FDA investigates cancer risk in Novartis gene therapy

Zolgensma works by slipping a healthy gene copy into a baby's cells. A virus carries it in. Novartis disclosed Nov. 5 that nine children treated with it later developed tumors. Two of those cases are different. Lab tests found the virus itself had wedged into a child's DNA. It switched on a cancer gene called GLI1. The FDA said Friday it's formally investigating.

Zolgensma's own label already carried a warning about this, calling it a 'theoretical risk.' Theoretical just became real. The FDA's warning now extends to Novartis's newer related therapy, Itvisma, too. No tumor cases have shown up there yet, but the FDA is watching as a precaution. Novartis says most of the nine reported tumors can't yet be tied to the treatment. Only two show that direct genetic link so far. Families and doctors are left to weigh a real cancer risk against a different danger. Left untreated, this disease kills most babies before age two.

Keep reading — what to watch

Will the FDA change Zolgensma's label or restrict who can get it? That decision could ripple across the whole gene-therapy field, not just one drug. Dozens of other gene therapies use the same delivery method, a modified virus that inserts itself into human DNA. If that method caused cancer here, regulators will have to ask whether it's a Zolgensma problem or a whole-field problem.