Vir Biotechnology, Inc. VIR announced encouraging initial data from a phase I study that evaluated its investigational pipeline candidates, VIR-5818 and VIR-5500, for the treatment of various solid tumors.

While VIR-5818 is designed to target a variety of HER2-expressing solid tumors, VIR-5500 is designed to target PSMA in metastatic castration-resistant prostate cancer (mCRPC).

Initial data from the phase I study demonstrated compelling early clinical response signals for both T-cell engagers (TCEs), VIR-5818 and VIR-5500, in heavily pretreated patients with various types of solid tumors.

Shares of Vir Biotechnology jumped 58.2% on Jan. 8 following the announcement of the news.

In the past year, shares of VIR have rallied 21.1% against the industry’s decline of 14.3%.

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Per the company, VIR-5818 and VIR-5500 leverage the PRO-XTEN masking technology with different TCEs targeting HER2 and PSMA, respectively. The technology is designed to allow the selective activation of TCEs in the tumor microenvironment, lowering the damage to healthy cells and toxicity.

Data on VIR's VIR-5818 for HER2-Expressing Cancers

A phase I study is currently evaluating the safety and pharmacokinetics of VIR-5818 as a monotherapy and in combination with Merck’s blockbuster PD-L1 inhibitor, Keytruda (pembrolizumab) for treating various types of HER2-expressing cancers, including breast and colorectal cancer (CRC).

Early efficacy data from the above study showed that treatment with VIR-5818 doses ≥400 µg/kg resulted in 50% of patients experiencing tumor shrinkage across multiple HER2-positive tumor types.

Strong anti-tumor activity was also seen in a subset of participants with HER2-positive CRC who have exhausted the standard of care. Treatment with VIR-5818 also led to a confirmed partial response of 33% in this subset of participants with HER2-positive CRC.

Treatment with VIR-5818 was generally safe and well tolerated.

Data on VIR's VIR-5500 for PSMA-Targeting Cancers

Another phase I study is evaluating the safety, pharmacokinetics and efficacy of VIR-5500 in participants with mCRPC.

Data from this study showed that all 12 patients who were treated with an initial dose of VIR-5500 ≥120 µg/kg experienced prostate-specific antigen (PSA) reductions. Also, PSA 50 response was confirmed in 58% of the participants who received a first dose ≥120 µg/kg.

Treatment with VIR-5500 was also generally safe and well tolerated with no dose-limiting cytokine release syndrome observed.

VIR's Zacks Rank & Stocks to Consider

Vir Biotechnology currently carries a Zacks Rank #4 (Sell).

Some better-ranked stocks from the biotech sector are Puma Biotechnology, Inc. PBYI, CytomX Therapeutics, Inc. CTMX and Castle Biosciences, Inc. CSTL, each sporting a Zacks Rank #1 (Strong Buy) at present. You can see the complete list of today’s Zacks #1 Rank stocks here.

In the past 60 days, estimates for Puma Biotechnology’s 2025 earnings per share have increased from 42 cents to 54 cents. In the past year, shares of PBYI have declined 24.7%.

PBYI’s earnings beat estimates in three of the trailing four quarters while missing the same on the remaining occasion, the average surprise being 32.78%.

In the past 60 days, estimates for CytomX Therapeutics’ loss per share have narrowed from 56 cents to 35 cents for 2025. In the past year, shares of CTMX have surged 28.3%.

CTMX’s earnings beat estimates in two of the trailing four quarters while missing the same on the remaining two occasions, the average surprise being 115.70%.

In the past 60 days, estimates for Castle Biosciences’ loss per share have narrowed from $1.88 to $1.84 for 2025. In the past year, shares of CSTL have surged 34.3%.

CSTL’s earnings beat estimates in each of the trailing four quarters, the average surprise being 172.72%.

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