RAHWAY, NJ, USA I February 28, 2023 I Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today provided updates on two Phase 3 trials, KEYNOTE-641 and KEYNOTE-789. Merck is discontinuing the Phase 3 KEYNOTE-641 trial evaluating KEYTRUDA® (pembrolizumab), Merck’s anti-PD-1 therapy, in combination with enzalutamide and androgen deprivation therapy (ADT) for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) based on the recommendation of an independent Data Monitoring Committee. At an interim analysis, KEYTRUDA in combination with enzalutamide and ADT did not demonstrate an improvement in radiographic progression-free survival (rPFS) or overall survival (OS), the trial’s dual primary endpoints, compared to placebo plus enzalutamide and ADT, and crossed a pre-specified futility boundary for OS. Merck is informing study investigators of the decision and advises patients in the study to speak to their physician regarding treatment.

Merck also announced that the Phase 3 KEYNOTE-789 trial evaluating KEYTRUDA in combination with pemetrexed plus platinum-based chemotherapy did not meet its dual primary endpoint of OS for the treatment of patients with metastatic nonsquamous non-small cell lung cancer (NSCLC), with epidermal growth factor receptor (EGFR)-genomic tumor mutations, who have previously progressed on a tyrosine kinase inhibitor (TKI), including osimertinib. At the final analysis of the study, there was an improvement in OS for patients who received KEYTRUDA plus pemetrexed with platinum-based chemotherapy compared to pemetrexed with platinum-based chemotherapy; however, these results did not meet statistical significance per the pre-specified statistical plan. At an earlier interim analysis, the trial’s other dual primary endpoint, progression-free survival (PFS) was tested and showed an improvement in the KEYTRUDA arm compared to chemotherapy alone, but these results did not reach statistical significance.

In KEYNOTE-641 and KEYNOTE-789, the safety profile of KEYTRUDA was consistent with that observed in previously reported studies and no new safety signals were identified. In KEYNOTE-641, the combination was associated with a higher incidence of Grade 3-5 adverse events and serious adverse events compared to the control arm. Results will be shared at future scientific congresses.

“Throughout the clinical development of KEYTRUDA, we have asked the tough questions in an effort to fully explore the potential of this breakthrough immunotherapy and determine how we could help as many patients as possible,” said Dr. Eliav Barr, senior vice president and head of global clinical development, chief medical officer, Merck Research Laboratories. “Science is rarely a straight line, and while we are disappointed in these study results, our research to investigate KEYTRUDA in many difficult-to-treat types of cancer continues in earnest. We are extremely grateful to all the investigators and patients for their participation in these studies.”

About KEYNOTE-641

KEYNOTE-641 is a randomized, double-blind Phase 3 trial (ClinicalTrials.gov, NCT03834493) evaluating KEYTRUDA in combination with enzalutamide and ADT versus placebo in combination with enzalutamide and ADT in patients with mCRPC who have not received chemotherapy for mCRPC, are abiraterone-naïve or are intolerant to or progressed on abiraterone acetate. The primary endpoints are OS and rPFS per Prostate Cancer Working Group-modified RECIST v1.1 as assessed by blinded independent central review. Secondary endpoints include objective response rate (ORR), duration of response (DOR) and safety. The trial enrolled an estimated 1,240 patients who were randomized to receive KEYTRUDA (200 mg intravenously every three weeks for up to two years) plus enzalutamide (160 mg daily) or placebo plus enzalutamide.

About metastatic castration-resistant prostate cancer

Prostate cancer is the second most common cancer in male patients globally and is associated with a significant mortality rate. Development of prostate cancer is often driven by male sex hormones called androgens, including testosterone. In patients with mCRPC, their prostate cancer grows and spreads to other parts of the body, despite the use of ADT to block the action of male sex hormones. Approximately 10-20% of patients with prostate cancer are estimated to develop castration-resistant prostate cancer (CRPC) within five years, with at least 84% of these patients presenting with metastases at the time of CRPC diagnosis. Of patients with no metastases at CRPC diagnosis, 33% are likely to develop metastases within two years.

About KEYNOTE-789

KEYNOTE-789 (ClinicalTrials.gov, NCT03515837) is a randomized, double-blind Phase 3 trial investigating KEYTRUDA with pemetrexed plus platinum-based chemotherapy compared with pemetrexed plus platinum-based chemotherapy for the treatment of patients with TKI-resistant, EGFR-mutated metastatic, nonsquamous NSCLC. These patients experienced disease progression per RECIST v1.1 criteria following treatment with TKI therapy and either had: a) T790M-negative mutation tumors; b) T790M-positive mutation tumors with prior exposure to osimertinib; or c) first-line osimertinib failure regardless of T790M mutation status. The primary endpoints are OS and PFS. Secondary endpoints include ORR, DOR and safety. The study enrolled 492 patients who were randomized to receive either:

  • KEYTRUDA (200 mg intravenously [IV] on Day 1 of each three-week cycle for up to 35 cycles) plus pemetrexed (500 mg/m2 by IV every three weeks with no restrictions on the number of cycles) plus platinum chemotherapy (either carboplatin [Area Under the Curve [AUC] 5 by IV every three weeks for four cycles] or cisplatin [75 mg/m2 by IV every three weeks for four cycles]); or
  • Placebo (saline by IV on Day 1 of each three-week cycle for up to 35 cycles) plus pemetrexed (500 mg/m2 by IV every three weeks with no restrictions on the number of cycles) plus platinum chemotherapy (either carboplatin [AUC 5 by IV every three weeks for four cycles] or cisplatin [75 mg/m2 by IV every three weeks for four cycles]).

