FDA to consider Isis' AIDS drug
Vitravene could pave way for new gene therapy
By Bara Vaida
Last Update: 07:15 PM July 21, 1998
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WASHINGTON (CBS.MW) -- A new breed of drug will be considered
by regulators Wednesday, when a Food and Drug Administration panel
discusses Isis Pharmaceuticals Inc.'s Vitravene treatment for
AIDS-related blindness.
The drug, known generically as fomivirsen, uses
antisense therapy, a new way of attacking a virus's
genetic code directly. The technology and the drug
will be weighed for safety and effectiveness by the
FDA's Ophthalmic Drugs Advisory Committee.
While approval wouldn't necessarily mean a
blockbuster product for Isis (ISIP), it would be a
shot in the arm for other products in development
which use the same technology. Isis shares fell
13/16 to 13 7/16 Tuesday.
"This is a potentially historic FDA panel because
this is the first antisense therapy to go before the FDA," said Matt
Murray, a senior biotechnology analyst with Lehman Brothers.
The technology works by using a strain of genetic material that attaches to
genes within a virus and interrupts the virus's replication process,
according to Isis spokeswoman Karen Handel. The interruption slows the
progress of the disease in the body. In Vitravene's case, the therapy is
targeted at the cytomegalovirus (CMV), which can cause blindness in
patients with advanced acquired immune deficiency syndrome.
Clinical studies
In two clinical studies, Isis, based in Carlsbad, Calif., found patients
treated with Vitravene were free from disease progression for 71 days,
compared with 13 days with patients who did not receive Vitravene.
Patients also had few side effects, the company said.
The current standard CMV treatment, ganciclovir,
is made by Roche Holdings AG. Because that drug
has more side effects than Vitravene, Isis's drug
could become the dominant treatment for CMV, if
it wins approvals, said Steven Delco,
biotechnology analyst with Miller, Tabak, Hirsch
& Co.
"Because [Vitravene] is a better-tolerated drug with
fewer side effects, we project that Isis will be
successful in taking significant market share from
their competition in the next few years," he said.
Modest revenue
If Vitravene does grab market share, revenue will
be modest. Annual sales for drugs for CMV are
about $100 million annually and that market is
expected to shrink to $85 million by 2001, as more
AIDS patients remain healthy as a result of new
anti-HIV treatments, Delco said. About 40 percent
of patients in the advanced stage of AIDS develop
sight problems because of CMV.
In the first quarter of 1998, Isis' revenue was $6.9 million, up from $5.6
million in the previous year. The company's loss widened to $11.5
million, or 43 cents a share, from $8.6 million, or 33 cents a share.
Isis has been working closely with Novartis AG's Ciba-Geigy vision unit
and the company has pledged to give Isis $20 million as it meets each
milestone toward approval of Vitravene. If the drug is approved,
Ciba-Geigy has marketing rights to sell the product in the U.S., Handel
said.
Bigger markets
More important than market share is the psychological boost that an FDA
recommendation could provide, analysts said. Isis is applying the antisense
therapy to other diseases, like cancer, Crohn's disease and asthma, which
have the potential for generating larger markets.
"Vitravene is not a potentially profitable drug, Murray said. But "if the
FDA panel recommends approval ... it makes it more likely that similar
types of antisense drugs will be approved in the future," Murray said.
"It would be an affirmation that antisense therapy is effective," said Ira
Loss, an analyst with HSBC Washington Analysis Group.
Isis's Handel said the company is "optimistic" the panel will recommend
approval, however, analysts were cautious about predicting the panel's
judgment of Isis's data.
'Weak data'
The clinical data for Vitravene is based on a small pool of patients -- 27 in
one study and 54 in another -- and therefore cannot be considered solidly
conclusive, said Charles Engelberg, an analyst with AmeriCal
Securities. "The data is weak," he said.
Handel said the pool of patients is small because those being treated are in
the most advanced stages of AIDS and some do not survive until the end
of the trial. In addition, it is difficult to recruit patients because most are
so ill, she said.
Isis has big hurdles to overcome. The FDA tends to be very cautious
about new classes of drugs and may ask the company for research and
clinical studies data before recommending approval. In addition, the
science behind antisense therapy is not yet conclusive for some analysts.
They say that it is not clear whether Vitravene works because it is
attacking the genes in the virus, as intended, or whether it is working in
some other way, said Eric Hecht of Merrill Lynch.
Priority drug
But to Isis's advantage, Vitravene is being considered by the FDA on a
priority status and the FDA "will be looking for an excuse to approve it"
because there are so few treatments for AIDS-related blindness,
Engelberg said.
The FDA has been working hard to speed up the approval process for
drugs in the face of stiff congressional and public health criticism that the
agency is being too cautious. Recently though, several drugs have been
withdrawn from the market by the FDA, raising criticism in the opposite
direction.
"Everything in life is a pendulum. There was a point when the FDA was
capricious in turning down drugs but now they are bending over
backwards to appease Congress," Engleberg said. "So that might be a
reason to think they might recommend approval. I think we'll find a happy
balance. These are a capable bunch of physicians and they will do the
right thing in the end."
Following the FDA's consideration of Vitravene, the agency's Arthritis
Drugs panel will meet on Aug. 7 to consider a new drug from Hoechst
AG's (HOE) Hoechst Marion Roussel Inc. The agency's Oncologic Drugs
Committee will meet between Sept. 1 and 3 to discuss new cancer
treatments. These meetings will be watched closely by Wall Street,
analysts said. |
