Swiss pharma giant Novartis AG (NVS.US) has suffered another clinical trial setback, marking the second high-profile candidate to fail in late-stage studies within a single week. The latest casualty is pelacarsen, its promising heart disease drug that successfully lowered lipoprotein(a) levels—a genetically driven cardiovascular risk factor affecting roughly one in five people. However, the company revealed on Friday evening that despite the reduction in lipoprotein(a), the drug failed to significantly cut cardiovascular deaths, heart attacks, or strokes compared to the placebo group.

This failure has dealt a heavy blow to industry hopes that the drug could pave a new path in cardiovascular disease prevention. The setback follows closely on the heels of another trial pause just days earlier, when Novartis temporarily halted an experimental cell therapy for autoimmune diseases after three patient deaths. In response to the news, Novartis shares trading in the U.S. dropped more than 7% in after-hours trading on Friday, while Amgen (AMGN.US), which is developing a similar heart drug, also slid nearly 6% in extended trading.

Jefferies analyst Michael Leuchten commented that this result raises fundamental doubts about whether any therapy that lowers lipoprotein(a) can ultimately deliver meaningful cardiovascular benefits. He also suggested that the market's reaction may be overblown, noting that even a successful trial would have prompted questions about which patients could truly benefit and how the drug would compete with rivals.

Novartis has been banking on a pipeline of new medicines to fuel growth as it faces upcoming patent expirations on several blockbuster products. CEO Vas Narasimhan had previously indicated that strong late-stage data could allow the company to raise its target of 5% to 6% annual sales growth by 2030. The next closely watched milestone for Novartis is an experimental injectable therapy designed to treat DM1, a muscle-wasting disease, at the genetic level rather than merely addressing symptoms. That treatment, del-desiran, is the centerpiece asset acquired through Novartis's $12 billion purchase of Avidity.

The implications of these two failures extend well beyond individual drugs. Novartis had positioned both pelacarsen and rapcabtagene autoleucel—or rap-cel—as potential game-changers in their respective fields, with the former targeting hereditary cardiovascular risk that was previously untouchable and the latter aiming to expand CAR-T cell therapy into autoimmune diseases. Notably, the pelacarsen disappointment came against the backdrop of a mixed week for Novartis, as another experimental therapy did deliver on its promise. Its oral multiple sclerosis drug remibrutinib succeeded in two late-stage trials, lifting shares more than 6% on Tuesday.

Novartis has yet to release detailed data from the failed pelacarsen study, including how close the drug came to meeting its primary endpoint and whether certain patient subgroups showed greater benefit. The company stated that full results will be presented at an upcoming medical conference.