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April 15, 2018 8:30 am ET

KEYTRUDA is First Anti-PD-1 Therapy to Show Recurrence-Free Survival (RFS) Benefit Across Stage IIIA (> 1 mm Lymph Node Metastasis), IIIB and IIIC Melanoma

EORTC1325/KEYNOTE-054 Results Presented Today in Opening Plenary at AACR 2018 and Published in The New England Journal of Medicine

Merck (NYSE:MRK), known as MSD outside the United States and Canada, and
the European Organisation for Research and Treatment of Cancer (EORTC),
today announced findings from the Phase 3 EORTC1325/KEYNOTE-054 trial
investigating KEYTRUDA^®, Merck’s anti-PD-1 therapy, as
adjuvant therapy in resected, high-risk stage III melanoma. Study
results showed KEYTRUDA significantly prolonged recurrence-free survival
(RFS), reducing the risk of disease recurrence or death by 43 percent
compared to placebo in the overall study population (HR=0.57 [98.4% CI,
0.43-0.74]; p<0.0001). For the primary endpoint of RFS in the overall
study population, the one-year RFS rate was 75.4 percent (95% CI,
71.3-78.9) for KEYTRUDA compared to 61.0 percent (95% CI, 56.5-65.1) for
placebo. For the co-primary endpoint of RFS in patients whose tumors
were considered PD-L1 positive, KEYTRUDA demonstrated significantly
prolonged RFS compared to placebo (HR=0.54; 95% CI, 0.42-0.69;
p<0.0001). The safety profile of KEYTRUDA was consistent with what has
been seen in previous trials among patients with advanced melanoma.
These results are being presented today for the first time in the
opening plenary session at the American Association for Cancer Research
(AACR) Annual Meeting 2018 (Abstract #10526), with simultaneous
publication in The New England Journal of Medicine.

“The EORTC is very pleased to have collaborated with Merck on this
important study which showed a significant recurrence-free survival
benefit across all stage III melanoma,” said Alexander Eggermont, study
chair, director general at the Gustave Roussy Cancer Institute,
professor of oncology, University of Paris-Saclay.

“These data demonstrate compelling evidence that adjuvant treatment with
KEYTRUDA provides significant recurrence-free survival benefit after
surgery in patients with high-risk Stage III melanoma,” said Roy Baynes,
M.D., Ph.D., senior vice president and head of Global Clinical
Development, chief medical officer, Merck Research Laboratories. “These
are the first data for KEYTRUDA in the adjuvant setting and mark an
important advancement for the treatment of resected stage III melanoma.
We are pleased to be sharing these data with global regulatory
authorities.”

KEYTRUDA is the first anti-PD-1 therapy to show RFS benefit across stage
IIIA (> 1 mm lymph node metastasis), IIIB and IIIC melanoma. The RFS
benefit was also seen regardless of BRAF mutation status (HR=0.64
[99% CI, 0.42-0.96] for patients with wild-type BRAF status;
HR=0.57 [99% CI, 0.37-0.89] for patients with mutant BRAF
status). As previously announced, Merck is working to submit data from
EORTC1325/KEYNOTE-054 to regulatory agencies in the U.S. and around the
world.

“As an organization dedicated to eliminating melanoma suffering and
death, we are thrilled to see these important new data on KEYTRUDA,”
said Louise M. Perkins, Ph.D., chief science officer, Melanoma Research
Alliance. “The ability to significantly prevent melanoma from coming
back after surgery, along with a demonstrated safety profile, makes this
a welcome development in the fight against melanoma.”

Merck has a broad clinical development program in melanoma with KEYTRUDA
as monotherapy and in combination with other novel mechanisms. The
program, which is comprised of more than 4,500 patients across 10
clinical studies, is evaluating KEYTRUDA across all settings and stages
of the disease.

