KEYTRUDA® (pembrolizumab) Plus Paclitaxel With or Without Bevacizumab Significantly Improved Key Secondary Endpoint of Overall Survival (OS) Versus Paclitaxel With or Without Bevacizumab in Patients With Platinum-Resistant Recurrent Ovarian Cancer

KEYTRUDA plus paclitaxel with or without bevacizumab is the first PD-1 inhibitor-based regimen to show a statistically significant improvement in OS regardless of PD-L1 status

Results from the final analysis of the Phase 3 KEYNOTE-B96 trial to be presented during a Best Oral Session at the European Society of Gynaecological Oncology 2026 Congress

Positive EU CHMP opinion granted for KEYTRUDA plus paclitaxel with or without bevacizumab in certain adults with PD-L1 (CPS ≥1) platinum-resistant ovarian carcinoma who have received one or two prior systemic treatment regimens

RAHWAY, N.J.–(BUSINESS WIRE)–$MRK #MRK–Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced results from the final analysis of the pivotal Phase 3 KEYNOTE-B96 trial, also known as ENGOT-ov65, showing that KEYTRUDA^® (pembrolizumab), Merck’s anti-PD-1 therapy, in combination with chemotherapy (paclitaxel) with or without bevacizumab significantly improved overall survival (OS), a key secondary endpoint, for patients with platinum-resistant recurrent ovarian cancer regardless of PD-L1 status versus paclitaxel with or without bevacizumab alone, the most active standard of care control arm for patients who are bevacizumab-eligible. These data will be presented for the first time today during a Best Oral Session at the European Society of Gynaecological Oncology (ESGO) 2026 Congress (abstract #526).

As previously reported at the European Society for Medical Oncology (ESMO) Congress 2025, KEYTRUDA plus paclitaxel with or without bevacizumab met its primary endpoint of progression-free survival (PFS) in the all comers population of patients with platinum-resistant recurrent ovarian cancer, as well as in patients whose tumors express PD-L1 (Combined Positive Score [CPS] ≥1). The KEYTRUDA regimen also met its key secondary endpoint of OS in patients with platinum-resistant recurrent ovarian cancer whose tumors express PD-L1 (CPS ≥1).

At the final analysis, after a median follow-up of 32.7 months (range, 26.1-44.1), KEYTRUDA plus paclitaxel with or without bevacizumab demonstrated a statistically significant and clinically meaningful improvement in OS in all comers, reducing the risk of death by 18% (HR=0.82 [95% CI, 0.69-0.97]; p=0.0115) compared to paclitaxel with or without bevacizumab alone. For patients who received the KEYTRUDA regimen, median OS was 17.7 months versus 14.0 months for patients receiving the placebo regimen. The observed OS is among the longest reported in any clinical trial for platinum-resistant recurrent ovarian cancer, showing a clinically meaningful benefit of this regimen relative to the most active standard of care control arm, weekly paclitaxel with bevacizumab in bevacizumab-eligible patients.

“Patients with platinum-resistant ovarian cancer show reduced responses to traditional treatment regimens and may experience poor overall survival,” said Dr. Nicoletta Colombo, director of the Gynecologic Oncology Program at the European Institute of Oncology in Milan, Italy. “These results build on prior data from the KEYNOTE-B96 trial and further define the clinical impact of this pembrolizumab-based regimen in appropriate patients with platinum-resistant recurrent ovarian cancer.”

Additionally, the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) adopted a positive opinion recommending approval of KEYTRUDA in combination with paclitaxel with or without bevacizumab for the treatment of platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal carcinoma in adults whose tumors express PD-L1 (CPS ≥1), and who have received one or two prior systemic treatment regimens.

In February, KEYTRUDA plus paclitaxel with or without bevacizumab was approved by the U.S. Food and Drug Administration (FDA) to treat adult patients with platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal carcinoma whose tumors express PD-L1 (CPS ≥1) as determined by an FDA-authorized test, and who have received one or two prior systemic treatment regimens based on previous data from the KEYNOTE-B96 trial.

“Results from the final analysis of KEYNOTE-B96, including overall survival data in the all comers population, demonstrate the continued clinical benefit of KEYTRUDA plus paclitaxel with or without bevacizumab for certain patients with platinum-resistant recurrent ovarian cancer,” said Dr. Gursel Aktan, vice president, global clinical development, Merck Research Laboratories. “Taken together, the recent FDA approval and CHMP positive opinion underscore our commitment to the ovarian cancer community and our ongoing focus on delivering therapies that can help patients with unmet needs across women’s cancers.”

