FIELD OF THE INVENTION

The present invention relates to heterobicyclic amides and related compounds which are inhibitors of CD38 and are useful in the treatment of cancer.

BACKGROUND OF THE INVENTION

CD38 (cluster of differentiation 38) is a member of the ADP-ribosyl cyclase family that is widely expressed on the surface of multiple cell types and is responsible for the degradation of nicotinamide adenine dinucleotide (NAD+). CD38 was first characterized as a surface antigen on immune cells as an activation marker, located on the plasma membrane and on the membranes of intracellular organelles (Quarona, V., et al.Cytometry B Cin Cytom84(4): 207-217 (2013)). Human CD38 contains 300 amino acid residues comprising a short N-terminal fragment, a single-pass trans-membrane helix, and a C-terminal catalytic domain. CD38 is generally classified as a type II membrane protein; however, it has also been reported as existing in a type III orientation (Zhao Y Z et al.Biochim Biophys Acta1853(9): 2095-2103 (2012)). CD38 converts NAD to ADP-ribose (ADPR) or cyclic ADPR (cADPR) and nicotinamide (Chini E N et al.Trends Pharmacol Sci39(4): 424-436 (2018)). While NAD+is recognized as the major substrate for CD38, it is also known to have other substrates such as nicotinamide adenine dinucleotide phosphate (NADP+) and nicotinamide mononucleotide (NMN+). Under some conditions, CD38 can also catalyze base exchange reactions with these same substrates (Preugschat, F et al.Arch Biochem Biophys,479: 114-20 (2008)). This CD38-dependent NAD+metabolism regulates levels of extracellular and intracellular metabolites, intracellular Ca2+, and signal transduction pathways (Horenstein, A L, et al.Oncoimmunology2(9): e26246 (2013)); Chini E N et al. 2018). CD38 also functions as a receptor, and the receptor-ligand activity of CD38 regulates development, activation, and differentiation of multiple immune cell types (Quorona B et al. 2013), and CD31/PECAM-1 has been reported to be a ligand for CD38 (Deaglio S,J Immunol,160: 395-402 (1998)).

CD38 exerts diverse physiological functions, and characterization of CD38 knockout (KO) mice has clarified the various roles played by this protein. CD38 KO mice are characterized by large decreases in endogenous cADPR levels in all tissues/organs analyzed except the brain (Partida-Sanchez S et al.Nat Med,7: 1209-16 (2001); Ceni C et al.J Biol Chem278(42): 40670-40678 (2003)) In the pancreatic islets, loss of CD38 impairs glucose-induced production of cADPR, intracellular Ca2+, and insulin secretion (Kato J et al.J Biol Chem,274: 1869-72 (1999)). CD38 KO also impairs acetylcholine-induced accumulation of cADPR in acinar cells, leading to marked alteration of Ca2+signaling patterns (Fukushi Y et al.J Biol Chem,276: 649-55 (2001)). Likewise, in neutrophils, cADPR production has been shown to regulate both intracellular Ca2+release and extracellular Ca2+influx during chemotaxis and is required for bacterial clearance in vivo (Partida-Sanchez S et al.Nat Med,7: 1209-16 (2001)). CD38 KO mice also show other defects, including disordered osteoclast formation and function (Sun L et al.FASEB J,17: 369-75 (2003)), altered airway responsiveness (Deshpande D A et al.Am J Respir Cell Mol Biol,32: 149-56 (2005)), impairment of dendritic cell trafficking and reduced humoral immune response (Partida-Sanchez S et al.Immunity,20: 279-91 (2004)), inhibition of α-adrenoceptor-stimulated contraction in the aorta (Mitsui-Saito M et al.J Vet Med Sci,65: 1325-30 (2003)), and cardiac hypertrophy (Takahashi J et al.Biochem Biophys Res Commun,312: 434-40 (2003)). These findings clearly demonstrate the diverse biological roles played by CD38.

