Jounce Therapeutics Presents Preclinical Data from JTX-8064 Program at the Society for Immunotherapy of Cancer's (SITC) 35th Annual Meeting

-Preclinical data highlight Jounce's approach to identify potential predictive and pharmacodynamic biomarkers to identify patients who may benefit from JTX-8064-

-Enrollment in Phase 1 monotherapy and PD-1 inhibitor combination trial planned to begin by year-end 2020-

CAMBRIDGE, Mass., Nov. 11, 2020 (GLOBE NEWSWIRE) -- Jounce Therapeutics, Inc. JNCE, a clinical-stage company focused on the discovery and development of novel cancer immunotherapies and predictive biomarkers, today reported new preclinical data on JTX-8064, the first tumor-associated macrophage program from their Translational Science Platform, at the 2020 Society for Immunotherapy of Cancer's (SITC) 35^th Annual Meeting. The poster presentation includes preclinical human histoculture data highlighting Jounce's approach to identifying potential predictive and pharmacodynamic (PD) markers of response to JTX-8064 that may identify patients more likely to benefit from JTX-8064 monotherapy or in combination with PD-1 inhibitors.

"The JTX-8064 poster at SITC showcases the strength of our Translational Science Platform for identification of targets and potential predictive and PD biomarkers to inform indication selection in our first clinical trial," said Elizabeth Trehu, M.D., chief medical officer of Jounce Therapeutics. "The mechanism of action of JTX-8064 coupled with this histoculture data suggests the potential to address PD1 inhibitor resistant tumors. The data presented at SITC supports the exploration of potential predictive biomarkers to identify patients more likely to benefit from JTX-8064 alone or in combination with a PD-1 inhibitor. We will be including retrospective assessment of potential predictive biomarkers in the first in human clinical trial, for which we expect to commence enrollment by the end of the year."

In a poster titled "Evaluating Biomarkers of JTX-8064 (anti-LILRB2/ILT4 monoclonal antibody) in an Ex Vivo Human Tumor Histoculture System to Inform Clinical Development," Jounce researchers highlighted:

• PD responses to JTX-8064 can be measured preclinically in an ex vivo human tumor histoculture system
• Baseline LILRB2, classical MHC I molecules and macrophage markers predict PD response to JTX-8064 in histoculture samples and will be an important component of indication selection in the clinic
• Some tumor samples that do not have a PD response to either JTX-8064 or anti-PD-1 antibodies alone respond to the combination of both agents, suggesting that JTX-8064-mediated LILRB2 inhibition could be a critical component in rescuing responsiveness
• Ex vivo evaluation of human tumors identified hypotheses for both predictive and PD markers that can be evaluated in the clinical development of JTX-8064

The poster is available on the "Our Pipeline" section of the Jounce Therapeutics website at www.jouncetx.com.

About JTX-8064
JTX-8064 is a humanized anti-LILRB2 (ILT4) antibody and is the first tumor-associated macrophage candidate to emerge from Jounce's Translational Science Platform. In addition to today's SITC poster presentation, preclinical data presented at the 2019 American Association for Cancer Research Annual Meeting supports the development of JTX-8064 as a novel immunotherapy to reprogram immune-suppressive macrophages and enhance anti-tumor immunity. A Phase 1 clinical trial for JTX-8064 as a monotherapy and in combination with a PD-1 inhibitor is planned for 2020.

About Jounce Therapeutics
Jounce Therapeutics, Inc. is a clinical-stage immunotherapy company dedicated to transforming the treatment of cancer by developing therapies that enable the immune system to attack tumors and provide long-lasting benefits to patients through a biomarker-driven approach. Jounce currently has multiple development stage programs ongoing while simultaneously advancing additional early-stage assets from its robust discovery engine based on its Translational Science Platform. Jounce's most advanced product candidate, vopratelimab, is a monoclonal antibody that binds to and activates ICOS, and is currently being studied in the SELECT Phase 2 trial. JTX-4014 is a PD-1 inhibitor intended for combination use in the SELECT trial and with Jounce's broader pipeline. Jounce's next development stage product candidate, JTX-8064, is a LILRB2 (ILT4) receptor antagonist shown to reprogram immune-suppressive tumor associated macrophages to an anti-tumor state. A Phase 1 trial evaluating JTX-8064 is planned to begin enrollment in the fourth quarter of 2020. Additionally, Jounce exclusively licensed worldwide rights to JTX-1811, a monoclonal antibody targeting CCR8 and designed to selectively deplete T regulatory cells in the tumor microenvironment, to Gilead Sciences, Inc. For more information, please visit www.jouncetx.com.

Cautionary Note Regarding Forward-Looking Statements
Various statements in this release concerning Jounce's future expectations and plans, including without limitation, Jounce's expectations regarding the timing and initiation of clinical trials of JTX-8064, may constitute forward-looking statements for the purposes of the safe harbor provisions under The Private Securities Litigation Reform Act of 1995 and other federal securities laws and are subject to substantial risks, uncertainties and assumptions. You should not place reliance on these forward-looking statements, which often include words such as "expect," "plan" or similar terms, variations of such terms or the negative of those terms. Although Jounce believes that the expectations reflected in the forward-looking statements are reasonable, Jounce cannot guarantee such outcomes. Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors, including, without limitation, risks that the COVID-19 pandemic may disrupt Jounce's business and/or the global healthcare system more severely than anticipated, which may have the effect of delaying enrollment and completion of Jounce's clinical trials, or delaying timelines or data disclosures and regulatory submissions for its product candidates; Jounce's ability to successfully demonstrate the efficacy and safety of its product candidates; Jounce's ability to successfully manage its clinical trials; the development plans of its product candidates and any companion or complementary diagnostics; management of Jounce's supply chain for the delivery of drug product and materials for use in clinical trials; actions of regulatory agencies, which may affect the initiation, timing and progress of preclinical studies and clinical trials of Jounce's product candidates; and those risks more fully discussed in the section entitled "Risk Factors" in Jounce's most recent Annual Report on Form 10-K filed with the Securities and Exchange Commission as well as discussions of potential risks, uncertainties, and other important factors in Jounce's subsequent filings with the Securities and Exchange Commission. All such statements speak only as of the date made, and Jounce undertakes no obligation to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise.

Investor and Media Contacts:
Mark Yore
+1-857-200-1255
myore@jouncetx.com 

Malin Deon
+1-857-259-3843
mdeon@jouncetx.com