Long-Acting Tumor-Activated Prodrug of a TGFßR Inhibitor.

Inhibition of TGFß signaling in concert with a checkpoint blockade has been shown to provide improved and durable antitumor immune response in mouse models. However, on-target adverse cardiovascular effects have limited the clinical use of TGFß receptor (TGFßR) inhibitors in cancer therapy. To restrict the activity of TGFßR inhibitors to tumor tissues and thereby widen the therapeutic index, a series of tumor-activated prodrugs of a selective small molecule TGFßR1 inhibitor 1 were prepared by appending 1 to a serine protease substrate and a half-life extension fatty acid carbon chain. The prodrugs were shown to be selectively metabolized in tumor tissues relative to the heart and blood and demonstrated a prolonged favorable increase in the tumor-to-heart ratio of the active drug in tissue distribution studies. Once-weekly administration of the most tissue-selective compound 10 provided anti-tumor efficacy comparable to the parent compound and reduced systemic exposure of the active drug.

Discovery and Preclinical Evaluation of BMS-986242, a Potent, Selective Inhibitor of Indoleamine-2,3-dioxygenase 1.

Indoleamine 2,3-dioxygenase 1 (IDO1) is a heme-containing dioxygenase enzyme implicated in cancer immune response. This account details the discovery of BMS-986242, a novel IDO1 inhibitor designed for the treatment of a variety of cancers including metastatic melanoma and renal cell carcinoma. Given the substantial interest around this target for cancer immunotherapy, we sought to identify a structurally differentiated clinical candidate that performs comparably to linrodostat (BMS-986205) in terms of both in vitro potency and in vivo pharmacodynamic effect in a mouse xenograft model. On the basis of its preclinical profile, BMS-986242 was selected as a candidate for clinical development.

Pharmacodynamics-based approach for efficacious human dose projection of BMS-986260, a small molecule transforming growth factor beta receptor 1 inhibitor.

Transforming growth factor beta (TGF-ß) is a pleiotropic cytokine that has a wide array of biological effects. For decades, tumor biology implicated TGF-ß as an attractive therapeutic target due to its immunosuppressive effects. Toward this end, multiple pharmaceutical companies developed a number of drug modalities that specifically target the TGF-ß pathway. BMS-986260 is a small molecule, selective TGF-ßR1 kinase inhibitor that was under preclinical development for oncology. In vivo studies across mouse, rat, dog, and monkey and cryopreserved hepatocytes predicted human pharmacokinetics (PK) and distribution of BMS-986260. Efficacy studies of BMS-986260 were undertaken in the MC38 murine colon cancer model, and target engagement, as measured by phosphorylation of SMAD2/3, was assessed in whole blood to predict the clinical efficacious dose. The human clearance is predicted to be low, 4.25 ml/min/kg. BMS-986260 provided a durable and robust antitumor response at 3.75 mg/kg daily and 1.88 mg/kg twice-daily dosing regimens. Phosphorylation of SMAD2/3 was 3.5-fold less potent in human monocytes than other preclinical species. Taken together, the projected clinical efficacious dose was 600 mg QD or 210 mg BID for 3 days followed by a 4-day drug holiday. Mechanism-based cardiovascular findings in the rat ultimately led to the termination of BMS-986260. This study describes the preclinical PK characterization and pharmacodynamics-based efficacious dose projection of a novel small molecule TGF-ßR1 inhibitor.

Discovery of BMS-986260, a Potent, Selective, and Orally Bioavailable TGFßR1 Inhibitor as an Immuno-oncology Agent.

Novel imidazole-based TGFßR1 inhibitors were identified and optimized for potency, selectivity, and pharmacokinetic and physicochemical characteristics. Herein, we report the discovery, optimization, and evaluation of a potent, selective, and orally bioavailable TGFßR1 inhibitor, 10 (BMS-986260). This compound demonstrated functional activity in multiple TGFß-dependent cellular assays, excellent kinome selectivity, favorable pharmacokinetic properties, and curative in vivo efficacy in combination with anti-PD-1 antibody in murine colorectal cancer (CRC) models. Since daily dosing of TGFßR1 inhibitors is known to cause class-based cardiovascular (CV) toxicities in preclinical species, a dosing holiday schedule in the anti-PD-1 combination efficacy studies was explored. An intermittent dosing regimen of 3 days on and 4 days off allowed mitigation of CV toxicities in one month dog and rat toxicology studies and also provided similar efficacy as once daily dosing.

Discovery of Pyridazinone and Pyrazolo[1,5-a]pyridine Inhibitors of C-Terminal Src Kinase.

C-terminal Src kinase (CSK) functions as a negative regulator of T cell activation through inhibitory phosphorylation of LCK, so inhibitors of CSK are of interest as potential immuno-oncology agents. Screening of an internal kinase inhibitor collection identified pyridazinone lead 1, and a series of modifications led to optimized compound 13. Compound 13 showed potent activity in biochemical and cellular assays in vitro and demonstrated the ability to increase T cell proliferation induced by T cell receptor signaling. Compound 13 gave extended exposure in mice upon oral dosing and produced a functional response (decrease in LCK phosphorylation) in mouse spleens at 6 h post dose.

