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New rhinitis therapy should help patients to breathe easy Rigel's new
intranasal inhibitor R112 could offer a useful alternative therapy for patients
suffering from allergic rhinitis, as Datamonitor's Shaun Falkingbridge explains.
Bolstered by supportive recent trial results, Rigel can now go on to seek
partner firms to realize full commercialization of the drug... Allergic
rhinitis describes a series of symptoms associated with nasal irritation or
inflammation caused by allergen exposure. The most common symptoms include runny
nose, itching in the eyes, nose and throat, sneezing and nasal obstruction due
to blockage or congestion. Datamonitor estimates a US prevalence rate of 57
million patients. R112
is an intranasal inhibitor to SYK, or spleen tyrosine kinase, which is a novel
drug target for respiratory diseases such as allergic rhinitis and asthma. SYK
is involved in immunoglobulin E signaling in mast cells, which play important
roles in both early and late phase allergic reactions. R112 is the most advanced
compound in development with this mechanism of action for allergic rhinitis: a
multidose safety trial of 24 patients conducted in 2003 indicated that R112 has
a favorable safety profile, with no local nasal irritation and no significant
laboratory abnormalities. An
alternative to corticosteroids needed
Last
week, there was more upbeat news on R112
as Rigel reported results from the phase
II trials. These studies took place in two locations in the US where patients
spent two days in an outdoor setting during the high pollen season. The newly
reported data showed that treatment with R112 achieved a statistically
significant improvement in Global Nasal Allergy Symptom Scores over placebo. Interestingly,
symptoms associated with chronic nasal congestion were dramatically
improved with R112 over the placebo group.
This suggests the drug may address one unmet need in allergic rhinitis: that
need being better, safer decongestants. Given
the non-fatal nature of allergic rhinitis, patients are unwilling to tolerate
severe side effects and many physicians are reluctant to prescribe therapies
that result in even minor side effects such as drowsiness. However, there is a
real need for a safe and efficacious alternative to corticosteroid prophylactic
therapy and, if successfully launched, R112 could represent the first
alternative to intranasal corticosteroids in this market. However,
it may struggle in a market dominated on one side by oral antihistamines, and
the other by intranasal steroids. Antihistamines are prescribed as first-line
therapy as they are highly effective for the key symptoms of the disease.
Patients that continue to suffer from symptoms may be prescribed an intranasal
corticosteroid. Rigel could
therefore position the drug as an add-on therapy in patients who are poorly
controlled on intranasal steroids. However, greater commercial success may come
from targeting patients who are not adequately managed with antihistamines
alone, but do not need or want intranasal corticosteroids. The non-steroidal
nature of the drug could be especially appealing for children with allergic
rhinitis. Partnership
may be the way ahead
Rigel's
business model is to develop product candidates through Phase II clinical
trials, after which it seeks partners for completion of clinical trials,
regulatory approval and marketing. Rigel is likely to want to partner with an
established major pharmaceutical player in this market, such as GSK, Aventis,
Pfizer or Schering-Plough. Rigel's problem is that some of the companies that
could make the best partners, based on current market share, already have
strategies to maintain and strengthen the current gold standards - for example,
GSK and Aventis are both developing novel intranasal steroids. Rigel
may have to demonstrate how the drug could be positioned to complement the
current gold standard therapies. For example, in clinical practice, if the
clinician is faced with treatment of a patient already severely symptomatic with
marked nasal congestion, R112 could perhaps be prescribed with an intranasal
steroid. R112 would address the nasal congestion, allowing the steroid to exert
an effect on the involved nasal mucosa. The
company could also convince potential partners that the mechanism of action
could be useful for treating asthma. GSK and Aventis both confirm the efficacy
of new respiratory drugs in asthma initially, followed later by the allergic
rhinitis indication. Rigel has taken the opposite route: its next generation SYK
inhibitors are anticipated to enter clinical trials for asthma in late 2004. Rigel's
strength is that it has a product with a truly novel mechanism of action, in a
market with relatively little innovation - especially in comparison to other
respiratory diseases such as asthma. Of all the companies currently in the
allergic rhinitis market, Aventis appears to be the most likely company to take
an interest this product. Aventis no longer has any R&D capability in this
area, and has an active history of licensing novel respiratory products from the
biotech industry. Related
research:
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