STRIDE-8 results presented at IDWeek build on the proven clinical profile of CAPVAXIVE, marking the latest Phase 3 study evaluating CAPVAXIVE to demonstrate robust immune responses in adults

CAPVAXIVE covers the serotypes responsible for approximately 84% of invasive pneumococcal disease cases in adults 50 and older

Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced results from STRIDE-8, a Phase 3 trial evaluating CAPVAXIVE™ (Pneumococcal 21-valent Conjugate Vaccine), at IDWeek 2024 in Los Angeles, California. The trial evaluated the immunogenicity, safety and tolerability of CAPVAXIVE compared to PCV15 (pneumococcal 15-valent conjugate vaccine) in combination with PPSV23 (pneumococcal 23-valent polysaccharide vaccine) in vaccine-naïve adults 18-64 years of age with certain chronic conditions that put them at an increased risk of pneumococcal disease.

Key findings from the STRIDE-8 trial include:

• CAPVAXIVE was immunogenic for all 21 serotypes (or strains) included in the vaccine, as measured by serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) (primary immunogenicity objective) and immunoglobulin G (IgG) geometric mean concentrations (GMCs) (secondary immunogenicity objective) at Day 30;
• Immune responses elicited by CAPVAXIVE were comparable to PCV15 followed by PPSV23 for the 13 common serotypes and higher for the eight serotypes unique to CAPVAXIVE, as measured by serotype-specific OPA GMTs and IgG GMCs 30 days post-vaccination;
• The proportions of participants with adverse events (AEs), including injection-site, systemic, and vaccine-related AEs, were numerically lower in the V116 + placebo group than in the PCV15 + PPSV23 group.

“Adults with chronic medical conditions, such as kidney disease or diabetes, are particularly vulnerable to invasive pneumococcal disease, which may increase their risk of severe illness,” said Dr. Walter Orenstein, professor emeritus of medicine, epidemiology, global health and pediatrics at Emory University and member of Merck’s Scientific Advisory Committee. “These data further demonstrate that the broad serotype coverage CAPVAXIVE provides can help prevent invasive disease among vulnerable adults.”

CAPVAXIVE is indicated for:

• Active immunization for the prevention of invasive disease and pneumonia caused by Streptococcus pneumoniae serotypes 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15B, 15C, 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F and 35B in adults individuals 18 years of age and older;
• Active immunization for the prevention of pneumonia caused by S. pneumoniae serotypes 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15C, 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F and 35B in individuals 18 years of age and older.

The indication for the prevention of pneumonia caused by S. pneumoniae serotypes 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15C, 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F and 35B is approved under accelerated approval based on immune responses as measured by opsonophagocytic activity (OPA). Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

CAPVAXIVE should not be administered to individuals with a history of a severe allergic reaction (e.g., anaphylaxis) to any component of CAPVAXIVE or to diphtheria toxoid; see additional Select Safety Information below.

“The data presented during IDWeek build on the robust clinical profile of CAPVAXIVE and illustrate the importance of improving equitable access for those at high risk for invasive pneumococcal disease,” said Dr. Macaya Douoguih, Therapeutic Area Head, Vaccines Clinical Research, Merck Research Laboratories. “Our commitment to prioritizing research and advancements that benefit populations at highest risk of invasive pneumococcal disease remains critical.”

In addition to STRIDE-8, Merck also presented results from a targeted literature review of the clinical and economic burden of pneumococcal disease in U.S. adults. The findings concluded that Black adults and adults in rural areas with lower levels of education and income face higher disease burden and lower rates of pneumococcal vaccination.

Data from a modeling study evaluating the health impact of the introduction of CAPVAXIVE in U.S. adults were also presented. The modeling study concluded that the use of CAPVAXIVE in adults reduced IPD incidence by 33.9% in the U.S. after 10 years, in the setting of continued pediatric PCV vaccination. This equated to approximately 14,000 fewer cases with CAPVAXIVE than PCV20 (pneumococcal 20-valent conjugate vaccine) after 10 years.

CAPVAXIVE is specifically designed to help protect adults against the serotypes that cause the majority of invasive pneumococcal disease (IPD) cases. Based on CDC data from 2018-2021, the serotypes covered by CAPVAXIVE are responsible for more cases of IPD in adults compared to PCV20.

