Vir Biotechnology, Inc. (NASDAQ: VIR) has recently announced the dosing of the first patient in its phase 1 clinical trial of Vir-5525, an investigational dual-masked T-cell engager (TCE) targeting EGFR (epidermal growth factor receptor). This trial is designed to evaluate the safety, pharmacokinetics, and preliminary efficacy of Vir-5525 as a monotherapy and in combination with pembrolizumab for the treatment of various EGFR-expressing solid tumors, including non-small cell lung cancer (NSCLC), colorectal cancer (CRC), head and neck squamous cell carcinoma (HNSCC), and cutaneous squamous cell carcinoma (CSCC).
The milestone payment triggered by the first patient dosing of Vir-5525 amounts to $75 million. This payment, part of the company's 2024 exclusive worldwide license agreement with Sanofi for the Pro-Xten™ platform and clinical-stage T-cell engagers, has been held as restricted cash since the transaction closing and was excluded from the company’s $1.02 billion in cash, cash equivalents, and investments reported as of March 31, 2025. It will be recognized as a research and development expense in the third quarter of 2025.
In addition to Vir-5525, the company is also advancing the dose escalation for its other dual-masked TCEs, Vir-5818 (targeting a variety of HER2-expressing solid tumors) and Vir-5500 (targeting PSMA in metastatic castration-resistant prostate cancer). Initial phase 1 data presented in January 2025 showed compelling early clinical response signals and promising safety profiles for both clinical candidates in heavily pretreated patients.
Vir Biotechnology's CEO, Marianne De Backer, emphasized the company's commitment to advancing innovative therapies that address substantial unmet needs in oncology, and the Chief Medical Officer, Mark Eisner, expressed enthusiasm for evaluating the potential of Vir-5525 in the phase 1 trial.
Vir-5525, which is currently being evaluated in a phase 1 clinical trial, combines a bispecific EGFR and CD3 binding TCE with the Pro-Xten™ masking technology. This technology is designed to keep the TCEs inactive (or masked) until they reach the tumor microenvironment, where tumor-specific proteases cleave off the mask and activate the TCEs, leading to the killing of cancer cells by T-cells. This approach aims to confine the activity exclusively to the tumor microenvironment, potentially reducing traditionally high toxicity associated with unmasked TCEs and increasing their efficacy and tolerability.
Vir Biotechnology, Inc. is a clinical-stage biopharmaceutical company focused on discovering and developing medicines for serious infectious diseases and cancer. Its clinical-stage portfolio includes programs for chronic hepatitis delta and multiple dual-masked T-cell engagers across validated targets in solid tumor indications. The company also has a preclinical portfolio of programs across a range of infectious diseases and oncologic malignancies. Today the company's shares have moved -0.09% to a price of $5.845. For the full picture, make sure to review Vir Biotechnology's 8-K report.
