Tom led a team of 30 Immunex scientists in a race to clone Interleukin 1 before teams in other companies around the world could beat him to the punch. Teams in the U.S. and Japan succeeded in cloning IL-1, but Tom's group outdid them, cloning two separate genes for IL-1 and discovering an entirely new biological mechanism for protein hormone secretion, the caspase activation system. Controversy dogged Tom's steps, as competing companies sued Immunex over who made the discoveries first, with $164 million in the balance.

Cistron Corporation, a Massachusets company founded specifically to clone Interleukin 1, claimed their patent filing predated Immunex's, which was true, but Immunex countered that Cistron's patented DNA sequence did not represent hormonally active IL-1, which was also true. Tom's team had made the key discovery of the caspase activation process, which was unsuspected by Cistron.

Before the courts decided whether Tom's discovery of the IL-1 activation mechanism could overturn Cistron's claims, Immunex decided to abandon IL-1 commercial development and hand over their patent (with Tom named as inventor) to Cistron. This outcome of the court case related more to Immunex's preoccupation with other projects, than to the validity of any Cistron claim. In the end, Tom's credit as discoverer of two genes for IL-1 and the activation machanisms of the hormones, remains intact.