How it is administered

Pembrolizumab is given as an intravenous (IV) infusion. It is administered by a healthcare professional, usually in a hospital or clinic setting. The typical dose for adults is 200 mg every 3 weeks or 400 mg every 6 weeks, infused over 30 minutes. For children, the dose is based on body weight (2 mg/kg up to a maximum of 200 mg every 3 weeks).

Pembrolizumab is supplied as a clear to slightly opalescent, colorless to slightly yellow solution in vials containing 100 mg in 4 mL. It must be diluted and prepared by a healthcare provider before administration.

How it works

Pembrolizumab is a type of immunotherapy known as a monoclonal antibody. It works by blocking a protein called PD-1 (programmed death receptor-1) on certain immune cells called T cells. Normally, PD-1 acts as a brake to keep the immune system from attacking normal cells in the body. Some cancer cells, including certain blood cancers, use this pathway to hide from the immune system.

By blocking PD-1, pembrolizumab releases the brakes on the immune system, allowing T cells to recognize and attack cancer cells more effectively. This helps the body’s own immune system fight the cancer. In blood cancers like classical Hodgkin lymphoma and primary mediastinal large B-cell lymphoma, pembrolizumab has shown to help shrink tumors and keep the cancer under control for longer periods.

Who Should take it

Pembrolizumab is indicated for patients with certain types of blood cancers, specifically:

• Adults with relapsed or refractory classical Hodgkin lymphoma (cHL)
• Pediatric patients with refractory cHL, or cHL that has relapsed after two or more lines of therapy
• Adults and pediatric patients with refractory primary mediastinal large B-cell lymphoma (PMBCL), or who have relapsed after two or more prior lines of therapy

It may also be used in other cancers, but for blood cancers, these are the main indications. Your doctor will determine if pembrolizumab is appropriate based on your specific cancer type, previous treatments, and overall health.

Who should not take it

There are no absolute contraindications listed for pembrolizumab, but it should not be used in patients who have had a severe allergic reaction to pembrolizumab or any of its ingredients.

Caution is needed in patients with active autoimmune diseases, those who have had organ transplants, or those who are pregnant, as pembrolizumab can cause immune-related side effects and may harm an unborn baby. Patients who have received allogeneic stem cell transplants may be at higher risk for complications. Always discuss your full medical history with your doctor before starting pembrolizumab.

Commonly used with

In blood cancers, pembrolizumab is usually used as a single agent, especially in relapsed or refractory classical Hodgkin lymphoma and PMBCL. It may be combined with other treatments in solid tumors, but for blood cancers, it is typically not combined with chemotherapy or other immunotherapies outside of clinical trials.

Commonly tested with

Pembrolizumab has been tested in combination with other cancer therapies in clinical trials, including chemotherapy and targeted therapies. However, in blood cancers like cHL and PMBCL, its main use is as a single agent after other treatments have failed. It is not recommended for use in combination with thalidomide analogues and dexamethasone for multiple myeloma outside of clinical trials, as this has been associated with increased risk of death.