What is Keytruda? How the cancer drug works and why it's in focus

Doctors break down how Keytruda works and who it helps, as a global probe raises concerns over patents, pricing, and access in India

  Keytruda, a widely used cancer immunotherapy developed and patented by Merck & Co. (known as Merck Sharp & Dohme Corp. or MSD outside the US and Canada), investigation has come into sharp focus again after a global investigation led by the International Consortium of Investigative Journalists (ICIJ). Spanning 37 countries and 47 media partners, the report examined how the company expanded the drug’s reach, including strategies that may delay more affordable alternatives.

 

The investigation found that MSD used a series of patent extensions and regulatory strategies to prolong exclusivity on Keytruda, thereby delaying cheaper alternatives. It also highlighted how expanding approvals across multiple cancer types significantly widened the drug’s market, raising concerns over affordability and access.

 

 

In India, a single infusion costs between ₹2 lakh and ₹4 lakh, and since treatment can continue for months or years, the total expense can run into tens of lakhs. For many families, this turns a medical recommendation into a difficult financial decision.

 

What makes Keytruda different from chemotherapy?

 

At its core, Keytruda represents a shift in how cancer is treated because instead of directly attacking cancer cells, it enables the immune system to do the work.

 

Dr Fahad Afzal, Consultant Oncologist at Saifee Hospital, Mumbai, explains, “Keytruda (Pembrolizumab) is an immunotherapy drug that helps the body’s own immune system fight cancer.”

 

He adds that cancer cells often evade detection by exploiting immune checkpoints involving PD-1 receptors (proteins on immune cells that act as brakes on immune responses) on T-cells, a type of white blood cell that helps the body fight infections and diseases. Keytruda blocks this pathway, which effectively removes the brakes on immune cells and allows them to recognise and attack cancer.

 

This approach differs from chemotherapy, which kills rapidly dividing cells, both healthy and cancerous, and because of this, immunotherapy can offer more targeted action and sometimes longer-lasting responses.

 

However, its effectiveness depends on careful patient selection.

 

Who gets prescribed Keytruda?

 

Doctors emphasise that Keytruda is not suitable for every cancer patient, and its use depends on a combination of clinical and biological factors. It is commonly prescribed for:

 

• Lung cancer
• Melanoma (skin cancer)
• Head and neck cancers
• Certain colorectal and gastrointestinal cancers
• Bladder and cervical cancers

 

But beyond the cancer type, oncologists assess tumour biology, previous treatments, overall health, and any history of autoimmune disease.

 

Dr Fahad Afzal notes that this reflects a broader move towards precision oncology, where treatment decisions are guided not just by the tumour’s location but by its underlying characteristics.

 

The science behind the decision: Why biomarkers matter

 

A key factor in deciding whether to use Keytruda is PD-L1 expression, which is a protein found on some cancer cells that helps them evade immune detection. Testing for PD-L1 helps doctors estimate how likely a patient is to respond to the drug.

 

“Biomarker testing like PD-L1 is critical because it helps us identify which patients are most likely to benefit, avoiding unnecessary costs and ineffective treatment,” says Dr Atul Narayankar, cancer physician at M|O|C Cancer Care Chembur & Ghatkopar.

 

Higher PD-L1 levels often indicate a better chance of response, although doctors also consider other markers such as microsatellite instability and tumour mutation burden.

 

In India, where treatment costs are high, this level of precision is especially important, because it helps ensure that expensive therapies are used where they are most likely to work.

 

Benefits and risks of the treatment

 

The main advantage of Keytruda lies in its potential for durable response, as some patients experience long-term control of their cancer and often tolerate the treatment better than traditional chemotherapy.

 

However, because it activates the immune system, it can also lead to immune-related side effects. These may include:

 

• Lung inflammation
• Liver dysfunction
• Skin reactions
• Thyroid disorders

 

Most of these effects are manageable if detected early, but they require close monitoring and timely intervention.

 

Access, affordability, and the bigger picture

 

The growing use of Keytruda globally reflects both its clinical success and the strategies that have expanded its indications across multiple cancers. In India, however, the reality is more complex.

 

High costs, limited insurance coverage, and delays in access mean that even when the drug is recommended, not all patients are able to receive it. Reports of patients navigating bureaucratic hurdles or seeking alternative access routes underline the gaps in the system.

 

At the same time, oncologists stress that Keytruda is not a universal solution. Its benefits depend on selecting the right patient based on scientific evidence, and using it at the right stage of disease. This creates a dual challenge of improving access while also ensuring appropriate use.

 

As experts point out, the way forward lies in balancing innovation with access, so that breakthroughs in cancer care translate into real-world impact for those who need them most.     

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This report is for informational purposes only and is not a substitute for professional medical advice.