Calithera Biosciences, Inc.

and CDKN2A. Telglenostat blocks glutamine consumption in tumor cells, which, due to specific genetic alterations, such as mutations in KRAS and CDKN2A, often become dependent on increased metabolism of glutamine. Approximately 50% of PDAC patients harbor mutations in both KRAS and CDKN2A. In preclinical studies with KRAS-mutated cancer models, Teleplanistat showed synergistic anti-tumor effects when used in combination with CDK4-6 inhibitors, such as Palvocyclib, enhancing cell cycle arrest and blocking cancer cell proliferation. Recently, we announced the initiation of the first clinical trial to evaluate our novel arginase inhibitor in cystic fibrosis, and we are pleased with the enrollment to date. The depletion of arginine in cystic fibrosis patients by the enzyme arginase results in reduced production of nitric oxide, a key antimicrobial and bronchodilator. Therefore, arginase inhibitors have potential in the treatment of cystic fibrosis, and we have selected CB280, a unique oral arginase inhibitor solely owned by Calthera for the treatment of cystic fibrosis. In October, we presented a trial in progress poster describing the trial design at the North American Cystic Fibrosis Conference. The presentation included preclinical study results which suggested CB280 significantly improved lung function and reduced Pseudomonas aeruginosa colony-forming units in preclinical models. Arginase inhibition with CB280 resulted in improved central airway resistance in CFTR knockout mice and decreased lung infection in wild-type and Delta 508 CFTR-expressing mice infected with Pseudomonas aeruginosa. We have also identified CB668, an investigational first-in-class potent orally administered IL-4I1 inhibitor as a novel immuno-oncology approach to cancer. CB668 is an inhibitor of the enzyme IL-4I1, an enzyme that is expressed by tumor cells and antigen-presenting cells, metabolizes phenylalanine, tyrosine, and tryptophan to produce hydrogen peroxide an inhibitor of T cell function. In particular, IL-4i1 can metabolize tryptophan to kynurenic acid and other metabolites that lead to immunosuppression in the tumor microenvironment. IL-4i1 expression has been correlated with poor outcomes in several tumor types, has a potential role in immune invasion, and may decrease the ability of checkpoint therapy to stimulate an anti-tumor immune response. IL-4i1 expression is elevated in multiple tumor types with particularly high expression in ovarian and B-cell tumors. New preclinical data for CB668 will be presented next week at the Society for Immunotherapy of Cancer virtual meeting. With that, I'll pass it over to Stephanie for an update on our financials.

Thank you, Keith, and good afternoon, everyone. Detailed financial results for the third quarter 2020 were included in today's press release. I will briefly review our results on this call. Califera remains well capitalized. Our cash, cash equivalents, and investments were $137.7 million at September 30, 2020. R&D expenses were $18.2 million for the quarter end of September 30, 2020, compared to $17.2 million for the same period prior year. The increase was primarily due to increases in the teleglinostat and CB280 programs, partially offset by decreases in the 1158 program and early stage research. G&A expenses were $4.7 million for the quarter end of September 30, 2020, compared with $3.9 million for the same prior year. The increase was primarily related to higher personnel-related and facility costs. Interest and other income net was $0.2 million for the quarter ended September 30, 2020, compared to $0.8 million for the same period prior year, mainly as a result of lower interest rates. Net loss for the quarter ended September 30, 2020, was $22.7 million, or 32 cents per share. And with that, I will now return the call back over to Susan. Thank you, Stephanie. And with that, operator, we are happy to open the line for questions.

Again, if you have a question, press star 1 on your telephone keypad. Your first question is from Jonathan Chang with SVB Lyric.