CD38 expression has also been associated with the immunosuppressive functions of regulatory T (Treg) cells, tumor-associated macrophages (TAMs) and myeloid-derived suppressive cells (MDSCs) (Feng X et al.Clin Cancer Res23(15): 4290-4300 (2017); Krejcik J et al.Blood128(3): 384-394 (2016); Chevrier S et al.Cell169(4): 736-749 e718 (2017);Levy A Neuro Oncol14(8): 1037-1049 (2012)). CD38 KO Treg cells are remarkably sensitive to NAD+-induced cell death due to their inability to consume NAD+(Chen J et al.J Immunol176(8): 4590-4599 (2006); Hubert, S B et al.J Exp Med,207: 2561-8 (2010)). Conversely, Tregs with high CD38 expression are more suppressive than other subsets with lower or no CD38 expression (Krejcik et al. 2016; Patton D T et al.PLoS One6(3): e17359 (2011)). Likewise, CD38highMDSCs possess greater capacity to suppress activated T cells. The activity of such CD38highMDSCs promoted esophageal tumor growth in mice, an effect that could be inhibited by CD38 blockade (Karakasheva T A et al.Cancer Res75(19): 4074-4085 (2015)). The expansion of functional CD38+MDSCs has also been described in colorectal cancer, especially in patients who have previously undergone therapy (Karakasheva T A et al.JCI Insight3(6) (2018)). Broad systems immunology approaches have revealed the association of CD38-expressing tumor-infiltrating lymphocytes (TILs) with poor prognosis in clear cell renal cell carcinoma (ccRCC) and early lung adenocarcinoma (Chevrier S et al. 2017; Lavin Y et al.Cell169(4): 750-765 e717 (2017)). In ccRCC, it was determined that CD38 was co-expressed with other markers of T cell exhaustion, whereas in lung adenocarcinoma, CD38highTreg cells were enriched in the tumor microenvironment (TME) (Chevrier S et al. 2017; Lavin Y et al. 2017). High co-expression of CD38 and CD101 on TILs in tumor tissue was correlated with poor survival of pancreatic cancer patients (Zhang M et al.Immunol Invest,48: 466-79 (2019)). A study looking into exhausted T cell populations in humans with chronic infection and various cancers identified CD38 as a T cell exhaustion marker, and the presence of such exhausted T cells was linked to more severe disease from HIV infection and dysfunctional TILs in lung cancer (Bengsch B et al.Immunity48(5): 1029-1045 e1025 (2018)). CD38 also dictates the metabolic fitness of T cells, and the inhibition of CD38 expression on T cells upregulates NAD+and activates T cells by promoting glutaminolysis, enhancing oxidative phosphorylation, and altering mitochondrial dynamics (Chatterjee S et al. 2018). This study further demonstrated that inhibition of CD38 prevented T cell exhaustion and thereby boosted the efficacy of adoptive T cell therapy (Chatterjee S et al.Cell Metab27(1): 85-100 e108 (2018)).

The role of CD38 in tumorigenesis and immune suppression is an active field of research, with multiple studies associating CD38 with tumor progression. CD38 was shown to promote cervical cancer cell growth by reducing levels of reactive oxygen species and inhibiting apoptosis (Liao S et al.Mol Carcinog56(10): 2245-2257 (2017)), and loss of CD38 in human lung adenocarcinoma cells inhibited cell growth, invasion, and xenograft growth in nude mice (Bu X et al.Carcinogenesis39(2): 242-251 (2017)). CD38 KO mice are more resistant to tumor growth and were shown to efficiently reject B16-F10 melanoma tumors (Baruch B B et al.Oncotarget,9: 31797-811 (2018)). Similarly, targeting CD38 expression or its activity in the TME inhibited glioma progression and prolonged the lifespan of glioma-bearing mice (Blacher E et al.Int J Cancer136(6): 1422-1433 (2013)). CD38 has also been identified as a biomarker of aggressive localized prostate cancer (Sahoo D et al.Oncotarget,9: 6550-61 (2018)).

