SOUTH SAN FRANCISCO, Calif. (Sept. 9, 2026) – Apeximmune Therapeutics, Inc., an IND-stage immuno-oncology company, today announced the publication of research in Nature validating PLA2G2D as a novel and mechanistically distinct immune checkpoint capable of addressing resistance to anti-PD-1 therapy. The publication represents the convergence of two independent
research programs – one led by Apeximmune, the other by researchers at Erasmus University Medical Center (Erasmus MC) in Rotterdam, the Netherlands – that arrived at the same target using fundamentally different scientific approaches.
Anti-PD-1 therapies have transformed the treatment of certain cancers, but the majority of patients across indications either fail to respond or eventually relapse. Response rates fall to single digits in gastrointestinal cancers and other tumor types. Overcoming this resistance remains one of the most significant unmet needs in oncology.[1]
Two paths, one target. Apeximmune and Erasmus MC reached phospholipase A2 group IID (PLA2G2D) by markedly different routes. Apeximmune's team, led by founder and CEO, Li-Fen Lee, PhD, applied a proprietary bioinformatics algorithm to more than 9,000 primary tumor samples from The Cancer Genome Atlas (TCGA), surfacing 70 candidate novel immune checkpoints. PLA2G2D
emerged as the top-ranked hit, well ahead of known checkpoints PD-1 and CTLA-4 in the same analysis.
Erasmus MC, working in parallel and unaware of Apeximmune's program, applied a spatial proteogenomic approach to melanoma patient samples from individuals who had divergent clinical outcomes. Their analysis independently identified PLA2G2D as a top hit in the dendritic cell and macrophage populations interacting with CD8+ T cells in patients with worse outcomes.
A mechanism the field had overlooked. Beyond identifying the target, the Apeximmune team uncovered a mechanism that had eluded prior investigators. PLA2G2D has long been characterized for its phospholipase activity, and previous efforts to drug the broader sPLA2 family, including terminated late-stage small-molecule programs for inflammation from major pharmaceutical
companies, had assumed its enzymatic function was central to its biology. Apeximmune demonstrated that an enzyme-dead form of PLA2G2D retains potent immunosuppressive activity, establishing that the molecule's role in tumor immune evasion is independent of its enzymatic activity.
Preclinical data suggest a dual therapeutic opportunity. Data reported in the Nature publication indicate that PD-1 and PLA2G2D are nonredundant and reciprocally regulated. More importantly, blockade of PLA2G2D not only restores anti-tumor immunity in preclinical models resistant to anti-PD-1 therapy but also potentiates the activity of anti-PD-1 in tumor types that are otherwise unresponsive to checkpoint inhibition. Together, the Nature findings on PLA2G2D point to two potential paths for patient benefit: a new therapeutic option for patients who have failed anti-PD-1 therapy, and a way to extend the reach of anti-PD-1 into tumors currently considered “cold.”
Apeximmune built an antibody against PLA2G2D. AI-306, the company's lead product candidate, is a first-in-class monoclonal antibody that blocks both the enzymatic and non-enzymatic activity of PLA2G2D. Backed by key patents covering target antagonism, antibody constructs, and combination therapies, AI-306 is currently in IND-enabling development with cell line development underway. GLP toxicology studies are scheduled to initiate in late 2026, and an IND filing is targeted for the second quarter of 2027. Apeximmune has developed proprietary PLA2G2D knockout and humanized mouse models that support the program.
Quotes:
Li-Fen Lee, PhD, founder and CEO of Apeximmune. “For nearly a decade, we have pursued PLA2G2D based on a conviction that the field was overlooking a fundamentally different kind of immune checkpoint. The independent identification of the same target by the Erasmus team, using entirely different methods and starting from patient samples rather than computational discovery, is the strongest possible validation of the underlying biology. What matters most is what this means for patients: a potential new therapeutic path for the majority who do not respond to anti-PD-1, and possibly a way to make PD-1 therapy work in tumor types where it currently cannot.”