Study design and additional data from KEYNOTE-B96/ENGOT-ov65
KEYNOTE-B96, also known as ENGOT-ov65, is a multicenter, randomized, double-blind placebo-controlled Phase 3 trial (ClinicalTrials.gov, NCT05116189) sponsored by Merck and conducted in collaboration with the European Network for Gynecologic Oncology Trial (ENGOT) groups investigating KEYTRUDA, Merck’s anti-PD-1 therapy, in combination with chemotherapy (paclitaxel) with or without bevacizumab compared to placebo plus paclitaxel with or without bevacizumab for the treatment of platinum-resistant recurrent ovarian cancer. The primary endpoint is PFS, as assessed by investigator according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1), and OS is a key secondary endpoint. The trial enrolled 643 patients with epithelial ovarian, fallopian tube or primary peritoneal carcinoma, regardless of PD-L1 tumor expression status, who received one or two prior lines of systemic therapy for ovarian carcinoma, including at least one line of platinum-based chemotherapy. Of the 643 enrolled patients, 72% of patients had tumors expressing PD-L1 (CPS ≥1). Patients were enrolled in KEYNOTE-B96 regardless of PD-L1 tumor expression status. Patients were randomized (1:1) to receive either KEYTRUDA plus paclitaxel with or without bevacizumab, or placebo plus paclitaxel with or without bevacizumab. KEYTRUDA (400 mg) or placebo were administered on Day 1 of each six-week treatment cycle and paclitaxel (80 mg/m²) was administered on Days 1, 8 and 15 of each three-week treatment cycle. The option to use bevacizumab was by investigator choice prior to randomization. Bevacizumab (10 mg/kg) was administered on Day 1 of a two-week treatment cycle.

At the final analysis, in the all comers population, KEYTRUDA plus paclitaxel with or without bevacizumab reduced the risk of disease progression or death by 27% (HR=0.73 [95% CI, 0.62-0.87]) compared to paclitaxel with or without bevacizumab alone. In patients with platinum-resistant recurrent ovarian cancer whose tumors express PD-L1 (CPS ≥1), the KEYTRUDA regimen reduced the risk of disease progression or death by 24% (HR=0.76 [95% CI, 0.62-0.93]) versus paclitaxel with or without bevacizumab alone. The KEYTRUDA regimen also continued to demonstrate a clinically meaningful improvement in OS, a key secondary endpoint of the study, in patients with platinum-resistant recurrent ovarian cancer whose tumors express PD-L1 (CPS ≥1), reducing the risk of death by 24% (HR=0.76 [95% CI, 0.62-0.93]) compared to paclitaxel with or without bevacizumab.

The safety profile of KEYTRUDA in this trial was consistent with that observed in previously reported studies; no new safety concerns were identified. Grade ≥3 treatment-related adverse events (TRAEs) occurred in 67.8% of patients receiving the KEYTRUDA regimen (n=320) versus 55.3% of patients receiving the placebo regimen (n=318). TRAEs led to death in 1.3% of patients receiving the KEYTRUDA regimen and 1.6% of patients receiving the placebo regimen.

Immune-mediated adverse events (AEs) and infusion reactions of any grade occurred in 39.4% of patients receiving the KEYTRUDA regimen and 18.9% of patients receiving the placebo regimen. The most common of these events (occurring in ≥10% of patients) was hypothyroidism (18.1%) in patients receiving the KEYTRUDA regimen. Immune-mediated AEs led to death in 0.6% of patients in the KEYTRUDA arm and in no patients in the placebo arm.

About platinum-resistant ovarian cancer
Ovarian cancer often begins in the fallopian tubes or the ovaries. As of 2022, it is the eighth most commonly diagnosed cancer and the eighth leading cause of cancer death among women worldwide. Globally, there were more than 324,000 patients diagnosed with ovarian cancer and almost 207,000 deaths from the disease in 2022. In many regions, its incidence has been increasing, with estimates projecting a 42% increase in new cases worldwide by 2040. Over 80% of patients diagnosed with ovarian cancer will experience disease progression following standard treatment with platinum-based chemotherapy regimens. Of these patients, approximately 25% will experience disease progression within six months of completing first-line platinum-based chemotherapy – defined as primary platinum-resistant ovarian cancer. Prognosis is particularly poor for these patients and approved treatment options are limited.

