The Central Drugs Standard Control Organisation (CDSCO) late on Thursday approved Zydus Cadila’s application to move to human trials for its ZyCov-D, hotting up India’s race for a vaccine against Covid-19. The trials will begin this month on over 1,000 patients across multiple sites, said the Ahmedabad-headquartered firm’s chairman, Pankaj R Patel. In an interview with The Indian Express, Patel discusses how the firm developed its vaccine candidate, the timeline it has in mind for its trials and other vaccine candidates it is considering. Edited excerpts:
What process did you follow in the development of your vaccine?
We started working in early March, when we saw that the S protein epitopes were responsible for this (Covid-19). We basically looked at some of those S protein epitopes and basically selected a few of them to clone into a vector and into a host…we tested them for the immunogenicity and the expression levels and, based on that, we selected one (from four potential candidates) which was good.
This was then extensively developed in terms of quality standards, purity, etc. Then, once it was completely developed, we administered it to animals to check the immune response and we got a very good immune response in those animals. We actually tested it on four different animal species…from mice to rats, to guinea pigs and rabbits. Then what we did was the sera we collected from the rabbits were tested for virus neutralisation assay. What you do is, you see whether this immune sera can kill the virus or not.
We found that the viruses were being killed. The antibodies were good to kill the virus.
Then we moved to pre-clinical toxicity in two species for 28 days to find out whether the vaccine was safe…here also, we found a good immune response. Based on that, we made the application for moving into the clinical phase…and they (CDSCO) approved the protocol we submitted to start the phase I/II trials.
(We received the approval) late last night.
How long are you expecting the first two phases of the trial to take?
We will move into the clinical phase now. We intend to test this vaccine in about 1,000 volunteers…We’re following the adaptive clinical trial protocol (phase I followed by phase II without much gap in between) which, in a pandemic or emergency area, is permitted by regulators across the world.
We will take about three months to complete the Phase I and II clinical trials, after which we will approach the DCGI for their consideration.
Do you plan on seeking an emergency authorisation for your vaccine, which would allow you to launch the product without phase III trials?
At the end of the phase I and II trials, we will go to our regulator and, whatever the regulator will tell us, we will follow.
By the time we are done with the first two phases of our trial, we will have more clarity (on the data)…then we will take a call.
Your vaccines are also being tracked globally by the World Health Organisation. What stage of development is the other candidate at?
One is this plasmid DNA vaccine that is going into (human) clinical trials now. The other one is being developed in our research centre in Italy. We have been updating data to WHO (about them). It is monitoring these developments because it is a global effort that people are trying to put in (to develop a Covid-19 vaccine).
The one in Italy is still in the preclinical stage. It is more challenging. What we are basically doing (with this vaccine) is reverse genetic (technique). We are trying to create a measles virus which can give immunity to Covid-19 and it’s kind of a challenging task, so we are optimising our yields.
It will take maybe another quarter or so to get some data on that.
Everyone is trying to put in every different kind of effort (to find a vaccine) and if anyone becomes successful, I will be very happy because, ultimately, somebody has to bring the vaccine to the market.
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