• In adults 50 years of age and older, CAPVAXIVE covers the serotypes responsible for approximately 84% of IPD cases, compared to approximately 52% covered by PCV20;
• In adults 65 years of age and older, CAPVAXIVE covers the serotypes responsible for approximately 85% of IPD cases, compared to approximately 51% covered by PCV20.

These values are based on CDC epidemiologic data and do not reflect the efficacy of the respective vaccines. There are currently no studies comparing the efficacy of CAPVAXIVE and PCV20.

The Phase 3 program for CAPVAXIVE spanned multiple studies, including STRIDE-3 (NCT05425732), STRIDE-4 (NCT05464420), STRIDE-5 (NCT05526716), STRIDE-6 (NCT05420961), STRIDE-7 (NCT05393037), STRIDE-8 (NCT05696080), STRIDE-9 (NCT05633992) and STRIDE-10 (NCT05569954).

Summary of Findings from Select Studies Presented at IDWeek

Data from STRIDE-8 (Abstract #P-45)

STRIDE-8 (NCT05696080) is a Phase 3, randomized, double-blind, active comparator-controlled clinical study, evaluating the immunogenicity, safety and tolerability of CAPVAXIVE in adults 18-64 years of age with increased risk for pneumococcal disease (including adults who experienced diabetes mellitus, heart disease, kidney disease, liver disease and lung disease) who had not previously received a pneumococcal vaccine (n=518). Immunogenicity of CAPVAXIVE was compared with sequential administration of PCV15 followed by PPSV23. Participants were randomized 3:1 to receive a single dose of CAPVAXIVE on Day 1 followed by placebo at Week 8, or a single dose of PCV15 on Day 1 followed by a single dose of PPSV23 at Week 8.

Primary objectives included serotype-specific OPA GMTs and IgG GMCs at Day 1 and 30-days post-vaccination (Day 30 for CAPVAXIVE + placebo and Week 12 for PCV15 + PPSV23). Safety was evaluated as the proportion of participants with adverse events. Results showed that:

• CAPVAXIVE was immunogenic for all 21 serotypes included in the vaccine, as measured by OPA GMTs and IgG GMCs at Day 30;
• Immune responses elicited by CAPVAXIVE were comparable to PCV15 and PPSV23 for the 13 common serotypes (3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 17F, 19A, 20A, 22F and 33F) with higher responses for the eight serotypes unique to CAPVAXIVE (15A, 15C, 16F, 23A, 23B, 24F, 31 and 35B) as measured by serotype-specific OPA GMTs and IgG GMCs 30 days post-vaccination;
• The proportions of participants with AEs, including injection-site, systemic, and vaccine-related AEs, were numerically lower in the V116 + placebo group than in the PCV15 + PPSV23 group.

Results from Disparities and Inequities in Pneumococcal Disease Burden Targeted Literature Review (Abstract # P-242)

A targeted literature review was conducted on the clinical and economic burden of pneumococcal disease in U.S. adults, with a focus on the disparities and inequities by race, geography, urbanicity, income, education and employment. Of 4,609 identified publications (published from January 2012 – July 2024), 12 studies were evaluated. Key findings showed that disparities in burden from pneumococcal disease exist in the U.S., particularly among Black adults and those living in rural areas with lower education and income. Detailed findings included:

• Black adults had the highest incidence and longest length of hospital stay due to IPD compared to other racial groups;
• Areas categorized as less urban displayed higher mortality rates for pneumococcal pneumonia;
• Vaccination rates were lower among Black adults compared to white adults;
• Vaccination rates were also low among adults who lived in rural areas with lower levels of income and education.

The study concluded that more research is needed to further examine disparities and inequities in the burden of pneumococcal disease.

Results from Modeling Study Quantifying the Impact of Introducing a New Adult-Focused PCV in the United States (Abstract #P-58)

A modeling study evaluated CAPVAXIVE in comparison to PCV20 to quantify the health impact of both vaccines in U.S. adults. The compartmental model captured pneumococcal carriage transmission in the presence of age- and serotype-specific pneumococcal vaccines and was calibrated to the corresponding IPD data in the U.S. The model was then used to quantify the impact of both CAPVAXIVE and PCV20 on overall IPD incidence in adults of all ages, accounting for continued pediatric PCV vaccination. Analysis assumed pediatric vaccination continued at 82% coverage with an 80/20 mix of PCV20/PCV15 in infants and that 57% of adults aged 65 and older would have received a PCV in the last 10 years.

