On October 13, the European Society for Medical Oncology (ESMO 2025) officially announced the results of selected study abstracts. Three clinical studies on chidamide (Epidaza®), a global first-in-class drug from Chipscreen Biosciences, were accepted for presentation. These studies cover relapsed/refractory NK/T-cell lymphoma, advanced sarcoma, and breast cancer. Notably, one of these studies was selected for the Congress's Proffered Paper Session, highlighting the strength of China's original innovation. All three studies focus on the innovative HDAC inhibitor-immunotherapy/chemotherapy strategy, further validating the potential of this combination across multiple tumor types.

Proffered Paper Session

Abstract Number: 1241O

Presenting Expert: Zhang Lei, The First Affiliated Hospital of Zhengzhou University

Presentation Time: October 17, 20:40-20:50 (Beijing Time) / October 17, 14:40-14:50 (Central European Time)

Study Title: PD-1 Inhibitor (Tislelizumab) Combined with Chidamide, Lenalidomide, and Etoposide for Relapsed/Refractory Extranodal NK/T-Cell Lymphoma: Preliminary Results from a Prospective, Multicenter, Single-Arm Phase II Trial

Study Background: Extranodal natural killer/T-cell lymphoma (ENKTL) is a highly aggressive non-Hodgkin lymphoma with a high incidence in Asia. Patients with r/r ENKTL have a poor prognosis and lack effective treatment options. Study Methods: This was a prospective, single-arm, multicenter Phase II clinical trial. It enrolled patients with r/r ENKTL who had failed at least one prior line of therapy. Patients received 6 cycles of treatment with tislelizumab (200 mg, Day 1), chidamide (20 mg, twice weekly), lenalidomide (25 mg, Days 1-10), and etoposide (100 mg/m², Days 1-3), with each cycle lasting 21 days. The primary endpoints were objective response rate (ORR) and progression-free survival (PFS). Enrolled Patients: From June 2020 to March 2024, 33 eligible patients with r/r ENKTL from 5 sites were enrolled. Efficacy and Safety Data: The last follow-up date was July 2024, with a median follow-up time of 20 months. Among the 33 evaluable patients, 27 (81.8%) achieved a response, with 22 (66.7%) achieving a complete response (CR). The 1-year, 2-year, and 3-year PFS rates were 68.9%, 58.3%, and 51.8%, respectively. The median PFS was not reached. The 1-year, 2-year, and 3-year OS rates were 80.9%, 72.7%, and 72.7%, respectively. The median OS was not reached. The most common treatment-related adverse events (TRAEs) were anemia (81.8%), leukopenia (78.8%), neutropenia (75.7%), and thrombocytopenia (60.6%). The most common grade ≥3 TRAE was neutropenia (54.3%). Grade ≥3 immune-related AEs included hypothyroidism and hyperglycemia, with 1 case each. Eight patients died due to ENKTL progression.

Conclusion: Tislelizumab combined with chidamide, lenalidomide, and etoposide demonstrated significant efficacy and favorable safety in treating r/r ENKTL. This therapy shows promising prospects but requires further investigation.

Mini Oral Session

Abstract Number: 2689MO

Presenting Expert: Zhang Xing, Sun Yat-sen University Cancer Center

Presentation Time: October 17, 22:28-22:33 (Beijing Time) / October 17, 16:28-16:33 (Central European Time)

Study Title: A Phase II Clinical Trial of Chidamide Combined with Toripalimab for Advanced Soft Tissue Sarcoma

Study Background: Chidamide is an oral subtype-selective histone deacetylase (HDAC) inhibitor effective in patients with hematological tumors. Chidamide can enhance the efficacy of checkpoint blockade therapy and modulate host immune responses. This report presents the results of a study evaluating the combination of Chidamide and toripalimab in patients with advanced sarcoma. Study Methods: This was an open-label, single-arm, Phase II study. Enrolled patients were allowed to have received any number of prior lines of therapy (excluding prior HDAC inhibitor and immune checkpoint inhibitor treatments). All patients received chidamide (30 mg, orally twice weekly) combined with toripalimab (240 mg, intravenous infusion every 21 days) until disease progression or intolerable toxicity.. Enrolled Patients: As of the data cutoff date (April 30, 2025), 69 patients were enrolled and included in the efficacy analysis. The median age of patients was 47 years (range, 16-68), and the median number of prior lines of therapy was 2 (range, 0-5). Major subtypes included leiomyosarcoma (29%), well-differentiated/dedifferentiated liposarcoma (34.8%), undifferentiated sarcoma (7.2%), myxoid/round cell liposarcoma (5.8%), and osteosarcoma (4.3%). Efficacy and Safety Data: Treatment was well-tolerated. The most common adverse events were primarily grade 1-2, including anemia (55.1%) and hypothyroidism (44.9%). Among grade 3-4 adverse events, the most common were neutropenia (27.5%) and thrombocytopenia (23.2%). Among the 69 efficacy-evaluable patients, the ORR and disease control rate (DCR) were 30.4% and 73.9%, respectively. The median time to initial response was 5 months (95% CI, 3-7). The median PFS was 7.1 months (95% CI, 4.0-10.2). Notably, the ORR in patients with well-differentiated/dedifferentiated liposarcoma was significantly higher than in other patients (62.5%, [15/24] vs. 13.3% [6/45], P<0.001). Compared with other patients, the median PFS was significantly prolonged in patients with well-differentiated/dedifferentiated liposarcoma (17.1 months vs. 3.6 months, P<0.001).