About Merck’s research in women’s cancers
Merck is advancing research aimed at expanding treatment options for certain breast and gynecologic (ovarian, cervical and endometrial) cancers, with a goal of improving outcomes for more patients affected by these diseases. Breast cancer and gynecologic cancers are the first and second most commonly occurring cancer types among women worldwide, respectively, and Merck aims to give patients facing these devastating diseases options. With more than 20 clinical trials in nearly 20,000 patients around the world, Merck is driving innovative research to purposefully advance standards of care in women’s cancers. Merck’s research efforts include trials focused on evaluating its medicines in earlier stages, as well as identifying novel mechanisms and new combinations with these treatments. Merck is working to develop a portfolio and pipeline to address the impact of women’s cancers on patients, their families and communities globally.

About KEYTRUDA^® (pembrolizumab) injection for intravenous use, 100 mg
KEYTRUDA is an anti-programmed death receptor-1 (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. There are currently more than 1,600 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.

Selected KEYTRUDA^® (pembrolizumab) Indications in the U.S.
Ovarian Cancer
KEYTRUDA, in combination with paclitaxel, with or without bevacizumab, is indicated for the treatment of adult patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal carcinoma whose tumors express PD-L1 (CPS ≥1) as determined by an FDA-authorized test, and who have received one or two prior systemic treatment regimens.

See additional selected KEYTRUDA indications in the U.S. after the Selected Important Safety Information.

Selected Important Safety Information for KEYTRUDA
Severe and Fatal Immune-Mediated Adverse Reactions
KEYTRUDA is a monoclonal antibody that belongs to a class of drugs that bind to either the programmed death receptor-1 (PD-1) or the programmed death ligand 1 (PD-L1), blocking the PD-1/PD-L1 pathway, thereby removing inhibition of the immune response, potentially breaking peripheral tolerance and inducing immune-mediated adverse reactions. Immune-mediated adverse reactions, which may be severe or fatal, can occur in any organ system or tissue, can affect more than one body system simultaneously, and can occur at any time after starting treatment or after discontinuation of treatment. Important immune-mediated adverse reactions listed here may not include all possible severe and fatal immune-mediated adverse reactions.

Monitor patients closely for symptoms and signs that may be clinical manifestations of underlying immune-mediated adverse reactions. Early identification and management are essential to ensure safe use of anti–PD-1/PD-L1 treatments. Evaluate liver enzymes, creatinine, and thyroid function at baseline and periodically during treatment. For patients with TNBC treated with KEYTRUDA in the neoadjuvant setting, monitor blood cortisol at baseline, prior to surgery, and as clinically indicated. In cases of suspected immune-mediated adverse reactions, initiate appropriate workup to exclude alternative etiologies, including infection. Institute medical management promptly, including specialty consultation as appropriate.

Withhold or permanently discontinue KEYTRUDA depending on severity of the immune-mediated adverse reaction. In general, if KEYTRUDA requires interruption or discontinuation, administer systemic corticosteroid therapy (1 to 2 mg/kg/day prednisone or equivalent) until improvement to Grade 1 or less. Upon improvement to Grade 1 or less, initiate corticosteroid taper and continue to taper over at least 1 month. Consider administration of other systemic immunosuppressants in patients whose adverse reactions are not controlled with corticosteroid therapy.

Immune-Mediated Pneumonitis
KEYTRUDA can cause immune-mediated pneumonitis. The incidence is higher in patients who have received prior thoracic radiation. Immune-mediated pneumonitis occurred in 3.4% (94/2799) of patients receiving KEYTRUDA, including fatal (0.1%), Grade 4 (0.3%), Grade 3 (0.9%), and Grade 2 (1.3%) reactions. Systemic corticosteroids were required in 67% (63/94) of patients. Pneumonitis led to permanent discontinuation of KEYTRUDA in 1.3% (36) and withholding in 0.9% (26) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, 23% had recurrence. Pneumonitis resolved in 59% of the 94 patients.

