MRUS Stock Soars 30% in 3 Months After Phase II Cancer Study Success

Merus N.V. MRUS shares have jumped 29.9% over the past three months. The uptrend was fueled by encouraging interim results from a phase II study evaluating its bispecific antibody, petosemtamab (MCLA-158), in combination with Merck’s MRK Keytruda (pembrolizumab) as a first-line treatment for PD-L1–positive recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). Per the data readout, the combo therapy has shown better efficacy than Keytruda monotherapy.

MRUS’ Interim Phase II HNSCC Study Data Readout in Detail

As of Feb. 27, 2025, data cutoff, 45 patients had been treated, with 43 considered efficacy-evaluable. The confirmed overall response rate (ORR) among these patients was 63%, including six complete responses and 21 partial responses. Notably, responses were observed across PD-L1 expression levels, including a 73% ORR in patients with a combined positive score (CPS) greater than 20 and 47% in those with CPS 1–19. Four of eight patients with human papillomavirus-associated tumors also responded.

Median progression-free survival reached nine months, while median overall survival and duration of response were not yet reached. At 12 months, the overall survival rate was 79%. 14 patients, all responders, remained on treatment at the time of data cutoff.

Year to date, shares of Merus have gained 31.1% compared with the industry’s 0.2% growth.

The safety profile of the combination appeared manageable, with no significant overlapping toxicities with Merck’s Keytruda. Treatment-related adverse events occurred in all patients. Infusion-related reactions were observed in 38% of patients, mostly during the first infusion, and resolved without escalation.

Based on such encouraging data, the petosemtamab combo therapy shows significant potential in becoming a new standard of care for treating HNSCC, a form of cancer that is associated with poor prognosis and a high mortality rate.

Please note that Merus is also currently evaluating petosemtamab in combination with Merck’s Keytruda in a registrational phase III LiGeR-HN1 study for first-line treatment of HNSCC. Simultaneously, a separate registrational phase III study, LiGeR-HN2, is evaluating petosemtamab monotherapy as a second or third-line treatment for HNSCC.

Per the latest phase II data, the combo therapy has shown better efficacy in the HNSCC patient population than Keytruda monotherapy, which is the control arm of the LiGeR-HN1 study. Top-line interim readout from one or both of Merus’ registrational phase III studies is expected in 2026. The company has several other candidates in its clinical pipeline currently under early to mid-stage development for different oncology indications

Merck’s Keytruda is a blockbuster anti-PD-1 therapy. It is currently marketed as the standard of care in the frontline treatment of metastatic non-small cell lung cancer patients. Merck’s Keytruda is also approved for several other cancer types, generating $7.21 billion in sales in first-quarter 2025, up 6% year over year and accounting for 53% of its Pharmaceutical segment revenues. Keytruda is continuously growing and expanding into new indications and markets globally, bolstering Merck’s position in the oncology market.

Merus N.V. Price and Consensus

Merus N.V. price-consensus-chart | Merus N.V. Quote

MRUS’ Zacks Rank and Stocks to Consider

Merus currently carries a Zacks Rank #3 (Hold).

Some better-ranked stocks in the biotech sector are Verona Pharma VRNA and Bayer BAYRY, 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 90 days, Verona Pharma’s bottom-line estimates for 2025 have significantly improved from a loss of 7 cents per share to earnings of 22 cents. During the same timeframe, estimates for 2026 earnings per share have improved from $2.21 to $2.88. VRNA stock has soared 125.8% so far this year.

Verona Pharma’s earnings beat estimates in one of the trailing four quarters and missed the mark on the other three occasions, delivering an average negative surprise of 6.76%.

BAYRY’s 2025 earnings per share estimate has increased from $1.20 to $1.32 for 2025 over the past 90 days, while that for 2026 has gone up from $1.28 to $1.37 over the same timeframe. Year to date, shares of Bayer have surged 66.4%.

BAYRY’s earnings beat estimates in one of the trailing four quarters, matched twice and missed on the remaining occasion, the average negative surprise being 13.91%.

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