated robust in vitro and in vivo anti-tumor profiles.

Acknowledgements: We thank Sanjib Das, Ajit Patil, Gauri Gawas, Savita Pandita, Priya Yadav, Sneha Pusadkar, Mayura Behere, Subhadip Das, Shravankumar Kolli and Radheshyam Yadav for their contributions to the project

References: 1. Clinical and Experimental Immunology, 204: 14-31, 2020

Citation Format: Murugan Chinnapattu, Sandeep Shelke, Prashant Ingale, Nayan Waghmare, Nanasaheb Kadlag, Manoj Pawar, Akshay Kangane, Sachin S. Chaudhari, Jagmohan Saini, Vidya Kattige, Arti Joshi, Colina Dutta, Debjyoti Boral, Sheetal Kadam, Varada Potdar, Jiju Mani, Pooja Sawant, Megha Marathe, Madhavi Mulay, Akshata Virdikar, Sravan Mandadi, Atul Akarte, Anuj Singh, Chandrasekhar Misra, Pandurang Lambade, Chaitanya Tirumalasetty, Raju Patole, Vikas Karande, Dayanidhi Behera, Pankaj Jain, Vishwanath Kurawattimath, Nagaraj Gowda, Pravin S. Iyer. A novel and potent Cblb inhibitor demonstrates robust immunological profile and anti-tumor efficacy [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 462.

Characterization of domains of the phosphoriboprotein P0 of Plasmodium falciparum

Antibodies against the amino-terminal domain of the Plasmodium falciparum P0 phosphoriboprotein were detected extensively in immune people living in malaria endemic areas of India. It has been shown earlier that specific antibodies raised against the PfP0N domain (17-61 amino acid) of the PfP0 protein inhibit P. falciparum growth in vitro. To study the properties of the rest of the protein, the remaining 61-316 amino acids on the carboxy-side of the PfP0 protein were expressed as a glutathione-S-transferase fusion protein (PfP0C). Antibodies raised against PfP0C identified the 38 kDa P0 protein on a parasite Western blot analysis. An ELISA assay using both the PfP0N and PfP0C fusion proteins showed no reactivity with malaria patient sera samples, but showed extensive reactions with the immune sera. Antibodies against both the PfP0C and PfP0N domains were raised in rabbits and different inbred strains of mice. T-cells from immunized mice showed lymphoproliferation when presented with PfP0 protein domains. IgG from both anti-PfP0N and anti-PfP0C sera inhibited the growth of P. falciparum in vitro in a concentration dependent manner. The IgG did not show any significant effect on the growth of intraerythrocytic stages, but specifically inhibited re-invasion of red cells. Merozoites and sexual stages showed surface reactivity to both anti-PfP0N and anti-PfP0C antibodies in immunofluorescence assays. These properties strongly indicate PfP0 as a possible target for invasion-blocking antibodies.