Merck Phase 3 Pipeline: ~80 Trials, Key Gaps
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Merck's Phase 3 program reveals significant gaps that could impact its competitive position. This article analyzes the implications for pharma teams and investors.
Merck Phase 3 execution is no longer a Keytruda-only story. Company disclosures through early 2026 describe roughly 80 Phase 3 studies ongoing, 18 positive late-stage trial results in 2025, and a crowded calendar of primary completion dates that will either diversify growth—or expose gaps if oral PCSK9, HIV, ADC, and immunology bets slip.
Contents10 sections
Key Takeaways
- Merck says approximately 80 Phase 3 studies are underway and reported positive late-stage results from 18 Phase 3 trials in 2025.
- The company began enrolling patients in 21 new Phase 3 studies in 2025 while advancing assets such as enlicitide (MK-0616), tulisokibart (MK-7240), and MK-1406.
- 2026 PCDs flagged in earnings materials include ISLEND-1/2 (HIV, April 2026) and ATLAS-UC (tulisokibart, August 2026).
- Pipeline PDFs dated 30-Apr-2026 list Phase 3 coverage across hypercholesterolemia, multiple solid tumors, HIV, influenza, and inflammatory bowel disease.
How large is Merck’s Phase 3 machine in 2026?
In its full-year 2025 results release, Merck stated it announced positive late-stage trial results from 18 Phase 3 trials in 2025, began enrolling patients in 21 new Phase 3 studies, and had approximately 80 Phase 3 studies underway. Earnings decks repeat the “~80 Phase 3 studies ongoing” framing into 1Q 2026.
That scale is the opportunity and the risk. A broad late-stage slate can offset Keytruda LOE pressure, but it also concentrates operational and capital risk across oncology ADCs, cardiometabolic oral PCSK9, HIV long-acting regimens, ophthalmology, and immunology.
Primary source: Merck FY2025 pipeline progress release.
Which 2026 readouts define the non-Keytruda growth thesis?
Company earnings materials highlight near-term Phase 3 primary completion dates that investors treat as gap-fillers:
- Islatravir/lenacapavir ISLEND-1 and ISLEND-2 HIV treatment PCDs in April 2026
- Tulisokibart (TL1A mAb) ATLAS-UC ulcerative colitis PCD in August 2026
- MK-3000 BRUNELLO diabetic macular edema PCD in September 2026
- MK-1406 influenza ANCHOR Phase 3 enrollment progressing toward a January 2027 PCD
These dates come from Merck’s 4Q25 earnings presentation and related 1Q26 materials—not from third-party market notes.
Where do oncology ADC and oral PCSK9 programs sit?
Merck’s public pipeline dated 30 April 2026 lists Phase 3 assets including enlicitide decanoate (MK-0616) for hypercholesterolemia, patritumab deruxtecan (MK-1022), sacituzumab tirumotecan (MK-2870), nemtabrutinib (MK-1026), and ifinatamab deruxtecan collaborations. Enlicitide Phase 3 CORALreef Lipids and HeFH data were highlighted as showing significant LDL-C reductions with a placebo-comparable safety profile in company communications.
See the Merck public pipeline PDF (2Q2026) for the labeled Phase 3 roster.
What “gaps” actually matter for competitive intelligence?
The practical gap is not missing Phase 3 volume—it is concentration risk if several 2026–2027 PCDs miss efficacy bars while Keytruda maturity continues. Teams should track:
- Whether oral PCSK9 efficacy translates into label and access that can compete with injectables
- Whether HIV weekly oral and long-acting combinations clear safety and adherence hurdles
- Whether TL1A and ADC programs deliver registrational endpoints without dose-limiting toxicity
Merck also disclosed European approval expansion for WINREVAIR in January 2026 based on ZENITH and a U.S. sBLA acceptance tied to HYPERION—examples of lifecycle work sitting beside net-new Phase 3 bets.
How should APAC medical affairs prioritize Merck Phase 3 signals?
APAC affiliate teams should map local enrollment and regulatory clocks against the U.S./global PCD calendar. Assets with multi-region Phase 3 footprints (oncology ADCs, HIV, influenza prophylaxis) will drive HTA and tender timing differently than U.S.-centric filings.
Use ClinicalTrials.gov registry pages for protocol-level endpoints when translating company PCD language into country launch scenarios, and keep Merck IR PDFs as the source of the ~80-trial claim.
Registry example: ClinicalTrials.gov for protocol lookups by MK number.
What remains unproven despite the ~80-trial headline?
Merck’s disclosures establish trial volume and selected positive toplines; they do not guarantee approval, pricing, or share gains for enlicitide, tulisokibart, or ADC combinations. Do not invent probability-of-success percentages or revenue bridges that Merck has not published.
Also avoid treating every Keytruda combination study as incremental growth—many are label-defense or sequencing experiments.
Related NovaPharma coverage
- Eli Lilly pipeline and deals: 2026 outlook
- Sanofi pipeline PDF: 2026 catalysts
- Merck Phase 3 program coverage
Frequently Asked Questions
How many Phase 3 studies does Merck say are underway?
Merck’s full-year 2025 results communication and subsequent earnings decks state that approximately 80 Phase 3 studies are currently underway, alongside 18 positive late-stage Phase 3 results announced in 2025.
Which Merck Phase 3 primary completion dates fall in 2026?
Company earnings materials flag April 2026 PCDs for ISLEND-1 and ISLEND-2 (islatravir/lenacapavir HIV treatment), an August 2026 PCD for the ATLAS-UC tulisokibart ulcerative colitis trial, and a September 2026 PCD for MK-3000 BRUNELLO in diabetic macular edema.
Where can analysts verify Merck’s Phase 3 asset list?
Merck publishes a dated public pipeline PDF (for example, the 2Q2026 file as of 30 April 2026) listing Phase 3 candidates by therapeutic area, complemented by news releases summarizing late-stage progress.
Primary Sources
Merck & Co. pipeline snapshot
One-screen view of active programs, phases, and recent catalysts from public sources.
Sources & references 1 primary sources
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