Vir Biotechnology Stock Soars On Prostate Cancer Trial Data - Here's Why

On Wednesday, Vir Biotechnology, Inc. VIR stock traded higher after the company presented initial Phase 1 data from two of its dual-masked T-cell engagers (TCEs): VIR-5818, which targets a variety of HER2-expressing solid tumors, and VIR-5500, which targets PSMA in metastatic castration-resistant prostate cancer (mCRPC).

Data show encouraging preliminary safety and efficacy profiles with no dose-limiting cytokine release syndrome (CRS), maximum tolerated dose (MTD) not yet reached as dose escalation continues, and early clinical response signals observed in heavily pretreated participants.

These initial results provide clinical support for Vir Biotechnology’s in-licensed PRO-XTEN masking technology, designed to enable the selective activation of TCEs in the tumor microenvironment, mitigating damage to healthy cells and reducing toxicity.

VIR-5818: PRO-XTEN Initial Proof-of-Concept and Potential First-in-Class HER2 Immunotherapy

• Early efficacy data indicate that 50% (10/20) of participants receiving VIR-5818 doses ≥400 µg/kg experienced dose-dependent tumor shrinkage across multiple HER2-positive tumor types.
• Strong anti-tumor activity was observed in a subset of participants with HER2-positive CRC who have exhausted standard of care. In this subset, confirmed partial responses (cPRs) were seen in 33% (2/6) of participants at early doses, and one patient continued in cPR for more than 18 months as of the data cut-off.
• Preliminary safety data demonstrate that VIR-5818 is generally well-tolerated, with minimal grade 1 or 2 CRS.

VIR-5500: First Dual-Masked PSMA-Targeting TCE

• Early efficacy data show encouraging signs of prostate-specific antigen (PSA) responses, and PSA reductions were observed in 100% (12/12) of participants after an initial dose ≥120 µg/kg. PSA50 response was confirmed in 58% (7/12) of participants receiving a first dose ≥120 µg/kg.
• Preliminary data show a promising safety profile, with no dose-limiting toxicities observed up to 1000 µg/kg without prophylactic corticosteroids.

In November, Vir Biotechnology announced end-of-treatment data from Part B of the MARCH Phase 2 study evaluating combinations of tobevibart and elebsiran, with or without pegylated interferon alfa (PEG-IFNα), in participants with chronic hepatitis B.

Price Action: VIR stock is up 73.60% at $13.70 at the last check on Wednesday.

Read Next:

• Franchise Fallout: Yum! Terminates Turkey Deal Over Standards Issues, Expects Pre-Tax Special Charge