About lung cancer

Lung cancer is the leading cause of cancer death worldwide. In 2020 alone, there were more than 2.2 million new cases and 1.8 million deaths from lung cancer globally. Non-small cell lung cancer is the most common type of lung cancer, accounting for about 81% of all cases. Among people with nonsquamous NSCLC, approximately 10-15% have EGFR mutations in the U.S. and Europe and up to 40-50% in Asia. In the U.S., the overall five-year survival rate for patients diagnosed with lung cancer is 25%, which is a 21% improvement over the last five years. 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. Early detection and screening remain an important unmet need, as 44% of lung cancer cases are not found until they are advanced. Only 5.8% of people in the U.S. who are eligible were screened for lung cancer in 2021.

About Merck’s research in 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 NSCLC, KEYTRUDA has five approved U.S. indications (see indications below) 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 coformulations with KEYTRUDA.

About KEYTRUDA® (pembrolizumab) injection, 100 mg

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 tumor 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 tumor cells and healthy cells.

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 program 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.

Selected KEYTRUDA® (pembrolizumab) Indications in the U.S.

Non-Small Cell Lung Cancer

KEYTRUDA, in combination with pemetrexed and platinum chemotherapy, is indicated for the first-line treatment of patients with metastatic nonsquamous non-small cell lung cancer (NSCLC), with no EGFR or ALK genomic tumor aberrations.

KEYTRUDA, in combination with carboplatin and either paclitaxel or paclitaxel protein-bound, is indicated for the first-line treatment of patients with metastatic squamous NSCLC.

KEYTRUDA, as a single agent, is indicated for the first-line treatment of patients with NSCLC expressing PD-L1 [tumor proportion score (TPS) ≥1%] as determined by an FDA-approved test, with no EGFR or ALK genomic tumor aberrations, and is:

  • stage III where patients are not candidates for surgical resection or definitive chemoradiation, or
  • metastatic.

KEYTRUDA, as a single agent, is indicated for the treatment of patients with metastatic NSCLC whose tumors express PD-L1 (TPS ≥1%) as determined by an FDA-approved test, with disease progression on or after platinum-containing chemotherapy. Patients with EGFR or ALK genomic tumor aberrations should have disease progression on FDA-approved therapy for these aberrations prior to receiving KEYTRUDA.

KEYTRUDA, as a single agent, is indicated as adjuvant treatment following resection and platinum-based chemotherapy for adult patients with stage IB (T2a ≥4 cm), II, or IIIA NSCLC.

Additional Indications for KEYTRUDA in the U.S.

Melanoma

KEYTRUDA is indicated for the treatment of patients with unresectable or metastatic melanoma.

KEYTRUDA is indicated for the adjuvant treatment of adult and pediatric (12 years and older) patients with stage IIB, IIC, or III melanoma following complete resection.

Head and Neck Squamous Cell Cancer

KEYTRUDA, in combination with platinum and fluorouracil (FU), is indicated for the first-line treatment of patients with metastatic or with unresectable, recurrent head and neck squamous cell carcinoma (HNSCC).

KEYTRUDA, as a single agent, is indicated for the first-line treatment of patients with metastatic or with unresectable, recurrent HNSCC whose tumors express PD-L1 [Combined Positive Score (CPS) ≥1] as determined by an FDA-approved test.

KEYTRUDA, as a single agent, is indicated for the treatment of patients with recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy.

Classical Hodgkin Lymphoma

KEYTRUDA is indicated for the treatment of adult patients with relapsed or refractory classical Hodgkin lymphoma (cHL).

KEYTRUDA is indicated for the treatment of pediatric patients with refractory cHL, or cHL that has relapsed after 2 or more lines of therapy.

Primary Mediastinal Large B-Cell Lymphoma

KEYTRUDA is indicated for the treatment of adult and pediatric patients with refractory primary mediastinal large B-cell lymphoma (PMBCL), or who have relapsed after 2 or more prior lines of therapy. KEYTRUDA is not recommended for treatment of patients with PMBCL who require urgent cytoreductive therapy.

Urothelial Carcinoma

KEYTRUDA is indicated for the treatment of patients with locally advanced or metastatic urothelial carcinoma (mUC):

  • who are not eligible for any platinum-containing chemotherapy, or
  • who have disease progression during or following platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.

