First Presentation of Early Data for Pembrolizumab (MK-3475), Merck’s Investigational Anti-PD-1 Antibody, in Advanced Head and Neck Cancer at ASCO 2014

Merck (NYSE:MRK), known as MSD outside the United States and Canada, today announced the first presentation of early findings from a Phase 1b study (KEYNOTE-012) evaluating pembrolizumab (MK-3475), Merck’s investigational anti-PD-1 antibody, as a single-agent (monotherapy) in patients with PD-L1 positive, advanced head and neck cancer. Early data showed a best overall response rate of 20 percent (confirmed and unconfirmed) (n=11/56) (95% CI, 10.2- 32.4) with 29 percent of patients having stable disease as measured by RECIST criteria (n=16/56) (95% CI, 17.3-42.2). Similar overall response rates were observed in Human papillomavirus (HPV)-positive and HPV-negative patients – HPV infection is a risk factor for some types of head and neck cancer. In the study, tumor shrinkage was demonstrated in 51 percent of evaluable patients who had measurable disease with one post baseline scan, per RECIST criteria (n=26/51).

These early findings will be presented today in an oral session by Dr. Tanguy Seiwert, associate director of the Head and Neck Cancer Program and assistant professor of medicine at The University of Chicago, at the 50th Annual Meeting of the American Society of Clinical Oncology (ASCO 2014) in Chicago (Abstract #6011; Sunday, June 1; 11:30AM CDT; Location – S100bc).

“Recurrent and metastatic head and neck cancer carries a very poor prognosis, and often is accompanied by poor quality of life and disfigurement. Additional treatment options are urgently needed,” said Dr. Seiwert. “These early response data with pembrolizumab as monotherapy provide an encouraging proof of concept and support further study of this novel investigational immunotherapy in this hard-to-treat cancer type.”

“We continue to observe robust signals of anti-tumor activity in response to pembrolizumab monotherapy across multiple tumor types and lines of therapy, including these data in head and neck cancer,” said Dr. Roy Baynes, senior vice president, global clinical development, Merck Research Laboratories. “The breadth of data to be presented at ASCO underscores why Merck is advancing a broad development program for pembrolizumab across more than 30 tumor types, including late-stage studies in head and neck and other cancers.”

Early Findings for Pembrolizumab in Advanced Head and Neck Cancer

Data to be presented from a cohort of KEYNOTE-012, a Phase 1b study across four solid tumor types, evaluated pembrolizumab monotherapy dosed at 10 mg/kg every two weeks in patients with advanced (locally recurrent and/or distant metastatic) head and neck cancer whose tumors were assessed as positive for PD-L1 expression using Merck’s proprietary immunohistochemistry (IHC) trial assay. Fifty-six patients were evaluable for response, of which 20 tested positive for HPV, 36 tested negative (or were unevaluable) for HPV. The majority of patients studied had received two or more prior lines of therapy.

Best Overall Response Rates in Advanced Head and Neck Cancer

Of advanced head and neck patients screened, 78 percent (n=81/104) were classified as PD-L1 positive based on greater than or equal to one percent of tumor cells demonstrating expression of the PD-L1 marker, or any positive staining with the same reagent in the tumor stroma. Employing a preliminary assay cut-point, evidence of a relationship was observed for the level of PD-L1 staining and the overall response rate (above cut-point: 45 percent (n=5/11); below cut-point: 11 percent (n=5/44)).

Adverse events reported were consistent with previously reported data on pembrolizumab. The most common treatment-related adverse events (occurring in greater than or equal to 5% of patients) included fatigue (17%), pruritus (10%), rash (7%), nausea (7%), myalgia (5%), and decreased appetite (5%). There was one treatment-related grade 3 rash reported.

New Nonproprietary Name: Pembrolizumab

Merck recently announced the nonproprietary name for MK-3475 is pembrolizumab. This follows the review of pembrolizumab by both the United States Adopted Names Council and the International Nonproprietary Names Programme of the World Health Organization. Pembrolizumab replaces the previously proposed name, lambrolizumab.

