FDA Fast Track for CLD-201: Stem Cell–Based Oncolytic Virus for Soft Tissue Sarcoma

July 29, 2025 | SAN DIEGO — Calidi Biotherapeutics has received Fast Track designation from the U.S. FDA for CLD-201 (SuperNova), its allogeneic adipose stem-cell loaded oncolytic virus, for the treatment of soft tissue sarcoma. The designation comes on the heels of FDA IND clearance earlier this year and underscores the urgent need for innovation in rare and aggressive tumors like sarcoma.

What does Fast Track mean for CLD-201?

The FDA’s Fast Track program is designed to accelerate the development and regulatory review of investigational drugs that target serious or life-threatening conditions, particularly those with limited existing treatment options. This designation provides Calidi with more frequent meetings and communications with the FDA throughout the clinical development process.

Additionally, it opens the door to Priority Review and Accelerated Approval, especially if early clinical data suggest that CLD-201 could be effective based on surrogate endpoints. For patients, this could mean faster access to a novel therapy that offers meaningful clinical benefit where current options fall short.

Inside CLD-201 – A Next-Gen Oncolytic Stem Cell Platform

CLD-201 is a novel virotherapy platform built from adipose-derived mesenchymal stem cells (AD-MSCs) loaded with an oncolytic vaccinia virus. This stem-cell-based viral delivery is designed to:

• Shield the virus from immune clearance

• Enable amplification within the stem cell

• Trigger a potent immune response at tumor sites

In preclinical models, this approach has demonstrated enhanced efficacy and immune activation, supporting its potential across several solid tumor types, including:

• Soft tissue sarcoma

• Triple-negative breast cancer (TNBC)

• Head and neck squamous cell carcinoma (HNSCC)

What’s Next in Clinical Development for CLD-201?

Following the IND clearance announced in April 2025, preparations are underway for a first-in-human, open-label, multicenter Phase 1 clinical trial. The study will assess the safety, tolerability, and preliminary efficacy of CLD-201 in patients with advanced solid tumors, including soft tissue sarcoma, triple-negative breast cancer (TNBC), and head and neck squamous cell carcinoma (HNSCC). This trial represents a critical step toward translating promising preclinical findings into clinical benefit for patients facing limited treatment options.

“FDA IND clearance and Fast Track designation represents an important milestone in the development of CLD-201. This designation underscores the unmet medical need in sarcoma and provides scientific and regulatory validation of CLD-201. We believe CLD-201 has the potential to provide durable and transformational treatment to patients with sarcoma as well as patients with other advanced tumor types. We want to thank the FDA for its support and partnership and look forward to continued collaboration with the agency”

said Dr. Guy Travis Clifton, Chief Medical Officer of Calidi.

What Is Soft Tissue Sarcoma?

Soft tissue sarcomas are a diverse group of malignant tumors that originate in the body’s connective tissues, including muscles, fat, nerves, and blood vessels. These tumors account for about 1% of all adult cancers, yet their complexity and heterogeneity—comprising more than 50 histological subtypes—make them particularly challenging to treat.

Patients diagnosed with high-grade or metastatic sarcomas face a poor prognosis, with five-year survival rates often below 50%. Traditional treatments like chemotherapy and radiation offer limited long-term control, and new therapeutic options are urgently needed. The Fast Track designation for CLD-201 reflects this critical therapeutic gap and the potential for more effective, immune-based interventions.

About Calidi Biotherapeutics

Calidi (NYSE American: CLDI) is a clinical-stage biotech innovating viral delivery platforms for oncology and gene therapy. Its proprietary Redtail platform uses immune-evasive viral vectors to deliver therapies to distal tumor sites, with candidates targeting:

• Non-small cell lung cancer

• Ovarian cancer

• And other high-need indications

Headquartered in San Diego, Calidi is advancing both systemic and intratumoral virotherapy approaches through a robust clinical and preclinical pipeline.

 Key Takeaways

•  CLD-201 receives FDA Fast Track for soft tissue sarcoma
•  Combines AD-MSCs with oncolytic vaccinia virus
•  Phase 1 study planned in sarcoma, TNBC, and HNSCC
•  Stem-cell shielding and immune amplification may offer improved efficacy
•  Supports Calidi’s broader Redtail platform for systemic virotherapy delivery

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