On October 7, 2021 Jounce Therapeutics, Inc. (NASDAQ: JNCE), a clinical-stage company focused on the discovery and development of novel cancer immunotherapies and predictive biomarkers, reported the initiation of patient enrollment in INNATE tumor-specific expansion cohorts for both JTX-8064 monotherapy and combination therapy of JTX-8064 with its internal PD-1 inhibitor, pimivalimab (Press release, Jounce Therapeutics, OCT 7, 2021, View Source [SID1234590942]). JTX-8064, the first tumor-associated macrophage candidate developed from Jounce’s Translational Science Platform, is a humanized IgG4 monoclonal antibody designed to specifically bind to the macrophage receptor Leukocyte Immunoglobulin Like Receptor B2 (LILRB2/ILT4). By inhibiting LILRB2 binding with its ligands, JTX-8064 reprograms immune-suppressive macrophages to an immune-active state in preclinical studies, potentially enhancing the T cell response and anti-tumor immunity.

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"We are very pleased to announce that we have started dosing patients in the tumor-specific JTX-8064 monotherapy and pimivalimab combination expansion cohorts of our INNATE study," said Beth Trehu, M.D., chief medical officer at Jounce Therapeutics. "We have made enormous progress in INNATE, having advanced the study from initiation of monotherapy dose escalation to the opening of tumor-specific, proof-of-concept, combination expansion cohorts in just nine months. This progress has been driven by the continued dedication of our employees, enthusiasm from investigators and, based on the science, our belief that the mechanism of action of JTX-8064 has the potential to address the major emerging unmet need in immuno-oncology, overcoming PD-(L)1 inhibitor resistance. We look forward to sharing updates on our continued execution of the INNATE study."

Proof-of-concept (POC) expansion cohorts in INNATE will address three different segments of IO patient populations; first, patients whose tumors progressed on or after a prior PD-1 or PD-L1 inhibitor (PD-(L)1i) and whose tumors exhibited primary or acquired resistance; second, IO naïve patients with tumors where no PD-(L)1i treatment is approved; and third, IO naïve patients with tumors that have a PD-(L)1i approval. POC expansion cohorts in INNATE follow a Simon’s two-stage design with the potential to enroll up to 29 patients per combination cohort and 47 patients in the monotherapy cohort if pre-specified criteria are met. If POC is established after evaluation of 29 or 47 patients, respectively, Jounce intends to move JTX-8064 rapidly into registrational trials on a cohort by cohort basis. INNATE will also assess pharmacodynamic and potential predictive biomarkers to guide future development, aligning with Jounce’s philosophy of developing the right immunotherapies for the right patients.

The INNATE trial (NCT04669899) is divided into 4 parts:

Part 1: JTX-8064 monotherapy dose escalation in solid tumors (completed July 2021)
Part 2: JTX-8064 + pimivalimab dose escalation in solid tumors (enrollment completed)
Part 3: JTX-8064 monotherapy expansion cohort in 2nd- to 4th-line PD-(L)1i naïve, platinum-resistant ovarian cancer (initiated August 2021)
Part 4: JTX-8064 + pimivalimab in indication-specific expansion cohorts (initiated October 2021)
Combination expansion cohorts include:
2nd- to 3rd-line non-small cell lung cancer that has progressed on or after a PD-(L)1i
2nd-line+ clear cell renal cell carcinoma that has progressed on or after a PD-(L)1i
2nd- to 4th-line triple-negative breast cancer that has progressed on or after a PD-(L)1i
2nd- to 3rd-line cutaneous squamous cell carcinoma that has progressed on or after a PD-(L)1i
1st-line PD-(L)1i naïve, PD-L1+ head and neck squamous cell carcinoma
2nd- to 4th-line PD-(L)1i naïve, platinum-resistant, ovarian cancer
2nd- to 4th-line PD-(L)1i naïve, undifferentiated pleomorphic sarcoma and liposarcoma
About JTX-8064
JTX-8064 is a humanized IgG4 monoclonal antibody designed to specifically bind to Leukocyte Immunoglobulin Like Receptor B2 (LILRB2/ILT4) and block interactions with its ligands. JTX-8064 is the first tumor-associated macrophage candidate developed from Jounce’s Translational Science Platform. Preclinical data presented at the 2020 Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper)’s Annual Meeting and the 2019 and 2021 American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meetings support the development of JTX-8064 as a novel immunotherapy to reprogram immune-suppressive macrophages and enhance anti-tumor immunity. A Phase 1 clinical trial named INNATE (NCT04669899) of JTX-8064 as a monotherapy and in combination with Jounce’s internal anti-PD-1 inhibitor, pimivalimab (formerly JTX-4014) is currently enrolling patients with advanced solid tumors into tumor-specific expansion cohorts.

About Pimivalimab
Pimivalimab (formerly JTX-4014) is a well-characterized fully human IgG4 monoclonal antibody designed to block binding to PD-L1 and PD-L2. Pimivalimab demonstrated a 17% durable overall response rate in a Phase 1 trial of 18 heavily pre-treated PD-(L)1 inhibitor naïve patients, which excluded all tumor types for which PD-(L)1 inhibitors were approved. In this Phase 1 trial, pimivalimab was shown to have an acceptable safety profile. Pimivalimab is currently being assessed in the INNATE Phase 1 trial (NCT04669899) in combination with JTX-8064, a LILRB2 (ILT4) inhibitor. Pimivalimab is also being assessed in the SELECT Phase 2 clinical trial (NCT04549025) in combination with vopratelimab, a clinical-stage monoclonal antibody that binds to and activates ICOS, the Inducible T cell CO-Stimulator, a protein on the surface of certain T cells commonly found in many solid tumors.