Recent research has investigated the role of CD38 in an ecto-enzyme cascade that generates immunosuppressive adenosine from NAD+. In addition to CD38, this cascade includes ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) and the 5′-ectonucleotidase CD73. CD38 generates ADPR that is further hydrolyzed by ENPP1 to produce AMP, and the subsequent conversion of AMP to adenosine is regulated by CD73 (Ferretti E et al.Immunol Lett205: 25-30 (2019)). This non-canonical adenosine generation pathway, which relies on CD38, occurs independently of ATP, and bypasses CD39 (Horenstein A L et al. 2013), plays a major role in creating an immunosuppressive TME, wherein dying cells provide NAD+that is eventually converted to adenosine (Haag F et al.Purinergic Signal3(1-2): 71-81 (2007); Zhu Y et al.Pharmacol Ther200: 27-41 (2019)).

Furthermore, a recent study demonstrated that cancer cells acquire resistance to immune checkpoint inhibitors that target programmed cell death protein 1 (PD-1) or its ligand (PD-L1) via upregulation of CD38, which blocks CD8+ T cell function through adenosine receptor signaling (Chen L et al.Cancer Discov8(9): 1156-1175 (2018)). CD38 blockade subsequently restored CD8+ T cell proliferation, antitumor cytokine secretion, and cytotoxic capabilities. Pathologic analysis of lung cancer specimens revealed positive immunohistochemical staining for CD38 on tumor cells in 15-23% of cases, and bioinformatic analyses of datasets from non-small cell lung cancer (NSCLC) and melanoma patients revealed a strong correlation between CD38 expression and an inflamed TME (Chen L et al. 2018).

CD38 is one of the main enzymes responsible for the age-related NAD+decline that occurs in mammals (Hogan K A et al.Front Immunol10: 1187 (2019)). CD38 KO mice are consistently protected from this progressive deficit and age-related metabolic dysfunction (Camacho-Pereira J et al.Cell Metab,23: 1127-39 (2016)). Inhibition of CD38 likewise reversed age-related NAD+decline and ameliorated several metabolic, structural, and molecular features of aging in chronologically aged and progeroid mice (Camacho-Pereira J et al. 2016). CD38 KO mice are also protected from diet-induced obesity, liver steatosis, and glucose intolerance due to enhanced energy expenditure (Barbosa M T et al.FASEB J21(13): 3629-3639 (2007)).

CD38 is a cell-surface marker for multiple myeloma and these cells are specifically susceptible to CD38 depletion, thus CD38 offers a useful therapeutic target for this malignancy (Chini E N et al. 2018). Clinical trials have demonstrated that CD38-targeting antibodies are specifically effective in relapsed/refractory multiple myeloma patients (Frerichs K A et al.Expert Rev Clin Immunol,14: 197-206 (2018); van de Donk N W C J et al.Front Immunol,9: 2134 (2018)), and the anti-CD38 antibody daratumumab has been approved by the FDA for multiple myeloma treatment. Several other therapeutic antibodies against CD38 are now in clinical development for multiple myeloma and other cancers (van de Donk NWCJ 2018).

