Shanghai and Suzhou, China, May 11, 2026 — Elpiscience announced today that the first patient has been successfully dosed in the Phase II clinical trial of its independently developed first-in-class CD39/TGF-β bispecific antibody, ES014, for the treatment of desmoid tumors. This marks a new and important stage of ES014. The study is being led by Professor Lin Shen of Beijing Cancer Hospital.

Professor Lin Shen, principal investigator from Beijing Cancer Hospital, said: "Desmoid tumors are rare, locally aggressive neoplasms with a high recurrence rate, causing chronic pain and organ dysfunction, often imposing a substantial disease burden and significantly impairing patients’ quality of life. Currently, no drug therapies are approved for desmoid tumors in China. By innovatively blocking two key immunosuppressive pathways, CD39 and TGF-β, ES014 offers a novel therapeutic approach for this disease. Phase I clinical data for ES014 demonstrated promising anti-tumor activity and a favorable safety profile in desmoid tumors. We look forward to further evaluating the efficacy and safety of ES014 in the Phase II study and potentially providing a new treatment option for patients with desmoid tumors."

Dr. Darren Ji, Co-founder and Chief Executive Officer of Elpiscience, commented:  " The successful enrollment of the first patient in the Phase II clinical trial of ES014 represents another key advancement in Elpiscience’s innovation in cancer immunotherapy. Desmoid tumors has long remained an area of significant unmet medical need. We are pleased that our original innovation may offer a precise therapeutic strategy to address this critical clinical challenge. We will fully advance the global clinical development of ES014, aiming to bring a novel and safer treatment option to patients with desmoid tumors as soon as possible. We also remain committed to exploring its potential in additional solid tumors, including non-small cell lung cancer and gastrointestinal stromal tumors."

About ES014

ES014 is Elpiscience's independently developed first-in-class and the first clinical-stage CD39/TGF-β bispecific antibody globally. By simultaneously targeting the CD39-adenosine pathway and the TGF-β pathway, two key immunosuppressive mechanisms in the tumor microenvironment, ES014 can inhibit the production of immunosuppressive adenosine, promote the formation of immunostimulatory adenosine triphosphate (ATP), and neutralize the immunosuppressive cytokine TGF-β. ES014 represents a novel therapeutic strategy for cancer treatment. In February 2026, it received Orphan Drug Designation from the U.S. Food and Drug Administration (FDA).

Phase I clinical data showed that ES014 demonstrated a favorable safety profile, with no dose-limiting toxicities (DLTs) observed and most adverse events being mild. In addition, single-agent anti-tumor activity was observed across multiple solid tumors, including desmoid tumors, non-small cell lung cancer, and gastrointestinal stromal tumors. Notably, encouraging antitumor signals were observed in desmoid tumors, with an objective response rate (ORR) of 40% and a disease control rate (DCR) of 100%.

Elpiscience is currently conducting the Phase II clinical study (Protocol No. ES014-2002), which is designed to evaluate the efficacy, safety, tolerability, patient-reported outcomes, pharmacokinetics, immunogenicity, and pharmacodynamics of ES014 in adult patients with desmoid tumors.

About Desmoid Tumors

Desmoid tumors are rare, locally aggressive neoplasms with a high recurrence rate, causing chronic pain and organ dysfunction, which can lead to chronic pain and organ dysfunction.¹ The clinical course is variable and unpredictable. Although desmoid tumors do not exhibit distant metastasis in biological behavior, they are characterized by significant local infiltrative growth and local recurrence, potentially compressing vital organs and tissues, causing severe pain, functional impairment, nerve damage, and intestinal obstruction or perforation². Despite a relatively low overall mortality rate, the considerable psychological and economic burden, as well as the negative impact on patients' quality of life, should not be overlooked.

In China, there are currently no approved drug therapies for desmoid tumors. Available systemic treatment options mainly include chemotherapy and TKIs, etc. ^1-2 However, none of these agents are approved specifically for desmoid tumors treatment, and high-level evidence-based medical evidence such as large-scale randomized controlled clinical trials or meta-analyse is still lacking.

There remains a significant unmet medical need in desmoid tumors, and patients urgently need more effective and safer treatment options.

References：

[1] The management of desmoid tumours: a joint global consensus-based guideline approach for adult and paediatric patients. European Journal of Cancer, 127, 96-107.

[2] Bektas, M., Bell, T., Khan, S. et al. Desmoid Tumors: A Comprehensive Review. Adv Ther 40, 3697–3722 (2023).