Abstract 3500: AUR103 an oral small molecule CD47 antagonist in combination with azacytidine and bortezomib exhibits potent anti-tumor activity in myeloma and leukemia models in vitro and in vivo

The CD47/signal regulatory protein alpha axis is a critical regulator of myeloid cell activation and serves as an immune checkpoint for macrophage mediated phagocytosis. Targeting CD47-SIRPα axis is emerging as one of the promising new immunotherapy approaches that targets innate immune response. Number of clinical trials are in progress to evaluate CD47/SIRPα blocking therapies. Most of these molecules are either anti-CD47 antibodies or SIRPα-Fc recombinant proteins. We have developed a novel small molecule CD47 antagonist, AUR103 as a therapeutic agent for solid and hematological cancers. AUR103 is efficacious as a single agent in tumors with high expression of “eat-me” signals and synergizes well in combination with tumor-targeting antibodies. We hypothesized that agents capable of inducing “eat-me” signals such as calreticulin (CRT) a pro-phagocytic signal, will synergize with AUR103 to enhance phagocytosis and antitumor activity. Here, we report the anti-tumor efficacy of AUR103 in combination with azacytidine and bortezomib in acute myeloid leukemia and multiple myeloma model of cancer, respectively.In the phagocytosis assay, HL-60 human myeloid leukemia or NCI-H929 human multiple myeloma cells were treated with azacytidine or bortezomib for 48 hours. Cells were stained with CFSE and were further treated with AUR103. Cells were then added to human macrophages and allowed to undergo phagocytosis. Phagocytosis of target cells was measured by detecting cells that were double positive for APC and CFSE by FACS. HL-60 cells were orthotopically implanted in NOD SCID mice while NCI-H929 multiple myeloma cells were sub-cutaneously implanted in NOD SCID mice. Tumor bearing mice were treated with AUR103 (10 and 30 mg/kg, b.i.d, and po) as a single agent or in combination with azacytidine (5 mg/kg i.p., twice weekly) or bortezomib (0.4 mg/kg i.v., twice weekly). AUR103 in combination with azacytidine and bortezomib significantly enhanced phagocytosis of HL-60 and NCI-H929 tumor cells, respectively when compared to individual treatments. In the combination efficacy studies, AUR103 combination treatments with azacytidine and bortezomib were well tolerated without any signs of toxicity. In the HL-60 orthotopic model, AUR103 combination with azacytidine significantly reduced the engraftment of HL-60 tumor cells. AUR103 combination with bortezomib resulted in enhanced tumor growth inhibition in NCI-H929 tumor model when compared to individual treatments. These results demonstrate the therapeutic potential of AUR103 in combination with agents that are capable of inducing “eat-me” or pro-phagocytic signals.

Citation Format: Girish C. Daginakatte, Sasikumar Pottayil, Sudarshan Naremaddepalli, Gundala Chennakrishnareddy, Prasad Bilugudi, Sai Krishna Tangella, Sandeep Patil, Nagesh Gowda, Kiran Aithal, Wesley Roy Balasubramanian, Amit Dhudashiya, Samiulla Dodheri, Kavitha Nellore, Susanta Samajdar, Murali Ramachandra. AUR103 an oral small molecule CD47 antagonist in combination with azacytidine and bortezomib exhibits potent anti-tumor activity in myeloma and leukemia models in vitro and in vivo [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 3500.

Design, synthesis, and biological evaluation of phenyl thiazole-based AR-V7 degraders

Multiple Splice variants of AR have been reported in the past few years. These splice variants are upregulated in most cases of CRPC resulting in poor prognosis. Most of these variants lack the ligand binding domain (LBD) but still bind to DNA resulting in constitutive activation of downstream targets. The AR-V7 splice variant has been characterized extensively and current clinical trials in CRPC are exploring the use of AR-V7 as a biomarker. New therapeutic molecules that selectively target AR-V7 are also being explored. However, there is a dearth of information available on the selectivity, phenotypic responses in AR-V7 dependent cell lines and pharmacokinetic properties of such molecules. Using our proprietary computational algorithms and rational SAR optimization, we have developed a potent and selective AR-V7 degrader from a known AR DNA binding domain (DBD) binder. This molecule effectively degraded AR-V7 in a CRPC cell line and demonstrated good oral bioavailability in mouse PK studies. This tool compound can be used to evaluate the pharmacological effects of AR-V7 degraders. Further exploration of SAR can be pursued to develop more optimized lead compounds.

