Keytruda Immunotherapy Drug: Uses, Mechanism, Cost, Risks & Cancer Treatment in India

13 Apr 2026

Keytruda, an immunotherapy cancer drug in focus due to reports of counterfeit/leaked vials in India’s supply chain, raising safety concerns.

About Immunotherapy

Immunotherapy is a form of treatment that enhances or modifies the body’s immune system to effectively fight diseases, particularly cancer.
Nature & Mechanism: Immunotherapy works by strengthening the body’s natural defense system.
- It provides targeted action against diseased cells and, in some cases, helps develop long-term immune memory, enabling sustained protection.

It is an immunotherapy drug — an umbrella term for treatments that train the immune system to tackle disease, primarily cancers.
- It is a part of cancer treatment that also includes radiotherapy, chemotherapy, and if needed, surgery.
Manufactured by: US-based global pharma major Merck & Co (MSD)
Commercial Availability: It is commercially available under the brand name of pembrolizumab.
Mechanism of Action: Keytruda belongs to the category of monoclonal antibodies, which are laboratory-made molecules designed to bind with specific targets, enabling the immune system to identify and destroy cancerous cells.
- Checkpoint inhibitors: It belongs to a class called “checkpoint inhibitors” — drugs that remove the brakes preventing the body’s T cells, which are a crucial weapon in the body’s immune system, from attacking cancerous cells.
Availability for Indian Patients: It is available through the company’s Patient Access Programme.
- This programme provides patients with 30 free vials on purchasing five initially for a total cost of around Rs 10 lakh.
- Patients may use a third-party health insurance to pay for the initial dose.
- Accessing the drug through the programme has some stipulations — the patient should not have a sum-insured or income of over Rs 25 lakh.

High Cost: Merck & Co. recommends a dose of 200 mg every three weeks. With each 100 mg vial costing over ₹1.5 lakh, treatment can exceed ₹3 lakh per month without insurance.
- However, its patent expiry in 2028 may allow cheaper generic versions, potentially reducing costs by up to 70%.
Not Universally Effective: It works only in certain cancers and specific patient profiles.
- It is effective in some lung cancer patients but may not work in others lacking specific biomarkers (like PD-L1 expression).
Immune-related Side Effects: It can cause the immune system to attack healthy organs. In some cases patients have been reported to develop inflammation of lungs (pneumonitis) or thyroid disorders.
Delayed Response: Therapeutic effects may take time compared to chemotherapy.
- Tumor size may initially appear unchanged or even increase before shrinking (pseudo-progression).

Enhancing Affordability and Access: There is a need to promote generic and biosimilar versions post-patent expiry of Keytruda (2028) to significantly reduce treatment costs and improve accessibility in countries like India.
Strengthening Regulatory Oversight: Robust monitoring mechanisms must be established to prevent issues such as counterfeit or leaked drugs in the supply chain, ensuring patient safety.
Promoting Domestic Research & Manufacturing: Encouraging indigenous R&D and production of immunotherapy drugs can reduce dependence on imports and make treatments more cost-effective.
Advancing Personalized Medicine: Greater focus on biomarker-based treatment (e.g., PD-L1 testing) is required to identify suitable patients, thereby improving effectiveness and reducing unnecessary costs.

Aspect	Chemotherapy	Immunotherapy
Definition	Uses drugs to kill rapidly dividing cells	Enhances or modifies the immune system to fight disease
Target	Non-specific (affects both cancerous and healthy fast-dividing cells)	Highly specific (targets cancer cells via immune mechanisms)
Mechanism	Directly destroys cancer cells	Stimulates immune system (e.g., T-cells) to attack cancer
Side Effects	Severe (hair loss, nausea, fatigue, low immunity)	Generally fewer, but may cause immune-related reactions
Effectiveness	Works for many cancers but may relapse	Effective in select cancers; durable response in some cases
Duration of Effect	Usually short-term; requires repeated cycles	Can provide long-term protection (immune memory)
Personalization	Less personalized	More scope for personalized treatment
Cost	Relatively cheaper (especially generics)	Expensive and less accessible
Examples	Cisplatin, Doxorubicin	Checkpoint inhibitors (e.g., Keytruda)

Although India’s cancer incidence rate is currently below the global average, it is climbing steadily.
Global Burden of Disease Estimates: It indicates that the rate of cancer occurrence rose from 84.8 per 100,000 population in 1990 to 107.2 per 100,000 in 2023.
WHO’s Global Cancer Observatory: Data from the WHO’s Global Cancer Observatory shows that India recorded 14.13 lakh cancer cases in 2022, a figure projected to surge by 73.8% to 24.56 lakh cases by 2045.
GLOBOCAN Database: The GLOBOCAN database puts India’s current incidence at 98.5 per 100,000.