The 2024 ASCO Breakthrough Summit, hosted by the American Society of Clinical Oncology (ASCO), was held in Yokohama, Japan, from August 8 to 10. This annual scientific conference, themed "Shining a Light on Advances in Cancer Care," aimed to gather leaders and innovators in the field of oncology to discuss and share the latest research findings and technological innovations. At this year's ASCO Breakthrough meeting, an abstract submitted by Escugen in collaboration with Professor Ma Fei from the Cancer Hospital of the Chinese Academy of Medical Sciences was presented in poster form. Encouragingly, the abstract received high praise from the conference and was awarded the Abstract Award.

Updated Efficacy of Anti-TROP2 ADC ESG401 for First-Line Metastatic TNBC in Phase Ib Study

Abstract Number 2: Updated Efficacy of Anti-TROP2 ADC ESG401 for First-Line Metastatic TNBC in Phase Ib Study

As of June 12, 2024, 28 patients in the first-line treatment cohort for metastatic triple-negative breast cancer (mTNBC) had received at least one dose of ESG401. The longest duration of treatment was 12.5 months for one patient, who is still receiving treatment; the median duration of response (DOR) and progression-free survival (PFS) have not yet been reached.

Key results of the study are as follows:

•Among the 22 evaluable subjects, the objective response rate (ORR) reached 86%, with 1 patient (5%) achieving complete response (CR); the disease control rate (DCR) was 100%. In the ESG401-101 study, first-line treatment for mTNBC patients was monotherapy with ESG401, whereas in the BEGONIA cohort 7, the treatment for the same indication was a combination of TROP2 ADC and PD-L1 inhibitor. The ORR in this study numerically exceeded the results reported in the BEGONIA cohort 7.

•In patients who achieved objective response, durable efficacy of ESG401 was observed, with median DOR and median PFS not yet reached; the 6-month DOR rate was 65.6% (95% CI: 26.0, 87.6), and the 9-month PFS rate was 73.3% (95% CI: 37.9, 90.6).

•In the Phase Ia/Ib trial, a total of 16 patients with brain metastases were enrolled. The intracranial objective response rate (IC-ORR) in these patients reached 31%, and the intracranial disease control rate (IC-DCR) was 75%. Meanwhile, the overall ORR in these patients was as high as 50%, with a DCR of 69%. The results suggest that the response of intracranial metastatic lesions in these patients is consistent with the response of systemic tumor lesions.

•In the first-line treatment cohort for mTNBC, 3 patients with brain metastases were enrolled. Among them, 1 patient achieved intracranial complete response (IC-CR), with an overall target lesion response assessment of PR. The intracranial metastatic lesions of the other two patients both achieved partial response (IC-PR), with reductions of 74.1% and 33.3%, respectively.

•In terms of safety, the safety profile of ESG401 in this cohort study was consistent with previously reported data, with no new or unexpected safety signals detected.

Professor Ma Fei from the Cancer Hospital of the Chinese Academy of Medical Sciences, the national principal investigator of this study, said: "I am delighted to share our latest research data with global peers at this year's ASCO Breakthrough meeting. TNBC is known for its high aggressiveness and malignancy, and the current treatment options are relatively limited, leading to low cure rates and poor prognosis. The results of this study demonstrate that ESG401, as a first-line treatment for metastatic TNBC patients, has significant antitumor activity, durable tumor response, and good safety. We believe that ESG401 can meet the urgent treatment needs of these patients and bring them new hope."

Dr. Xiaoyan Xing, Chief Medical Officer of Escugen Biotechnology, said: "The recognition of the research results of ESG401 with the Abstract Award at this year's ASCO Breakthrough meeting represents the high recognition from international academic peers. I am honored to present our research results on behalf of the research team led by Professor Ma Fei at the ASCO Breakthrough meeting and to receive the award for this study abstract. We have observed that ESG401 monotherapy has shown encouraging antitumor activity, high response rates, and durable efficacy in the first-line treatment of metastatic TNBC patients. These research results motivate us to further accelerate the development process of ESG401, and we look forward to this highly promising therapeutic drug benefiting Chinese patients as soon as possible. Escugen Biotechnology will continue to work hard to bring more innovative therapies to global patients, committed to improving the quality and effectiveness of cancer treatment and bringing new hope and more treatment options to cancer patients."