Additional Data and Safety Information from EORTC1325/KEYNOTE-054
(Abstract #10526)

EORTC 1325/KEYNOTE-054 is a randomized, double-blind, Phase 3 study
(ClinicalTrials.gov, NCT02362594) sponsored by Merck and conducted in
collaboration with the EORTC. The study is evaluating adjuvant therapy
with KEYTRUDA compared to placebo in patients with resected high-risk
melanoma (stage IIIA [> 1 mm lymph node metastasis], IIIB and IIIC). In
total, the study enrolled 1,019 patients who were randomly assigned to
receive either an intravenous infusion of KEYTRUDA 200 mg (n=514) or
placebo (n=505) every three weeks for up to 1 year (a total of 18
doses). Upon documented recurrence, patients were eligible for
cross-over/re-challenge with KEYTRUDA. Co-primary endpoints were RFS for
all patients and RFS in patients whose tumors express PD-L1; secondary
endpoints include distant metastases-free survival and overall survival
(OS) in all patients and in patients whose tumors express PD-L1. RFS was
defined as the time from randomization until the date of first
recurrence (local, regional or distant metastasis) or death from any
cause. In accordance with the trial protocol, the study is continuing in
order to evaluate secondary endpoints including OS.

With an overall median follow-up of 15.1 months, in the overall
intent-to-treat population the 12-month RFS rate was 75.4 percent (95%
CI, 71.3-78.9) in the KEYTRUDA group and 61.0 percent (95% CI,
56.5-65.1) in the placebo group. RFS was significantly prolonged,
resulting in reduced risk of recurrence or death of 43 percent with
KEYTRUDA (HR=0.57; 98.4% CI, 0.43-0.74; p<0.0001) compared to placebo.
At 18 months, the RFS rates were 71.4 percent (95% CI, 66.8-75.4) and
53.2 percent (95% CI, 47.9-58.2), respectively.

In patients with PD-L1 positive tumors (n=853), the 12-month RFS rate
was 77.1 percent (95% CI, 72.7-80.9) in the KEYTRUDA group and 62.6
percent (95% CI, 57.7-67.0) in the placebo group. In these patients, RFS
was significantly longer, resulting in reduced risk of recurrence or
death of 46 percent with KEYTRUDA (HR=0.54; 95% CI, 0.42-0.69; p<0.0001)
compared to placebo. RFS benefit demonstrated with KEYTRUDA was
consistent in patients with PD-L1-negative tumors and in those with an
undetermined tumor PD-L1 expression.

In addition, RFS benefit seen with KEYTRUDA was similar across other
subgroups including stage of disease and nodal involvement; BRAF-status,
sex and baseline body mass index did not significantly influence the
treatment difference.

The safety profile of KEYTRUDA was consistent with what has been seen in
previously reported studies among patients with advanced melanoma.
Drug-related grade 3 to 5 adverse events were reported in 14.7 percent
of patients in the KEYTRUDA group and 3.4 percent in patients in the
placebo group. The most common treatment-related adverse events (TRAEs)
for KEYTRUDA were fatigue or asthenia (37.1%), skin reactions (28.3%),
diarrhea (19.1%), arthralgia (12.0%), and nausea (11.4%). The highest
incidence of immune-related adverse events (irAEs), mostly grade 1 to 2,
were endocrine disorders (most commonly hypothyroidism [14.3%],
hyperthyroidism [10.2%], and thyroiditis [3.1%]). The incidence of grade
3-5 irAEs was 7.1 percent and included colitis (2.0%), pneumonitis
(0.8%), and hepatitis (1.4%); all others had incidences ≤ 1 percent.
There was one death due to myositis in the KEYTRUDA group.

About EORTC

The European Organisation for Research and Treatment of Cancer (EORTC)
unites cancer clinical research experts to define better treatments for
cancer patients to prolong survival and improve quality of life. Both
international and multidisciplinary, EORTC’s Network comprises over 4600
collaborators involved in cancer treatment and research in more than 800
hospitals across 35 countries. Through translational and clinical
research, EORTC offers an integrated approach to therapeutic strategies,
drug evaluation programs, survivorship issues, and quality of life.
EORTC Headquarters, a unique international clinical research
infrastructure, is based in Brussels, Belgium, from where its various
activities are coordinated and run.

