Merck & Co Stock Price, News & Analysis

Merck (NYSE: MRK) and Daiichi Sankyo reported Phase 2 REJOICE-Ovarian01 results for raludotatug deruxtecan in platinum-resistant ovarian, primary peritoneal and fallopian tube cancer (data cut-off Feb 26, 2025).

Key outcomes: a confirmed objective response rate of 50.5% (n=107) across three doses, disease control rate 77.6%, and median time to response ~7.1 weeks. The 5.6 mg/kg dose was selected for Phase 3. Safety: common TEAEs included nausea, anemia, asthenia and neutropenia; 3.7% had treatment-related ILD/pneumonitis. R-DXd received Breakthrough Therapy Designation from FDA in Sept 2025.

Merck (NYSE: MRK) reported first and second interim results from the Phase 3 KEYNOTE-B96 trial in platinum-resistant recurrent ovarian cancer presented at ESMO 2025.

Key clinical results: at 15.6-month median follow-up KEYTRUDA+chemotherapy ± bevacizumab reduced risk of progression or death by 30% (HR=0.70) in all comers; 12-month PFS 33.1% vs 21.3%. At 26.6-month follow-up KEYTRUDA reduced risk of death by 24% (HR=0.76) in PD-L1 CPS≥1 patients; 12-month OS 69.1% vs 59.3% and 18-month OS 51.5% vs 38.9%.

Safety signals included higher Grade 3–5 TRAEs (67.5% vs 55.3%) and immune-mediated AEs (39.1% vs 18.9%). The FDA accepted an sBLA for priority review with a PDUFA date of Feb 20, 2026.

Merck (NYSE: MRK) reported Phase 3 KEYNOTE-905/EV-303 results showing perioperative KEYTRUDA (pembrolizumab) plus Padcev (enfortumab vedotin) reduced the risk of event-free survival (EFS) events by 60% (HR=0.40; p<0.0001) and reduced the risk of death by 50% (HR=0.50; p=0.0002) versus surgery alone in cisplatin-ineligible or -declining muscle-invasive bladder cancer (MIBC) patients after a median follow-up of 25.6 months.

Median EFS was not reached for the combination versus 15.7 months for surgery alone. Pathologic complete response (pCR) rose to 57.1% with the combination versus 8.6% with surgery (increase of 48.3 percentage points; p<0.000001). Safety showed higher treatment-emergent adverse events with the combination (100% vs 64.8%; Grade ≥3: 71.3% vs 45.9%). Results were presented at ESMO 2025 and the companies plan to share data with regulators worldwide.

Merck (NYSE: MRK) and Eisai reported five-year results from the Phase 3 KEYNOTE-775/Study 309 trial showing durable survival benefit for KEYTRUDA (pembrolizumab) plus LENVIMA (lenvatinib) versus chemotherapy in advanced endometrial carcinoma after prior platinum therapy.

In the pMMR subgroup at median follow-up 68.8 months, five-year OS was 16.7% vs 7.3%, median OS 18.0 vs 12.2 months (HR 0.70). All-comers five-year OS was 19.9% vs 7.7%, median OS 18.7 vs 11.9 months (HR 0.66). Safety was consistent with prior data; no new signals.

Merck (NYSE: MRK) announced that the Phase 3 KEYNOTE-B96 trial met its secondary endpoint of overall survival (OS) in all comers with platinum-resistant recurrent ovarian cancer when KEYTRUDA (pembrolizumab) was added to paclitaxel with or without bevacizumab.

The regimen previously met the primary endpoint of progression-free survival (PFS) and earlier OS analyses in PD-L1–expressing tumors; the final analysis showed a statistically significant and clinically meaningful OS benefit in all comers. Safety was consistent with prior studies and no new safety signals were identified. Final results will be presented at an upcoming medical meeting.

Merck (NYSE: MRK) presented additional Phase 3 data for the investigational once-daily oral two-drug regimen DOR/ISL (100 mg/0.25 mg) in adults with virologically suppressed HIV-1. Data showed minimal changes in weight and body composition at Week 48 and no clinically meaningful effects on fasting lipids or HOMA-IR, comparable to participants who continued BIC/FTC/TAF or baseline ART. In MK-8591A-052, mean weight change at Week 48 was −0.03 kg for DOR/ISL vs +0.28 kg for BIC/FTC/TAF; 14.6% of DOR/ISL participants had ≥5% weight gain. The FDA accepted the NDA for DOR/ISL with a PDUFA target action date of April 28, 2026.

Merck (NYSE: MRK) will present new HIV treatment and prevention data at the 20th European AIDS Conference (EACS) in Paris, Oct. 15–18, 2025. Presentations include Week 48 weight and body composition results from the Phase 3 MK-8591A-052 trial comparing doravirine/islatravir (DOR/ISL 100mg/0.25mg) vs bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF), Week 48 fasting lipids and insulin resistance analyses from MK-8591A-051 and MK-8591A-052, 96-week safety and PK data from the Phase 2 weekly islatravir+lenacapavir study (NCT05052996), and Phase 1 PK/safety of monthly MK-8527 in renal impairment. The company noted DOR/ISL is under FDA review. Merck will also host policy and medical symposia on Oct. 16 and Oct. 17 open to registered attendees.

Merck (NYSE: MRK) will present more than 100 abstracts across 20+ cancer types at ESMO Congress 2025 (Oct 17–21) in Berlin. Key highlights include first-time Phase 3 data from KEYNOTE-905 (enfortumab vedotin + pembrolizumab) and KEYNOTE-B96 (pembrolizumab ± bevacizumab) featured in Presidential Symposium sessions.

Long-term follow-up includes 5‑year and 10‑/8‑year exploratory results for pembrolizumab in multiple lung and endometrial studies. Multiple investigational ADCs (R-DXd, I-DXd, sac-TMT) and other pipeline candidates will have clinical updates.

Merck (NYSE: MRK) completed the acquisition of Verona Pharma on October 7, 2025, acquiring all ADS for $107 per ADS (each ADS = eight ordinary shares) for a total transaction value of approximately $10 billion. Verona Pharma becomes a wholly owned Merck subsidiary and its ADS will no longer trade on Nasdaq.

The deal adds Ohtuvayre (ensifentrine)—an FDA‑approved (June 2024) first‑in‑class inhaled maintenance treatment for COPD—to Merck’s cardio‑pulmonary portfolio, and Ohtuvayre is being evaluated in bronchiectasis trials. Merck expects most of the purchase price to be capitalized as an intangible asset and amortized for GAAP purposes, and estimates a ~$0.16 negative impact on non‑GAAP EPS in the first 12 months related to financing costs partially offset by Ohtuvayre performance.