Promising Data for Investigational Innovative Bispecific Ivonescimab Featured at ASCO 2023

Summit Therapeutics Inc. (NASDAQ: SMMT) (“Summit,” “we,” or the “Company”) today announced promising data for its novel, potential first-in-class investigational bispecific antibody, ivonescimab, that is being presented today from 8:00 to 11:00am at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, IL.

AK112-201 (NCT04736823) is an open-label Phase II study evaluating ivonescimab plus chemotherapy for 174 patents across three cohorts of patients. The poster features data from 135 patients in Cohort 1 of this study: patients who are treatment-naïve with advanced or metastatic non-small cell lung cancer (NSCLC) whose tumors do not have actionable genomic alterations (i.e., patients’ tumors do not have actionable mutations in endothelial growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK)).

Notably, this Phase II data set summarizes results to date from 63 patients with squamous histology. These patients experienced a median progression-free survival (PFS) of 11.0 months (95% CI: 9.5 to 16.8 months) and an overall response rate (ORR) of 67% (95% CI: 53% to 78%). After a median follow-up time of 13.3 months, median overall survival (OS) was not reached; although, estimated 9-month OS was 93.2%. The frequency of Grade ≥3 treatment-related adverse events (TRAEs) was 41%. The most frequent treatment-emergent adverse events were anemia, decreased neutrophil counts, and alopecia.

Summit has begun clinical development activities on the Phase III HARMONi-3 study, which intends to evaluate ivonescimab combined with chemotherapy in first-line metastatic squamous NSCLC patients. Summit intends to treat patients in the HARMONi-3 trial during the second half of 2023.

The poster is being presented by Dr. Li Zhang, Sun Yat-Sen University Cancer Center,¹ with data generated and analyzed by our collaboration and licensing partner, Akeso, Inc. (HKEX Code: 9926.HK).

In addition to the patients with squamous histology described above, Cohort 1 includes updated data from 72 patients with non-squamous histology. Median PFS experienced by these patients was 12.3 months (95% CI: 8.3 to 19.3 months) and median overall survival was not reached after 13.3 months of median follow-up time. The frequency of Grade ≥3 TRAEs was 19%. The most frequent treatment-emergent adverse events were anemia, decreased neutrophil counts and constipation.