About Melanoma

Melanoma, the most serious form of skin cancer, is characterized by the
uncontrolled growth of pigment-producing cells. The incidence of
melanoma has been increasing over the past four decades – approximately
232,000 new cases were diagnosed worldwide in 2012. In the U.S.,
melanoma is one of the most common types of cancer diagnosed and is
responsible for the vast majority of skin cancer deaths. In 2018, an
estimated 91,270 people are expected to be diagnosed and an estimated
9,320 people are expected to die of the disease in the U.S. alone.

Merck Investor Webcast

Merck will hold a live investor audio webcast in conjunction with the
2018 AACR Annual Meeting on Monday, April 16 at 6:45 p.m. CDT (7:45 p.m.
EDT). Those interested in participating can register and join here.

About KEYTRUDA

^®

(pembrolizumab) Injection
100mg

KEYTRUDA is an anti-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, which currently involves more than 700 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.

KEYTRUDA

^®

(pembrolizumab) Indications and
Dosing

Melanoma

KEYTRUDA is indicated for the treatment of patients with unresectable or
metastatic melanoma at a fixed dose of 200 mg every three weeks until
disease progression or unacceptable toxicity.

Lung Cancer

KEYTRUDA, as a single agent, is indicated for the first-line treatment
of patients with metastatic non-small cell lung cancer (NSCLC) whose
tumors have high PD-L1 expression [tumor proportion score (TPS) ≥50%] as
determined by an FDA-approved test, with no EGFR or ALK genomic tumor
aberrations.

KEYTRUDA, as a single agent, is also 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, in combination with pemetrexed and carboplatin, is indicated
for the first-line treatment of patients with metastatic nonsquamous
NSCLC. This indication is approved under accelerated approval based on
tumor response rate and progression-free survival. Continued approval
for this indication may be contingent upon verification and description
of clinical benefit in the confirmatory trials.

In metastatic NSCLC, KEYTRUDA is administered at a fixed dose of 200 mg
every three weeks until disease progression, unacceptable toxicity, or
up to 24 months in patients without disease progression.

When administering KEYTRUDA in combination with chemotherapy, KEYTRUDA
should be administered prior to chemotherapy when given on the same day.
See also the Prescribing Information for pemetrexed and carboplatin.

Head and Neck Cancer

KEYTRUDA is indicated for the treatment of patients with recurrent or
metastatic head and neck squamous cell carcinoma (HNSCC) with disease
progression on or after platinum-containing chemotherapy. 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. In HNSCC, KEYTRUDA is
administered at a fixed dose of 200 mg every three weeks until disease
progression, unacceptable toxicity, or up to 24 months in patients
without disease progression.

Classical Hodgkin Lymphoma

KEYTRUDA is indicated for the treatment of adult and pediatric patients
with refractory classical Hodgkin lymphoma (cHL), or who have relapsed
after three or more prior lines of therapy. 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. In adults with cHL, KEYTRUDA is administered at a
fixed dose of 200 mg every three weeks until disease progression or
unacceptable toxicity, or up to 24 months in patients without disease
progression. In pediatric patients with cHL, KEYTRUDA is administered at
a dose of 2 mg/kg (up to a maximum of 200 mg) every three weeks until
disease progression or unacceptable toxicity, or up to 24 months in
patients without disease progression.

Urothelial Carcinoma

KEYTRUDA is indicated for the treatment of patients with locally
advanced or metastatic urothelial carcinoma who are not eligible for
cisplatin-containing chemotherapy. This indication is approved under
accelerated approval based on tumor response rate and duration of
response. Continued approval for this indication may be contingent upon
verification and description of clinical benefit in the confirmatory
trials.

KEYTRUDA is also indicated for the treatment of patients with locally
advanced or metastatic urothelial carcinoma who have disease progression
during or following platinum-containing chemotherapy or within 12 months
of neoadjuvant or adjuvant treatment with platinum-containing
chemotherapy.

In locally advanced or metastatic urothelial carcinoma, KEYTRUDA is
administered at a fixed dose of 200 mg every three weeks until disease
progression or unacceptable toxicity, or up to 24 months in patients
without disease progression.