Conclusion: The combination of chidamide and toripalimab (administered in 21-day cycles) was well-tolerated and demonstrated encouraging efficacy in patients with advanced sarcoma, particularly in those with well-differentiated/dedifferentiated liposarcoma.

Poster

Abstract Number: 564P

Presenting Author: Yuan Zhongyu, Sun Yat-sen University Cancer Center

Study Title: A Phase II Clinical Study of PD-1 Antibody Combined with Chidamide in the Treatment of Metastatic Triple-Negative Breast Cancer

Study Background: Due to the high primary resistance in metastatic triple-negative breast cancer (mTNBC), immune checkpoint inhibitors (ICIs) as monotherapy have limited efficacy. Histone deacetylase (HDAC) inhibitors have demonstrated potential in remodeling the tumor immune microenvironment and enhancing immunogenicity. Evidence from other tumor types suggests that combining HDAC inhibitors with ICIs can improve anti-tumor efficacy with manageable safety. Based on these findings, this study aimed to investigate the efficacy and safety of the selective HDAC inhibitor chidamide combined with a PD-1 inhibitor in patients with mTNBC who had failed prior systemic therapies. Study Methods: SYSUCC-019 is a single-arm Phase II clinical trial enrolling patients with 1-7 prior lines of therapy and measurable lesions. Treatment continued until disease progression or intolerable toxicity. The primary endpoint was objective response rate (ORR); secondary endpoints included clinical benefit rate (CBR), progression-free survival (PFS), overall survival (OS), and safety (NCI-CTCAE v5.0). Exploratory biomarker analysis involved peripheral blood immune profiling (using xCell algorithm) and tumor microenvironment characterization. Enrolled Patients: Forty-one female patients with mTNBC were enrolled and treated. Efficacy and Safety Data: In the overall population, 3 patients achieved complete response (CR), 5 achieved partial response (PR), 6 had stable disease (SD), and 27 experienced progressive disease (PD). The ORR was 19.5% (95% CI, 9.0%–34.0%). The median PFS was 7.0 months and the median OS was 18.4 months in patients who achieved disease control. As of the data cutoff date (April 22, 2025), the median follow-up was 10.28 months, with 5 patients still on treatment. The most frequently reported adverse events of any grade included anemia, neutropenia, and thrombocytopenia. Pre-treatment immune profiling showed that baseline CD8+ T-cell counts were higher in patients who achieved disease control.

Conclusion: Chidamide combined with a PD-1 inhibitor demonstrated significant anti-tumor activity and manageable safety in patients with mTNBC, with baseline CD8+ T-cell levels showing promise as a potential predictive biomarker.

The ESMO Congress will be held from October 17 to 21 in Berlin, Germany. As one of the world's most influential oncology academic conferences, it brings together clinicians and researchers from around the globe to share the latest advances in cancer treatment. According to statistics, a total of 35 studies from Chinese scholars were selected for oral presentations. Chidamide has received significant recognition in both hematological malignancies and solid tumors, once again highlighting the cross-tumor application potential of the HDACi + IO/chemotherapy strategy. The study on relapsed/refractory extranodal NK/T-cell lymphoma (r/r ENKTL), as one of only two breakthrough studies from China selected for the Proffered Paper Session in the hematological oncology field at ESMO, will be presented alongside top-tier research from Europe and the United States. As the world's first subtype-selective HDAC inhibitor, chidamide, leveraging its unique epigenetic regulatory mechanism, can reactivate the tumor immune microenvironment. It demonstrates broad prospects in areas such as HDACi+IO, either alone or in combination with other drugs for treating malignancies, offering patients new therapeutic directions.