Critical role of kinase activity of hematopoietic progenitor kinase 1 in anti-tumor immune surveillance.

Immunotherapy has fundamentally changed the landscape of cancer treatment. Despite the encouraging results with the checkpoint modulators, response rates vary widely across tumor types, with a majority of patients exhibiting either primary resistance without a significant initial response to treatment or acquired resistance with subsequent disease progression. Hematopoietic progenitor kinase 1 (HPK1) is predominantly expressed in hematopoietic cell linages and serves as a negative regulator in T cells and dendritic cells (DC). While HPK1 gene knockout (KO) studies suggest its role in anti-tumor immune responses, the involvement of kinase activity and thereof its therapeutic potential remain unknown. To investigate the potential of pharmacological intervention using inhibitors of HPK1, we generated HPK1 kinase dead (KD) mice which carry a single loss-of-function point mutation in the kinase domain and interrogated the role of kinase activity in immune cells in the context of suppressive factors or the tumor microenvironment (TME). Our data provide novel findings that HKP1 kinase activity is critical in conferring suppressive functions of HPK1 in a wide range of immune cells including CD4+, CD8+, DC, NK to Tregs, and inactivation of kinase domain was sufficient to elicit robust anti-tumor immune responses. These data support the concept that an HPK1 small molecule kinase inhibitor could serve as a novel agent to provide additional benefit in combination with existing immunotherapies, particularly to overcome resistance to current treatment regimens.

Discovery of 4-Azaindole Inhibitors of TGFßRI as Immuno-oncology Agents.

The multifunctional cytokine TGFß plays a central role in regulating antitumor immunity. It has been postulated that inhibition of TGFß signaling in concert with checkpoint blockade will provide improved and durable immune response against tumors. Herein, we describe a novel series of 4-azaindole TGFß receptor kinase inhibitors with excellent selectivity for TGFß receptor 1 kinase. The combination of compound 3f and an antimouse-PD-1 antibody demonstrated significantly improved antitumor efficacy compared to either treatment alone in a murine tumor model.

Intrinsic conduction through topological surface states of insulating Bi2Te3 epitaxial thin films.

Topological insulators represent a novel state of matter with surface charge carriers having a massless Dirac dispersion and locked helical spin polarization. Many exciting experiments have been proposed by theory, yet their execution has been hampered by the extrinsic conductivity associated with the unavoidable presence of defects in Bi2Te3 and Bi2Se3 bulk single crystals, as well as impurities on their surfaces. Here we present the preparation of Bi2Te3 thin films that are insulating in the bulk and the four-point probe measurement of the conductivity of the Dirac states on surfaces that are intrinsically clean. The total amount of charge carriers in the experiment is of the order of 10(12) cm(-2) only, and mobilities up to 4,600 cm(2)/Vs have been observed. These values are achieved by carrying out the preparation, structural characterization, angle-resolved and X-ray photoemission analysis, and temperature-dependent four-point probe conductivity measurement all in situ under ultra-high-vacuum conditions. This experimental approach opens the way to prepare devices that can exploit the intrinsic topological properties of the Dirac surface states.

The 5(th) percentile dummy in a 56 kmph full-frontal barrier crash test.

In 1998, the National Highway Traffic Safety Administration (NHTSA) tested the 5(th) percentile dummy and the 50(th) percentile dummy in 48 KMPH (30 MPH) belted full-frontal crash tests. From these tests, it was concluded that the 5(th) percentile dummy experienced increased injury measures to the neck and tibia compared to the 50(th) percentile dummy when crashed in the same vehicle. In 2001, the agency conducted ten belted 56 KMPH (35 MPH) frontal vehicle crash tests using the 5(th) percentile dummy. This paper summarizes the results and findings of those tests. The results indicate that the 5(th) percentile dummy is a robust and very durable dummy, which could be used as a tool for safety information. The testing also showed that, for some vehicles, the 5(th) percentile dummy incurred greater injury measures than the 50(th) percentile dummy tested in the same vehicle, particularly for the neck and the lower extremities. The average Nij reading for the 5(th) percentile driver dummy was 0.82, while for the 50(th) percentile driver dummy, the average Nij reading was 0.39. Also, the average normalized neck tension reading for the 5(th) percentile driver dummy was 0.70, whereas it was 0.41 for the 50(th) percentile driver dummy for the vehicles of this test series. Average normalized neck tension readings for the 5(th) percentile passenger dummy were 0.40, whereas 0.28 was the average normalized reading for the 50(th) percentile passenger dummy in the vehicles tested. For the 5(th) percentile driver, all but three vehicles exceed one of the four indices for the tibia, whereas only four vehicles exceeded one of these indices for the 50(th) percentile driver. Finally, the testing revealed the need for different stature dummies to ensure equal protection for all occupants.