Microsatellite Instability-High (MSI-H) 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 that have progressed following prior treatment and who
  have no satisfactory alternative treatment options, or
• colorectal cancer that has progressed following treatment with
  fluoropyrimidine, oxaliplatin, and irinotecan.

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.

In adult patients with MSI-H cancer, KEYTRUDA is administered at a fixed
dose of 200 mg every three weeks until disease progression, unacceptable
toxicity, or up to 24 months in patients without disease progression. In
children with MSI-H cancer, KEYTRUDA is administered at a dose of 2
mg/kg (up to a maximum of 200 mg) every three weeks until disease
progression or unacceptable toxicity, or up to 24 months in patients
without disease progression.

Gastric Cancer

KEYTRUDA is indicated for the treatment of patients with recurrent
locally advanced or metastatic gastric or gastroesophageal junction
(GEJ) adenocarcinoma whose tumors express PD-L1 [Combined Positive Score
(CPS) ≥1] as determined by an FDA-approved test, with disease
progression on or after two or more prior lines of therapy including
fluoropyrimidine- and platinum-containing chemotherapy and if
appropriate, HER2/neu-targeted therapy. 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 recommended dose of KEYTRUDA is 200 mg every
three weeks until disease progression, unacceptable toxicity, or up to
24 months in patients without disease progression.

Selected Important Safety Information for KEYTRUDA

^®

KEYTRUDA can cause immune-mediated pneumonitis, including fatal cases.
Pneumonitis occurred in 94 (3.4%) of 2799 patients receiving KEYTRUDA,
including Grade 1 (0.8%), 2 (1.3%), 3 (0.9%), 4 (0.3%), and 5 (0.1%)
pneumonitis, and occurred more frequently in patients with a history of
prior thoracic radiation (6.9%) compared to those without (2.9%).
Monitor patients for signs and symptoms of pneumonitis. Evaluate
suspected pneumonitis with radiographic imaging. Administer
corticosteroids for Grade 2 or greater pneumonitis. Withhold KEYTRUDA
for Grade 2; permanently discontinue KEYTRUDA for Grade 3 or 4 or
recurrent Grade 2 pneumonitis.

KEYTRUDA can cause immune-mediated colitis. Colitis occurred in 48
(1.7%) of 2799 patients receiving KEYTRUDA, including Grade 2 (0.4%), 3
(1.1%), and 4 (<0.1%) colitis. Monitor patients for signs and symptoms
of colitis. Administer corticosteroids for Grade 2 or greater colitis.
Withhold KEYTRUDA for Grade 2 or 3; permanently discontinue KEYTRUDA for
Grade 4 colitis.

KEYTRUDA can cause immune-mediated hepatitis. Hepatitis occurred in 19
(0.7%) of 2799 patients receiving KEYTRUDA, including Grade 2 (0.1%), 3
(0.4%), and 4 (<0.1%) hepatitis. Monitor patients for changes in liver
function. Administer corticosteroids for Grade 2 or greater hepatitis
and, based on severity of liver enzyme elevations, withhold or
discontinue KEYTRUDA.

KEYTRUDA can cause hypophysitis. Hypophysitis occurred in 17 (0.6%) of
2799 patients receiving KEYTRUDA, including Grade 2 (0.2%), 3 (0.3%),
and 4 (<0.1%) hypophysitis. Monitor patients for signs and symptoms of
hypophysitis (including hypopituitarism and adrenal insufficiency).
Administer corticosteroids and hormone replacement as clinically
indicated. Withhold KEYTRUDA for Grade 2; withhold or discontinue for
Grade 3 or 4 hypophysitis.

