Say use of highly sophisticated prime-boost clinical trial in Phase I opens up platform for trials for other vaccines
The hunt for an HIV vaccine continues to be elusive with clinical trials unlikely to move to Phase II at the premier National AIDS Research Institute (NARI) in Pune and the Tuberculosis Research Centre (TRC) at Chennai,but scientists do not perceive it as a setback.
They say conducting such highly sophisticated prime-boost clinical trials using complex vectors – DNA-based vaccine ADVAX was used as prime and Modified Vaccinia Ankara (MVA) as boost in Phase 1- has in fact opened up a platform for trials for other vaccines.
When contacted,Dr V M Katoch,Director General,Indian Council of Medical Research (ICMR) said an HIV vaccine committee is reviewing the process. Our advances in research have in fact helped us to now to take on trials for developing other vaccines, Katoch told The Indian Express.
Phase I trials are meant for studying safety of the vaccine in humans and its ability to stimulate immune responses. ADVAX was earlier tested in the US and found safe. MVA vector,tested at TRC in 2008,also showed it was safe.
The recent HIV vaccine trial tested both DNA/MVA or MVA/MVA prime-boost strategies,says Dr R S Paranjape,Director,NARI. Both these regimens were found safe and evoked a modest immune response in majority of the volunteers in Phase 1.
However,when genetic stability assessment studies were undertaken to determine stability of the encoded genes,we found that the vector was identified as genetically unstable. This was despite several strategies assessed in parallel to stabilize the vector, says Paranjape.
Observations like those seen with this candidate are normal in course of vaccine development,said Dr V D Ramanathan,Director Grade Scientist at TRC,Chennai and one of the principal investigators of the trial.
India started it search for an AIDS vaccine in 2005 and the Adeno associated vector study was the first vaccine trial taken up. The trials were completed in December 2006. The vaccine met safety criteria,but did not induce immune responses in sufficient number of volunteers to meet the criteria for further trials.
The International AIDS Vaccine Initiative (IAVI) has been partnering with the Ministry of Health and Family Welfare in India through the National AIDS Control Organisation (NACO) and the Indian Council of Medical Research (ICMR) since 2002 to implement AIDS vaccine research and development programme.
Dr Rajat Goyal,Director of International AIDS Vaccine Initiative,India operations,said the road to vaccine development has been traditionally very difficult,but due to the clinical trials,the infrastructure and human resource capacity developed in various ICMR institutes that participated in HIV vaccine trials will be able to contribute to evaluation of other potential vaccines as well.