TidBits Of Info

DESPITE INEFFECTIVENESS, VECTIBIX APPROVED BY FDA

The US Food and Drug Administration (FDA) has yet again given accelerated approval to a new cancer drug despite the fact that the drug has only a minimal effect on the disease. On Sept. 23, 2006, the regulatory agency gave permission to Amgen, Inc. to market Vectibix (panitumumab) as a treatment for advanced cancers of the colon and rectum. Vectibix was approved as a so-called "third-line" or "last-resort" treatment, to be used after standard chemotherapy regimens, such as 5-FU, oxaliplatin and irinotecan, have failed.

In the single clinical trial cited by FDA, Vectibix delayed the progression of cancer for an average of about five weeks. However, as FDA admitted, Vectibix did not actually increase the patients' overall survival.

Vectibix is known as a 'targeted' therapy because it is designed to seek out and inactivate a specific growth-controlling protein called EGFR, found on the surface of tumor cells. EGFR (which stands for 'epidermal growth factor receptor') is expressed at abnormally high levels by tumor cells in a number of different types of cancer, and is associated with their rapid growth. The purpose of blocking EGFR is to reduce the ability of tumor cells to multiply. Unfortunately, although this is an elegant theory, targeted drugs in practice have generally performed disappointingly. Even when administered in conjunction with chemotherapy they are only marginally effective, and typically do not improve survival in the most common forms of cancer.

Vectibix is very similar to an already approved drug, Erbitux. The supposed advantage of Vectibix - and the rationale for its approval - is that it allegedly causes fewer allergy-like reactions than Erbitux. However, it is a mistake to believe, as has often been claimed, that such targeted therapies have minimal side effects. In its press release announcing the approval of Vectibix, the FDA itself states that the drug has serious adverse events, including pulmonary fibrosis (formation of scar-like tissue in the lungs), severe skin rash complicated by infections, infusion reactions, abdominal pain, nausea, vomiting and constipation. Skin rash is seen in around 90 percent of patients, according to one study. Other common reactions include fatigue, abdominal pain, nausea, and diarrhea. This doesn't sound all that different from the miseries accompanying standard chemotherapy (Gibson 2006).

The clinical trial on which the FDA based its approval of Vectibix involved 463 people who had undergone chemotherapy for metastatic cancer of the colon or rectum. The average time until either the disease progressed, or the patient died, was 96 days for patients who received Vectibix, and 60 days for patients who did not get the drug. Thus, at best, this new drug delayed the forward momentum of the disease by about a month.

It is said that as a condition of approval, the manufacturer of Vectibix committed to conducting a postmarketing trial to show whether the drug improves patients' actual survival. Such commitments are very often requested by FDA as a precondition of approval. Astonishingly, however, most of these promised "phase IV" trials are either never conducted or never reported - a situation which the FDA seems content simply to tolerate.

Lower Prices

Unable to point to much in the way of novelty or efficacy for Vectibix, its manufacturer, Amgen, Inc., has set the price at 20 percent below that of ImClone's competing drug, Erbitux.

"The move by Amgen appeared to be both a competitive strategy and an acknowledgment of recent public concerns about the costs of some of the newest cancer drugs, which run tens of thousands of dollars a year," wrote reporter Andrew Pollack in the New York Times (Pollack 2006).

"Given the nature of scrutiny now on oncology therapeutics," Jim Daly, the senior vice president for North American commercial operations, told Pollack, "we thought the best policy was a meaningful discount on Erbitux."

Nonetheless, Vectibix will still cost US $4,000 for an infusion every two weeks, which would add up to more than $100,000 over the course of a year. Even if the patient fails to survive for more than a few months, treatment with Vectibix will still cost tens of thousands of extra dollars, most of which will be borne by insurance companies (and eventually by the public in the form of rising insurance premium costs).

Leonard B. Saltz, MD, a colon cancer specialist at Memorial Sloan-Kettering Cancer Center (MSKCC) in Manhattan, who has previously spoken out against high drug costs, said of Amgen's decision: "I don't think this solves the problem in any way, shape or form in terms of the ridiculous price of chemotherapy drugs. It is a baby step in the right direction."

But despite its lack of efficacy, Eric Schmidt, an analyst with Cowen & Company, estimated that Vectibix could eventually achieve annual sales in a range of $500 million to an astonishing $2 billion. "Amgen doesn't want to be a charity," said Schmidt, "and if others are getting away with it and they can price at a modest discount instead of a substantial discount, why not?"

~ Ralph W. Moss, Ph.D.

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