How NASA Space Experiments Helped Transform Cancer Drug Keytruda

What happens when cancer medicine leaves Earth? In the case of Keytruda (pembrolizumab), the answer was a medical breakthrough that now saves patients hours in hospitals.

In a rare and scientifically verified collaboration, US pharmaceutical major Merck partnered with NASA to study the behaviour of pembrolizumab crystals aboard the International Space Station (ISS). The experiment did not change what the drug does — but it fundamentally changed how it is delivered to patients.

Space station research gave insights that informed development of a new FDA-approved cancer therapy, cutting treatment time from a 2-hour port to a 1- to 2-minute injection. This advancement offers faster, easier care for cancer patients. 💉💫https://t.co/YIaK3dBhFA

— International Space Station (@Space_Station) January 6, 2026

Why Keytruda went to space

On Earth, gravity interferes with crystal growth. Drug particles tend to settle, collide, and clump together, making it difficult to achieve perfectly uniform structures — a key challenge for injectable biologic medicines.

Microgravity changes that.

In the weightless environment of the ISS, Merck scientists observed that pembrolizumab crystals:

• Formed more evenly

• Maintained greater structural stability

• Displayed higher consistency and purity

These space-grown crystals offered researchers a clear reference model — revealing how the drug behaves under near-ideal physical conditions. Those findings were then used to fine-tune formulation and manufacturing processes back on Earth.

NASA later highlighted the project as a prime example of how space-based research can solve problems that resist conventional laboratory approaches.

The real-world impact: hours erased from cancer care

For years, Keytruda was administered only through intravenous infusion — often requiring patients to remain in hospitals for 30 minutes to two hours per session.

Using insights derived from the ISS experiments, Merck scientists succeeded in developing a subcutaneous formulation of pembrolizumab — one that could be delivered in a much smaller volume.

The result is striking:

• A single injection under the skin

• Takes about one minute

• Administered once every three weeks

In September 2025, this new formulation received approval from the US Food and Drug Administration, confirming that its effectiveness and drug exposure are comparable to the intravenous version.

What makes pembrolizumab different

Pembrolizumab is not a traditional cancer drug. It is a monoclonal antibody immunotherapy that acts as an “immune shield.”

Instead of directly killing cancer cells, it blocks the PD-1 pathway, allowing the body’s own immune system to recognise and attack tumours more effectively. Because of this mechanism, Keytruda has become one of the most widely used cancer treatments globally, particularly in:

• Lung cancer

• Melanoma

• Several advanced and hard-to-treat cancers

A win for patients and hospitals alike

The shift from IV infusion to a quick injection carries major system-wide benefits:

Time reclaimed — patients no longer spend hours tethered to drips
Lower healthcare costs — reduced use of infusion chairs, equipment, and staff time
Better quality of life — treatment fits into daily routines
Hospital relief — oncology units can treat more patients efficiently

For a drug used by millions worldwide, these gains are far from marginal.

A message written in orbit

Importantly, Keytruda is not manufactured in space. The ISS served as a research laboratory — a place where gravity could be removed to unlock insights impossible to obtain on Earth.

Yet the implications are profound. The Merck–NASA collaboration shows that space science is no longer confined to rockets and planets. It is quietly reshaping medicine, treatment delivery, and patient experience.

In the story of Keytruda, one thing is clear:
a discovery made hundreds of kilometres above Earth is now giving cancer patients something priceless — time.