By Lisa Richwine
WASHINGTON, Oct 23 (Reuters) - A Human Genome Sciences Inc drug worked better than a placebo but similar to antibiotics for treating anthrax exposure in animal studies, U.S. drug reviewers said in a summary released on Friday.
The rabbit and monkey studies of the experimental drug, ABthrax or raxibacumab, had limitations and 'it is still unknown how well these models and results predict efficacy in humans,' the Food and Drug Administration staff said.
Human Genome shares fell 3.8 percent to close at $19.63 on Nasdaq. Shares have gained nearly 500 percent since July after unexpectedly positive results for an experimental lupus drug that analysts see as a potential blockbuster.
The FDA will ask an advisory panel that meets Tuesday if the drug's benefits outweigh risks for treating potentially deadly infections caused from inhaling anthrax, a bacterium feared as a possible biological weapon. FDA rules allow companies to study two animals in lieu of people to show effectiveness for some dangerous infections.
Adding a single intravenous dose of ABthrax to antibiotics produced similar effectiveness to antibiotics alone, FDA staff said. The advisory panel will be asked if the drug might interfere with antibiotics, or if more data is needed to show ABthrax provided any benefit. Antibiotics in the studies successfully treated between 95 percent and 100 percent of the animals, an unexpectedly high rate, the agency reviewers said.
'Given the high efficacy of the (antibiotic) arms' in the rabbit and monkey studies, 'the added benefit of raxibacumab ... could not be determined,' FDA staff said.
The U.S. government already has ordered 65,000 doses of ABthrax for a national stockpile of emergency medicines. In July, the company said it would record more than $160 million though the first two quarters of 2009 from government sales of the drug. It is due to receive $10 million more if ABthrax wins FDA approval.
Headaches were the most common reaction in people who took the drug to test its safety, FDA staff said. Some animals that died from anthrax had meningitis and other central nervous system problems, but a review of that issue was 'limited' in people because they were not exposed to anthrax, reviewers said.
In a separate summary prepared for the advisory panel, Human Genome said antibiotics alone could cure all anthrax infections in tests but 'the 2001 attacks and other real-world experiences have demonstrated that antibiotics alone are not 100 percent effective' and new options were needed.
If inhaled, anthrax can take hold quickly and by the time symptoms start showing it is often too late for successful treatment with antibiotics.
In 2001, letters carrying powdered anthrax killed five out of 11 people who got sick from the bacteria and were treated with antibiotics.
ABthrax was developed under the government's Project BioShield effort to encourage new drugs and vaccines against potential biological weapons.
The drug takes a new approach to fighting anthrax by targeting the toxin made by the bacteria rather than the microbe itself. It is designed to attack and neutralize the toxin that makes anthrax so deadly.
The 'demonstrated increase in survival rate and survival time constitutes a meaningful clinical benefit in the treatment of a serious, life-threatening infection,' Human Genome said of the drug.
(Reporting by Lisa Richwine, editing by Gerald E. McCormick and Matthew Lewis) Keywords: HUMANGENOME/FDA (lisa.richwine@thomsonreuters.com; + 1 202 310-5691; Reuters Messaging: lisa.richwine.reuters.com@thomsonreuters.net) COPYRIGHT Copyright Thomson Reuters 2009. All rights reserved. The copying, republication or redistribution of Reuters News Content, including by framing or similar means, is expressly prohibited without the prior written consent of Thomson Reuters.
WASHINGTON, Oct 23 (Reuters) - A Human Genome Sciences Inc drug worked better than a placebo but similar to antibiotics for treating anthrax exposure in animal studies, U.S. drug reviewers said in a summary released on Friday.
The rabbit and monkey studies of the experimental drug, ABthrax or raxibacumab, had limitations and 'it is still unknown how well these models and results predict efficacy in humans,' the Food and Drug Administration staff said.
Human Genome shares fell 3.8 percent to close at $19.63 on Nasdaq. Shares have gained nearly 500 percent since July after unexpectedly positive results for an experimental lupus drug that analysts see as a potential blockbuster.
The FDA will ask an advisory panel that meets Tuesday if the drug's benefits outweigh risks for treating potentially deadly infections caused from inhaling anthrax, a bacterium feared as a possible biological weapon. FDA rules allow companies to study two animals in lieu of people to show effectiveness for some dangerous infections.
Adding a single intravenous dose of ABthrax to antibiotics produced similar effectiveness to antibiotics alone, FDA staff said. The advisory panel will be asked if the drug might interfere with antibiotics, or if more data is needed to show ABthrax provided any benefit. Antibiotics in the studies successfully treated between 95 percent and 100 percent of the animals, an unexpectedly high rate, the agency reviewers said.
'Given the high efficacy of the (antibiotic) arms' in the rabbit and monkey studies, 'the added benefit of raxibacumab ... could not be determined,' FDA staff said.
The U.S. government already has ordered 65,000 doses of ABthrax for a national stockpile of emergency medicines. In July, the company said it would record more than $160 million though the first two quarters of 2009 from government sales of the drug. It is due to receive $10 million more if ABthrax wins FDA approval.
Headaches were the most common reaction in people who took the drug to test its safety, FDA staff said. Some animals that died from anthrax had meningitis and other central nervous system problems, but a review of that issue was 'limited' in people because they were not exposed to anthrax, reviewers said.
In a separate summary prepared for the advisory panel, Human Genome said antibiotics alone could cure all anthrax infections in tests but 'the 2001 attacks and other real-world experiences have demonstrated that antibiotics alone are not 100 percent effective' and new options were needed.
If inhaled, anthrax can take hold quickly and by the time symptoms start showing it is often too late for successful treatment with antibiotics.
In 2001, letters carrying powdered anthrax killed five out of 11 people who got sick from the bacteria and were treated with antibiotics.
ABthrax was developed under the government's Project BioShield effort to encourage new drugs and vaccines against potential biological weapons.
The drug takes a new approach to fighting anthrax by targeting the toxin made by the bacteria rather than the microbe itself. It is designed to attack and neutralize the toxin that makes anthrax so deadly.
The 'demonstrated increase in survival rate and survival time constitutes a meaningful clinical benefit in the treatment of a serious, life-threatening infection,' Human Genome said of the drug.
(Reporting by Lisa Richwine, editing by Gerald E. McCormick and Matthew Lewis) Keywords: HUMANGENOME/FDA (lisa.richwine@thomsonreuters.com; + 1 202 310-5691; Reuters Messaging: lisa.richwine.reuters.com@thomsonreuters.net) COPYRIGHT Copyright Thomson Reuters 2009. All rights reserved. The copying, republication or redistribution of Reuters News Content, including by framing or similar means, is expressly prohibited without the prior written consent of Thomson Reuters.