The literature is replete with references reporting the potential therapeutic benefits of inhibiting abnormal expression or activity of CD38. For example, the following diseases are characterized by abnormal expression or activity of CD38: non-small cell lung cancer, melanoma, checkpoint therapy treated and/or resistant cancers, and adenosine-dependent tumors (Chen L et al. “CD38-mediated immunosuppression as a mechanism of tumor cell escape from PD-1/PD-L1 blockade.”Cancer Discov.8, 1156-1175 (2018)); lung cancer (adenocarcinoma) (Bu X et al. “CD38 knockout suppresses tumorigenesis in mice and clonogenic growth of human lung cancer cells.”Carcinogenesis39, 242-251 (2018)); cervical cancer (Liao S et al. “CD38 enhances the proliferation and inhibits the apoptosis of cervical cancer cells by affecting the mitochondria functions.”Mol. Carcinog.56, 2245-2257 (2017)); glioma (Blacher E et al. “Inhibition of glioma progression by a newly discovered CD38 inhibitor.”Int. J. Cancer136, 1422-1433 (2015)); colorectal cancer (Karakasheva T A et al. “CD38+M-MDSC expansion characterizes a subset of advanced colorectal cancer patients.”JCI Insight3, 1-8 (2018)); esophageal cancer (Karakasheva T A et al. “CD38-expressing myeloid-derived suppressor cells promote tumor growth in a murine model of esophageal cancer.”Cancer Res.75, 4074-4085 (2015)); clear cell renal cell carcinoma (Chevrier S et al. “An immune atlas of clear cell renal cell carcinoma.”Cell169, 736-749 (2017)); prostate cancer (Sahoo D et al. “Boolean analysis identifies CD38 as a biomarker of aggressive localized prostate cancer.”Oncotarget9, 6550-6561 (2018)); treg-infiltrated tumors (Lavin Y et al. “Innate immune landscape in early lung adenocarcinoma by paired single-cell analyses.”Cell169, 750-757.e15 (2017)); MDSC-infiltrated tumors (Karakasheva T A et al. “CD38+M-MDSC expansion characterizes a subset of advanced colorectal cancer patients.”JCI Insight3, 1-8 (2018)); HIV/AIDS (Bengsch B et al. “Epigenomic-guided mass cytometry profiling reveals disease-specific features of exhausted resource epigenomic-guided mass cytometry profiling reveals disease-specific features of exhausted CD8 T cells.”Cell48, 1029-1045 (2018)); adoptive T cell therapy (Chatterjee S et al. “CD38-NAD+axis regulates immunotherapeutic anti-tumor T cell response.”Cell Metab.27, 85-100.e8 (2018)); pancreatic cancer (Zhang M et al. “Prognostic values of CD38+CD101+PD1+CD8+T cells in pancreatic cancer.”Immunol. Invest.48, 466-479 (2019)); and multiple myeloma (Chini E N et al. “The Pharmacology of CD38/NADase: An Emerging Target in Cancer and Diseases of Aging.”Trends Pharmacol. Sci.39, 424-436 (2018)).

In summation, CD38 is a multifunctional enzyme and signaling receptor that plays important functions in cancer progression, the creation of an immunosuppressive TME, metabolic fitness of T cells, and the modulation of NAD+levels in aging and other physiological conditions. The inhibition of CD38 in various disease states—including tumor growth—has already shown clinical promise, and the development of potent and selective small-molecule inhibitors will create therapeutic options for other conditions characterized by abnormal expression or activity of CD38. The compounds, compositions, and methods described herein will help meet these and other needs.

SUMMARY OF THE INVENTION

The present invention provides a compound of Formula I:


or a pharmaceutically acceptable salt thereof, wherein constituent members are defined herein.

The present invention is also directed to a pharmaceutical composition comprising a compound of Formula I, or a pharmaceutically acceptable salt thereof, and at least one pharmaceutically acceptable carrier.

The present invention is also directed to a method of inhibiting a function of CD38 by contacting the CD38 with a compound of Formula I, or a pharmaceutically acceptable salt thereof.

The present invention is also directed to a method of treating a disease associated with abnormal activity or expression of CD38 by administering a therapeutically effective amount of a compound of Formula I, or a pharmaceutically acceptable salt thereof, to a patient in need thereof.

The present invention is further directed to a compound of the invention, or a pharmaceutically acceptable salt thereof, for use in the treatment of a disease associated with abnormal activity or expression of CD38.

The present invention is further directed to use of a compound of the invention, or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for use in therapy.