Non-muscle Invasive Bladder Cancer

KEYTRUDA is indicated for the treatment of patients with Bacillus Calmette-Guerin-unresponsive, high-risk, non-muscle invasive bladder cancer (NMIBC) with carcinoma in situ with or without papillary tumors who are ineligible for or have elected not to undergo cystectomy.

Microsatellite Instability-High or Mismatch Repair Deficient Cancer

KEYTRUDA is indicated for the treatment of adult and pediatric patients with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) solid tumors, as determined by an FDA-approved test, that have progressed following prior treatment and who have no satisfactory alternative treatment options.

This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials. The safety and effectiveness of KEYTRUDA in pediatric patients with MSI-H central nervous system cancers have not been established.

Microsatellite Instability-High or Mismatch Repair Deficient Colorectal Cancer

KEYTRUDA is indicated for the treatment of patients with unresectable or metastatic MSI-H or dMMR colorectal cancer (CRC) as determined by an FDA-approved test.

Gastric Cancer

KEYTRUDA, in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, is indicated for the first-line treatment of patients with locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma.

This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

Esophageal Cancer

KEYTRUDA is indicated for the treatment of patients with locally advanced or metastatic esophageal or gastroesophageal junction (GEJ) (tumors with epicenter 1 to 5 centimeters above the GEJ) carcinoma that is not amenable to surgical resection or definitive chemoradiation either:

  • in combination with platinum- and fluoropyrimidine-based chemotherapy, or
  • as a single agent after one or more prior lines of systemic therapy for patients with tumors of squamous cell histology that express PD-L1 (CPS ≥10) as determined by an FDA-approved test.

Cervical Cancer

KEYTRUDA, in combination with chemotherapy, with or without bevacizumab, is indicated for the treatment of patients with persistent, recurrent, or metastatic cervical cancer whose tumors express PD-L1 (CPS ≥1) as determined by an FDA-approved test.

KEYTRUDA, as a single agent, is indicated for the treatment of patients with recurrent or metastatic cervical cancer with disease progression on or after chemotherapy whose tumors express PD-L1 (CPS ≥1) as determined by an FDA-approved test.

Hepatocellular Carcinoma

KEYTRUDA is indicated for the treatment of patients with hepatocellular carcinoma (HCC) who have been previously treated with sorafenib. This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

Merkel Cell Carcinoma

KEYTRUDA is indicated for the treatment of adult and pediatric patients with recurrent locally advanced or metastatic Merkel cell carcinoma (MCC). This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

Renal Cell Carcinoma

KEYTRUDA, in combination with axitinib, is indicated for the first-line treatment of adult patients with advanced renal cell carcinoma (RCC).

KEYTRUDA is indicated for the adjuvant treatment of patients with RCC at intermediate-high or high risk of recurrence following nephrectomy, or following nephrectomy and resection of metastatic lesions.

Endometrial Carcinoma

KEYTRUDA, as a single agent, is indicated for the treatment of patients with advanced endometrial carcinoma that is MSI-H or dMMR, as determined by an FDA-approved test, who have disease progression following prior systemic therapy in any setting and are not candidates for curative surgery or radiation.

Tumor Mutational Burden-High Cancer

KEYTRUDA is indicated for the treatment of adult and pediatric patients with unresectable or metastatic tumor mutational burden-high (TMB-H) [≥10 mutations/megabase] solid tumors, as determined by an FDA-approved test, that have progressed following prior treatment and who have no satisfactory alternative treatment options. This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials. The safety and effectiveness of KEYTRUDA in pediatric patients with TMB-H central nervous system cancers have not been established.

Cutaneous Squamous Cell Carcinoma

KEYTRUDA is indicated for the treatment of patients with recurrent or metastatic cutaneous squamous cell carcinoma (cSCC) or locally advanced cSCC that is not curable by surgery or radiation.

Triple-Negative Breast Cancer

KEYTRUDA is indicated for the treatment of patients with high-risk early-stage triple-negative breast cancer (TNBC) in combination with chemotherapy as neoadjuvant treatment, and then continued as a single agent as adjuvant treatment after surgery.

KEYTRUDA, in combination with chemotherapy, is indicated for the treatment of patients with locally recurrent unresectable or metastatic TNBC whose tumors express PD-L1 (CPS ≥10) as determined by an FDA-approved test.

Merck’s focus on cancer

Our goal is to translate breakthrough science into innovative oncology medicines to help people with cancer worldwide. At Merck, the potential to bring new hope to people with cancer drives our purpose and supporting accessibility to our cancer medicines is our commitment. As part of our focus on cancer, Merck is committed to exploring the potential of immuno-oncology with one of the largest development programs in the industry across more than 30 tumor types. We also continue to strengthen our portfolio through strategic acquisitions and are prioritizing the development of several promising oncology candidates with the potential to improve the treatment of advanced cancers. For more information about our oncology clinical trials, visit www.merck.com/clinicaltrials.

About Merck

At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.merck.com and connect with us on Twitter, Facebook, Instagram, YouTube and LinkedIn.

SOURCE: Merck