KEYTRUDA can cause thyroid disorders, including hyperthyroidism,
hypothyroidism, and thyroiditis. Hyperthyroidism occurred in 96 (3.4%)
of 2799 patients receiving KEYTRUDA, including Grade 2 (0.8%) and 3
(0.1%) hyperthyroidism. Hypothyroidism occurred in 237 (8.5%) of 2799
patients receiving KEYTRUDA, including Grade 2 (6.2%) and 3 (0.1%)
hypothyroidism. The incidence of new or worsening hypothyroidism was
higher in patients with HNSCC, occurring in 28 (15%) of 192 patients
with HNSCC, including Grade 3 (0.5%) hypothyroidism. Thyroiditis
occurred in 16 (0.6%) of 2799 patients receiving KEYTRUDA, including
Grade 2 (0.3%) thyroiditis. Monitor patients for changes in thyroid
function (at the start of treatment, periodically during treatment, and
as indicated based on clinical evaluation) and for clinical signs and
symptoms of thyroid disorders. Administer replacement hormones for
hypothyroidism and manage hyperthyroidism with thionamides and
beta-blockers as appropriate. Withhold or discontinue KEYTRUDA for Grade
3 or 4 hyperthyroidism.

KEYTRUDA can cause type 1 diabetes mellitus, including diabetic
ketoacidosis, which have been reported in 6 (0.2%) of 2799 patients.
Monitor patients for hyperglycemia or other signs and symptoms of
diabetes. Administer insulin for type 1 diabetes, and withhold KEYTRUDA
and administer antihyperglycemics in patients with severe hyperglycemia.

KEYTRUDA can cause immune-mediated nephritis. Nephritis occurred in 9
(0.3%) of 2799 patients receiving KEYTRUDA, including Grade 2 (0.1%), 3
(0.1%), and 4 (<0.1%) nephritis. Monitor patients for changes in renal
function. Administer corticosteroids for Grade 2 or greater nephritis.
Withhold KEYTRUDA for Grade 2; permanently discontinue KEYTRUDA for
Grade 3 or 4 nephritis.

Immune-mediated rashes, including Stevens-Johnson syndrome (SJS), toxic
epidermal necrolysis (TEN) (some cases with fatal outcome), exfoliative
dermatitis, and bullous pemphigoid, can occur. Monitor patients for
suspected severe skin reactions and based on the severity of the adverse
reaction, withhold or permanently discontinue KEYTRUDA and administer
corticosteroids. For signs or symptoms of SJS or TEN, withhold KEYTRUDA
and refer the patient for specialized care for assessment and treatment.
If SJS or TEN is confirmed, permanently discontinue KEYTRUDA.

KEYTRUDA can cause other clinically important immune-mediated adverse
reactions. These immune-mediated reactions may occur in any organ
system. For suspected immune-mediated adverse reactions, ensure adequate
evaluation to confirm etiology or exclude other causes. Based on the
severity of the adverse reaction, withhold KEYTRUDA and administer
corticosteroids. Upon improvement to Grade 1 or less, initiate
corticosteroid taper and continue to taper over at least 1 month. Based
on limited data from clinical studies in patients whose immune-related
adverse reactions could not be controlled with corticosteroid use,
administration of other systemic immunosuppressants can be considered.
Resume KEYTRUDA when the adverse reaction remains at Grade 1 or less
following corticosteroid taper. Permanently discontinue KEYTRUDA for any
Grade 3 immune-mediated adverse reaction that recurs and for any
life-threatening immune-mediated adverse reaction.

The following clinically significant immune-mediated adverse reactions
occurred in less than 1% (unless otherwise indicated) of 2799 patients:
arthritis (1.5%), uveitis, myositis, Guillain-Barré syndrome, myasthenia
gravis, vasculitis, pancreatitis, hemolytic anemia, and partial seizures
arising in a patient with inflammatory foci in brain parenchyma. In
addition, myelitis and myocarditis were reported in other clinical
trials, including classical Hodgkin lymphoma, and postmarketing use.

Solid organ transplant rejection has been reported in postmarketing use
of KEYTRUDA. Treatment with KEYTRUDA may increase the risk of rejection
in solid organ transplant recipients. Consider the benefit of treatment
with KEYTRUDA vs the risk of possible organ rejection in these patients.

