By
James DeGiulio —

After
over a decade of suspicion following the death of an 18-year-old patient, gene
therapy is experiencing a revival among scientists and drugmakers, according to
a recent Bloomberg report ("'Dead as Doornail' Gene Therapy Revival Spurs Genzyme").  Since the patient's death in 1999,
scientists have linked many of the safety problems with gene therapy to the
modified adenovirus vectors used to deliver the gene.  Current trials utilize a new generation of gene delivery
vectors, such as adeno-associated virus (AAV), which trigger a milder immune
response than the adenovirus used in previous studies and are consequently much
safer.

Recent
successes have rejuvenated the gene therapy field.  The Bloomberg report highlights
Genzyme, which has invested more than $200 million over the past 10 years on
gene therapy technology.  Genzyme's recent Parkinson's disease trial showed a
dopamine gene injected into patients' brains effectively reached the targeted
nerve cells in the region of the brain controlling movement.  This is an important discovery because
efficient gene delivery is a major limitation of gene therapy.  Genzyme is preparing to test the
therapy in a larger trial using AAV that could begin next year.

Other
recent successes have been reported in high impact factor journals.  The
November 6 issue of Science contained a report that showed brain damage in two 7-year-olds with an inherited condition called
adrenoleukodystrophy was halted or reversed using gene therapy ("Hematopoietic
Stem Cell Gene Therapy with a Lentiviral Vector in X-Linked
Adrenoleukodystrophy").  In this study, doctors
removed the patients' blood-forming stem cells, inserted gene-bearing viruses
into them, and reinfused the patients with the modified cells.

The
November 7 issue of The Lancet reported that delivery of a therapeutic gene to patients with Leber's congenital
amaurosis resulted in significant vision recovery, with the most improvement
noted in children ("Age-dependent effects of RPE65 gene therapy for Leber's congenital amaurosis: a phase 1 dose-escalation trial").  In this study, genes
were delivered directly to target cells using AAV virus injected into patients.

Large
drug companies are forming partnerships to further gene therapy development.  In
January, Novartis licensed gene treatments for hearing loss and balance
disorders from GenVec in a deal worth up to $213 million.  In February, startup Tacere
Therapeutics announced that Pfizer would license its hepatitis C treatment in
an agreement valued at as much as $145 million.

Other
trends show the industry's renewed interest in gene therapy.  According to the
FDA, there are currently 354 U.S. gene therapy studies under way, up from only
116 worldwide in 2008.  A Jain Pharmabiotech report released this month indicates that a total of 189 companies are currently
developing gene therapies, up from only 44 in 1995.

However,
despite the recent scientific successes, gene therapy is unlikely to produce
revenue for any U.S. company for several years, as no gene therapies have been
approved for actual medical use.  Only China has approved gene therapies for two
types of cancers.  Nonetheless,
there is no shortage of economic optimism.  An October 2008 report from Global Industry Analysts predicts gene therapy products will have revenue
of $465 million in 2015.

James
DeGiulio has a doctorate in molecular biology and genetics from
Northwestern University and is a third-year law
student at the Northwestern University School of Law.  Dr. DeGiulio
was a member of MBHB's 2009 class of summer associates, and he can be
contacted at degiulio@mbhb.com.