ImmunityBio (IBRX) is trading lower as the market continues to price in fallout from the FDA’s warning letter dated March 13, 2026, which challenged promotional communications that implied broader cancer benefits and described ANKTIVA as a “cancer vaccine.” In addition, new April 15, 2026 deadline notices for a securities class action are resurfacing uncertainty around potential litigation costs, discovery risk, and management distraction.

The FDA warning letter focused on alleged misleading efficacy and risk messaging in direct-to-consumer materials, and it required a written response within 15 working days of receipt. While the company has said it addressed the correspondence and outlined corrective actions, investors often treat these episodes as an ongoing headline risk until there is clear closure and promotional practices stabilize.

Deadline alerts related to the proposed securities class action can weigh on sentiment even without new operational developments, because they remind investors of the March 24, 2026 share-price shock and keep downside scenarios in rotation. For a mid-cap biotech-commercial story like IBRX, incremental uncertainty around governance, compliance, and potential settlements can translate into daily volatility when there isn’t a stronger, competing catalyst.

Near-term, traders will look for signs that the promotional review is fully implemented across all channels and that there are no follow-on actions. Separately, the next widely cited legal milestone is the May 26, 2026 lead-plaintiff deadline, which can be another headline moment for the stock.