KEYTRUDA can cause severe or life-threatening infusion-related
reactions, including hypersensitivity and anaphylaxis, which have been
reported in 6 (0.2%) of 2799 patients. Monitor patients for signs and
symptoms of infusion-related reactions, including rigors, chills,
wheezing, pruritus, flushing, rash, hypotension, hypoxemia, and fever.
For Grade 3 or 4 reactions, stop infusion and permanently discontinue
KEYTRUDA.

Immune-mediated complications, including fatal events, occurred in
patients who underwent allogeneic hematopoietic stem cell
transplantation (HSCT) after being treated with KEYTRUDA. Of 23 patients
with cHL who proceeded to allogeneic HSCT after treatment with KEYTRUDA
on any trial, 6 patients (26%) developed graft-versus-host disease
(GVHD), one of which was fatal, and 2 patients (9%) developed severe
hepatic veno-occlusive disease (VOD) after reduced-intensity
conditioning, one of which was fatal. Cases of fatal hyperacute GVHD
after allogeneic HSCT have also been reported in patients with lymphoma
who received a PD-1 receptor–blocking antibody before transplantation.

These complications may occur despite intervening therapy between PD-1
blockade and allogeneic HSCT. Follow patients closely for early evidence
of transplant-related complications such as hyperacute GVHD, severe
(Grade 3 to 4) acute GVHD, steroid-requiring febrile syndrome, hepatic
VOD, and other immune-mediated adverse reactions, and intervene promptly.

In clinical trials in patients with multiple myeloma, the addition of
KEYTRUDA to a thalidomide analogue plus dexamethasone resulted in
increased mortality. Treatment of these patients with a PD-1 or PD-L1
blocking antibody in this combination is not recommended outside of
controlled clinical trials.

Based on its mechanism of action, KEYTRUDA can cause fetal harm when
administered to a pregnant woman. If used during pregnancy, or if the
patient becomes pregnant during treatment, apprise the patient of the
potential hazard to a fetus. Advise females of reproductive potential to
use highly effective contraception during treatment and for 4 months
after the last dose of KEYTRUDA.

In KEYNOTE-006, KEYTRUDA was discontinued due to adverse reactions in 9%
of 555 patients with advanced melanoma; adverse reactions leading to
discontinuation in more than one patient were colitis (1.4%), autoimmune
hepatitis (0.7%), allergic reaction (0.4%), polyneuropathy (0.4%), and
cardiac failure (0.4%). Adverse reactions leading to interruption of
KEYTRUDA occurred in 21% of patients; the most common (≥1%) was diarrhea
(2.5%). The most common adverse reactions with KEYTRUDA vs ipilimumab
were fatigue (28% vs 28%), diarrhea (26% with KEYTRUDA), rash (24% vs
23%), and nausea (21% with KEYTRUDA). Corresponding incidence rates are
listed for ipilimumab only for those adverse reactions that occurred at
the same or lower rate than with KEYTRUDA.

In KEYNOTE-010, KEYTRUDA monotherapy was discontinued due to adverse
reactions in 8% of 682 patients with metastatic NSCLC. The most common
adverse event resulting in permanent discontinuation of KEYTRUDA was
pneumonitis (1.8%). Adverse reactions leading to interruption of
KEYTRUDA occurred in 23% of patients; the most common (≥1%) were
diarrhea (1%), fatigue (1.3%), pneumonia (1%), liver enzyme elevation
(1.2%), decreased appetite (1.3%), and pneumonitis (1%). The most common
adverse reactions (occurring in at least 20% of patients and at a higher
incidence than with docetaxel) were decreased appetite (25% vs 23%),
dyspnea (23% vs 20%), and nausea (20% vs 18%).

