Jennifer McNealey - Senior Director, Investor Relations Susan Molineaux - Founder, President and Chief Executive Officer William Waddill - Senior Vice President and Chief Financial Officer

Good day, ladies and gentlemen, and welcome to the Calithera Biosciences Fourth Quarter 2015 Earnings Conference Call. At this time, all participants are in a listen-only mode. Later, we will conduct a question-and-answer session and instructions will follow at that time. [Operator Instructions] As a reminder, this conference call maybe recorded. I would now like to introduce your host for today’s conference, Ms. Jennifer McNealey, Senior Director, Investor Relations. Ma'am, you may begin.

Good morning, everyone and welcome to Calithera’s fourth quarter and year end 2015 conference call. Joining me today are Susan Molineaux, our Founder, President and CEO; and Will Waddill, our Senior Vice President and CFO. Before we begin, I would like to remind you that today's discussion will include statements about the company's future expectations, plans, and prospects that constitute forward-looking statements for the purposes of the Safe Harbor provisions under the Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors including those discussed in the Risk Factors section of our Annual Report on Form 10-K, which we plan to file with the SEC before the market opens today. In addition, any forward-looking statements represent our views only as of today and should not be relied upon as representing our views as of any subsequent date. While we may elect to update these forward-looking statements at some point in the future, we specifically disclaim any obligation to do so even if our views change. Please note that this call is being recorded. With that, I will turn the call over to Susan.

Thanks, Jennifer, and good morning everyone. Thank you for joining us today on our quarterly conference call. 2015 was a productive year at Calithera. Our programs progressed well as we have shown in the fourth quarter with multiple abstracts presented at peer reviewed medical and scientific meetings. At the AACR-EORTC-NCI meeting we presented updated data on the solid tumor, dose expansion, monotherapy cohorts for our lead product CB-839 and at the American Society of Hematology Meeting in December we presented initial combination data. CB-839 is a first-in-class selective important inhibitor of glutaminase and we believe it is the only glutaminase inhibitor currently in clinical development. CB-839 continues to demonstrate single agent solid tumor clinical benefit across a variety of solid tumor types and in addition we have seen an objective response in the renal cancer patients treated with CB-839 as monotherapy as well as further signs of durability and continuation of our positive safety profile. In addition, we presented CB-839 preclinical metabolic driven data at the 2015 Global Technology Community Novel Cancer Therapeutic Summit demonstrating impressive immunologic activity with checkpoint inhibitors. For our immuno-oncology program CB-1158 which is our oral inhibitor of arginase, we recently presented the first preclinical data for CB-1158. This is a small molecule arginase inhibitor with the potential to treat cancer by blocking the immunosuppression of the tumor microenvironment. The data demonstrated single agent antitumor efficacy in mouse models, a twofold synergistic increase in efficacy with the checkpoint inhibitors anti-PD1 and anti-PD-L1 tolerability as a single agent and in combination with checkpoint inhibitors in animal studies. At Calithera, our three programs targeting glutamine, arginine and glucose metabolism are interrelated with each program targeting a different aspect of tumor-specific metabolism. Tumor metabolism and immune-oncology have emerged as promising new fields for cancer drug discovery and recent clinical successes with therapeutic agents in each field have demonstrated the potential to create fundamentally new therapies for cancer patients. We are developing agents to take advantage of the unique metabolic requirements of tumor cells and cancer fighting immune cells such as cytotoxic T-cells. With these programs we believe that we have multiple opportunities to positively impact clinical outcomes for cancer patients by building a pipeline of novel therapeutic product candidates. Let's begin with a more detailed update on CB-839, our most advanced product candidate. The three phase mono clinical trial with CB-839 in solid tumors in hematological malignancies continued to enroll throughout 2015 with 184 patients enrolled as of January 2016 across the three trials. In November, we presented data from our CB-839 solid tumor study and this was our first update since the day that we presented at the American Society of Clinical Oncology or ASCO Meeting in June with more patients enrolled in the dose expansion cohort. We achieved a single agent partial response in a renal cell carcinoma patient, who has now been treated for over nine months and remains on the study. This patient who had three prior therapies showed a 32% reduction in target lesions by RECIST with generalized shrinkage of target and non-target lymph node metastases. Furthermore, among the evaluable patients with RCC, 60% or nine out of 15 had a partial response or stable disease lasting at least three cycles or 124 days. Of note, the partial response had triggered an expansion of the RCC monotherapy cohort. The data in RCC showing a favorable stable disease rate of 60% and a single agent PR is prompting us to focus additional attention on this tumor type as we move forward. Across all cohorts in the Phase 1 study, data demonstrated stable disease across a variety of tumor types was presented. Among efficacy-evaluable patients across this range of solid tumor types on the current dosing schedule of twice-daily with food, 22 out of 50 patients or 44% experienced stable disease or better. Five stable disease patients currently on study have been treated with CB-839 for over eight months without progression. Overall we are very encouraged by these results and are continuing on our plan to explore the potential for CB-839 in combination with other targeted agents across multiple tumor types. In addition, the first results of CB-839 dose in combination therapy in multiple myeloma were presented at the American Society of Hematology Annual Meeting in December. We remain on track to enroll several combination trials with CB-839 with data beginning to emerge from these trials in mid 2016. Two new combination trials will also be initiated by midyear. Our checkpoint inhibitor combination trial and an investigator sponsor trial and a biomarker selective colorectal cancer [indiscernible]. First, the checkpoint inhibitor trial. Preclinical data of CB-839 in combination with anti-PD1 and anti-PD-L1 has led to the design of a stage 1/2 study with a checkpoint inhibitor to begin in 1H16. Glutamine which is frequently depleted in the tumor micro environment due to avid uptake by tumor cells has been shown to be an important nutrient for T-cell growth. Administration of CB-839 to tumor bearing animals substantially enhances the anti-tumor activity of checkpoint inhibitors and restores the levels of glutamine in the tumor micro environment, thereby enabling T-cells to proliferate. Checkpoint inhibitors promote the activation and tumor killing properties of the patient's own immune cells such as cytotoxic T-cells. CB-839 could potentially have a one-two Punch in the treatment of cancer by first charging the tumor cells and second, facilitating the activation of T-cells and the nutrients deprived tumor micro environment. We plan to begin enrolling this trial midyear. The other planned trial is an investigator sponsored trial at Case Western Reserve University and we will be enrolling colorectal cancer patients with a PIK3CA mutation for treatment with the combination of CB-839 and 5-fluorouracil. An academic research group at Case Western Reserve University demonstrated that single agent CB-839 inhibits the growth of colorectal cancers with PIK3CA mutation in immunocompromised mice, but these tumors with a normal PIK3CA were not inhibited. Remarkably the combination of CB-839 with 5-fluorouracil induced complete and long lasting tumor regressions in animals bearing PIK3CA [ph] tumors but not tumors with normal PIK3CA suggesting that this combination therapy may be a unique and effective approach in the clinic. These investigators are planning to initiate an investigator sponsored clinical trial in the first half of 2016 to be overseen by Dr. Jennifer Eads, Alok Khorana and Neal Meropol at Case Western. Again we expect initial data to be available from our ongoing combination trial in 2016 with data from the two planned new trials in 2017. Next, an update on our arginase inhibitor immune-oncology program. We believe the drugs targeting immune-oncology including metabolic checkpoints have the potential to be transformational in the treatment of cancer. In November, we presented data at the AACR-NCI-EORTC meeting showing that CB-1158 is a highly selective, orally bio-available small molecule inhibitor of human arginase with nanomolar potency. Arginase is an enzyme secreted by myeloid cells in the tumor micro environment that blocks the activation and proliferation of affected T-cells by depleting them of the nutrient arginine. We presented data demonstrating that the arginase inhibitor CB-1158 has single agent efficacy in mouse tumor models. In addition of tumor growth was accompanied with a rapid increase in the local concentration of arginine and the induction of multiple pro-inflammatory changes in the tumor microenvironment. CB-1158 when administered with anti-CTLA-4 increased CB-8 positive T-cell infiltrates in the tumor. The addition of CB-1158 to anti-CTLA-4 and anti-PD1 significantly inhibited tumor growth in a mouse model that was resistant to the dual checkpoint inhibitor therapy alone. CB-1158 was well-tolerated as a single agent and in combination with checkpoint inhibitors in animal studies. We are very excited about the significant progress we have made in our CB-1158 program and remain on track to file an investigative new drug application for IND by mid 2016. We are planning initial trials as a monotherapy with the ability to move into combination therapy as quickly as possible. Similar to the IDO inhibitors there is a rationale to combine CB-1158 with other immune-oncology therapies that target T-cell activation such as CTLA-4 and PD-1 antibodies. Our near term anticipated milestones include the following: for CB-839 additional preclinical data will be presented at the AACR meeting in April. We are continuing to enroll patients in our CB-839 combination expansion cohorts. We are initiating the checkpoint inhibitor combination trial and the investigator sponsor trial in colorectal cancer. And we will present combination therapy data in mid 2016. For CB-1158 we plan to present additional preclinical data at the AACR meeting in April and file our IND for arginase inhibitor in the first half of 2016. With that, I’ll pass it over to Will for an update on our financials.