Floris Dammeijer, MD, PhD, Erasmus MC. “When we began this work, we were asking a straightforward question: how do cancer cells block effective anti-tumor immune responses where they are first generated, in the lymph node? The answer, unexpectedly, kept pointing to PLA2G2D.”
Ralph Stadhouders, PhD, Erasmus MC. “Discovering that a team at Apeximmune had independently reached the same target, from an entirely different starting point, was extraordinary. The collaboration that followed has produced a body of evidence neither group could have generated alone."
Dan Ross, managing partner at BioPharma Capital and advisor to Apeximmune. “This publication marks an inflection point for Apeximmune and the AI-306 program. We are actively engaging with partners who share our commitment to bringing this therapy to patients as quickly as possible.”
About Apeximmune Therapeutics, Inc.: Apeximmune Therapeutics, Inc. is an IND-stage biotechnology company in South San Francisco, Calif., focused on developing novel immunotherapies for patients who do not respond to existing immune checkpoint inhibitors. Founded by Li-Fen Lee, PhD, the company applies proprietary computational target discovery to identify mechanistically distinct immune checkpoints with the potential to expand the reach of immuno-oncology. For more
information, visit www.apeximmune.com.
Nature Publication: “PLA2G2D in tumour-draining lymph nodes regulates anti-tumour immunity.” Nature. Sept. 9, 2026. DOI: 10.1038/s41586-026-10954-1. Anneloes van Krimpen, Julie Huang, Mike Eterman, Vivian Gerretsen, Michihisa Umetani, Josephine C. Janssen, Menno van Nimwegen, Nina Rozendaal, Thierry P. P. van den Bosch, Xinguo Jiang, Kathryn Logronio, Angela Z. Liu, Yun-Ru Liu, Yuki Nagasaki, Makoto Murakami, Anne Onrust-Van Schoonhoven, Asabi Leliveld, Disha Vadgama, Hedwig Langeveld, Rogier van Wijck, Eric Bindels, Jan von der Thüsen, Antien Mooyaart, Febe van Maldegem, Claudia M. Brenis, Stijn Verwaerde, Rudi W. Hendriks, Bart N. Lambrecht, Dirk J. Grünhagen, Cornelis Verhoef, Joachim G. J. V. Aerts, Li-Fen Lee, Kan V. Lu, Ralph Stadhouders, Floris Dammeijer.
Forward-Looking Statements: This press release contains forward-looking statements, including statements regarding the development of AI-306, anticipated regulatory milestones including the timing of the IND filing, and the potential clinical and commercial opportunity for PLA2G2D-directed therapy. Actual results may differ materially from those expressed or implied by these statements as a result of various factors, including the risks inherent in preclinical and clinical drug development. Apeximmune undertakes no obligation to update these statements.
Media Contact: Liz Wilkins, Capwell Communications, +1 562-233-1263, media@capwellcomm.com
Company Contact: Li-Fen Lee, PhD, founder and CEO, Apeximmune Therapeutics, Inc., llee@apeximmune.com
Strategic Partnering Contact: Dan Ross, managing partner at BioPharma Capital,dan@biopharmacapital.com
FOR IMMEDIATE RELEASE
Apeximmune Therapeutics Announces Successful Close of Series A Fundraising Round to Advance Next-Generation Immunotherapies
Burlingame, CA – March 31, 2025 – Apeximmune Therapeutics, a biotechnology company pioneering next-generation immunotherapies, today announced the successful close of its Series A financing round, raising $21.3 million, exceeding its original goal of $20 million. The funding was led by PharmaEssentia Corporation, with participation from DCI Partners, Taya Venture Capital, KDI Marketing, Huahai US, Hercules BioVenture LP, and TTM 2025 LLC. We are thrilled to share that Judy Swanson invested with TTM 2025 LLC as part of the round. Judy, whose late husband Robert A. Swanson co-founded Genentech and was a pioneering force in biotechnology, has long been an advocate for advancing cancer research.