In KEYNOTE-021(G1), when KEYTRUDA was administered in combination with
carboplatin and pemetrexed (carbo/pem) in advanced nonsquamous NSCLC,
KEYTRUDA was discontinued in 10% of 59 patients. The most common adverse
reaction resulting in discontinuation of KEYTRUDA (≥2%) was acute kidney
injury (3.4%). Adverse reactions leading to interruption of KEYTRUDA
occurred in 39% of patients; the most common (≥2%) were fatigue (8%),
neutrophil count decreased (8%), anemia (5%), dyspnea (3.4%), and
pneumonitis (3.4%). The most common adverse reactions (≥20%) with
KEYTRUDA compared to carbo/pem alone were fatigue (71% vs 50%), nausea
(68% vs 56%), constipation (51% vs 37%), rash (42% vs 21%), vomiting
(39% vs 27%), dyspnea (39% vs 21%), diarrhea (37% vs 23%), decreased
appetite (31% vs 23%), headache (31% vs 16%), cough (24% vs 18%),
dizziness (24% vs 16%), insomnia (24% vs 15%), pruritus (24% vs 4.8%),
peripheral edema (22% vs 18%), dysgeusia (20% vs 11%), alopecia (20% vs
3.2%), upper respiratory tract infection (20% vs 3.2%), and arthralgia
(15% vs 24%). This study was not designed to demonstrate a statistically
significant difference in adverse reaction rates for KEYTRUDA as
compared to carbo/pem alone for any specified adverse reaction.

In KEYNOTE-012, KEYTRUDA was discontinued due to adverse reactions in
17% of 192 patients with HNSCC. Serious adverse reactions occurred in
45% of patients. The most frequent serious adverse reactions reported in
at least 2% of patients were pneumonia, dyspnea, confusional state,
vomiting, pleural effusion, and respiratory failure. The most common
adverse reactions (reported in at least 20% of patients) were fatigue,
decreased appetite, and dyspnea. Adverse reactions occurring in patients
with HNSCC were generally similar to those occurring in patients with
melanoma or NSCLC, with the exception of increased incidences of facial
edema (10% all Grades; 2.1% Grades 3 or 4) and new or worsening
hypothyroidism.

In KEYNOTE-087, KEYTRUDA was discontinued due to adverse reactions in 5%
of 210 patients with cHL, and treatment was interrupted due to adverse
reactions in 26% of patients. Fifteen percent (15%) of patients had an
adverse reaction requiring systemic corticosteroid therapy. Serious
adverse reactions occurred in 16% of patients. The most frequent serious
adverse reactions (≥1%) included pneumonia, pneumonitis, pyrexia,
dyspnea, GVHD, and herpes zoster. Two patients died from causes other
than disease progression; one from GVHD after subsequent allogeneic HSCT
and one from septic shock. The most common adverse reactions (occurring
in ≥20% of patients) were fatigue (26%), pyrexia (24%), cough (24%),
musculoskeletal pain (21%), diarrhea (20%), and rash (20%).

In KEYNOTE-052, KEYTRUDA was discontinued due to adverse reactions in
11% of 370 patients with locally advanced or metastatic urothelial
carcinoma. The most common adverse reactions (in ≥20% of patients) were
fatigue (38%), musculoskeletal pain (24%), decreased appetite (22%),
constipation (21%), rash (21%), and diarrhea (20%). Eighteen patients
(5%) died from causes other than disease progression. Five patients
(1.4%) who were treated with KEYTRUDA experienced sepsis which led to
death, and 3 patients (0.8%) experienced pneumonia which led to death.
Adverse reactions leading to interruption of KEYTRUDA occurred in 22% of
patients; the most common (≥1%) were liver enzyme increase, diarrhea,
urinary tract infection, acute kidney injury, fatigue, joint pain, and
pneumonia. Serious adverse reactions occurred in 42% of patients, the
most frequent (≥2%) of which were urinary tract infection, hematuria,
acute kidney injury, pneumonia, and urosepsis.

In KEYNOTE-045, KEYTRUDA was discontinued due to adverse reactions in 8%
of 266 patients with locally advanced or metastatic urothelial
carcinoma. The most common adverse reaction resulting in permanent
discontinuation of KEYTRUDA was pneumonitis (1.9%). Adverse reactions
leading to interruption of KEYTRUDA occurred in 20% of patients; the
most common (≥1%) were urinary tract infection (1.5%), diarrhea (1.5%),
and colitis (1.1%). The most common adverse reactions (≥20%) in patients
who received KEYTRUDA vs those who received chemotherapy were fatigue
(38% vs 56%), musculoskeletal pain (32% vs 27%), pruritus (23% vs 6%),
decreased appetite (21% vs 21%), nausea (21% vs 29%), and rash (20% vs
13%). Serious adverse reactions occurred in 39% of KEYTRUDA-treated
patients, the most frequent (≥2%) of which were urinary tract infection,
pneumonia, anemia, and pneumonitis.

