India continues to progress in AIDS vaccine development efforts

A second Phase I AIDS vaccine clinical trial in India was successfully completed, the Indian Council of Medical Research, the National AIDS Control Organization and the International AIDS Vaccine Initiative announced. The results of the trial of an MVA-based AIDS vaccine candidate (TBC-M4), which was conducted in Chennai, indicated that the vaccine candidate had acceptable levels of safety and was well tolerated. The proportion of volunteers whose immune systems responded to the vaccine candidate suggests the candidate holds promise. The trial was done using two doses of the candidate vaccine. After three injections, 82 percent of the volunteers who received a low dose and 100 percent of those who received a high dose registered immune responses to the vaccine. The 100 percent response rate is greater than that seen with the majority of AIDS vaccine candidates tested in humans to date. However the strength and diversity of these immune responses were modest. It may be possible to boost the immune response, if this vaccine is used in combination with other candidate AIDS vaccines.

"We are pleased to see that the MVA-based candidate tested in Chennai was safe and showed promising initial immune responses. We do not know whether these observed responses will ultimately translate into an effective vaccine that will help protect individuals from HIV infection, but hope to learn more through further testing," said Dr. S K Bhattacharya, Additional Director General of the Indian Council of Medical Research. "India is playing a significant role in global AIDS vaccine discovery efforts given our strong medical and scientific capabilities. There is a need for continued efforts for the creation of novel, reliable mechanisms for long-term research on AIDS vaccines and other new prevention technologies."

The Phase I clinical trial was initiated in January 2006 at the Tuberculosis Research Center (TRC), an Indian Council of Medical Research (ICMR) institute in Chennai, and was completed in February 2008. This trial was conducted under the aegis of a Memorandum of Understanding (MoU) between the Government of India—through the Indian Council of Medical Research (ICMR) and the National AIDS Control Organization (NACO)—and the not-for-profit International AIDS Vaccine Initiative (IAVI). YRG CARE, based in Chennai, collaborated with TRC to mobilize the community around the Phase I trial.

Dr. Narayanan, former Director of the Tuberculosis Research Center, added, "Consistent innovation in science despite setbacks has ensured the development of many effective prevention technologies. The successful conduct of the trial in Chennai re-affirms the need for continued vaccine development initiatives, where learnings from every effort will contribute to global advancement of the AIDS vaccine field."

About the Phase I MVA-based (TBC-M4) AIDS vaccine trial

The trial was a double blind, dose-escalation, randomized, placebo-controlled trial, which was initiated after receiving all necessary regulatory and ethical clearances. The objectives of such a Phase I trial are to evaluate the safety of the vaccine candidate and to gather preliminary results of immune responses induced by the candidate. The total duration of the trial was approximately 24 months. The volunteers recruited for this trial were 32 healthy, HIV-uninfected men and women between 18 and 50 years of age, from all socio-economic strata. Three intra-muscular injections of TBC-M4 or placebo were administered to the volunteers.

Moving forward

The results of the Phase I vaccine trial of TBC-M4 suggest that further research is warranted. Currently, two additional Phase I trials testing the MVA-based candidate in a prime-boost regime are planned and under review by the relevant authorities in India and approved in the UK. The trials are designed to use different modes of administration of the priming vaccine, different dosages and different vaccine regimens. It is hoped that the prime-boost regimen will help to strengthen the modest immune responses observed in the Phase I trial of the MVA-based candidate alone. Collectively, the results will help determine whether and how to move forward with additional testing of this MVA-based AIDS vaccine candidate.

Simultaneously, IAVI has undertaken work to modify the MVA-based vaccine candidate so that it is ready for large-scale manufacturing should the trial results suggest further testing is warranted.

Source: International AIDS Vaccine Initiative