A malaria vaccine in development by US biopharma company Sanaria has demonstrated sustained protection against the parasite, according to the results of a clinical trial.
The PfSPZ vaccine had previously been shown to provide a short-term immunological response targeted at the malaria parasite, but in the latest trial was shown to provide protection against infection for ‘at least 14 months’.
If confirmed in follow-up trials, the vaccine could turn out to be “the first malaria vaccine providing durable protection against infection with malaria parasites”, according to the company.
The vaccine is based on inactivated Plasmodium falciparum sporozoites, a key stage in the parasite’s life cycle. Intravenous injections were shown to protect against exposure to malaria-infected mosquitoes in nine out of 14 (55%) recipients after 21 weeks.
Moreover, looking at a subgroup of five patients followed up for over a year, the team found all of them were protected when exposed once again to infected mosquitoes – a 100% protection rate at 59 weeks – according to the study. The results have been published in the journal Nature Medicine.
That data looks pretty good when compared to trials of the Mosquirix malaria vaccine developed by GlaxoSmithKline (GSK) – which has already been given a positive opinion by the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) despite what the panel described as ‘limited efficacy’.
Mosquirix (formerly known as RTS,S) also targets P. falciparum – the most virulent form of malaria which affects 214m people a year and kills around 438,000. It was shown to have an initial protection rate of around 31-56%, depending on the age of the patient, although efficacy seemed to decline after the first year.
Sanaria chief executive Stephen Hoffmann said that in light of the latest data with PfSPZ, an optimised vaccine could be entered into trials that would provide “80% protection at six months”.
That level of protection could have a significant impact on malaria as it could be used to protect at-risk individuals as well as reduce transmission of the parasite in populations.
“It’s reasonable to suggest that within three to four years a safe, reliable vaccine could be a commercial reality and provide medical benefit to a huge population,” added Hoffmann.
Sanaria’s vaccine – which has been developed alongside researches at the National Institute of Allergy and Infectious Diseases (NIAID) – does however have some drawbacks.
In particular, being based on inactivated sporozoites means that the current version must be stored at very low temperatures, which could make it difficult to achieve widespread distribution in some regions of the world with less-developed infrastructure.
Nevertheless, the NIAID’s director Anthony Fauci said the study is “an encouraging step forward in our goal to control and ultimately eradicate malaria”.