Abgenix's Drug May Not Match Wall Street's High Hopes
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CHICAGO --
Abgenix
(ABGX)
and
Amgen
(AMGN) - Get Report
said Saturday that their targeted cancer drug, ABX-EGF, was effective in shrinking tumors in patients with advanced colon cancer, but the scope of the drug's efficacy may fall short of Wall Street's elevated expectations.
According to an interim look at 40 patients in an ongoing phase II study, four patients treated with ABX-EGF -- or 10% -- saw their tumors shrink by at least 30%. Patients in the study, all of whom had failed chemotherapy, were given ABX-EGF once weekly for eight weeks, and then assessed for tumor response. The data were presented today at the annual meeting of the American Society of Clinical Oncology.
The fact that ABX-EGF invoked a 10% response rate in these very sick colon cancer patients is clinically meaningful -- and robust enough for Abgenix and Amgen to continue the study, which is now enrolling 150 patients. But that may not be good enough to appease some of Wall Street's biotech fund managers, who have bid up Abgenix shares in anticipation of a response rate in the upper end of the 10% to 15% range, or even higher.
"This data is preliminary but we're encouraged to see responses in patients that are heavily pre-treated," says Gisela Schwab, Abgenix's chief medical officer. "This signals activity of
ABX-EGF in this patient population." Schwab adds that other than a skin rash (more on that later), ABX-EGF caused no significant safety problems, including no antibody formation or any type of hypersensitivity reactions.
One biotech hedge fund manager is not as sanguine. "From my perspective, this data is a disappointment because I expected ABX-EGF to perform better than Erbitux," he says. This fund manager was long Abgenix in the weeks leading up to ASCO but currently has no position in the stock.
Erbitux, the embattled cancer drug from
ImClone Systems
(IMCLE)
, also invoked a 10% response when used as a standalone treatment in similarly advanced colon cancer patients, according to previously published study results. The latest Erbitux data, as we all know by now, will be center stage Sunday at ASCO.
Schwab warns against reading too much into comparisons of the new ABX-EGF data with anything -- old or new -- from Erbitux. "There is really no statistical basis upon which you can compare the studies," she says.
Both ABX-EGF and Erbitux -- engineered monoclonal antibodies given by injection -- are members of the closely watched class of drugs that attempts to halt the growth of cancer cells by blocking a key enzyme, epidermal growth factor receptor.
Since the middle of February, Abgenix shares have jumped 156% on
hopes and expectations that ABX-EGF would prove to be a more potent drug than Erbitux. The runup in Abgenix shares was also attributable to the fact that many investors viewed the biotech firm as undervalued relative to ImClone. Abgenix shares hit a recent high of $11.74 on May 27. The stock closed Friday at $10.64.
Investors have largely used Abgenix, rather than Amgen, as a proxy for ABX-EGF because the former company discovered the drug and does not yet have any approved products on the market. Amgen, of course, is the world's largest biotech firm, with three blockbuster drug franchises to its name already.
To be fair to Abgenix, results presented today only offer a partial window into ABX-EGF's efficacy, since the study is ongoing. That means the final response may change as data are collected and analyzed on another 110 patients.
Abgenix's Schwab says additional data presented on ABX-EGF today continue to support the theory that the drug is the most potent of the so-called EGFR inhibitors, including Erbitux. One of the outward signs of this potency is a skin rash that develops on patients who are given these so-called EGFR inhibitor drugs. ABX-EGF caused a rash on 100% of the patients in the study reported today. By comparison, Erbitux has caused a rash in about 80% of patients, according to previously released data.
There will be data presentations sponsored by other companies at ASCO this year talking about a direct correlation between skin rash and efficacy with this class of drugs. However, this thesis may be called into question somewhat by the fact that response rate for ABX-EGF and Erbitux as standalone therapies for colon cancer now appear equivalent.
The ABX-EGF phase II study was originally designed to enroll 100 patients, but Amgen and Abgenix have decided to boost patient numbers by another 50. Enrollment should be completed "in a matter of weeks, not months" said an Amgen spokesman.
The Amgen spokesman also said that the remaining clinical and regulatory path for the drug has not changed. Amgen, which is largely in control of the drug's development for colon cancer, intends to conduct a phase III study once the phase II study is completed. That keeps ABX-EGF behind Erbitux. ImClone and partner
Bristol-Myers Squibb
(BMY) - Get Report
are expected to resubmit their drug to the Food and Drug Administration this year.
Adam Feuerstein writes regularly for RealMoney.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. He invites you to send
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