Discovery of CA-4948, an Orally Bioavailable IRAK4 Inhibitor for Treatment of Hematologic Malignancies

Small molecule potent IRAK4 inhibitors from a novel bicyclic heterocycle class were designed and synthesized based on hits identified from Aurigene's compound library. The advanced lead compound, CA-4948, demonstrated good cellular activity in ABC DLBCL and AML cell lines. Inhibition of TLR signaling leading to decreased IL-6 levels was also observed in whole blood assays. CA-4948 demonstrated moderate to high selectivity in a panel of 329 kinases as well as exhibited desirable ADME and PK profiles including good oral bioavailability in mice, rat, and dog and showed >90% tumor growth inhibition in relevant tumor models with excellent correlation with in vivo PD modulation. CA-4948 was well tolerated in toxicity studies in both mouse and dog at efficacious exposure. The overall profile of CA-4948 prompted us to select it as a clinical candidate for evaluation in patients with relapsed or refractory hematologic malignancies including non-Hodgkin lymphoma and acute myeloid leukemia.

Discovery of CA-4948, an Orally Bioavailable IRAK4 Inhibitor for Treatment of Hematologic Malignancies

Small molecule potent IRAK4 inhibitors from a novel bicyclic heterocycle class were designed and synthesized based on hits identified from Aurigene's compound library. The advanced lead compound, CA-4948, demonstrated good cellular activity in ABC DLBCL and AML cell lines. Inhibition of TLR signaling leading to decreased IL-6 levels was also observed in whole blood assays. CA-4948 demonstrated moderate to high selectivity in a panel of 329 kinases as well as exhibited desirable ADME and PK profiles including good oral bioavailability in mice, rat, and dog and showed >90% tumor growth inhibition in relevant tumor models with excellent correlation with in vivo PD modulation. CA-4948 was well tolerated in toxicity studies in both mouse and dog at efficacious exposure. The overall profile of CA-4948 prompted us to select it as a clinical candidate for evaluation in patients with relapsed or refractory hematologic malignancies including non-Hodgkin lymphoma and acute myeloid leukemia.

Abstract 3852: Combination efficacy and safety profile of an orally bioavailable small molecule agent targeting CD47/SIRPα axis

Introduction: Most of the immunotherapies currently approved in the clinic target immune checkpoint proteins that suppress T-cell responses. There is growing evidence that the innate immune system also plays an important role in the initiation and propagation of enduring antitumor responses. Targeting CD47-SIRPα axis is emerging as one of the promising new immunotherapy approaches that targets innate immune response. A number of clinical trials are in progress to evaluate CD47/SIRPα blocking therapies. Most of these molecules are either anti-CD47 antibodies or SIRPα-Fc recombinant proteins. We are developing a novel small molecule CD47 antagonist, AUR-104, as therapeutic agent for solid and hematalogical cancers. AUR-104 is a CD47 antagonist that disrupts CD47- SIRPα interaction and enhances phagocytosis of tumor cells. AUR-104 exhibits good drug-like properties and demonstrates antitumor activity in several pre-clinical tumor models. Here, we report the anti-tumor efficacy of AUR-104 in combination with tumor specific antibodies in pre-clinical models of cancer and also present the safety profile of AUR-104 in rodents.

Materials and Methods: Syngeneic murine tumor models: MC38 colon carcinoma cells were subcutaneously implanted in C57BL/6J mice while A20 B-cell lymphoma cells were implanted in BALB/c mice. Tumor bearing mice were treated with AUR-104 (30 mg/kg, b.i.d, and po) as a single agent or in combination with anti-PD1 antibody (100 µg/animal) or anti-PDL1 antibody (200 µg/animal). Tumor volumes were recorded with calliper's measurement over period of treatment.

A single dose maximum tolerated dose (MTD) study in BALB/c mouse followed by a 14-day repeat dose toxicity study in BALB/c mouse: Adult male and female BALB/c, are dosed with AUR-104 at ascending doses up to the limit dose. End points monitored include clinical observations, toxicokinetic parameters, body weights, food consumption, hematology, clinical pathology investigations, organ weights and histopathology of selected tissues.

