I am (unfortunately) not among the CLTR holders, but I've been looking at it with interest. I thought you might be interested in the following letter to IBD from the President of IDEC:
Chemotherapy Comparisons
I read with considerable vested interest "Making Drug To 'Chase
Down' Cancer Cells" (New America, Nov. 25), which deals with Coulter
Pharmaceutical Inc.'s Bexxar treatment for non-Hodgkin's lymphoma.
At IDEC Pharmaceuticals Inc., we have successfully developed
Rituxan for treatment of relapsed or refractory, low-grade or
follicular, CD20 positive, B-cell non-Hodgkin's lymphoma. In fact,
we received final marketing clearance Nov. 26 from the FDA for this
new biologic agent.
IDEC is also developing an experimental-stage radioimmunotherapy,
IDEC-Y2B8, for the treatment of lymphoma.
Despite good intent, the article is misleading. Historical
comparisons, as are made in the accompanying table, are perilous at
best. Valid comparisons can only be made by conducting large,
randomized clinical trials that compare different agents in uniform
patient populations and with standard "end points." The table's
comparisons fall far short of this.
The development of immunotherapies has been driven by the
selectivity of antibody molecules. Antibodies seek out and attach to
very specific targets within the patient's body. In the case of
IDEC's Rituxan and IDEC-Y2B8, as well as Coulter's Bexxar, the target
is the CD20 marker on both normal and malignant B-cells.
Rituxan is in a class of its own. It is now approved by the FDA,
and it is a "naked" antibody. By contrast, both IDEC-Y2B8 and Bexxar
are experimental agents, and both rely primarily on attached
radioisotopes for their anti-tumor activity.
Radioimmunotherapies are expected to have higher activity and
higher toxicity than "naked" antibodies. Radioimmunotherapeutic
agents are designed to localize at tumor sites, but inevitably some
radiation is delivered to normal tissue, causing some normal cell
death. In contrast to Rituxan, it is expected that the toxicities
from radioimmunotherapies would be both more prevalent and more
severe.
We expect that Rituxan will be used, following relapse from
chemotherapy, throughout the course of a patient's disease, and
mainly in the community-based group practice or oncology clinic where
most lymphoma is treated.
By contrast, radioimmunotherapies properly belong late in the
course of disease, and will require patient referrals for treatment
to nuclear medicine specialists or radiation oncologists at major
medical centers. Thus, Rituxan and radioimmunotherapies, once
cleared for marketing, will be more complementary than competitive.
The comparisons in the table are misleading for other reasons.
First, different response criteria have been used by Coulter and by
IDEC in measuring overall response rates. There are no standard
response criteria for judging responses in lymphoma. This makes
different studies hard to compare.
Finally, the clinical data used in the table do not reflect the
most recently available information. Abstracts are now published for
the American Society of Hematology meeting in San Diego in December.
The Coulter abstract would suggest that the response rate for Bexxar
from early single-institution trials (83% reported in the table) has
not held up in multicenter trials.
So, for many reasons, comparing Rituxan and any radioimmunotherapy
is like comparing an apple and an orange. And data are not available
today that would allow a meaningful comparison to be made of Bexxar
vs. IDEC-Y2B8.
William H. Rastetter Chairman, President and CEO IDEC
Pharmaceuticals San Diego, Calif.
Congratulations to you all on some nice stock-picking.
Peter |
