Early Findings with Pembrolizumab, Merck's Investigational Anti-PD-1 Therapy, in Patients with Advanced Pleural Mesothelioma Presented at AACR Annual Meeting

Pembrolizumab Demonstrated 28 Percent Overall Response Rate and 76 Percent Disease Control Rate in Difficult-to-Treat Cancer

First Findings from KEYNOTE-028, Merck's Innovative Basket Trial in 20 Cancers

KIRKLAND, QC, April 19, 2015 /CNW Telbec/ - Merck (NYSE: MRK), known as MSD outside the United States and Canada, today announced the first presentation of data investigating the use of pembrolizumab, the company's investigational anti-PD-1 therapy, in 25 patients with advanced pleural mesothelioma, a difficult-to-treat cancer of the lining of the lungs, abdomen and other organs. The early findings presented showed an overall response rate (confirmed and unconfirmed) of 28 percent with pembrolizumab in patients with tumours that expressed PD-L1. Additionally, 48 percent of patients had stable disease, resulting in a disease control rate of 76 percent. These data, from KEYNOTE-028, will be presented today at the American Association for Cancer Research (AACR) Annual Meeting by Dr. Evan Alley, Abramson Cancer Center, University of Pennsylvania, and were part of the AACR official press program (abstract #CT103). This is the first data to be presented from KEYNOTE-028, Merck's innovative basket trial designed to evaluate the efficacy and safety of pembrolizumab in patients with 20 difficult-to-treat cancers.

"This presentation at AACR marks the first time that data involving an investigational anti-PD-1 therapy have been presented in pleural mesothelioma, which is a rare, hard-to-treat cancer with very limited treatment options," said Dr. Alley, clinical associate professor of medicine, Abramson Cancer Center. "While early, the disease control rates observed in this study are very encouraging, and indicate that further study is warranted to evaluate the potential role of pembrolizumab in the treatment of malignant pleural mesothelioma."

"This unique study is helping to accelerate our understanding of where pembrolizumab may work in cancers with limited or no treatment options," said Dr. Roger Dansey, therapeutic area head and senior vice president, oncology late stage development, Merck Research Laboratories. "These early data in advanced pleural mesothelioma reinforce the clinically meaningful results we are seeing with pembrolizumab across multiple cancers."

At the time of the analysis, 40 percent of patients (n=10/25) remained on treatment. Adverse events in the study were consistent with previously reported safety data for pembrolizumab. The most common treatment-related adverse events (occurring in greater than twenty percent of patients) were fatigue (24%) and nausea (24%). Two Grade 3 treatment-related adverse events occurred: ALT increased (n=1) and thrombocytopenia (n=1). Some patients experienced adverse events of special interest, including rash (n=4), ALT/AST increased (n=1), hypersensitivity (n=1) and iridocyclitis (n=1); two required a dose interruption (one because of ALT/AST increased, one because of iridocyclitis). No patients discontinued as a result of treatment-related adverse events, and there were no treatment-related deaths.

About the KEYNOTE-028 Study

KEYNOTE-028 is an ongoing, multi-cohort, non-randomized Phase 1b basket trial evaluating the safety, tolerability, and anti-tumour activity of pembrolizumab monotherapy (10 mg/kg dosed every two weeks) in 320 patients with PD-L1 positive advanced solid tumours that have not responded to current therapy or for which current therapy is not appropriate.

About Pembrolizumab

Pembrolizumab is a humanized monoclonal antibody that blocks the interaction between PD-1 and its ligands, PD-L1 and PD-L2. By binding to the PD-1 receptor and blocking the interaction with the receptor ligands, pembrolizumab releases the PD-1 pathway-mediated inhibition of the immune response, including the anti-tumour immune response.

Merck is advancing a broad and fast-growing clinical development program for pembrolizumab with more than 85 clinical trials – across more than 30 tumour types and over 14,000 patients – both as a monotherapy and in combination with other therapies.

About Malignant Mesothelioma1

Malignant mesotheliomas are cancers of a covering tissue that lines the lung, abdomen, heart and testes. There are four main types of mesotheliomas that are named based on where they develop: the chest (pleural mesotheliomas); the abdomen (peritoneal mesotheliomas); the covering around the heart (pericardial mesotheliomas); and the covering layer of the testicles (mesotheliomas of the tunica vaginalis). In 2010, 515 Canadians, (415 men and 95 women) were diagnosed with mesothelioma.  In 2009, 421 Canadians died from mesothelioma, (355 men, 66 women). The main risk factor for developing mesothelioma is exposure to asbestos; others include infection with simian virus 40 (SV40), older age (65 or older), and male gender.

Our Focus on Cancer

Our goal is to translate breakthrough science into biomedical innovations to help people with cancer worldwide. For Merck Oncology, helping people fight cancer is our passion, supporting accessibility to our cancer medicines is our commitment, and pursuing research in immuno-oncology is our focus to potentially bring new hope to people with cancer. For more information about our oncology clinical trials, visit www.merck.com/clinicaltrials.

About Merck

Today's Merck is a global healthcare leader working to help the world be well. Merck is known as MSD outside Canada and the United States. Through our prescription medicines, vaccines, biologic therapies, and consumer care and animal health products, we work with customers and operate in more than 140 countries to deliver innovative health solutions. We also demonstrate our commitment to increasing access to healthcare through far-reaching policies, programs and partnerships. For more information about our operations in Canada, visit www.merck.ca.

Forward-Looking Statement

This news release includes "forward-looking statements" within the meaning of the safe harbor provisions of the United States Private Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs and expectations of Merck's management and are subject to significant risks and uncertainties. There can be no guarantees with respect to pipeline products that the products will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements.

Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; Merck's ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of Merck's patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions.

Merck undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in Merck's 2014 Annual Report on Form 10-K and the company's other filings with the Securities and Exchange Commission (SEC) available at the SEC's Internet site (www.sec.gov).

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1 Canadian Cancer Society. Mesothelioma.  Retrieved on April 16, 2015 from https://www.cancer.ca/en/cancer-information/cancer-type/mesothelioma/risks/?region=on