Promontory Therapeutics Announces Early Phase 2 Clinical Trial Data From the National Cancer Institute, Demonstrating PT-112's Immune Activation in Thymic Epithelial Tumors

• Clinical activity was demonstrated in 9 of 11 (81%) evaluable patients

• Immune activation by PT-112 monotherapy observed in peripheral blood sampling crosses both adaptive and innate anti-cancer immune cell types

• Interim data presented in an oral presentation at the ITMIG2023 Annual Meeting at New York's Memorial Sloan Kettering Cancer Center

NEW YORK, Oct. 5, 2023 /PRNewswire/ -- The National Cancer Institute (NCI), part of the National Institutes of Health, under formal collaboration with Promontory Therapeutics Inc., a clinical stage pharmaceutical company advancing immunogenic small molecule approaches in oncology, today presented preliminary results from the Phase 2 clinical trial of Promontory's lead therapeutic candidate, PT-112, in patients with recurrent thymic epithelial tumors (TETs).

During an oral presentation at the International Thymic Malignancy Interest Group (ITMIG) 2023 Annual Meeting, Arun Rajan, MD, Principal Investigator at the NCI, highlighted PT-112's encouraging clinical activity, including evidence of immune activation. PT-112's safety profile also excluded new immune-related adverse events, which constitute a risk to the use of other immunotherapy approaches in TETs, rare cancers with no FDA approved drug. The ITMIG2023 Annual Meeting is taking place October 4-6, 2023 at Memorial Sloan Kettering Cancer Center in New York.

"In a previous Phase 1 clinical trial, PT-112 showed strong safety and durable clinical activity in patients with thymoma, a type of TET, which provided us with the confidence to move into Phase 2 in collaboration with the NCI," said Promontory Therapeutics Chief Medical Officer Johan Baeck, MD. "There is a clear need to develop treatments for patients with recurring TETs, for which there are currently no approved drugs. In this ongoing Phase 2 study, PT-112 has demonstrated promising clinical activity in patients with TETs. Our immune analyses showed evidence of immune activation—a key mechanism of PT-112 in the fight against cancer cells. These early results certainly support further evaluation."

PT-112 induces immunogenic cell death and stimulates an anti-cancer adaptive immune response. The ongoing Phase 2 clinical trial for thymic epithelial tumors (NCT05104736) is examining the response rate in patients with disease progression after prior platinum-based treatments or immune checkpoint inhibitors failed to achieve results. Patients have been administered PT-112 on days 1, 8, and 15 of a 28-day cycle, whereby researchers then analyzed the effects of PT-112 on the immune system and the tumor microenvironment.

Additional preliminary results include:

• Out of a total of eleven patients evaluable for response, one (9%) achieved a partial response, eight achieved stable disease (73%) and two had progressive disease (18%).
• No new immune-related AEs have been observed.
• Findings in peripheral blood included an increase in activated T cells, NK cells, and pro-inflammatory cytokines, and a decrease in immunosuppressive serum analytes.

For more information about Promontory's clinical trials, visit www.PromontoryTx.com.

About PT-112
PT-112 is the first small-molecule conjugate of pyrophosphate in clinical development in oncology. PT-112 has numerous advantages — including its tolerability and inhibition of ribosomal biogenesis (RiBi) which leads to immunogenic cell death (ICD), through the release of damage associated molecular patterns (DAMPs) that bind to dendritic cells and lead to downstream immune effector cell recruitment in the tumor microenvironment. PT-112 represents a highly potent inducer of this immunological form of cancer cell death. Further, PT-112 harbors a property known as osteotropism, or the propensity of the drug to reach its highest concentrations in certain areas of the bone, making it a candidate for treatment of patients with cancers that originate in, or metastasize to, the bone. The first in-human study of PT-112 demonstrated an attractive safety profile and evidence of long-lasting responses among heavily pre-treated patients and data were published in eClinicalMedicine, part of The Lancet.  The combination Phase 1b dose escalation study of PT-112 with PD-L1 checkpoint inhibitor avelumab in solid tumors was reported in a mini-oral presentation at the ESMO 2020 Virtual Congress and the Phase 2a dose confirmation cohort in non-small cell lung cancer (NSCLC) patients was reported at ESMO I-O 2022. The Phase 1 study in patients with relapsed or refractory multiple myeloma presented at ASH 2020 is the third completed Phase 1 study of PT-112. Monotherapy Phase 2 development is ongoing in mCRPC, and includes the Phase 2 proof of concept study in thymic epithelial tumors under the company's formal CRADA with the NCI. Interim data from the NCI study were published at ASCO 2023.

About Promontory Therapeutics
Promontory Therapeutics Inc. is a privately held, clinical stage drug development company focused on small molecule immunotherapy in cancer. Clinical data generated across three Phase 1 studies of lead molecule PT-112 have demonstrated single-agent and combination anti-cancer activity and an attractive tolerability profile. The Company's lead Phase 2 study in late-stage metastatic castration-resistant prostate cancer patients is underway in the United States and France. The company applies a borderless collaboration model for research and development work, which has been conducted in the United States, Europe and Asia. As part of its recent expansion into France, Promontory was selected as the first international company member of the Paris-Saclay Cancer Cluster, Europe's emerging biotech hub for oncology. The company also has an active Phase 2 trial underway with the National Cancer Institute (NCI) utilizing PT-112 in thymic epithelial tumors (TETs), a rare disease with no FDA approved drug, for which PT-112 has received FDA Orphan Drug designation.

To learn more about Promontory Therapeutics, visit the company's website here.

CONTACTS:

Promontory Therapeutics
Brooke Raphael, MS
VP, Strategy & Operations
Tel: +1 (646) 974-6453
Email: [email protected]

Investors: 
Stan Musial
Tel: +1 (646) 222-6932
Email: [email protected]

ICR Westwicke

Media: 
Alexis Feinberg
Tel: +1 (203) 939-2225
Email: [email protected]

SOURCE Promontory Therapeutics Inc.