Merck to discontinue phase 3 KeyVibe-008 Trial for Vibostolimab and Pembrolizumab Combination
Merck to discontinue phase 3 KeyVibe-008 trial of fixed-dose combination of vibostolimab and pembrolizumab in patients with extensive-stage SCLC
Overview
Merck, known as MSD outside of the United States and Canada, announced the discontinuation of the phase 3 KeyVibe-008 trial based on the recommendation of an independent Data Monitoring Committee (DMC). The trial is evaluating the investigational fixed-dose combination (coformulation) of vibostolimab, an anti-TIGIT antibody, and pembrolizumab (Keytruda), Merck’s anti-PD-1 therapy, in combination with chemotherapy compared to atezolizumab in combination with chemotherapy, for the first-line treatment of patients with extensive-stage small cell lung cancer (ES-SCLC). At a pre-planned analysis, data showed that the primary endpoint of overall survival (OS) met the pre-specified futility criteria. Additionally, when compared to patients in the control arm, patients in the vibostolimab and pembrolizumab fixed-dose combination arm experienced a higher rate of adverse events (AEs) and immune-related AEs. A comprehensive analysis of this study is ongoing.
Merck’s Announcement
Merck is notifying study investigators of the decision and that patients should stop ongoing treatment with the fixed-dose combination of vibostolimab and pembrolizumab and be offered the option to be treated with atezolizumab. Results will be shared with the scientific community.
From the Oncology Dept: Merck Research Laboratories
- Small cell lung cancer remains a difficult disease to treat, as evident by the seven percent five-year survival rate and limited advancements in treatment options,” said Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories.
- Innovative research plays a critical role in improving our understanding to help patients achieve better outcomes, and while we hoped the results would be different, we remain committed to investigating novel approaches to treat this debilitating disease. We are extremely grateful to all of the patients, caregivers and investigators for their participation in this study.
Clinical development programme for lung cancer
Merck has an extensive clinical development programme in lung cancer and is advancing multiple registration-enabling studies, with research directed at earlier stages of disease and novel combinations.
Latest Dosing for Phase 3
- In SCLC, Merck and Daiichi Sankyo recently announced that the first patient has been dosed in the IDeate-Lung02 phase 3 trial evaluating the efficacy and safety of investigational ifinatamab deruxtecan (I-DXd) in patients with relapsed SCLC versus treatment of physician’s choice of chemotherapy.
- Merck and Daiichi Sankyo also expanded their existing global co-development and co-commercialization agreement for three investigational DXd antibody-drug conjugates to include Merck’s MK-6070, an investigational delta-like ligand 3 (DLL3) targeting T-cell engager that is currently being evaluated in a phase 1/2 clinical trial (NCT04471727).
- The companies are planning to evaluate MK-6070 in combination with I-DXd in certain patients with SCLC, as well as other potential combinations.
- Merck obtained MK-6070 through its acquisition of Harpoon Therapeutics.
Evaluation Of Fixed Dose Combination
- Ongoing phase 3 studies evaluating the vibostolimab and pembrolizumab fixed-dose combination in lung cancer, which are routinely monitored by external data monitoring committees, include KeyVibe-003, KeyVibe-006 and KeyVibe-007.
- Interim external data monitoring committee safety reviews have not resulted in any study modifications to date and the studies are undergoing ongoing comprehensive safety monitoring.
About KeyVibe-008
- KeyVibe-008 is a randomized, double-blind phase 3 trial (ClinicalTrials.gov, NCT05224141 ) evaluating a fixed-dose combination of vibostolimab and pembrolizumab (MK-7684A) in combination with etoposide and platinum chemotherapy followed by the vibostolimab and pembrolizumab fixed-dose combination versus atezolizumab in combination with etoposide and platinum chemotherapy followed by atezolizumab for the first-line treatment of patients with ES-SCLC.
- The primary endpoint is OS, and key secondary endpoints include progression-free survival, objective response rate, duration of response, all as assessed by blinded independent central review (BICR). The trial enrolled 460 patients who were randomized (1:1) to receive:
Combined Therapy
Vibostolimab/pembrolizumab fixed-dose combination (pembrolizumab 200 mg and vibostolimab 200 mg intravenously [IV] every three weeks [Q3W] for four cycles) in combination with etoposide and platinum chemotherapy (carboplatin or cisplatin) Q3W for a total of approximately 12 weeks followed by additional cycles of the vibostolimab/pembrolizumab fixed-dose combination until any of the conditions for discontinuation are met; or Atezolizumab (1,200 mg Q3W) in combination with etoposide and platinum chemotherapy (carboplatin or cisplatin) Q3W for a total of approximately 12 weeks followed by additional cycles of atezolizumab until any of the conditions for discontinuation are met.
About Lung Cancer
- Lung cancer is the leading cause of cancer death worldwide.
- In 2022 alone, there were approximately 2.48 million new cases and 1.8 million deaths from lung cancer globally.
- In 2024, the overall five-year survival rate for patients diagnosed with lung cancer is 25% in the United States.
- Improved survival rates are due, in part, to earlier detection and screening, reduction in smoking, advances in diagnostic and surgical procedures, as well as the introduction of new therapies.
- The two main types of lung cancer are non-small cell and small cell. Small cell lung cancer accounts for about 15% of all lung cancers.
- Patients with small cell lung cancer have a particularly poor prognosis, with an estimated five-year survival rate of 7% for patients in the United States with any stage of the disease.
- Early detection and screening remain an important unmet need, as 44% of lung cancer cases are not found until they are advanced.
Merck Focs for Lung Cancer
- Merck is advancing research aimed at transforming the way lung cancer is treated, with a goal of improving outcomes for patients affected by this deadly disease.
- Through nearly 200 clinical trials evaluating more than 36,000 patients around the world, Merck is at the forefront of lung cancer research. In non-small cell lung cancer, Keytruda has six approved US indications and is approved for advanced disease in more than 95 countries.
- Among Merck’s research efforts are trials focused on evaluating Keytruda in earlier stages of lung cancer as well as identifying new combinations and fixed-dose combinations with Keytruda.
About Vibostolimab
- Vibostolimab (MK-7684) is an investigational humanized anti-TIGIT antibody discovered and developed by Merck.
- Vibostolimab restores antitumor activity by blocking the TIGIT receptor from binding to its ligands (CD112 and CD155), thereby activating T lymphocytes that help destroy tumour cells.
- The fixed-dose combination of vibostolimab and pembrolizumab is being evaluated in a wide range of cancers, including lung, other solid tumours and blood cancers.
About Keytruda
- Keytruda is an anti-programmed death receptor-1 (PD-1) therapy that works by increasing the ability of the body’s immune system to help detect and fight tumour cells.
- Keytruda is a humanized monoclonal antibody that blocks the interaction between PD-1 and its ligands, PD- L1 and PD-L2, thereby activating T lymphocytes which may affect both tumour cells and healthy cells.
Merck’s Clinical Research Program
- Merck has the industry’s largest immuno-oncology clinical research program.
- There are currently more than 1,600 trials studying Keytruda across a wide variety of cancers and treatment settings.
- The Keytruda clinical programme seeks to understand the role of Keytruda across cancers and the factors that may predict a patient's likelihood of benefitting from treatment with Keytruda, including exploring several different biomarkers.
Keytruda is not indicated for the treatment of patients with SCLC.

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