Results: AUR-104 combination treatment with anti-PD1 antibody significantly enhanced anti-tumor efficacy in MC38 colon carcinoma model. Combination study with anti-PDL1 antibody in A20 tumor model is in progress. Preliminary observations from efficacy studies indicate that AUR-104 combination treatments with antibodies are well tolerated without any signs of toxicity. Advance in vitro safety evaluation and in vivo 14 day repeat day toxicity study in mice are being initiated. In summary, AUR-104 plus anti-PD1 antibody was a well-tolerated drug combination that exhibited a much greater in vivo antitumor response as compared to the single agent treatments. These results demonstrate the therapeutic potential of CD47 antagonist AUR-104 in combination with other tumor specific antibodies for the treatment of cancer.

Citation Format: Girish Daginakatte, Sasikumar Pottayil, Gundala Chennakrishna, Wesley Roy Balasubramanian, Sudarshan Naremaddepalli, Archana Bhumireddy, Sandeep Patil, Kavitha Nellore, Priyabrata Chand, Kiran Aithal, Amit Dhudashiya, Samiulla DS, Rajesh Eswarappa, Murali Ramachandra. Combination efficacy and safety profile of an orally bioavailable small molecule agent targeting CD47/SIRPα axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3852.

Abstract 4798: Efficacy and safety of highly selective novel IRAK4 inhibitors for treatment of ABC-DLBCL

Interleukin-1 receptor associated kinases (IRAKs) are serine/threonine protein kinases belonging to the tyrosine-like kinase (TLK) family. IRAKs function as mediators of Toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) signaling pathways and play an important role in innate immune signaling. TLR/IL-1R stimulation leads to recruitment of MYD88, an adaptor molecule, to the activated receptor complex, which then complexes with IRAK4 and activates IRAK1. TRAF6 is then activated by IRAK1 leading to NFkB activation. Recent studies have reported the occurrence of gain of function oncogenic mutation (L265P) in MYD88 in ∼30% of activated B cell diffuse large B-cell lymphoma(ABC DLBCL) and ∼90% of Waldenstrom's macroglobulinemia (WM) leading to constitutive activation of IRAK4 and NFkB pathway. Among the DLBCL subtypes (GCB, ABC DLBCL and PMBL), ABC DLBCL is the most refractory. Inhibition of constitutive IRAK4 signalling can be used as a therapeutic strategy to treat ABC DLBCL

Small molecule inhibitors of IRAK4 were synthesized based on hits originating from Aurigene's compound library. Structure guided drug design approach was used to further improve the potency. Lead compounds demonstrated moderate to very high selectivity towardsIRAK4 (S35 score of 0.03) when screened against a large panel of 329 kinases. Aurigene's lead compounds have excellent PK profile and good oral bioavailability in mice, leading to good in-vivo activity in TLR4 induced cytokine release model. Selected lead compounds were tested in a OCI-Ly3 xenograft model, which has a MYD88(L265P) mutation leading to constitutive activation of IRAK4 signaling. An advanced lead compound has demonstrated excellent efficacy in OCI-Ly3 model, with tumor stasis at low doses and tumor regression at higher doses. The compound is well tolerated and has a good therapeutic window as determined in a 14 day rodent toxicity study. In summary, a selective IRAK4 inhibitor has been identified with excellent efficacy and good safety profile.

Citation Format: Wesley Roy Balasubramanian, Venkateshwar Rao Gummadi, Kavitha Nellore, Subhendu Mukherjee, Sivapriya Marappan, Aravind Basavaraju, Bharathi Raja Ainan, Girish Daginakatte, Sreevalsam Gopinath, Sanjeev Giri, Thomas Antony, Shekar Chelur, Susanta Samajdar, Chetan Pandit, Murali Ramachandra. Efficacy and safety of highly selective novel IRAK4 inhibitors for treatment of ABC-DLBCL. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4798.