Pneumonitis occurred in 8% (31/389) of adult patients with cHL receiving KEYTRUDA as a single agent, including Grades 3-4 in 2.3% of patients. Patients received high-dose corticosteroids for a median duration of 10 days (range: 2 days to 53 months). Pneumonitis rates were similar in patients with and without prior thoracic radiation. Pneumonitis led to discontinuation of KEYTRUDA in 5.4% (21) of patients. Of the patients who developed pneumonitis, 42% interrupted KEYTRUDA, 68% discontinued KEYTRUDA, and 77% had resolution.

Pneumonitis occurred in 7% (41/580) of adult patients with resected NSCLC who received KEYTRUDA as a single agent for adjuvant treatment of NSCLC, including fatal (0.2%), Grade 4 (0.3%), and Grade 3 (1%) adverse reactions. Patients received high-dose corticosteroids for a median duration of 10 days (range: 1 day to 2.3 months). Pneumonitis led to discontinuation of KEYTRUDA in 26 (4.5%) of patients. Of the patients who developed pneumonitis, 54% interrupted KEYTRUDA, 63% discontinued KEYTRUDA, and 71% had resolution.

Immune-Mediated Colitis
KEYTRUDA can cause immune-mediated colitis, which may present with diarrhea. Cytomegalovirus infection/reactivation has been reported in patients with corticosteroid-refractory immune-mediated colitis. In cases of corticosteroid-refractory colitis, consider repeating infectious workup to exclude alternative etiologies. Immune-mediated colitis occurred in 1.7% (48/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (1.1%), and Grade 2 (0.4%) reactions. Systemic corticosteroids were required in 69% (33/48); additional immunosuppressant therapy was required in 4.2% of patients. Colitis led to permanent discontinuation of KEYTRUDA in 0.5% (15) and withholding in 0.5% (13) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, 23% had recurrence. Colitis resolved in 85% of the 48 patients.

Hepatotoxicity and Immune-Mediated Hepatitis
KEYTRUDA as a Single Agent
KEYTRUDA can cause immune-mediated hepatitis. Immune-mediated hepatitis occurred in 0.7% (19/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (0.4%), and Grade 2 (0.1%) reactions. Systemic corticosteroids were required in 68% (13/19) of patients; additional immunosuppressant therapy was required in 11% of patients. Hepatitis led to permanent discontinuation of KEYTRUDA in 0.2% (6) and withholding in 0.3% (9) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, none had recurrence. Hepatitis resolved in 79% of the 19 patients.

KEYTRUDA With Axitinib
KEYTRUDA in combination with axitinib can cause hepatic toxicity. Monitor liver enzymes before initiation of and periodically throughout treatment. Consider monitoring more frequently as compared to when the drugs are administered as single agents. For elevated liver enzymes, interrupt KEYTRUDA and axitinib, and consider administering corticosteroids as needed. With the combination of KEYTRUDA and axitinib, Grades 3 and 4 increased alanine aminotransferase (ALT) (20%) and increased aspartate aminotransferase (AST) (13%) were seen at a higher frequency compared to KEYTRUDA alone. Fifty-nine percent of the patients with increased ALT received systemic corticosteroids. In patients with ALT ≥3 times upper limit of normal (ULN) (Grades 2-4, n=116), ALT resolved to Grades 0-1 in 94%. Among the 92 patients who were rechallenged with either KEYTRUDA (n=3) or axitinib (n=34) administered as a single agent or with both (n=55), recurrence of ALT ≥3 times ULN was observed in 1 patient receiving KEYTRUDA, 16 patients receiving axitinib, and 24 patients receiving both. All patients with a recurrence of ALT ≥3 ULN subsequently recovered from the event.

Immune-Mediated Endocrinopathies
Adrenal Insufficiency
KEYTRUDA can cause primary or secondary adrenal insufficiency. For Grade 2 or higher, initiate symptomatic treatment, including hormone replacement as clinically indicated. Withhold KEYTRUDA depending on severity. Adrenal insufficiency occurred in 0.8% (22/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (0.3%), and Grade 2 (0.3%) reactions. Systemic corticosteroids were required in 77% (17/22) of patients; of these, the majority remained on systemic corticosteroids. Adrenal insufficiency led to permanent discontinuation of KEYTRUDA in <0.1% (1) and withholding in 0.3% (8) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement.

