Celyad Oncology Presents Data Update from Phase 1 alloSHRINK Trial for CYAD-101 in mCRC at ASCO-GI Symposium

• Median overall survival and median progression free survival from the dose-escalation segment of the trial were 10.6 months and 3.9 months, respectively
• Tumor burden decrease observed in eight of 15 refractory unresectable mCRC patients, including six of nine patients at the highest dose level of 1×10⁹ cells per infusion
• Emergence of new T cell clones in the peripheral blood T cell repertoire four months after therapy was observed in patients analyzed from the highest dose level who experienced either a confirmed partial response or stable disease suggesting that modulation of the endogenous immune response may be an important mechanism of action of CYAD‑101 in mCRC patients
• Preliminary data from the ongoing expansion cohort of the Phase 1 alloSHRINK expected in the first half of 2021

Mont-Saint-Guibert, Belgium – Celyad Oncology SA (Euronext & Nasdaq: CYAD), a clinical-stage biotechnology company focused on the discovery and development of chimeric antigen receptor T cell (CAR T) therapies for cancer, today announced updates from the  Phase 1 alloSHRINK trial evaluating CYAD-101, the Company’s allogeneic NKG2D-receptor and T cell receptor (TCR) inhibitory molecule (TIM)-based, non-gene edited CAR T candidate administered concurrently with FOLFOX chemotherapy for the treatment of refractory metastatic colorectal cancer (mCRC), presented at the American Society of Clinical Oncology 2021 Gastrointestinal Cancers Symposium (ASCO-GI), held virtually from January 15-17, 2021.

“We continue to build on the promise of CYAD-101, a highly differentiated cell therapy investigational candidate which has delivered preliminary evidence of clinical benefit for an allogeneic CAR T in solid tumors,” said Filippo Petti, Chief Executive Officer of Celyad Oncology. “At ASCO-GI, we highlighted the encouraging median progression free-survival data from alloSHRINK which complements the previously reported tolerability, objective response rate for CYAD-101 in patients with mCRC. Moreover, translational data from the trial suggests that immune modulation underpins the clinical responses observed in the alloSHRINK trial and supports further development of CYAD-101 with therapies with complementary mechanisms of action including checkpoint inhibitors. We’re excited about the next steps for the CYAD-101 program for the treatment of advanced colorectal cancer and we look forward to future updates from the alloSHRINK trial as well as initiating the upcoming Phase 1b KEYNOTE-B79 trial.”

Phase 1 alloSHRINK Trial Update

Background

• A total of 15 patients with relapsed/refractory mCRC who progressed after previous treatment with oxaliplatin-based or irinotecan-based chemotherapies were treated in the dose-escalation segment of the alloSHRINK trial evaluating three dose levels of CYAD-101 (1×10⁸, 3×10⁸, 1×10⁹ cells per infusion) administered concurrently with FOLFOX as preconditioning chemotherapy. The number of prior therapies received by patients enrolled in the trial ranged from one to six with a mean of three.
• Previously reported data for primary and secondary safety and clinical activity endpoints include:
• Two patients achieved a confirmed partial response (PR) according to RECIST 1.1 criteria, including one patient with a KRAS-mutation
• Nine patients achieved stable disease (SD), with seven patients demonstrating disease stabilization lasting more than or equal to three months of duration
• Median progression free survival (mPFS) for the dose-escalation segment of the trial was 3.9 months
• No clinical evidence of Graft-versus-Host Disease (GvHD)
• Treatment was observed to be well-tolerated with no treatment-related adverse events greater than Grade 3
• The recommended dose of 1×10⁹ CYAD-101 cells per infusion will be further evaluated in the expansion cohort of the alloSHRINK trial concurrently with FOLFIRI chemotherapy

Updated Clinical and Translational Data

• Recent analysis of the dose-escalation segment of the alloSHRINK trial showed median overall survival (mOS) was 10.6 months
• Tumor burden decrease was observed in eight of 15 patients, including six of nine patients at dose level 3 (1×10⁹ cells per infusion)
• Of four patients treated at the highest dose level of 1×10⁹ CYAD-101 cells per infusion available for analysis, three patients who achieved either a confirmed PR or SD also showed hyper-expanded TCR repertoire post-treatment through the emergence of new T cell clones in the peripheral blood T cell repertoire, while the patient with progressive disease displayed no evidence of new T cell clones
• Cytokine modulation was also observed after the first and second infusions of CYAD-101 in the patient who achieved a confirmed PR from the highest dose level

Next Steps

• Preliminary data from the expansion cohort of the Phase 1 alloSHRINK trial are expected during the first half of 2021
• Initiation of the Phase 1b KEYNOTE-B79 trial of CYAD-101 following FOLFIRI, with Merck’s KEYTRUDA® in refractory mCRC patients with microsatellite stable (MSS) / mismatch-repair proficient (pMMR) disease is expected to be initiated during the first half of 2021