USA – Moderna announced that it has dosed the first patient in a trial testing its second mRNA HIV jab, less than six weeks after launching human trials for its first jab in January.

This sets the stage for a race between Moderna and Excision BioTherapeutics for a breakthrough HIV therapy.

Moderna’s second HIV shot, mRNA-1574, differs from the first in that it targets HIV envelope trimers via mRNA rather than eliciting broad antibodies against the virus.

Its trial is the result of yet another collaboration between the Cambridge-based biotech and the National Institutes of Health, this time with the National Institute of Allergy and Infectious Diseases’ Division of AIDS.

The phase 1 study will enroll up to 108 HIV negative adults ages 18 to 55 years, to evaluate the safety and immunogenicity of three candidate vaccines.

Doses of 100 micrograms or 250 micrograms will be administered via intramuscular injections into the deltoid muscle. A dose escalation plan will be implemented in the low-dose groups.

The HIV trimer mRNA vaccine trial comes after the company launched a phase 1 trial for its other HIV vaccine in January, which tests sequential administration of HIV immunogens via mRNA as a way to elicit strong and durable B-cell responses.

The company’s hypothesis, based on research from Scripps University’s William Schief, Ph.D., is that B-cell responses will evolve over time into more broad and robust neutralizing antibodies.

Two-horse race

The start of its second trial is the latest development in the race for a new HIV therapy, which now appears to be a two-horse race between Moderna and Excision BioTherapeutics.

Excision BioTherapeutics the had launched its own nine-patient phase 1/2 trial to test its CRISPR-based therapeutic, which it boldly touts as a “functional cure” for the virus.

Both Moderna’s and Excision’s treatments could be game changers in the standard course of care for HIV-positive patients, known as antiretroviral therapy, the first of which was approved more than 30 years ago.

Antiretroviral treatments work by reducing HIV’s viral load to undetectable levels, making it impossible for the virus to spread. However, such treatments must be taken on a daily basis and are not a cure.

The phase 1 trials conducted by both companies are not the only potential advances in HIV treatment. A day before they were released in late January, new research showed that the popular PD-1 inhibitor cancer therapy Keytruda helped to bring HIV out of dormancy in patients on antiretroviral therapy.

The findings suggested that future therapies could be more effective while also being less common.

Moderna did not provide a timeframe for top-line data for mRNA-1574, but the primary completion date of its other vaccine’s phase 1 trial is set for April 2023.

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