14 February 2019 - - US-based biotechnology company Moderna, Inc., (NASDAQ: MRNA) has received topline data from the first planned interim analysis of safety and immunogenicity from its Phase 1 study of mRNA-1653 in healthy adults, the company said.

mRNA-1653 is a wholly-owned program in Moderna's prophylactic vaccine modality. mRNA-1653 is designed to protect against human metapneumovirus and parainfluenza type 3, two viruses that cause respiratory infections. 

It is a combination vaccine that consists of two distinct mRNA sequences encoding the fusion (F) proteins of hMPV and PIV3 formulated in Moderna's proprietary lipid nanoparticle technology.

These Phase 1 interim data show that a single vaccination with mRNA-1653 boosted serum neutralization titers against hMPV and PIV3, and that the magnitude of the boost was similar at all dose levels tested.

Consistent with prior exposure to hMPV and PIV3, all study participants had neutralizing antibodies against both viruses at baseline.

One month after a single mRNA-1653 vaccination, the hMPV neutralization titers were approximately six-fold baseline and PIV3 neutralization titers were approximately three-fold baseline (based on geometric mean ratios).

A second mRNA-1653 vaccination one month after the first vaccination did not further boost antibody titers, suggesting a single vaccination was sufficient to achieve a plateau in neutralizing antibodies in this pre-exposed population.

mRNA-1653 was found to be generally well tolerated. No serious adverse events, adverse events of special interest, or adverse events leading to withdrawal were reported. Injection site pain was the most commonly reported adverse event and the most common Grade 3 adverse event.

Much of Moderna's commercial vaccine development efforts are focused on addressing major causes of respiratory infections, including hMPV+PIV3 and respiratory syncytial virus.

These infections share many of the same features, often causing upper and lower respiratory tract illness, characterised by wheezing, bronchiolitis and pneumonia and are associated with a substantial burden of hospitalizations and outpatient visits among children throughout the first five years of life.

There are currently no approved vaccines for hMPV, PIV3 or RSV.

mRNA-1653-P101 is a Phase 1, first-in-human, randomized, observer-blind, placebo-controlled, dose-ranging study in healthy adults. The trial's key objectives include evaluating the safety and tolerability, reactogenicity and humoral immunogenicity of mRNA-1653, and selecting the optimal dose and vaccination schedule for further clinical development.

This study is being conducted in the United States, and enrolled 124 subjects across four dose levels of mRNA-1653 (25, 75, 150, and 300 µg) and placebo. Subjects were randomized to a one-dose or two-dose vaccination schedule, with the second vaccination of mRNA-1653 administered one month after the first vaccination.

Moderna has 21 mRNA development candidates in its pipeline, with 12 programmes now in clinical development.

These investigational medicines are grouped together into six modalities based on similar mRNA technologies, delivery technologies and manufacturing processes.

Typically, programs within a modality will also share similar pharmacology profiles, including the desired dose response, expected dosing regimen, target tissue for protein expression, safety and tolerability goals as well as their pharmaceutical properties.

Moderna scientists designed the company's prophylactic vaccines modality to prevent or control infectious diseases. This modality now includes nine programs, all of which are vaccines against viruses.

Some of these programs are designed for commercial use and others for public health. The goal of any vaccine is to safely pre-expose the immune system to a small quantity of a protein from a pathogen, called an antigen, so that the immune system is prepared to fight the pathogen if exposed in the future, and prevent infection or disease.

Moderna currently has four development candidates for potential commercial uses in this modality including: RSV (mRNA-1777 with Merck), cytomegalovirus vaccine (mRNA-1647), hMPV+PIV3 vaccine (mRNA-1653) and varicella zoster virus vaccine (mRNA-1278 with Merck).

Five development candidates in this modality are being explored for potential global health uses including: influenza H10N8 vaccine (mRNA-1440), influenza H7N9 vaccine (mRNA-1851), Zika vaccine (mRNA-1325 and mRNA-1893 with BARDA) and chikungunya vaccine (mRNA-1388 with DARPA).

hMPV was discovered in 2001 as the cause of acute respiratory infections in up to 15 % of patients. The virus primarily affects young children but can also infect adults, the elderly and those who are immunocompromised. Symptoms range from a mild upper respiratory tract infection to life-threatening severe bronchiolitis and pneumonia.

Despite the need, there is currently no approved vaccine for hMPV.

Infections from PIV account for up to 7% of acute respiratory infections among children younger than five years of age.

Of the four PIV types identified, PIV3 most frequently results in infections and leads to the more serious lower respiratory tract infections. Though PIV3-related infections were identified in the past, their burden to patients and hospitals has been elevated over the past few years. There is currently no approved vaccine for PIV3.

Headquartered in Cambridge, Mass., Moderna currently has strategic alliances for development programs with AstraZeneca, Plc. and Merck, Inc., as well as the Defense Advanced Research Projects Agency (DARPA), an agency of the US Department of Defense and the Biomedical Advanced Research and Development Authority (BARDA), a division of the Office of the Assistant secretary for Preparedness and Response within the US Department of Health and Human Services.