Results showed that while the continued use of both CAPVAXIVE and PCV20 led to reductions in IPD incidence when compared to current disease rates, the use of CAPVAXIVE led to fewer overall cases than the use of PCV20 after 10 years, with a 33.9% reduction across all ages versus a 28.9% reduction, respectively. These results equated to approximately 14,000 fewer cases of IPD in adults with CAPVAXIVE than with PCV20. Findings also showed that despite a greater number of cases in the serotypes not included in CAPVAXIVE when compared to adult PCV20 use, indirect protection of adults from pediatric vaccination resulted in continued declines in these serotypes from present values.

About CAPVAXIVE

CAPVAXIVE is Merck’s approved 21-valent pneumococcal conjugate vaccine indicated for active immunization for the prevention of invasive disease and pneumonia in adults 18 years of age and older. CAPVAXIVE is specifically designed to help address Streptococcus pneumoniae serotypes predominantly responsible for adult invasive pneumococcal disease (IPD), including eight unique serotypes, 15A, 15C, 16F, 23A, 23B, 24F, 31 and 35B compared to other pneumococcal vaccines. CAPVAXIVE is administered as a single dose.

Select Safety Information for CAPVAXIVE

Do not administer CAPVAXIVE to individuals with a history of a severe allergic reaction (eg, anaphylaxis) to any component of CAPVAXIVE or to diphtheria toxoid.

Individuals with altered immunocompetence, including those receiving immunosuppressive therapy, may have a reduced immune response to CAPVAXIVE.

The most commonly reported (>10%) solicited adverse reactions in individuals 18 through 49 years of age who received CAPVAXIVE were: injection-site pain (73.1%), fatigue (36.0%), headache (27.5%), myalgia (16.4%), injection-site erythema (13.8%), and injection-site swelling (13.3%).

The most commonly reported (>10%) solicited adverse reactions in individuals 50 years of age and older who received CAPVAXIVE were: injection-site pain (41.2%), fatigue (19.7%), and headache (11.0%).

Vaccination with CAPVAXIVE may not protect all vaccine recipients.

About Pneumococcal Disease

Pneumococcal disease is an infection caused by a bacteria called Streptococcus pneumoniae. There are about 100 different types (referred to as serotypes) of pneumococcal bacteria, which can affect adults differently than children. Pneumococcal disease can be invasive or non-invasive. Non-invasive pneumococcal illnesses include pneumonia (when pneumococcal disease is confined to the lungs), whereas invasive pneumococcal illnesses include pneumococcal bacteremia (infection in the bloodstream), bacteremic pneumococcal pneumonia (pneumonia with bacteremia) and pneumococcal meningitis (infection of the coverings of the brain and spinal cord). Pneumococcal pneumonia is a type of bacterial pneumonia, which is the most common clinical presentation of pneumococcal disease in adults. It’s estimated that over 150,000 adults are hospitalized from pneumococcal pneumonia each year in the U.S.

Merck’s Commitment to Pneumococcal Disease Protection

Merck has been at the forefront of pneumococcal disease prevention through vaccination for more than four decades and remains committed to helping to protect people of all ages from this disease. Merck’s ongoing pneumococcal vaccine development program is designed to provide options that address the specific needs of different populations, including infants and children, healthy adults and at-risk sub-groups. This approach recognizes that disease burden in pediatric and adult populations is often driven by different bacterial strains, or serotypes, and aims to address unmet needs by offering vaccine options that target serotypes posing the greatest global risk to each population. To learn more about Merck’s pipeline, visit www.merck.com.

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 X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn.

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

This news release of Merck & Co., Inc., Rahway, 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. 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 Annual Report on Form 10-K for the year ended December 31, 2023 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 CAPVAXIVE (Pneumococcal 21-valent Conjugate Vaccine) at https://www.merck.com/product/usa/pi_circulars/c/capvaxive/capvaxive_pi.pdf and Patient Information/Medication Guide for CAPVAXIVE at https://www.merck.com/product/usa/pi_circulars/c/capvaxive/capvaxive_ppi.pdf.

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