Boston – A recently released paper by Project R&R published in the journal Alternatives to Laboratory Animals (ATLA 37, 399–416), presents a serious challenge to long-standing claims that animals are an important part of human cancer research. “An Examination of Chimpanzee Use in Human Cancer Research” found that chimpanzees, our closest genetic relatives, have contributed little to combating cancers and cost society not only time but wasted research dollars. The paper comes on the heels of a national ad campaign (ResearchSaves, Sept.16, 2009) launched by The Foundation for Biomedical Research advocating animal use.

Geneticist Jarrod Bailey, Ph.D., Science Director for Project R&R: Release and Restitution for Chimpanzees in U.S. Laboratories, conducted a comprehensive analysis of the use of chimpanzees in cancer research over the past four decades as well as proposed future uses.

According to Bailey, “There are significant biological differences between humans and chimpanzees. Despite an overall – although superficial – genetic similarity to humans, and despite claims by the research industry, chimpanzees have proven to be a poor model for human cancer research.”

The study found that chimpanzee tumors are extremely rare and biologically different from human cancers. Literature describing potential new cancer therapies tested in chimpanzees included significant caveats concerning species differences, and described interventions that had not been pursued in humans, presumably due to adverse reactions. Further, available evidence indicates that chimpanzees are not essential in the development of monoclonal antibody therapies for cancer treatment.

The U.S. is the only remaining large-scale user of chimpanzees in biomedical research in the world. Arguments regarding the inefficacy of chimpanzee use in biomedical research for humans have been mounting. H.R. 1326, the Great Ape Protection Act, was recently introduced to the House of Representatives. The bill seeks to end invasive biomedical research and testing on an estimated 1,000 chimpanzees remaining in U.S. laboratories.

The study concludes: “It would be unscientific to claim that chimpanzees are vital to cancer research and reasonable to conclude that cancer research would not suffer if the use of chimpanzees were prohibited in the U.S.” The cancer paper follows other studies investigating chimpanzee use to study human health and disease, including HIV/AIDS vaccine development. That study found chimpanzee use has not benefited but rather has hindered our search for an effective human vaccine against HIV/AIDS.  

On September 24, 2009, results from an HIV vaccine clinical trial (known as the Thai Phase III HIV vaccine study or RV144) revealed a new experimental vaccine to be 31 percent effective in preventing HIV infection. Over 16,000 men and women participated in the trial, which was conducted in Thailand by the Thai Ministry of Public Health and sponsored by the U.S. Army Surgeon General in collaboration with the Department of Defense and the National Institute for Allergy and Infectious Diseases.

This is welcome news, but according to Dr. Jarrod Bailey, Science Director of Project R&R: Release and Restitution for Chimpanzees in Laboratories, optimism should be guarded.  Notably, greater than two-thirds of the human trial participants remained unprotected from HIV infection. Further, the vaccine’s efficacy in other racial groups and against other strains of HIV remain to be seen.

A comprehensive review by Project R&R revealed that components of the RV144 vaccine have been widely tested in other trials in humans and animals, including chimpanzees.  According to Bailey, previous failures and the limited efficacy of this vaccine are the result of misleading data from chimpanzee experiments. Further, variants of the “ALVAC” component have been trialled alone and in combination with other vaccine types. Almost all provided protection from HIV infection in chimpanzees, but all failed in humans. The “AIDSVAX” component failed to protect several thousand clinical trial volunteers, despite many similar vaccines protecting chimpanzees from infection. Variations on the vaccine used in the Thai trial have been investigated previously with apparent success in chimpanzees, yet failure in humans.

Project R&R’s investigation demonstrates the futility of chimpanzee use in HIV-vaccine research. The Thai partial success should not deflect attention from the myriad vaccines (around 100 vaccines tested in over 200 human trials) that have shown great promise in chimpanzees only to fail in humans. The Thai vaccine trial adds no validity to arguments that chimpanzees are necessary or helpful in AIDS vaccine testing.

The case for human-relevant investigations was echoed by AIDS vaccine expert, clinical virologist Scott Hammer, M.D., who commented on the Thai data: “The positive results point to the crucial role of human testing in the development of any vaccine…human immune system variability or virus diversity can’t really be mimicked by any of the currently used laboratory animal models.”

The Thai vaccine’s limited success underscores the need for alternatives to chimpanzees and other animals in vaccine development.