The proceeds from this round will focus on accelerating the development of Apeximmune's lead candidate, AI-306, through IND and into clinical trials. AI-306 is a first-in-class antagonist monoclonal antibody designed to reverse the immune suppressive functions of AIM-103 to reinvigorate anti-tumor T cell immunity. AIM-103 is a novel target discovered by Apeximmune's proprietary discovery and validation platform that is highly expressed in the most devastating gastrointestinal cancers such as pancreatic, liver, colon, and esophageal cancers. Apeximmune has discovered that AIM-103 controls both the innate and adaptive immune systems. Additionally, the company has developed several novel bispecific macrophage engagers utilizing proven formats. The company plans to advance its lead candidate into clinical trials, expand its research and development capabilities, and further strengthen its scientific and executive teams.
“We are thrilled to have the support of such a strong group of investors who share our vision for transforming immunotherapy,” said Dr. Li-Fen Lee, CEO of Apeximmune Therapeutics. “This funding marks a significant milestone in our journey to develop groundbreaking therapies that have the potential to improve patient outcomes in oncology and autoimmune diseases.”
Apeximmune is pioneering a new generation of therapeutic antibodies and biologics, which have demonstrated promising preclinical results in enhancing immune response and targeting disease-specific mechanisms. The Series A funding will enable the company to move closer to clinical validation and bring its innovative treatments to patients in need.
“Immunotherapy continues to be one of the most promising frontiers in medicine, and Apeximmune’s cutting-edge science has the potential to make a significant impact,” said Lih-Ling Lin, CSO of PharmaEssentia Corporation. “We are excited to support the company as it advances its lead programs and builds a strong foundation for future success.”
“We believe AI-306 could have the potential to become another blockbuster that significantly contributes to cancer treatment,” said Hiroki Narita, the CEO of DCI Partners. “Our team is thrilled to support the company’s journey to success and look forward to its growth and innovation ahead.”
With this funding, Apeximmune is well-positioned to accelerate its mission of redefining immunotherapy and addressing unmet medical needs. The company will continue to explore strategic collaborations and partnerships to further expand its impact in the biotechnology sector.
For more information, please visit apeximmune.com or contact Gary Kiang at gkiang@apeximmune.com.
About Apeximmune Therapeutics
Apeximmune Therapeutics is a biotechnology company focused on developing next-generation immunotherapies for cancer and autoimmune diseases. By leveraging cutting-edge science and a deep understanding of immune mechanisms, the company aims to deliver transformative treatments that improve patient outcomes.
Media Contact:info@apeximmune.com
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Apeximmune Therapeutics Awarded $400,000 NIH-SBIR (Small Business Innovation Research) grant to Advance First-in-Class Immunotherapy Targeting AIM-103 in Cancer
Burlingame, CA — June 1, 2023 — Apeximmune Therapeutics, a pre-clinical-stage biotechnology company developing next-generation immunotherapies for treatment-resistant cancers, today announced it has been awarded a $400,000 grant from the National Institutes of Health (NIH) Small Business Innovation Research (SBIR) program. The funding will support the development of AI-306, a novel therapeutic designed to target AIM-103, a newly identified immune checkpoint protein implicated in some of the world’s most lethal cancers.
AIM-103 is highly expressed in multiple cancer types but most importantly in pancreatic, liver, colon, stomach, and esophageal cancers, tumor types known for their aggressive nature and resistance to standard immunotherapies. AI-306 is the first drug candidate developed to specifically inhibit this target, aiming to restore immune recognition and destruction of these hard-to-treat tumors .
About Apeximmune Therapeutics
Apeximmune Therapeutics is developing breakthrough immunotherapies designed to overcome immune resistance in cancer. The company’s proprietary platform targets novel immune escape mechanisms across high-mortality tumors, with a pipeline led by AI-306, a first-in-class therapeutic targeting the newly discovered checkpoint protein AIM-103.
Media Contact:info@apeximmune.com
apeximmune.com