Zarnestra developed by Johnson and Johnson Pharmaceutical Research and Development appears promising for the treatment of some patients with recurrent acute myeloid leukemia (AML), or for patients with AML who are not suitable candidates for more intensive therapy. Zarnestra is an inhibitant agent that is classified as a farnesyl transferase inhibitor and is still in clinical trials. It is estimated that 30% of leukemias have a mutated ras gene. The ras gene is a part of the biological pathway that transmits growth signals from the surface of a cell to within a cell. However, a mutation within the ras gene can stimulate a cell to grow and replicate in an unrestrained manner. Additionally, ras mutations have been implicated in suppressing another significant growth regulatory pathway controlled by the p53 gene. The p53 gene is liable for the suppression of cellular replication when a cell perceives a genetic mutation, such as in the development of cancer.

Zarnestra has been designed to block a key enzyme (protein) that is involved in the mutated ras pathway. This slows down or terminates the excessive replication of cancer cells caused by the mutated ras pathway. It is speculated that Zarnestra may create anti-cancer effects through other biological pathways as well.

The first clinical trial presented at the meeting was a multi-institutional clinical trial evaluating Zarnestra in patients with recurrent AML. This trial included more than 300 patients, whose cancer returned following previous therapy or had stopped responding to standard therapies, including one-third of the patients who had been treated with a stem cell transplant.