India's Zydus starts phase 2 COVID-19 vaccine trial after clearing safety test

Zydus Cadila has completed (PDF) a phase 1 clinical trial of its COVID-19 vaccine ZyCoV-D, setting it up to move straight into a 1,000-subject phase 2 study. The Indian company said the DNA vaccine was well tolerated in the first stage of the adaptive phase 1/2 trial it initiated last month.

ZyCoV-D is designed to introduce DNA that encodes for a viral protein into human cells. By ordering human cells to make the protein, ZyCoV-D could elicit an immune response against the coronavirus. The approach is similar to that pursued by Inovio Pharmaceuticals. Like Inovio, Zydus sees the ability of its vaccine to withstand higher temperatures than some rival approaches as a differentiator.

Whether ZyCoV-D works as well as other COVID-19 vaccine candidates remains to be seen. So far, Zydus has only said that the vaccine was well tolerated by people who received it in the first phase of the trial. Zydus monitored subjects in a clinical pharmacological unit for 24 hours after dosing and in the community for seven days thereafter. 

Based on the safety profile seen so far, which Zydus said was endorsed by the Data Safety Monitoring Board, the study is set to progress into its larger, 1,000-subject, placebo-controlled phase 2 portion on Thursday. 

The milestone continues the speedy advance of the vaccine through the clinic. Zydus wrapped up its preclinical assessments of the vaccine and secured clearance to start clinical trials in early July. Less than two weeks later, Zydus began dosing the first subjects in an adaptive phase 1/2 study. Zydus is set to start the phase 2 portion of the trial three weeks after getting the phase 1 underway.

Zydus’ progress into and through the clinic has benefited from the willingness of the Indian regulator to fast track processes. India is currently averaging more than 50,000 new cases of COVID-19 a day. 

The Serum Institute of India has secured a license to AstraZeneca’s COVID-19 vaccine, setting it up to make 400 million doses for low- and middle-income countries by the end of 2020, but with Western governments buying up supplies of other candidates, India may need more local players to step up if it is to embark on a mass-immunization program capable of ending the crisis.

Aspects of Zydus’ vaccine mean that, if it is safe and effective, it may be well suited to use in India. Vaccines that use mRNA to induce an immune response, such as those in development at CureVac, Moderna and BioNTech and Pfizer, typically need to be transported along cold chains. That can make it hard to ship the vaccines in industrialized countries. In rural India, the requirement could severely limit access. 

Zydus said its DNA vaccine approach achieves “much improved vaccine stability and lower cold chain requirements making it easy for transportation to remotest regions of the country.” AstraZeneca’s AZD1222 also has less demanding storage requirements than the mRNA vaccines.

In June, Zydus said the DNA vaccine is one of two COVID-19 candidates it is developing. Zydus is yet to share details of the approach it is taking with the second follow-on vaccine candidate.