Discovery of selective RORγ inverse agonists and demonstration of efficacy in inflammatory disease models

The nuclear hormone receptor RORγ controls the differentiation of Th17 cells that plays a key pro-inflammatory role in a variety of autoimmune diseases. RORγ inverse agonists from multiple structural classes were discovered and screened in a RORγ radio-ligand binding assay as well as in a cell based reporter assay and functional effect was evaluated using primary mouse/human CD4+ve T-cells differentiation to Th17 cells. Pharmacokinetic profile of potent compounds was determined to support evaluation of efficacy as well as safety profile in rodents.

Lead compounds have demonstrated good activity (< 100 nM) in reporter assay. Crystal structure of RORγ in complex with known inverse agonists as well as novel compounds, were solved to support lead optimization. Selected compounds demonstrated >100 fold selectivity against RORα as well as other nuclear receptors with significant inhibition of IL-17 release in Th17 differentiation assay. Lead compounds have shown optimal physicochemical profile including good solubility and high free fraction, leading to excellent pharmacokinetic profile in mice and rats. Efficacy of lead compounds has been demonstrated in multiple disease models including asthma, psoriasis, Experimental auto immune encephalomyelitis and collagen induced arthritis. Potential lead candidates have been identified with excellent in-vitro safety profile including CEREP-44 safety panel, Ames test and cytotoxicity. One of the lead candidates has also demonstrated good therapeutic window as determined by a 7 day rat toxicity study.

Conclusions

We have identified structurally diverse small molecule inverse agonists of RORγ and have demonstrated efficacy in relevant disease models as well as good therapeutic window.

Abstract C191: Efficacy of novel IRAK4 inhibitors in ABC-DLBCL and AML models

Interleukin-1 receptor associated kinases (IRAKs) are serine/threonine protein kinases belonging to tyrosine-like kinase (TLK) family. The IRAK family consists of IRAK1, IRAK2, IRAK3 and IRAK4 out of which only IRAK1 and IRAK4 exhibit kinase activity. IRAKs function as mediators of Toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) signaling pathways and play an important role in innate immune signaling. Recent studies have reported the occurrence of oncogenic mutations in MYD88 in 30% of activated B cell diffuse large B-cell lymphoma (ABC DLBCL) and 90% of Waldenstrom's macroglobulinemia (WM) leading to constitutive activation of the IRAK4 and NFkB pathway. Recent studies have also highlighted the association of dysregulated innate immune signaling with Myelodysplastic syndrome (MDS) and Acute Myeloid leukaemia (AML). TLRs and their associated signal transducers are frequently overexpressed and/or constitutively activated in MDS. Overexpression and activation of IRAK1 is observed in AML. Thus IRAKs are attractive therapeutic targets for treatment of tumors with altered innate immune signaling such as ABC DLBCL and AML.

We have designed, synthesized and tested small molecule inhibitors of IRAK4 based on hits originating from Aurigene's compound library. We have identified a series of novel bicyclic heterocycles as potent inhibitors of IRAK-4 with moderate to very high selectivity (S35 score = 0.03) in a 329 kinase panel. Lead compounds were profiled in proliferation and mechanistic assays (p-IRAK1 and p-TAK1 inhibition) in appropriate ABC DLBCL/AML cell lines. Aurigene lead compounds demonstrate potent inhibition of cellular proliferation with a good correlation to inhibition of phosphorylation of signaling intermediates in mechanistic assays. Lead compounds exhibit excellent PK profile and good oral bioavailability in mice. Preliminary in-vitro toxicology studies indicate a clean safety profile. Selected compounds demonstrate excellent in-vivo efficacy in relevant tumor models with >90% tumor growth inhibition and good in-vivo PD modulation. In summary, a series of potent and selective IRAK4 inhibitors have been discovered and are being evaluated for treatment of cancers with dysregulated innate immune signaling.

Citation Format: Venkateshwar Rao, Wesley Roy Balasubramanian, Kavitha Nellore, Sivapriya Marappan, Aravind Basavaraju, Bharathi Raja Ainan, Girish Daginakatte, Sreevalsam Gopinath, Sanjeev Giri, Thomas Antony, Shekar Chelur, Susanta Samajdar, Chetan Pandit, Murali Ramachandra. Efficacy of novel IRAK4 inhibitors in ABC-DLBCL and AML models. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C191.

