Keytruda (pembrolizumab) is a drug developed by Merck used in cancer therapy. It is a monoclonal antibody, a protein that binds to specific ligands, which increases the ability of the immune system to help detect and fight tumor cells.

Keytruda has already been approved by the U.S. Food and Drug Administration (FDA) for the treatment of certain types of cancers including melanoma, non-small cell lung cancer, recurrent or metastatic head and neck cancer, classical Hodgkin lymphoma, and urothelial carcinoma. The drug is still under investigation for the treatment of ovarian cancer.

How Keytruda works

Keytruda works by binding to specific receptors called programmed cell death 1 (PD-1) that are present on the surface of certain types of immune cells. This binding blocks PD-1’s interaction with its ligands, PD-L1 and PD-L2, which are present on the surface of cancer cells. The interaction between PD-1/PD-L1 suppresses the immune response, allowing the cancer cells to avade it. Keytruda-mediated blocking of PD-1, therefore, activates the immune system (particularly tumor-killing T-cells) against cancer cells.

Clinical studies with Keytruda

Recently, Keytruda was granted accelerated approval for the treatment of unresectable or metastatic solid tumors based on a common genetic marker called microsatellite instability high (MSI-H) or mismatch repair deficient (dMMR), rather than the location of the tumor. The safety and efficacy of Keytruda were studied in 149 patients with 15 cancer types with MSI-H or dMMR solid tumors (with defects in DNA repair) enrolled in one of five uncontrolled, single-arm KEYNOTE clinical trials. The approval was based on the percentage of patients who experienced complete or partial tumor shrinkage (39.6 percent) and the length of time for which the response lasted (six months or more in 78 percent patients). On the accelerated approval track, the treatment can be prescribed to patients, but continued FDA approval will depend on the results of ongoing clinical trials.

There is a large number of clinical trials testing Keytruda for the treatment of ovarian cancer. These are listed below:

An open-label, single-arm, multicenter Phase 2 clinical study (NCT02674061) is underway to evaluate the efficacy and safety of Keytruda monotherapy in women with advanced recurrent ovarian cancer. Participants will receive the drug every three weeks for up to two years.

A pilot study (NCT02728830) is underway to investigate the effect of Keytruda on tumor response in patients with ovarian cancer, uterine endometrial cancer, fallopian tube cancer, and peritoneal cancer.

A Phase 2 study (NCT02644369) is ongoing whose main purpose is to evaluate gene changes and immune biomarkers during Keytruda treatment in patients with solid tumors including ovarian cancer.

Another Phase1/2 clinical study (NCT02452424) aims to study the combined effect of Keytruda and PLX3397 another potential chemotherapy agent, in patients with several types of tumors including ovarian cancer.

A Phase 1/2 study (NCT02657889) is currently recruiting participants and aims to evaluate the safety and efficacy of a combination treatment with Keytruda and niraparib in patients with advanced or metastatic breast cancer or recurrent ovarian cancer. Niraparib is a drug that was recently approved for the treatment of recurrent epithelial ovarian, fallopian tube, and primary peritoneal cancer.

A Phase 2 study (NCT02865811) is underway that aims to investigate if a combination of Keytruda with pegylated liposomal doxorubicin (PLD) could be used for the treatment of recurrent ovarian, fallopian tube, or peritoneal cancer that is resistant to platinum therapy.

An open-label, single arm Phase 2 clinical study (NCT02853318) is underway in patients with recurrent ovarian, fallopian tube, or primary peritoneal cancer that aims to assess the efficacy of Keytruda in combination with two other drugs that are already approved for ovarian cancer, Avastin (bevacizumab) and Cytoxan (cyclophosphamide). The study is being conducted by Roswell Park Cancer Institute and is currently recruiting participants. The study also aims to analyze the patients’ microbiomes in blood, stool, vaginal, and skin samples to identify possible correlations between bacterial composition and the treatment response.

A Phase 2 study (NCT02520154) is ongoing that aims to study the safety of Keytruda in combination with chemotherapy drugs, carboplatin and paclitaxel, for the treatment of ovarian, primary peritoneal, and fallopian tube cancer. Two more Phase 2 studies (NCT02834975 and NCT02766582) are also investigating the effect of this combination therapy – Keytruda, carboplatin and paclitaxel – on the advanced stage epithelial ovarian cancer, fallopian tube cancer, and peritoneal cancer.

A Phase 2 study (NCT02608684) is underway that aims to evaluate the safety and efficacy of Keytruda in combination with chemotherapy drugs – cisplatin and gemcitabine – in female patients with recurrent platinum-resistant ovarian cancer.

Keytruda side effects

Common side effects associated with the use of Keytruda include fatigue, itchy skin, diarrhea, nausea, decreased appetite, rash, fever, cough, difficulty breathing, musculoskeletal pain, constipation, and joint pain. Keytruda can cause the immune system to attack normal organs and tissues in the body resulting in serious side effects, including inflammation of organs such as lungs, colon, liver, endocrine glands, and kidneys. Keytruda use has also led to complications or death related to stem cell transplantation after its use.

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