Melanoma represents a serious form of skin cancer that can spread to other parts of the body. The field of cancer treatment has seen significant progress with the advent of immunotherapy, which harnesses the body’s own defenses. Among these advancements, pembrolizumab, known commercially as Keytruda, has emerged as an important immunotherapy drug for melanoma. This medication works by empowering the immune system to recognize and fight cancer cells more effectively.
Understanding Pembrolizumab’s Action
Pembrolizumab functions as a type of drug called an “immune checkpoint inhibitor.” The immune system has built-in “brakes” to prevent it from attacking healthy cells, and these are often controlled by proteins like Programmed Death-1 (PD-1) found on immune cells, specifically T-cells. Cancer cells can exploit this natural system by displaying their own proteins, such as Programmed Death-Ligand 1 (PD-L1), which bind to PD-1 on T-cells. This binding essentially “turns off” the T-cells, allowing the cancer to evade detection and destruction by the immune system.
Pembrolizumab is a humanized monoclonal antibody that specifically targets and blocks the PD-1 receptor on T-cells. By doing so, it prevents PD-1 from interacting with PD-L1 and PD-L2, which are often found on tumor cells. This action effectively “releases the brakes” on the T-cells, allowing them to become reactivated and recognize the melanoma cells as foreign threats. Once reactivated, these T-cells can then launch an attack to destroy the cancerous cells.
When Pembrolizumab is Used for Melanoma
Pembrolizumab is used in specific situations for melanoma treatment, particularly when the cancer has advanced. It is indicated for unresectable melanoma, meaning the cancer cannot be surgically removed, or for metastatic melanoma, which has spread to distant parts of the body. In these advanced cases, pembrolizumab is frequently considered a first-line treatment option.
The drug is also utilized as an adjuvant therapy following surgery for high-risk melanoma. In this context, it aims to reduce the risk of the cancer returning after the primary tumor has been removed.
Managing Treatment Side Effects
Because pembrolizumab works by activating the immune system, its side effects often arise from the immune system mistakenly attacking healthy tissues throughout the body, similar to autoimmune reactions. Patients may experience common side effects such as fatigue, skin rash, or diarrhea. Other potential effects include musculoskeletal pain, decreased appetite, and itchy skin.
The immune system’s overactivity can also lead to inflammation in various organs, including the thyroid gland, which can result in thyroid issues. More severe, though less common, side effects can involve inflammation of the lungs (pneumonitis), colon (colitis), liver (hepatitis), or kidneys (nephritis). These immune-related adverse events are typically managed with corticosteroids or other immunosuppressants. It is important for patients to report any new or worsening symptoms to their healthcare team promptly to ensure timely and appropriate management.
The Treatment Experience and Outlook
Pembrolizumab is administered intravenously, meaning it is given directly into a vein, typically over about 30 minutes. The treatment schedule usually involves infusions every three weeks or every six weeks, depending on the specific treatment plan. The total duration of treatment can vary, with some patients receiving it for up to two years, while others may continue as long as they are benefiting and tolerating the therapy.
The introduction of pembrolizumab has significantly improved the outlook for many individuals with melanoma. It has been shown to improve survival rates and can lead to long-lasting responses in a considerable number of patients.