Experiments in the weightless environment of space have led to "crazy progress" in the fight against cancer, NASA officials said at a recent event highlighting an important and personal initiative of US President Joe Biden.

Space is "a unique place for research," astronaut Frank Rubio said at the event in Washington.

The 48-year-old, a physician and former military helicopter pilot, conducted cancer research during his recent mission to the International Space Station (ISS), orbiting some 400 kilometers (250 miles) above the Earth's surface.

Not only do cells there age more rapidly, speeding up research, their structures are also described as "purer."

"They all don't clump together (as they do) on Earth because of gravity. They are suspended in space," enabling better analysis of their molecular structures, NASA chief Bill Nelson told AFP in an interview.

Research conducted in space can help make cancer drugs more effective, Nelson added.

Pharmaceutical giant Merck has conducted research on the ISS with Keytruda, an anti-cancer drug that patients now receive intravenously.

Its key ingredient is difficult to transform into a liquid. One solution is crystallization, a process often used in drug manufacturing.