First Presentation of Data for Pembrolizumab, Merck’s Investigational Anti-PD-1 Antibody, in Patients with Previously-Untreated, Advanced Non-Small Cell Lung Cancer (NSCLC) at ASCO 2014

Merck (NYSE:MRK), known as MSD outside the United States and Canada, today announced the first presentation of data evaluating pembrolizumab (MK-3475), Merck’s investigational anti-PD-1 antibody, as initial therapy in patients with PD-L1 positive, advanced non-small cell lung cancer (NSCLC). In previously-untreated patients, the objective response rate (ORR) (confirmed and unconfirmed) with pembrolizumab as a single-agent (monotherapy) was 47 percent by investigator-assessed, immune-related response criteria (irRC) (n=21/45: 95% CI, 32-62) and 26 percent by centrally evaluated RECIST v1.1 (Response Evaluation Criteria in Solid Tumors) (n=11/42: 95% CI, 14-42). In evaluable patients who had measurable disease with one post baseline scan, 80 percent demonstrated tumor shrinkage as measured by centrally evaluated RECIST criteria (n=28/35). The median duration of response has not been reached, with some patients continuing on treatment with pembrolizumab as monotherapy for at least one year.

These new data, from the company’s large ongoing Phase 1b study (KEYNOTE-001), will be presented today in an oral session by Dr. Naiyer Rizvi, medical oncologist, Thoracic Oncology Service, Memorial Sloan Kettering Cancer Center, at the 50th Annual Meeting of the American Society of Clinical Oncology (ASCO 2014) in Chicago (Abstract #8007; 3:00 PM CDT; Location – E Hall D2).

“These initial data show that early use of pembrolizumab as monotherapy provides robust anti-tumor activity in patients with previously-untreated, advanced non-small cell lung cancer,” said Dr. Rizvi. “Today, there are few options for people with advanced lung cancer and early data suggests that pembrolizumab, which activates the body’s immune system to target cancer cells, may be a promising new approach.”

First Data for Pembrolizumab as Initial Therapy in Advanced Lung Cancer

Data to be presented from a cohort of KEYNOTE-001, the largest Phase 1b study to date of an anti-PD-1 antibody, evaluated pembrolizumab monotherapy as initial therapy in patients with stage IV NSCLC who had no prior systemic therapy and whose tumors were assessed as positive for PD-L1 expression. As measured by Merck’s proprietary, immunohistochemistry (IHC) trial assay, tumors 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 tumor stroma. In the study cohort, 78 percent of evaluable advanced NSCLC patients were determined to be PD-L1 positive (n=57/73).

Objective Response Rates (ORR) and Disease Control Rates (DCR) in Advanced NSCLC, as Assessed by irRC and RECIST Criteria

Analysis cut-off date: 03 March 2014
Objective response rate = confirmed complete response and partial response
Disease control rate = complete response, partial response, and stable disease
13 patients did not have measurable disease by RECIST v1.1 per independent central review at baseline and were not evaluated for response using this criteria
†Includes confirmed and unconfirmed responses

At the time of analysis, 90 percent (n=19/21) and 100 percent (n=11/11) of overall responses (confirmed and unconfirmed) in evaluable patients were ongoing by irRC and RECIST criteria, respectively. None of the responders discontinued treatment due to progression of disease. The interim, median progression-free survival (PFS) was 37 weeks by irRC (95% CI, 27.0-NR) and 27 weeks by RECIST (95% CI, 13.6-45.0). The interim, median duration of treatment among evaluable patients with ongoing responses was 27.1 weeks based on both measurement criteria (irRC range, 6.1 – 57.1+) (RECIST range, 15.0+ - 48.3+).

Adverse events were consistent with previously reported data for pembrolizumab. The most common investigator-assessed, treatment-related, adverse events (greater than 5 percent) included fatigue (22%), pruritus (13%), hypothyroidism (9%), dermatitis acneiform (7%), diarrhea (7%), dyspnea (7%), and rash (7%). Investigator-designated, treatment-related, adverse events resulting in discontinuation were pneumonitis (one grade 3) and acute kidney injury (one grade 2). Other investigator-designated, treatment-related, adverse events included pericardial effusion (one grade 3) and elevated blood creatine phosphokinase levels (one grade 4).

New Studies in PD-L1 Positive, Advanced Lung Cancer

Based on these data, Merck has enrolled 50 additional patients in the KEYNOTE-001 study with previously-untreated, advanced NSCLC with PD-L1 positive-staining tumors. For this cohort, cut points of greater than or equal to one percent and 50 percent tumor cells stained will be evaluated as part of the efficacy analysis. Additionally, Merck plans to initiate a Phase 3 study (KEYNOTE-024) evaluating pembrolizumab monotherapy versus platinum-based doublet chemotherapy (cisplatin, carboplatin combined with either: docetaxel, paclitaxel, vinorelbine, gemcitabine or irinotecan) in previously-untreated patients with PD-L1 positive, advanced NSCLC in September 2014.

“As clinical experience with pembrolizumab grows in advanced non-small cell lung cancer we are seeing durable responses across multiple lines of therapy, including in the first-line treatment setting,” said, Dr. Roy Baynes, senior vice president, Global Clinical Development, Merck Research Laboratories. “Exploring the clinical utility of tumor characteristics, such as expression of PD-L1 as a potential marker for patient selection or study enrichment, is an important part of our research program in this disease.”

Additional Advanced Lung Cancer Data at ASCO 2014

New data evaluating pembrolizumab in previously-treated NSCLC including findings from an additional study cohort will be presented in a poster discussion on Tuesday, June 3 (Abstract #8020; 8:00 AM CDT; Location – E354b). For more information about data in advanced NSCLC, see the ASCO iPlanner: https://iplanner.asco.org/am2014.

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 also can also listen to the event by dialing (866) 486-2604 or (706) 902-0743 and using ID code number 53194490.

About the KEYNOTE-001 Study

The Phase 1b trial (KEYNOTE-001) is an ongoing multi-center, single-arm, open-label study evaluating pembrolizumb monotherapy in more than 1,000 patients with diverse late-stage cancers (metastatic carcinoma) – predominantly lung and melanoma. Three dosing regimens of pembrolizumab were evaluated, including 10mg/kg every two weeks, 10mg/kg every three weeks or 2mg/kg every three weeks. The primary endpoint of the study includes overall response rate (ORR) and safety; the secondary endpoints include progression-free survival (PFS), overall survival (OS) and duration of response. Tumor response in advanced NSCLC was evaluated every 9 weeks by investigator-assessed, immune-related response criteria (irRC), and by independent, central, blinded radiographic review per RECIST 1.1 (Response Evaluation Criteria in Solid Tumors).

About Pembrolizumab in Advanced Lung Cancer

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 the PD-1 pathway.

Pembrolizumab is being evaluated across more than 30 types of cancers, as monotherapy and in combination. Merck is advancing a clinical program in advanced NSCLC evaluating pembrolizumab as monotherapy and in combination across lines of therapy, and is exploring different tumor characteristics such as PD-L1 expression as predictors of responsiveness. For information about Merck’s oncology clinical studies, please click here.

About Lung Cancer

Lung cancer has been the most common cancer in the world, other than skin cancer. In the U.S. there will be an estimated 159,260 deaths from lung cancer in 2014. Lung cancer is divided into two major types: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). NSCLC is the most common type of lung cancer – accounting for > 85 percent of all lung cancers.

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 an early and late-stage 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.

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