Odonate Therapeutics Initiates Cohort 3 of CONTESSA TRIO to Evaluate Tesetaxel Monotherapy in Patients with Metastatic Breast Cancer

Cohorts 2 and 3 of CONTESSA TRIO will expand on results from TOB203, a Phase 2 study that evaluated tesetaxel monotherapy in 38 patients with hormone receptor-positive, HER2-negative MBC. In this study, the confirmed response rate was 45%. Neutropenia was the most common Grade ≥3 adverse event and occurred in 32% of patients, and febrile neutropenia occurred in 5% of patients. The results of TOB203 were presented at the 2018 American Society of Clinical Oncology (ASCO) Annual Meeting.

“Taken together, TOB203 and CONTESSA TRIO will evaluate tesetaxel monotherapy in more than 150 patients with metastatic breast cancer,” said Lee Schwartzberg, M.D., FACP, Chief Medical Director, West Cancer Center & Research Institute. “The promising clinical results to date, combined with tesetaxel’s unique, once-every-three-weeks oral dosing regimen, make this investigational agent an exciting potential new treatment option for patients.”

About Tesetaxel

Tesetaxel is an investigational, orally administered chemotherapy agent that belongs to a class of drugs known as taxanes, which are widely used in the treatment of cancer. Tesetaxel has several pharmacologic properties that make it unique among taxanes, including: oral administration with a low pill burden; a long (~8-day) terminal plasma half-life in humans, enabling the maintenance of adequate drug levels with relatively infrequent dosing; no history of hypersensitivity (allergic) reactions; and significant activity against chemotherapy-resistant tumors. In patients with metastatic breast cancer, tesetaxel was shown to have significant, single-agent antitumor activity in two multicenter, Phase 2 studies. Tesetaxel currently is the subject of three studies in breast cancer, including a multinational, multicenter, randomized, Phase 3 study in patients with metastatic breast cancer, known as CONTESSA. Odonate recently announced positive top-line results from CONTESSA, and full results are scheduled to be presented at the San Antonio Breast Cancer Symposium in December 2020.

About CONTESSA TRIO

CONTESSA TRIO is a multi-cohort, multicenter, Phase 2 study of tesetaxel, an investigational, orally administered taxane, in patients with metastatic breast cancer (MBC).

• In Cohort 1, approximately 200 patients with triple-negative MBC who have not received prior chemotherapy for advanced disease will be randomized 1:1:1 to receive tesetaxel dosed orally at 27 mg/m² on the first day of each 21-day cycle plus either: (1) nivolumab at 360 mg by intravenous (IV) infusion on the first day of each 21-day cycle; (2) pembrolizumab at 200 mg by IV infusion on the first day of each 21-day cycle; or (3) atezolizumab at 1,200 mg by IV infusion on the first day of each 21-day cycle. Nivolumab and pembrolizumab (programmed cell death protein 1 [PD-1] inhibitors) and atezolizumab (a programmed death-ligand 1 [PD-L1] inhibitor) are immuno-oncology (IO) agents approved for the treatment of multiple types of cancer. Two of these agents, atezolizumab and pembrolizumab, have been approved by the U.S. Food and Drug Administration (FDA) as a first-line treatment for patients with triple-negative MBC. The primary endpoints for Cohort 1 are objective response rate (ORR) and progression-free survival (PFS) in patients with PD-L1 positive status. The secondary endpoints are ORR and PFS in all patients, duration of response (DoR) and overall survival (OS). Efficacy results for each of the three PD‑(L)1 inhibitor combinations will be assessed for correlation with the results of each of the three approved PD-L1 diagnostic assays.

• In Cohort 2, approximately 60 elderly patients with human epidermal growth factor receptor 2 (HER2)‑negative MBC who have not received prior chemotherapy for advanced disease will receive tesetaxel monotherapy dosed orally at 27 mg/m² on the first day of each 21-day cycle. The primary endpoints for Cohort 2 are ORR and PFS in patients with hormone receptor‑positive, HER2‑negative disease. The secondary endpoints are ORR and PFS in patients with triple‑negative disease, DoR and OS.

• In Cohort 3, approximately 60 non-elderly adult patients with HER2-negative MBC who have not received prior chemotherapy for advanced disease will receive tesetaxel monotherapy dosed orally at 27 mg/m² on the first day of each 21-day cycle. The primary endpoints for Cohort 3 are ORR and PFS in patients with hormone receptor-positive, HER2-negative disease. The secondary endpoints are ORR and PFS in patients with triple-negative disease, DoR and OS.

About Odonate Therapeutics, Inc.

Odonate Therapeutics, Inc. is a pharmaceutical company dedicated to the development of best-in-class therapeutics that improve and extend the lives of patients with cancer. Odonate’s initial focus is on the development of tesetaxel, an investigational, orally administered chemotherapy agent that belongs to a class of drugs known as taxanes, which are widely used in the treatment of cancer. Odonate’s goal for tesetaxel is to develop an effective chemotherapy choice for patients that provides quality-of-life advantages over current alternatives. To learn more, please visit www.odonate.com.

Forward-looking Statements

This press release contains “forward-looking statements” as defined by the Private Securities Litigation Reform Act of 1995. We caution investors that forward-looking statements are based on management’s expectations and assumptions as of the date of this press release and involve substantial risks and uncertainties that could cause the actual outcomes to differ materially from what we currently expect. These risks and uncertainties include, but are not limited to, those associated with: expectations regarding the outcome of CONTESSA, our Phase 3 study of tesetaxel in patients with metastatic breast cancer; expectations regarding the enrollment, completion and outcome of our other clinical studies; expectations regarding the timing for our planned New Drug Application submission for tesetaxel; expectations regarding our ability to obtain regulatory approval of tesetaxel; the unpredictable relationship between preclinical study results and clinical study results; and other risks and uncertainties identified in our filings with the U.S. Securities and Exchange Commission. Forward-looking statements in this press release apply only as of the date made, and we undertake no obligation to update or revise any forward‑looking statements to reflect subsequent events or circumstances.

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