Phase I prime-boost vaccine trial to be conducted in Chennai, Pune

Published in The Hindu on August 16, 2008

Next year may see the start of a Phase I prime-boost AIDS vaccine trial at the National AIDS Research Institute (NARI), Pune, and the Tuberculosis Research Centre (TRC), Chennai.

The prime to be used will be ADVAX, a DNA-based vaccine, and the boost will be the MVA vaccine that was tested during the Phase I trial at the TRC. A separate Phase I prime-boost vaccine trial using ADVAX and MVA will be conducted in London.

Prime-boost vaccine strategies are adopted to produce stronger and long-lasting immune responses.

The final results of the Phase I AIDS vaccine trial using Modified Vaccinia Ankara (MVA) vector indicated good response in the volunteers at both low and high doses. However, the level of immune responses was only modest and the persistence of the responses was not very encouraging.

“It may be possible to boost the [level of] immune responses when the vaccine is used in combination with other candidate AIDS vaccines. This is what the prime-boost trial aims to determine,” Patricia Fast, Executive Director (Medical Affairs) of the International AIDS Vaccine Initiative (IAVI) told this correspondent over telephone from New York.

It was found that the immune responses of the MVA vaccine declined over several months. “Probably after the prime [dose], the immune responses would last much longer,” Dr. Fast said.

The ADVAX has been tested in the U.S. According to Dr. Fast, the DNA vaccine was found to be safe. While the ADVAX dose to be used would be four milligrams, the MVA boost would be the low-dose one.

“Immunologists generally prefer to give a lower dose of a vaccine as it is thought to give qualitatively better immune responses,” said V.D. Ramanathan, explaining the choice of low dose (5×10{+7}) MVA for the prime-boost trial. Dr. Ramanathan is a Deputy Director at the TRC and the Principal Investigator of the trial at centre.

The trial will be conducted simultaneously at the NARI and the TRC.

“Thirty-two volunteers will be recruited. It will be 16 volunteers each at the NARI and the TRC,” said Dr. Fast. The proposal is to split the 16 volunteers at the NARI and the TRC into two groups of eight each. One arm would get only MVA while the other one would get ADVAX and MVA. Each arm would have two volunteers who would get a placebo (dummy).

“The trial at the Imperial College, London, will start in October,” said Dr. Fast. “The trials [in London and India] are not linked to one another.”

The trial would be conducted by the Government of India — through the ICMR and NACO — and the not-for-profit IAVI, headquartered in New York.