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Phase 1/1b Study of VLP Vaccine Candidate Launches Against Respiratory Syncytial Virus

September 9, 2021 • 1:37 pm CDT
(Precision Vaccinations)

Seattle-based Icosavax, Inc. announced the initiation of a Phase 1/1b clinical trial of IVX-121, a VLP displaying a Respiratory Syncytial Virus (RSV) stabilized pre-fusion F antigen in healthy adults and older adults.

Icosavax stated in a press release, 'Assuming favorable results from the IVX-121 Phase 1/1b clinical trial and favorable preclinical data from its human Metapneumovirus (hMPV) VLP candidate, Icosavax plans to initiate thereafter a Phase 1 clinical trial of its IVX-A12 bivalent RSV/hMPV vaccine candidate.'

The Phase 1 part of the trial is expected to enroll up to 90 healthy adults in Belgium.

The Phase 1b part of the clinical trial is expected to enroll up to 217 healthy older adults. In addition, it is anticipated that a subset of the older adult subjects will be followed for 12 months after vaccination to assess the durability of immune response to IVX-121.

Virus-Like Particles (VLPs) enable the multivalent display of antigens in a manner that closely resembles viruses but contain no genetic material, says the company.

Approved vaccines derived from naturally occurring VLPs have shown efficacy when formulated as combination vaccines. In addition, they have shown the ability to induce high and sustained levels of neutralizing antibodies (nAbs) in adults, which are generally associated with protective antibodies immunity.

“I am delighted with the clinical progress Icosavax has recently made. The initiation of our second clinical trial in just three months bears testament to the concerted effort our team exerted in the development and manufacturing of our vaccine candidates,” commented Adam Simpson, CEO of Icosavax, in the related press statement.

“As part of our core strategy, we plan to transition IVX-121, our RSV monovalent VLP candidate, into a combination vaccine with RSV and hMPV, IVX-A12."

"With the vision of creating combination VLP vaccines, we believe that developing a bivalent vaccine targeting two of the leading viral causes of pneumonia in older adults could represent a compelling offering for both providers and patients."

"Currently, neither RSV nor hMPV has approved vaccines; IVX-A12 has the potential to prevent disease caused by both viruses in a single shot.”

The Phase 1/1b clinical trial of IVX-121 is a randomized, observer-blind, placebo-controlled multi-center study designed to evaluate the safety and immunogenicity of three dose levels of non-adjuvanted and aluminum-adjuvanted IVX-121 in healthy adults, including older adults.

The trial will inform the dose of IVX-121 to be evaluated in combination with the Icosavax hMPV VLP candidate IVX-241 for the anticipated Phase 1 clinical trial of the RSV/hMPV bivalent vaccine candidate IVX-A12.

After completing the Phase 1/1b clinical trial of IVX-121, Icosavax intends to shift its development of the VLP vaccine candidate for RSV to an RSV/hMPV bivalent combination vaccine strategy.

The company plans to submit an investigational new drug application to the U.S. FDA in the first half of 2022 and, thereafter, initiate a Phase 1 clinical trial of IVX-A12.

'We believe combining two VLP vaccine candidates, IVX-121 and IVX-241, into a single combination vaccine, IVX-A12, will provide a potential benefit to vaccinators and patients over monovalent vaccines in clinical development,' says the company's website.

RSV is a common respiratory virus. It usually causes mild, cold-like symptoms. But it can cause serious lung infections, especially in infants, older adults, and people with serious medical problems, says

Icosavax (NASDAQ: ICVX) is a biopharmaceutical company leveraging its innovative VLP platform technology to develop vaccines against infectious diseases, with an initial focus on life-threatening respiratory diseases.