Dr. Jerry McLaughlin, a scientist at Purdue University School of Pharmacy, embarked on a 28 year search for an effective cancer treatment. He led a team of researchers attempting to find substances from plants that would yield cancer cures. They screened approximately 3,500 plant species. The Paw Paw tree gave some molecules, known as acetogenins, were found to be very effective for a number of diseases.
The most unfortunate part of the story is that the scientists had identified the most active molecules in the plant, but they could not figure out a way to synthesize them. This meant that they could not make the massive profits that pharmaceutical companies look for in the products that they sell. Because of this, they shelved this cancer treatment. This is video one in a series that goes into some depth about Paw Paw.