New agreement on Chinese malaria vaccine candidate

Mar 15 2006

In a move that promises to expand the clinical testing of another promising malaria vaccine candidate, the US-based PATH Malaria Vaccine Initiative (MVI) and the Chinese company Shanghai Wanxing Bio-Pharmaceuticals today announced an agreement that supports the development of a pediatric malaria vaccine against Plasmodium (P.) falciparum, the most deadly strain of malaria.

The agreement focuses on the candidate vaccine known as PfCP2.9. Under development for close to a decade, the vaccine was created at the Shanghai Second Military Medical University by a team headed by Professor Pan Weiqing, whose research has long been recognized and supported by the World Health Organization (WHO). The technology was licensed to Wanxing Bio-Pharmaceuticals in 2001 for development.

The project announced today will allow improvements in the manufacturing process and will lead to the safety evaluation of the vaccine. It is the first step in a clinical development plan that is meant to generate proof that the product can safely and effectively prevent children from dying from infection with the deadly parasite.

“MVI is excited to be a partner in this project and is pleased to support the development of this promising vaccine candidate,” said MVI Director, Dr. Melinda Moree. “Malaria has been killing humans for millennia. The world will need multiple strategies—including a vaccine—to conquer the disease.”

Wanxing General Manager Mr. Yang Banjun said he expected the partnership to lead to the validation of his company’s expertise and its product. “The ultimate target population for this vaccine is young children who are at risk of infection with the parasite P. falciparum. This trial is an important step toward saving their lives.”

Malaria continues to exact a heavy toll on the health and economic welfare of the world’s poorest communities. P. falciparum is responsible for the annual deaths of more than one million people, the overwhelming majority of them children under the age of five in sub-Saharan Africa. Malaria is also a serious public health problem in other parts of the world. In China, which has witnessed a resurgence of the disease since 2000, the impact is greatest in the southern regions of Yunnan and Hainan.

No licensed malaria vaccine exists, but Mr. Yang, Dr. Moree, and others say that with many more quality vaccine candidates entering the clinical development process than ever before, the world may not be far from licensing and delivering a safe, effective, and affordable product to communities that need it. MVI itself is working on 20 vaccine candidates through partnerships that span five continents.

“For the first time in malaria vaccine development, there is a robust pipeline of candidate vaccines to be evaluated in clinical trials,” said Dr. Marie-Paule Kieny, director of the WHO Initiative for Vaccine Research.

The Chinese vaccine candidate targets the malaria parasite at its most destructive stage—its rapid replication in human red blood cells. By combining the key segments of the blood-stage proteins MSP1 and AMA1 into one molecule, PfCP2.9 aims to elicit the antibodies necessary to inhibit the parasite’s invasion of red blood cells. Pre-clinical studies have demonstrated that with the correct conformation, this fusion protein is effective at accomplishing this function.

The trial, which began in February, is sponsored by Shanghai Wanxing Bio-pharmaceuticals in collaboration with MVI and WHO. It follows a previous WHO-supported trial that established initial safety of the vaccine in healthy adults in 2004. The new trial is meant to provide Wanxing and MVI with the data needed to determine the optimal dose levels and vaccination schedule required to maximize the vaccine’s safety and tolerability. Changhai Hospital in Shanghai will conduct the eight-month trial, which will involve 70 healthy adult volunteers. If successful, the trial will be followed by additional studies involving adults and children in malaria-endemic settings.