Promising Anti-Tumor Activity and Safety of Ivonescimab in Combination Therapies in CRC, TNBC, and HNSCC Featured at ESMO 2024

Two Oral Presentations Featured Updated Ivonescimab Data from Phase II Studies in CRC and TNBC in Addition to Poster Presentation on HNSCC

Encouraging Phase II Data Supports the Continuing Expansion of the Clinical Development of Ivonescimab Outside of Metastatic Non-Small Cell Lung Cancer

MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) (“Summit,” “we,” or the “Company”) today announced that data for the novel, potential first-in-class investigational bispecific antibody, ivonescimab, was presented at the 2024 European Society for Medical Oncology Annual Meeting (ESMO 2024) in Barcelona, Spain, including two presentations and one poster featuring updated ivonescimab data in advanced triple-negative breast cancer (TNBC), recurrent / metastatic head and neck squamous cell carcinoma (HNSCC), and metastatic microsatellite-stable (MSS) colorectal cancer (CRC). Each trial from which the data was generated was a Phase II study conducted in China sponsored by Akeso Inc. (HKEX Code: 9926.HK) with data generated and analyzed by Akeso.

Based on the results of these Phase II data sets as well as data announced earlier in 2024, including early-stage non-small cell lung cancer and biliary tract cancer, Summit intends to explore further clinical development of ivonescimab in solid tumor settings outside of metastatic non-small cell lung cancer, the Company’s current area of focus in its Phase III clinical trials.

Metastatic MSS Colorectal Cancer

The first oral presentation was presented by Dr. Yanhong Deng, Sun Yat-Sen University. The presentation was entitled, The efficacy and safety of ivonescimab with or without ligufalimab in combination with FOLFOXIRI (chemotherapy) as first-line treatment for metastatic CRC, presenting the current data from AK112-206, included data from this single-region (China), multicenter, open-label, Phase II randomized study of patients with first-line metastatic MSS CRC (NCT05382442).

The study was designed to assess patients who were randomly assigned to receive ivonescimab plus FOLFOXIRI with or without ligufalimab (anti-CD47 monoclonal antibody). Note that ligufalimab, or AK117, is Akeso’s proprietary, investigational product that is not approved by any regulatory authority, and to which Summit does not have any license or ownership rights.

As of February 29, 2024, 22 patients received ivonescimab plus FOLFOXIRI (“Group A” with median follow-up time of 9 months); 18 patients received ivonescimab plus ligufalimab plus FOLFOXIRI (“Group B” with median follow-up time of 9.6 months).

a As of data cutoff, one patient in Group B had not yet had a post-baseline tumor assessment; Group B response and control rates based on n=17.

All patients in both Group A and Group B experienced a reduction in their tumor burden compared to their baseline tumor assessment. The overall response rate and the disease control rate for the 39 patients who had a least one post-baseline tumor assessment was 84.6% and 100%, respectively. Median progression-free survival was not reached in either group at the time of this analysis.

The safety profile in this Phase II study was acceptable and manageable. No patients receiving ivonescimab plus FOLFOXIRI and one patient receiving ivonescimab plus ligufalimab plus FOLFOXIRI permanently discontinued drug treatment due to treatment-related adverse events. The most common TRAEs were anemia, proteinuria, white blood cell count decreases, and neutrophil count decreases in this Phase II data set.

Advanced Triple Negative Breast Cancer

The second oral presentation was presented by Dr. Xiaojia Wang, Zhejiang Cancer Hospital. The presentation was entitled, The safety and efficacy of ivonescimab in combination with chemotherapy as first-line (1L) treatment for triple-negative breast cancer (TNBC), presenting the current data from AK117-203, included data from this single-region (China), multicenter, open-label, Phase II study (NCT05227664).

The results presented were from the portion of the study intended to assess patients who received ivonescimab plus chemotherapy (either paclitaxel or nab-paclitaxel) with locally advanced or metastatic TNBC.

As of May 31, 2024, 30 patients received ivonescimab plus chemotherapy with median follow-up time of 10.2 months. Sixty percent of patients had previously received taxane-based chemotherapy in either the neoadjuvant or adjuvant setting in this Phase II data set.