All this should be very encouraging for the field. Yet the story also describes the many travails of companies seeking regulatory approval for their gene transfer products. One is Introgen, which sought approval for its adenovirus-p53 cancer product Advexin. FDA returned Introgen's submission with a "refuse to file" letter indicating that the materials were incomplete. The study on which this filing was based was presented at the American Society of Gene Therapy meeting last Spring. As I indicated in my June 10 posting, a major concern with this study was that its efficacy claims were based on a subgroup analysis of genetic profiles. Others, like TheStreet.com columnist Adam Feuerstein, have been far less guarded in their assessment of Advexin; Feuerstein called Introgen "a living textbook for what investors need to be wary of when considering a biotech investment."
The second product profiled in the Nature Biotechnology story is Ark's Cerepro, which uses herpes simplex virus vectors to deliver a gene, thymidine kinase, to the tumor bed of patients with malignant glioma (a highly aggressive form of brain cancer); the gene then converts a pro-drug, ganciclovir, into a toxin that kills tumor tissue. Ark is reportedly planning to file a license application to EMEA. Preliminary data in a randomized controlled trial against standard of care vs. standard of care + Cerepro indicate a median extension of survival by 42 days (with serious side effects).
One last product profiled briefly is Amsterdam Molecular Therapeutic's product, Glybera, for a very rare genetic disease lipoprotein lipase deficiency. Amsterdam intends to file for licensure "later this year."
The fortunes of clinical gene transfer might indeed be flying North. But with some lead products showing such incremental gains in survival and dependence on combination with standard care, clinical application seems less likely to arrive with a bang than with a modest honk. (photo credit: denis collette, 2007)