Switzerland's Novartis said delays of two blockbuster hopefuls - heart drug Leqvio that cost it $10 billion and $2.1m-per-patient Zolgensma - remain in regulators' hands, dragging on sales already hit by the pandemic.
Chief executive Vas Narasimhan said the company's fourth-quarter results missed expectations.
He said cholesterol-reducing Leqvio's approval timeline depends on the US Food and Drug Administration, after the agency flagged a supplier's "facility inspection-related conditions".
Expanding Zolgensma to older patients has also stalled, as the FDA seeks safety data.
Like many drugmakers, Novartis in faced challenges due to the coronavirus pandemic, as lockdowns kept patients away from hospitals. The regulatory obstacles add to his burden this year.
"Largely the timelines are out of our control," he told reporters on a call, on the FDA's scrutiny of Leqvio.
Narasimhan, who did not provide details on "unresolved" issues at the Italian plant of supplier Corden Pharma, said Novartis would respond to the FDA in the second or third quarter.
Leqvio is approved in Europe.
Expanding Zolgensma to older patients - the therapy is approved for babies with spinal muscular atrophy (SMA) and reaped $900m in 2020 - is also stalled after primate studies raised safety worries and necessitated further FDA scrutiny.
The delay helps rival drugs including from Roche establish an SMA foothold.
"We continue to await our animal data in the mid part to second half of this year," Narasimhan said, on prospects of Zolgensma trials resuming.
His regulatory updates came as Novartis's fourth-quarter core net income rose 3% to $3.03 billion, compared to the average analyst forecast of $3.15 billion in a Refinitiv poll.
Sales rose 1% to $12.77 billion, missing the $12.88 billion poll forecast, as Covid-19 lockdowns hurt drug sales.
"We expect to continue to see pandemic affects on the health care system through the first half," Narasimhan said.
Novartis proposed raising its dividend 1.7% to 3 Swiss francs, and forecast 2021 net sales growing at a low- to mid-single-digit percentage rate.
Novartis does not have vaccines in the works for Covid-19, and several of its medicines failed efforts to repurpose them for pandemic use.
But it is still holding out hope for a partnership with Swiss biotech Molecular Partners to yield a new treatment for the coronavirus.
