The combination of intratumoral sotigalimab and systemic pembrolizumab was well-tolerated and demonstrated an improved clinical response rate relative to the standard of care, pembrolizumab monotherapy-

-Activation of antigen-presenting cells stimulated broad innate and adaptive anti-tumor responses in both local as well as distant tumor lesions-

SAN CARLOS, CA, USA I November 11, 2022 I Apexigen, Inc. (NASDAQ: APGN) a clinical-stage company focused on developing innovative antibody-based therapeutics for the treatment of cancer with a focus on immuno-oncology, today announced new data from an ongoing Phase 2 investigator-sponsored trial evaluating intratumoral sotigalimab (sotiga), Apexigen’s CD40 agonist antibody, in combination with systemic pembrolizumab (anti-PD-1 antibody) in first-line metastatic melanoma. Results showed that the combination therapy was well-tolerated in the trial and an improved best overall response rate (ORR) was observed relative to the standard of care, pembrolizumab monotherapy. Broad innate and adaptive immune activation was observed in both local and distant (non-injected) lesions. The data were featured in an oral presentation at the Society for Immunotherapy of Cancer’s (SITC) 37th Annual Meeting, taking place in Boston, Massachusetts from November 8-12, 2022.

“While checkpoint inhibitors are the current standard of care for metastatic melanoma, many patients are unresponsive or develop resistance after initial tumor regression,” said Adi Diab, M.D., Associate Professor of Melanoma Medical Oncology at The University of Texas MD Anderson Cancer Center and Principal Investigator of the study. “Results from the ongoing Phase 2 trial of intratumoral sotigalimab and the PD-1 inhibitor pembrolizumab showed a promising ORR including responses achieved in PD-L1 negative tumors. Moreover, this encouraging anti-tumor activity correlated with treatment-induced immunologic changes, such as activated myeloid dendritic cells and macrophages, which support the mechanism of action and differentiated activity of sotigalimab – ultimately leading to inflammatory immune responses in the local injected tumor as well as distant non-injected lesions.”

Frank Hsu, M.D., Chief Medical Officer of Apexigen commented, “We are encouraged by the emerging data that suggest sotiga-based combinations may address the need for improved treatments for advanced and metastatic melanoma patients, bringing us one step closer to paving the way for novel strategies to optimize anti-tumor immune responses and improve clinical benefits. The intratumoral administration of sotiga further validates its ability to turn an inflammatory ‘cold’ tumor to one that is ‘hot and demonstrates the induction/expansion of T-cell clones in both the injected and distal tumors – indicating a systemic effect and the possible expansion of the repertoire of antitumor responses. This encouraging work indicates that sotiga may be an effective and well-tolerated method of in situ vaccination that can lead to improved clinical benefit for patients with cancer.”

Key data and conclusions featured in the SITC presentation include:

  • Safety and tolerability: Intratumoral administration of sotiga in combination with pembrolizumab was well-tolerated. The most common adverse events were injection site reactions. Grade 3 immune-related adverse events were observed at a frequency similar to that reported with anti-PD-1 therapy alone. There were no dose limiting toxicities and no discontinuations or deaths due to treatment-related events. No immunosuppressive therapy was needed.
  • Efficacy: The objective response rate (ORR) was 47% (n=32) in all patients, including patients enrolled in the dose escalation portion of the trial. At the recommended Phase 2 dose of sotiga the ORR was 50% (n=24), which compares favorably to standard of care of pembrolizumab alone (34%). Clinical responses were achieved in both PD-L1 negative tumors and patients with elevated LDH
  • Immune Priming: Effects included rapid increases in activated macrophages and dendritic cells and an early upregulation of genes associated with antigen-presenting cells 24 hours post sotiga administration followed by T-cells activation and expansion in the tumor microenvironment (TME) in local and distant tumor sites.
  • Immune changes in the TME correlate with clinical response: Post treatment analyses revealed increases in activated macrophages, dendritic cells and CD8+ T-cells correlated with clinical response.

Details of the SITC presentation and its corresponding abstract are as follows:

  • Presentation Title: Intratumoral sotigalimab with pembrolizumab activates antigen-presenting cells and induces local and distant anti-tumor responses in first-line metastatic melanoma: Results of a phase I/II study
  • Presentation number: 782
  • Presenter: Salah-Eddine Bentebibel, Ph.D., MD Anderson

About Apexigen

Apexigen is a clinical-stage biopharmaceutical company focused on discovering and developing a new generation of antibody therapeutics for oncology, with an emphasis on new immuno-oncology agents designed to harness the patient’s immune system to combat and eradicate cancer. Sotigalimab and Apexigen’s other programs were discovered using Apexigen’s proprietary APXiMAB™ discovery platform. This platform has enabled Apexigen and its collaboration partners to discover and develop therapeutic antibodies against a variety of molecular targets, including targets that are difficult to drug with conventional antibody technologies. Multiple product candidates have been discovered using the APXiMAB platform, one of which is commercially available and the others are in clinical development, either internally by Apexigen or by its licensees. For more information, please visit www.apexigen.com.

SOURCE: Apexigen