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Girding for a marketplace battle in oncology, Amgen Inc. offered encouraging data regarding its anemia product Aranesp (darbepoetin alfa), approved in September for dialysis and nondialysis patients with chronic renal failure and already being used off-label for cancer patients.

"We've started to enroll in an enormous global Phase III study," said Amgen spokesman Michael Beckerich, adding that the company has not disclosed a completion date.

"We haven't given any specifics on location, patients or endpoints," he told BioWorld Today. "It's going to have to be a very large study."

Extended-release Aranesp allows for fewer injections than epoetin alfa, which is marketed as Epogen by Amgen and as Procrit by New Brunswick, N.J.-based Johnson & Johnson, a licensee and Amgen competitor.

The Phase III study will further explore findings from a Phase II Aranesp "loading" study, data from which were disclosed at the American Society of Clinical Oncology meeting in Orlando, Fla.

Data from the 12-week head-to-head study of Aranesp compared to Procrit involved 122 patients. The trials used anemic patients receiving chemotherapy who received a fixed dose of Aranesp in a four-week priming phase, followed by an eight-week Aranesp maintenance phase or Procrit given at 40,000 units per week.

At four weeks, the results show the change (more than 2 g/dL hemoglobin increase from baseline) in hemoglobin was 80 percent greater in patients who got Aranesp than in patients receiving Procrit.

After 12 weeks of treatment, the data showed, 61 percent of patients treated with Aranesp responded to treatment (>2 g/dL hemoglobin increase from baseline), compared with 49 percent of patients responding to Procrit therapy. This held true even when Procrit doses were increased to 60,000 units per week for those patients whose initial responses were inadequate. Aranesp doses were not increased for patients who did not respond.

"Some patients need to get the hemoglobin up very fast, especially since they're only on chemotherapy an average of 18 weeks," Beckerich said. "For those patients, this loading dose concept might be the way to go."

Because hemoglobin rises slowly with conventional regimens, physicians "are not knowing until six or seven weeks after they've started administering the drug" whether it's working, he said.

"For an oncologist, this is quite frustrating," Beckerich said - and the patients may lose valuable time.

Aranesp, devised by changing what Amgen has called "the amino-acid backbone" and adding new carbohydrate chains, has an advantage for cancer patients with anemia not related to chemotherapy, according to data from another poster among those Amgen presented at ASCO.

"They have cancer and for some reason they're not getting chemo, and this once-a-month dosing might be ideal for them," Beckerich said.

"Having a needle put in your body is not so fun, so if you can reduce the amount of shots to once a month, that's phenomenal for patients," he noted. Procrit is administered two to three times per week.

"These studies were no secret," he added. "But the fact we were able to get the data in, computed and put together the results is what is the big deal about the meeting."

A year ago at the ASCO meeting, Thousand Oaks, Calif.-based Amgen presented data from a 314-patient, double-blind, placebo-controlled, randomized Phase III study in lung cancer patients receiving multicycle platinum-based chemotherapy regimens. Results showed the proportion of patients taking Aranesp who needed a red blood cell transfusion was reduced by more than 50 percent over the course of the treatment phase. (See BioWorld Today, May 15, 2001.)

Submitted to the FDA for approval in the third quarter of 2001 for chemotherapy patients with anemia, Aranesp (approved in Europe last June) is expected to be the subject of a decision by July 19.

"That's the date [specified under the Prescription Drug User Fee Act]," Beckerich said. "Do they keep those dates? Sometimes, sometimes not. We haven't said when we think we're going to be launching this, but a lot of the reimbursement pieces are in place."

In February, the United States Pharmacopeia, an independent source for labeled and unlabeled drug information, accepted Aranesp (darbepoetin alfa) for the treatment of chemotherapy-associated anemia and anemia associated with chronic renal failure.

"[Insurance] claims are going through," Beckerich said. "Oncologists actually treat chronic renal insufficiency, so they're using Aranesp already and getting experience with the drug, and trying it in cancer patients. We're very excited that the claims are starting to go through, whether it be private or public payers."

Reimbursements have been made for 200 mcg every other week, he added, "and that's pretty equivalent to what is generally used for Procrit, but [patients are] getting the advantage of one less shot. In the future, we might be able to deliver not only on less frequent dosing, but on faster response and with more people responding."

Estimates of the anemia oncology market in the U.S. are in the $5 billion range. In Europe, analysts have pegged the Aranesp market at potentially $1 billion, split roughly evenly between dialysis and oncology.

Amgen's shares (NASDAQ:AMGN) closed Tuesday at $48.65, down $1.14.

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