Merck Oncology Briefing Webcast

Merck will hold a webcast in conjunction with ASCO 2014 on June 2 at 6:15 p.m. CDT. Investors and journalists may access a live audio webcast of the event on Merck’s website at www.merck.com. Software needed to listen to the webcast is available on the corporate website and should be downloaded prior to the beginning of the webcast. Institutional investors, analysts and members of the media can also listen to the event by dialing (866) 486-2604 or (706) 902-0743 and using ID code number 53194490.

About the KEYNOTE-012 Study

KEYNOTE-012 is an ongoing multi-center, non-randomized Phase 1b trial evaluating the safety, tolerability and anti-tumor activity of pembrolizumab monotherapy in patients with advanced triple negative breast cancer (TNBC), advanced head and neck cancer, advanced urothelial cancer, or advanced gastric cancer. Two dosing regimens of pembrolizumab are being evaluated, 10mg/kg every 2 weeks and 200 mg IV once every 3 weeks. The primary endpoints of the study include overall safety and tolerability, and anti-tumor activity (as measured by RECIST 1.1 [Response Evaluation Criteria in Solid Tumors]) in PD-L1 positive tumors; secondary endpoints include progression-free survival (PFS), overall survival (OS), duration of response and subgroup analyses by HPV status.

An additional 110 patients with advanced head and neck cancer are planned to be enrolled in KEYNOTE-012. Analyses of tumor PD-L1 levels are planned.

About Pembrolizumab

Pembrolizumab (MK-3475) is an investigational selective, humanized monoclonal anti-PD-1 antibody designed to block the interaction of PD-1 on T-cells with its ligands, PD-L1 and PD-L2, to reactivate anti-tumor immunity. Pembrolizumab exerts dual ligand blockade of PD-1 pathway.

Today, pembrolizumab is being evaluated across more than 30 types of cancers, as monotherapy and in combination. It is anticipated that by the end of 2014, the pembrolizumab development program will grow to more than 24 clinical trials across 30 different tumor types, enrolling an estimated 6,000 patients at nearly 300 clinical trial sites worldwide, including new Phase 3 studies in head and neck and other cancers. For information about Merck’s oncology clinical studies, please click here.

The Biologics License Application (BLA) for pembrolizumab is under priority review with the U.S. Food and Drug Administration (FDA) for the proposed indication for the treatment of patients with advanced melanoma previously-treated with ipilimumab; the PDUFA date is October 28, 2014. Pembrolizumab has been granted FDA’s Breakthrough Therapy designation for advanced melanoma. If approved by the FDA, pembrolizumab has the potential to be the first PD-1 immune checkpoint modulator approved in this class. The company plans to file a Marketing Authorization Application in Europe for pembrolizumab for advanced melanoma in 2014.

About Head and Neck Cancer

Head and neck cancers are a related group of cancers that involve the oral cavity, pharynx and larynx. Most head and neck cancers are squamous cell carcinomas that begin in the flat, squamous cells that make up the thin surface layer (epithelium) of the head and neck (called the). The leading risk factors for head and neck cancer include tobacco and alcohol use. Infection with certain types of HPV, also called human papillomaviruses, is a risk factor for some types of head and neck cancer, specifically cancer of the oropharynx, which is the middle part of the throat including the soft palate, the base of the tongue, and the tonsils. Each year there are approximately 400,000 cases of cancer of the oral cavity and pharynx, with 160,000 cancers of the larynx, resulting in approximately 300,000 deaths.

About Merck Oncology: A Focus on Immuno-Oncology

At Merck Oncology, our goal is to translate breakthrough science into biomedical innovations to help people with cancer worldwide. Harnessing immune mechanisms to fight cancer is the priority focus of our oncology research and development program. The Company is advancing a pipeline of immunotherapy candidates and combination regimens. Cancer is one of the world's most urgent unmet medical needs. Helping to empower people to fight cancer is our passion. For information about Merck’s commitment to Oncology visit the Oncology Information Center at http://www.mercknewsroom.com/oncology-infocenter.

About Merck

Today's Merck is a global healthcare leader working to help the world be well. Merck is known as MSD outside the United States and Canada. 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, visit www.merck.com and connect with us on Twitter, Facebook and YouTube.

Forward-Looking Statement

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