Non-clinical evidence supporting the upcoming CLD-201 clinical trial: Cell-based oncolytic virotherapy for multiple solid tumors.
Authors: Nguyen Duong , Minev Ivelina , Songco Stephanie , Alamillo Ashley , Neuharth Forrest , Alemu Selamawit Worku , Schneider Laura Edith , Kleinholz Daniela , Kang Yunyi , Sy-Quia Ana , Smith Trevor , Seikkula Matthew , Minev Boris , Herrmann Thomas , Santidrian Antonio F. 
Published: June 2024

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Background: Oncolytic virotherapy is a promising approach that uses viruses to target and destroy cancer cells while activating an anti-tumor immune response. However, a major challenge is the rapid elimination of oncolytic viruses (OVs) by the patient’s immune system. Calidi’s innovative platform addresses this issue by combining allogeneic stem cells with an OV payload, preventing immune system elimination, and promoting viral amplification at tumor sites. This induces immunogenic cell death and stimulates potent anti-tumor immune responses, effectively targeting primary and metastatic tumors. Prior clinical studies have demonstrated the effectiveness of autologous stem cells loaded with Vaccinia virus CAL1 (ACAM2000) in multiple tumor types, especially when combined with checkpoint inhibitors. However, this approach is costly, lacks scalability and reproducibility. To overcome those limitations, we developed CLD-201 (or SuperNova-1), an innovative concept based on CAL1-loaded allogeneic mesenchymal stem cells, specifically designed for intratumoral administration. This study presents selected non-clinical studies performed to support the upcoming clinical trial to treat multiple solid tumors. Methods: We tested the tumor selectivity and efficacy of CLD-201 in Melanoma, Triple Negative Breast Cancer, and Squamous Cell Carcinoma. We also assessed its ability to kill cancer cells in the presence of complement and neutralizing antibodies. Immune cell infiltration in treated and untreated tumors was analyzed using flow cytometry. We conducted dose escalation, safety, toxicology, and biodistribution studies of CLD-201 in multiple immune-compromised and immunocompetent mouse models. Results: Vaccinia virus CAL1 showed preferential amplification in tumor cells and, when loaded into adipose stem cells (CLD-201), demonstrated greater resistance to inactivation by the humoral immune system compared to the unprotected CAL1 virus. CLD-201 significantly inhibited the growth of tumors even at a very low dose of 1.5x103 cells containing 1.6x104viral plaque-forming units (PFU). Massive CD4 and CD8 T-cell infiltrations were detected in both treated and untreated tumors. CLD-201’s safety profile is studied in both GLP and non-GLP toxicology/ biodistribution nonclinical studies. Conclusions: CLD-201 offers several important advantages over the autologous approach, including enhanced potency through significant viral amplification within the stem cells, improved manufacturing reproducibility, off-the-shelf ability to treat multiple cancer types, and significantly lower cost. Non-clinical studies revealed that both intratumoral and systemic administration were well-tolerated. A phase I non-randomized clinical trial has been designed to evaluate the safety and initial anti-tumor effects of intratumoral administration of CLD-201.