The US Food and Drug Administration is to consult with its Oncologic Drugs Advisory Committee on Thursday this week on whether further restrictions and warnings should be placed on the use of a class of drugs used to treat anemia induced by chemotherapy.

Erythropoiesis-stimulating agents, or ESAs, are used to boost red blood cells in patients who typically become anemic from kidney disease or chemotherapy. Examples include include Amgen’s Aranesp and Epogen, and Johnson & Johnson’s Procrit.

The FDA announced in January that it had received new data from two studies about the safety of ESAs. The data showed that patients with breast or advanced cervical cancer taking ESAs for chemotherapy-induced anemia had a shorter survival rate or faster tumour growth compared to similar patients who did not take the drug.

The agency said together with another six studies they had already reviewed, the overall picture was that patients with non-small cell lung, breast, head and neck, lymphoid or cervical cancer who were treated with ESAs experienced faster tumour growth or died sooner than their counterparts who did not take ESAs.

In a posting on its website this week, the FDA said there was not enough data to rule out tumour progression or risk of death when using the label recommended dose of the drugs in any cancer patient group other than those with non-small cell lung cancer.

The agency said a new assessment of the risks and benefits was needed, mentioning that some of the drugs were first approved in 1993.

Part of the difficulty in coming to a decision about whether to increase restriction and warnings will be that the studies that showed the increased risk of tumour progression and reduced survival rates were using target levels of hemoglobin higher than those recommended in the label.

The label recommends target levels of 10 to 12 grams per decilitre, and no higher, whereas in the first group of studies reviewed by the FDA, the ESAs were given in an attempt to reach a target hemoglobin level of 12 grams per deciliter or greater, although the agency noted that many patients did not reach that level.

The studies that used ESAs to reach these off-label targets are detailed in the black box warnings currently accompanying the drugs.

The FDA said ESAs help a significantly higher proportion of kidney patients to avoid blood transfusion compared to cancer patients.

A statement from Johnson & Johnson quoted by CNN/Dow Jones said that when ESAs are used within label targets they have not been linked to increased risk of death and tumour progression.

A joint statement from Amgen and J&J reported by Reuters said the drugs “continue to provide significant benefits” such as reduced need for blood transufsions, and that these outweighed the risks.

The FDA said trials are currently testing use of ESAs with cancer patients within the targets stated on the labels, but these will not complete for some years.

Click here to read the full FDA brief to its Oncologic Drugs Advisory Committee (PDF).

Sources: FDA, CNN/Dow Jones, Reuters.

Written by: Catharine Paddock, PhD