• John Evans

First trial of leishmaniasis vaccine shows promise


Photo by: abanima via Wikimedia Commons

The first completed trial of a new vaccine for leishmaniasis has demonstrated both safety and the successful development of an immune response.

In a press release from the University of York in York, U.K., where the vaccine is being developed, the researchers note that there are currently no vaccines to prevent the tropical disease, spread by the bite of sandflies. They also note that the existing treatment options for the disease have many side effects and are difficult to administer.

“We have always thought that vaccines should be our greatest weapon against the different forms of leishmaniasis, but it has been a long journey to develop vaccines for testing in the clinic,” said Professor Paul Kaye, PhD, in the release. Dr. Kaye is a Professor of Immunology at the University of York and is the principal investigator on the Wellcome Trust Translation Award that funded the development of the vaccine.

The new vaccine, known as ChAd63-KH, uses a non-replicating virus to introduce genes that code for Leishmania proteins into the human body. In the current clinical trials, ChAd63-KH is being tested to see if it can be used to treat rather than prevent disease.

In this first trial, the vaccine was given to patients with a chronic skin form of leishmaniasis and was shown to be safe and to stimulate immune responses associated with a cure. The findings were published online ahead of print in Molecular Therapy (Mar. 27, 2021; S1525-0016(21)00149-0).

“These results are very encouraging, showing that the vaccine we have developed is safe and immunogenic in patients,” said Dr. Kaye. “It is now important to test this vaccine as a therapy in different forms of leishmaniasis where drugs are poorly effective, and to see if it can prevent the spread of the disease.”

The research team is undertaking a second trial of the vaccine to determine whether vaccination helps patients to recover from their disease without the need for other medications.

Another study is planned to test the vaccine in healthy volunteers to determine whether it can protect them from getting the disease after exposure to infected sandflies.

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