Back in November 2016, when Novavax was picking up the scraps from a Phase III crash of its RSV vaccine in older adults, the company pointed to the Gates Foundation-backed program to test the vaccine in infants as a “significant commercial opportunity.” It went on to become the lead program as Novavax mounted an arduous comeback campaign for RSV-F vaccine.
But today, execs conceded that the infant trial has suffered the same late-stage fate.
Investors showed little patience for a company that’s been quick with explanations but slow to deliver. The stock $NVAX tanked more than 65% in pre-market trading to $2.13.
As it turned out, immunizing mothers with ResVax while they are pregnant did not prevent medically significant lower respiratory tract infections caused by RSV in infants for the first three months of their lives — the primary endpoint.
To be sure, Novavax is operating in a tough field littered with setbacks, including a flop from Regeneron (which has since dropped its RSV antibody). In a rare win, AstraZeneca recently secured expedited reviews in the US and EU for a different approach — a single dose long-acting drug for a broad swath of newborns.
What the treatment did achieve — and this is the silver lining that execs are holding onto as they try to beat down a path to approval — was protecting infants from “some of the most serious consequences of RSV, including RSV LRTI hospitalizations and RSV LRTI with severe hypoxemia,” CEO Stanley Erck said in a statement.
In other words, execs elaborated on a conference call, while the vaccine was not deemed effective for common — but less severe — manifestations of the respiratory syncytial virus, it appears to protect the small group of infants who get the worst attacks.
They also suggested that vaccinating mothers at an earlier stage of gestation (from 28 to 33 weeks) might increase efficacy — potentially a key point in their pitch to regulators.
Novavax offered a peek on the data, which it plans to unveil at a medical meeting. Respectively, the efficacy rates of ResVax in per-protocol infants were as follows::
- 39% against medically significant RSV LRTI (97.5%CI, -1% to 64%)
- 44% against RSV LRTI hospitalizations (95%CI, 20% to 62%)
- 48% against RSV LRTI with severe hypoxemia (95%CI, -8% to 75%)
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