Thank you, Susan and good morning everyone. Calithera finished 2015 in a well capitalized position which we believe enabled us to drive our wholly-owned first-in-class programs to meaningful valuation and flexion points in 2016 and beyond. That’s why our financials cash, cash equivalents and investments totaled $71.9 million at December 31, 2015 compared with $102 million at December 31, 2014. Research and development expenses for full year 2015 were $23.7 million compared with $16.4 million in the prior year. The increase of $7.4 million in 2015 primarily attributed to higher expenses associated with the company’s arginase inhibitor program including the selection of 1158 and its advancement through preclinical development and continued enrollment of CB-839, the company’s first-in-class glutaminase inhibitor in Phase 1 clinical trials. Research and development expenses for the fourth quarter 2015 were $5.8 million compared to $5 million for the same period last year. General and administrative expenses for the full year 2015 were $9.1 million compared to $5.4 million for the prior year. The increase of $3.7 million in 2015 was primarily due to higher employment related expenses including stock-based compensation expense and professional service fees related to Calithera’s cost associated with operating as a public traded company. General and administrative expenses for the fourth quarter of 2015 were $2.3 million compared to $1.9 million for the same period last year. Loss from operations for the three months and year end December 31, 2015 were $8.1 million and $32.6 million respectively. As for our financial guidance for 2016, Calithera expects cash, cash equivalents and investments to be at least $35 million at the end of 2016 exclusive of any funds arriving from new collaborations, partnerships, equity financing or other new sources of funds arising from any additional equity financing, collaborations or other new sources of capital. And with that I will turn it back over to Susan.

Thank you, Will. And with that, operator, we are happy to open the line for questions.

A -

Thank you. [Operator Instructions] And I am showing no further questions at this time.

Once again, thank you all for joining the call today and in closing we look forward to seeing you at AACR and ASCO as well as at investor conferences. Thank you and have a good day.

Ladies and gentlemen, thank you for participating in today's conference. This concludes today's program. You may all disconnect. Everyone have a great day.