Hypophysitis
KEYTRUDA can cause immune-mediated hypophysitis. Hypophysitis can present with acute symptoms associated with mass effect such as headache, photophobia, or visual field defects. Hypophysitis can cause hypopituitarism. Initiate hormone replacement as indicated. Withhold or permanently discontinue KEYTRUDA depending on severity. Hypophysitis occurred in 0.6% (17/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (0.3%), and Grade 2 (0.2%) reactions. Systemic corticosteroids were required in 94% (16/17) of patients; of these, the majority remained on systemic corticosteroids. Hypophysitis led to permanent discontinuation of KEYTRUDA in 0.1% (4) and withholding in 0.3% (7) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement.

Thyroid Disorders
KEYTRUDA can cause immune-mediated thyroid disorders. Thyroiditis can present with or without endocrinopathy. Hypothyroidism can follow hyperthyroidism. Initiate hormone replacement for hypothyroidism or institute medical management of hyperthyroidism as clinically indicated. Withhold or permanently discontinue KEYTRUDA depending on severity. Thyroiditis occurred in 0.6% (16/2799) of patients receiving KEYTRUDA, including Grade 2 (0.3%). None discontinued, but KEYTRUDA was withheld in <0.1% (1) of patients.

Hyperthyroidism occurred in 3.4% (96/2799) of patients receiving KEYTRUDA, including Grade 3 (0.1%) and Grade 2 (0.8%). It led to permanent discontinuation of KEYTRUDA in <0.1% (2) and withholding in 0.3% (7) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement. Hypothyroidism occurred in 8% (237/2799) of patients receiving KEYTRUDA, including Grade 3 (0.1%) and Grade 2 (6.2%). It led to permanent discontinuation of KEYTRUDA in <0.1% (1) and withholding in 0.5% (14) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement. The majority of patients with hypothyroidism required long-term thyroid hormone replacement. The incidence of new or worsening hypothyroidism was higher in 1185 patients with HNSCC, occurring in 16% of patients receiving KEYTRUDA as a single agent or in combination with platinum and FU, including Grade 3 (0.3%) hypothyroidism. The incidence of new or worsening hypothyroidism was higher in 389 adult patients with cHL (17%) receiving KEYTRUDA as a single agent, including Grade 1 (6.2%) and Grade 2 (10.8%) hypothyroidism. The incidence of new or worsening hyperthyroidism was higher in 580 patients with resected NSCLC, occurring in 11% of patients receiving KEYTRUDA as a single agent as adjuvant treatment, including Grade 3 (0.2%) hyperthyroidism. The incidence of new or worsening hypothyroidism was higher in 580 patients with resected NSCLC, occurring in 22% of patients receiving KEYTRUDA as a single agent as adjuvant treatment (KEYNOTE-091), including Grade 3 (0.3%) hypothyroidism.

Type 1 Diabetes Mellitus (DM), Which Can Present With Diabetic Ketoacidosis
Monitor patients for hyperglycemia or other signs and symptoms of diabetes. Initiate treatment with insulin as clinically indicated. Withhold KEYTRUDA depending on severity. Type 1 DM occurred in 0.2% (6/2799) of patients receiving KEYTRUDA. It led to permanent discontinuation in <0.1% (1) and withholding of KEYTRUDA in <0.1% (1) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement.

Immune-Mediated Nephritis With Renal Dysfunction
KEYTRUDA can cause immune-mediated nephritis. Immune-mediated nephritis occurred in 0.3% (9/2799) of patients receiving KEYTRUDA, including Grade 4 (<0.1%), Grade 3 (0.1%), and Grade 2 (0.1%) reactions. Systemic corticosteroids were required in 89% (8/9) of patients. Nephritis led to permanent discontinuation of KEYTRUDA in 0.1% (3) and withholding in 0.1% (3) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, none had recurrence. Nephritis resolved in 56% of the 9 patients.

Immune-Mediated Dermatologic Adverse Reactions
KEYTRUDA can cause immune-mediated rash or dermatitis. Exfoliative dermatitis, including Stevens-Johnson syndrome, drug rash with eosinophilia and systemic symptoms, and toxic epidermal necrolysis, has occurred with anti–PD-1/PD-L1 treatments. Topical emollients and/or topical corticosteroids may be adequate to treat mild to moderate nonexfoliative rashes.

Contacts

Media Contacts:

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(617) 519-6264

Sofia DiMartino Bu
(857) 274-4296

Investor Contacts:

Peter Dannenbaum
(732) 594-1579

Steven Graziano
(732) 594-1583

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