It is not known whether KEYTRUDA is excreted in human milk. Because many
drugs are excreted in human milk, instruct women to discontinue nursing
during treatment with KEYTRUDA and for 4 months after the final dose.

There is limited experience in pediatric patients. In a study, 40
pediatric patients (16 children aged 2 years to younger than 12 years
and 24 adolescents aged 12 years to 18 years) with advanced melanoma,
lymphoma, or PD-L1–positive advanced, relapsed, or refractory solid
tumors were administered KEYTRUDA 2 mg/kg every 3 weeks. Patients
received KEYTRUDA for a median of 3 doses (range 1–17 doses), with 34
patients (85%) receiving KEYTRUDA for 2 doses or more. The safety
profile in these pediatric patients was similar to that seen in adults
treated with KEYTRUDA. Toxicities that occurred at a higher rate (≥15%
difference) in these patients when compared to adults under 65 years of
age were fatigue (45%), vomiting (38%), abdominal pain (28%),
hypertransaminasemia (28%), and hyponatremia (18%).

Merck’s Focus on Cancer

Our goal is to translate breakthrough science into innovative oncology
medicines to help people with cancer worldwide. At Merck, helping people
fight cancer is our passion and supporting accessibility to our cancer
medicines is our commitment. Our focus is on pursuing research in
immuno-oncology and we are accelerating every step in the journey – from
lab to clinic – to potentially bring new hope to people with cancer.

As part of our focus on cancer, Merck is committed to exploring the
potential of immuno-oncology with one of the fastest-growing development
programs in the industry. We are currently executing an expansive
research program evaluating our anti-PD-1 therapy across more than 30
tumor types. We also continue to strengthen our immuno-oncology
portfolio through strategic acquisitions and are prioritizing the
development of several promising immunotherapeutic 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

For more than a century, Merck, a leading global biopharmaceutical
company known as MSD outside of the United States and Canada, has been
inventing for life, bringing forward medicines and vaccines for many of
the world’s most challenging diseases. Through our prescription
medicines, vaccines, biologic therapies 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 health care through far-reaching policies, programs
and partnerships. Today, Merck continues to be at the forefront of
research to advance the prevention and treatment of diseases that
threaten people and communities around the world – including cancer,
cardio-metabolic diseases, emerging animal diseases, Alzheimer’s disease
and infectious diseases including HIV and Ebola. For more information,
visit www.merck.com
and connect with us on Twitter, Facebook, Instagram,
YouTube
and LinkedIn.

Forward-Looking Statement of Merck & Co., Inc., Kenilworth, N.J., USA

This news release of Merck & Co., Inc., Kenilworth, N.J., USA (the
“company”) includes “forward-looking statements” within the meaning of
the safe harbor provisions of the U.S. Private Securities Litigation
Reform Act of 1995. These statements are based upon the current beliefs
and expectations of the company’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; the company’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 the company’s patents
and other protections for innovative products; and the exposure to
litigation, including patent litigation, and/or regulatory actions.

The company 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 the company’s 2017 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).

Please see Prescribing Information for KEYTRUDA (pembrolizumab) at

https://www.merck.com/product/usa/pi_circulars/k/keytruda/keytruda_pi.pdf


and

Patient Information/Medication Guide for KEYTRUDA at

https://www.merck.com/product/usa/pi_circulars/k/keytruda/keytruda_mg.pdf

.

Media:
Merck
Pamela Eisele, 267-305-3558
Elizabeth Sell, 267-305-3877
or
EORTC
Davi Kaur, +32 (0)2 774 1513
or
Investors:
Merck
Teri Loxam, 908-740-1986
Michael DeCarbo, 908-740-1807