Abstract 3646: Novel IRAK-4 inhibitors exhibit highly potent anti-proliferative activity in DLBCL cell lines with activating MYD88 L265P mutation

Interleukin-1 Receptor Associated Kinase-4 (IRAK-4) is a serine/threonine protein kinase belonging to tyrosine like kinase (TLK) family. IRAK-4 is one of the important signalling components downstream of IL-1/Toll family of receptors (IL-1R, IL-18R, IL-33R, Toll-like receptors). Recent studies have reported occurrence of oncogenic mutations in MYD88 in 30% of ABC diffuse large B cell lymphomas (ABC DLBCL) and 90% of Waldenstrom's macroglobulinemia (WM). Most of ABC DLBCLs have a single amino acid substitution of proline for the leucine at position 265 (L265P) in the TIR domain of MYD88 protein resulting in constitutive activation of IRAK-4. Thus, IRAK4 is an attractive therapeutic target for the treatment of B-cell lymphomas with activating MYD88 L265P mutation. We have designed, synthesized and tested small molecule IRAK-4 inhibitors based on hits originating from Aurigene’ s compound library. These novel compounds were profiled for IRAK4 kinase inhibition, anti-proliferative activity, kinase selectivity, and drug-like properties. Furthermore, selected compounds were tested in a proliferation assay and pIRAK1 mechanistic assay using ABC-DLBCL cell lines with activating MYD88 L265P mutation, OCI-lLy10 and OCI-lLy3. We have identified a series of novel bicyclic heterocycles as potent inhibitors of IRAK-4. Aurigene Lead compound exhibited potent inhibitory activity for IRAK-4 with an IC50 of 3nM in biochemical assay. Aurigene Lead compound inhibited pIRAK1 levels, and proliferation of OCI-Ly3 and OCI-Ly10 cells with an IC501of 132nM and 52nM respectively. To the best of our knowledge, Aurigene Lead compound represents the most potent IRAK4 inhibitor reported for target modulation and anti-proliferative activity in DLBCL cell lines with activating MYD88 L265P mutation. Aurigene Lead compound has good oral pharmacokinetic profile in mice and has demonstrated excellent pharmacodynamic effect in an in vivo LPS induced TNF-α model with an ED50 of 3.8 mg/Kg in mice. Preliminary in vitro tox studies indicated clean safety profile. Demonstration of efficacy in OCI-lLy10 mouse tumor model is ongoing. In summary, a series of potent IRAK-4 inhibitors belonging to 3 different chemical series have been discovered and are being evaluated for treatment of B-cell lymphomas.

Citation Format: Wesley Roy Balasubramanian, Venkateshwar Rao Gummadi, Ravi Krishna Babu D, Sivapriya Marappan, Bhavesh Choudhary, Sreevalsam Gopinath, Kavitha Nellore, Shekar Chelur, Girish Daginakatte, Murali Ramachandra. Novel IRAK-4 inhibitors exhibit highly potent anti-proliferative activity in DLBCL cell lines with activating MYD88 L265P mutation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3646. doi:10.1158/1538-7445.AM2015-3646

A simple method for the production of recombinant proteins from mammalian cells

Expression of recombinant proteins in mammalian cells is useful for obtaining products with normal post-translational modifications. We describe a simple and economical method for the production of milligram levels of proteins in murine fibroblasts. Retroviral or LIPOFECTAMINE (Gibco Laboratories) transduction was employed to generate stable murine-fibroblast producer cells. Confluent cultures of stable fibroblast clones were maintained for up to 1 month in 0.5% serum. Culture medium was collected every 2-3 days and polyhistidine-tagged proteins were purified by ammonium sulphate precipitation and Ni(2+)-nitrilotriacetic acid affinity chromatography. Highly pure, active, glycosylated recombinant proteins, including human beta-glucuronidase, mouse beta-glucuronidase, aminopeptidase N (CD13) and a single-chain antibody-enzyme fusion protein, were obtained with yields of 3-6 mg/l of culture medium. Fc-tagged proteins were also produced and purified in a single step by Protein A affinity chromatography with yields of 6-12 mg/l. The techniques described here allow simple and economical production of recombinant mammalian proteins with post-translational modifications.