BIONEWS
Pelacarsen lowered lipoprotein(a), a lipid tied to heart attack risk in roughly 1 in 5 adults, but did not cut cardiovascular events.
Roughly one in five adults has elevated Lp(a), a liver-made particle that drives heart attack and stroke risk through a mechanism that statins and PCSK9 inhibitors do not fully address. On Thursday, the first Lp(a)-lowering drug to reach a large late-stage trial reported that it did exactly what it was designed to do, and still failed.
Novartis's Lp(a)HORIZON Phase III trial tested pelacarsen, a drug originally developed at Ionis and licensed to Novartis for late-stage development. The topline result: pelacarsen did not reduce heart attacks, strokes, or cardiovascular death in patients with established cardiovascular disease over more than seven years of follow-up. The Novartis release landed days after a separate cardiovascular outcomes failure from Novo Nordisk, and STAT+ framed the back-to-back news as having "popped a hole in the balloon" of an entire Lp(a)-lowering drug class.
Pelacarsen was the first large, late-stage test of an Lp(a)-lowering therapy, the field's first real chance to convert a genetic risk factor into a treatment. BioPharma Dive and the Healio cardiology trade had both pointed to the readout as the test case for a class backed by billions of dollars in investment across multiple programs, with follow-on programs at Amgen (olpasiran), Silence Therapeutics (SLN360), and Roche positioned as the next layer.
The biology of Lp(a) has not moved. Mendelian randomization studies, which treat inherited variants as a natural randomized trial, have linked elevated Lp(a) to cardiovascular events independently of LDL cholesterol. The hypothesis the trial was testing was narrower: that lowering Lp(a) in patients who already have cardiovascular disease, by enough, and fast enough, would prevent events. That narrower hypothesis did not hold.
The remaining readouts are designed around three levers: longer follow-up, larger Lp(a) reductions, and earlier intervention in patients who have not yet had a cardiovascular event. Amgen's OCEAN(a) outcomes trial, the Silence Therapeutics program, and Roche's pelacarsen-class follow-on are each built around some combination: a higher-risk primary prevention population in one, a deeper Lp(a) cut in another, a longer follow-up window in a third. Commentary on BiotechReality framed the Lp(a)HORIZON result as a "cracked hypothesis" rather than a closed door, and the practical effect is that each of the next readouts is now being measured against a higher bar.
The Lp(a)-lowering field had drawn billions of dollars in investment across multiple programs. A negative primary readout in patients with established disease does not, on its own, kill a class whose remaining trials are designed around primary prevention or higher-risk subpopulations. It does change how the next three readouts will be priced. Novo Nordisk's SELECT cardiovascular readout earlier this month had already cooled the GLP-1 cardiovascular expansion thesis, and the back-to-back failures give investors a reason to widen the discount.
About one in five adults carries an Lp(a) elevation that raises heart attack and stroke risk through a pathway the existing cardiovascular armamentarium does not touch. For them, the Lp(a)HORIZON result is a delay, not a verdict. The next eighteen to twenty-four months of readouts will set the field's direction. Amgen's OCEAN(a) outcomes trial is the next to report.