Icosavax has been rocked by the Covid flop and says its RSV candidate passed the early test. But investors still need more persuasion – Endpoints News

Three months after a disappointing announcement of its Covid-19 vaccine, Icosavax is back with so-called positive topline data for another VLP vaccine candidate — although investors aren’t impressed.

IVX-121, a respiratory syncytial virus (RSV) vaccine candidate, appeared to generate “robust” immune responses in both young and older adults, as measured by neutralizing antibodies, and appeared to be generally well tolerated, Icosavax reported.

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The preliminary Phase I/Ib results provide an important proof of concept for the Seattle-based biotech’s underlying virus-like particle platform technology, said CEO Adam Simpson. VLP spontaneously assembles proteins that Neil King, Icosavax co-founder and synthetic biology researcher, had previously described as football-like.

“They also reinforce our strategy of combining multiple pathogen targets in one vaccine,” he said in a statement. “As planned, Icosavax will now advance the development of IVX-121 in combination with a human metapneumovirus (hMPV) VLP as our IVX-A12 bivalent vaccine candidate.”

RSV and hMPV are two major causes of pneumonia, he added, and neither of them have an approved vaccine.

However, a variety of companies are aiming to bring the first RSV vaccine to market, with Pfizer, GSK and Bavarian Nordic all touting late-stage data.

Icosavax licensed a pre-fusion stabilized form of RSV F antigen from the NIH. But his plan, outlined in an S-1 last year, has always been to forego a monovalent vaccine in favor of a 2-in-1 vaccine.

In a note, Cowen’s Phil Nadeau noted that the neutralizing antibody titers produced by IVX-121 — up to 7,687 IU/mL for the younger group and up to 7,561 IU/mL for the older group — “are in the range of those produced by Pfizer RSV vaccine candidate PF-06482077 (RSVpreF) and RSVpreF3 OA from GSK, suggesting that Icosavax has a viable RSV component for its RSV+hMPV vaccine.”

Jefferies’ Roger Song also praised the data:

While investors might think that nAb GMFR is generally comparable to Comps (slightly lower in older populations) and thus the market positioning that was late to market is unclear, we see that the vaccine differentiates from Co on several fronts supported by today’s preliminary data: 1) no decrease in nAb titer from young to older adults, 2) very benign reactogenicity/tolerability, 3) wide window for combination vaccine with equal immunogenicity at the lowest dose and cheap AE at the highest dose.

Nonetheless, shares are down about 14% in premarket trading, taking the share price to $7.27.

In addition to its vaccine, Icosavax also tested an aluminum hydroxide adjuvant in the study to make sure it didn’t work, having previously failed in studies by other companies. And investigators found that the adjuvant made no difference.

The company plans to submit an IND application and start a Phase I study for IVX-A12 in the second half of the year.

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