FDA Warning Letter Over Misleading Anktiva Ads Sends ImmunityBio Stock Plunging

On a January podcast, Dr. Patrick Soon-Shiong told host Sean Spicer that ImmunityBio's bladder-cancer drug Anktiva was "approved for bladder cancer, but it actually can treat all cancers." That claim, and dozens like it spread across a TV advertisement and the same episode of The Sean Spicer Show, landed the company a formal FDA warning letter. When the letter went public Tuesday, investors responded immediately.

ImmunityBio's stock plummeted about 24% from its opening price of just over $9 to fall below $7 by midday. Reuters put the full-day decline at 26%. The sudden loss reflected how squarely the regulatory action struck the company's core commercial story: Anktiva has one approved use, treating adult patients with BCG-unresponsive non-muscle invasive bladder cancer with carcinoma in situ, with or without papillary tumors, delivered directly into the bladder alongside BCG therapy.

The FDA's Office of Prescription Drug Promotion reviewed both a direct-to-consumer broadcast advertisement identified as US-ANK-250065-v1 and a podcast titled "Is the FDA BLOCKING Life Saving Cancer Treatments?" featuring Dr. Patrick Soon-Shiong, ImmunityBio's Executive Chairman and Global Chief Scientific and Medical Officer. The podcast originally aired on The Sean Spicer Show on January 19, 2026.

The TV ad, which features Richard Adcock as CEO and Soon-Shiong as Executive Chairman, includes Soon-Shiong saying: "There's an ability to actually create a cancer vaccine so that we can treat the tumor, and it doesn't come back." The podcast went further, with Soon-Shiong describing interleukin-15 as "the most important molecule that could cure cancer." At another point in the episode, he said Anktiva is "on the path to curing the cancer" and, at the 47-minute mark, told listeners: "We have the therapy to prevent cancer if you were exposed to radiation, and that's Anktiva."

The FDA repeatedly took issue with Soon-Shiong's characterization of Anktiva as "a single jab" and a "little vial that you inject subcutaneously," though Anktiva is approved only for intravesical use. Regulators also flagged the podcast's description of the drug as a "cancer vaccine," which the FDA said was false, and noted that neither the ad nor the podcast contained adequate information about the drug's risks. The most common adverse reactions include increased creatinine, dysuria, hematuria, urinary tract infection, musculoskeletal pain, chills, and pyrexia.

The warning letter is the first full-fledged warning letter of 2026 from OPDP, arriving amid a stream of less-severe untitled letters. One of those earlier letters, sent in early 2026, went to ImmunityBio itself and echoed concerns from a September 2025 letter. In the March 13 warning, the OPDP stated it "is concerned that, despite receiving these previous Untitled Letters, ImmunityBio continues to promote Anktiva in a similarly misleading manner."

The September 9, 2025 and January 7, 2026 untitled letters had been sent to Altor BioScience, LLC, an indirect wholly-owned subsidiary of ImmunityBio, over similar presentations of Anktiva's efficacy. Those letters addressed misleading claims drawn from QUILT-3.0325, a single-arm study that the FDA said could not support the efficacy interpretations the company was promoting. The FDA's letter stated that "QUILT-3.032 did not provide interpretable results on disease-free survival" and that it was "not aware of data that support the efficacy claims and representations that ANKTIVA can cure cancer."

The company took rapid steps to limit the exposure of the flagged content. The TV commercial is no longer available online. The podcast episode was removed from ImmunityBio's website, though it remained live on YouTube and podcast platforms at the time of initial reporting.

ImmunityBio acknowledged the letter without contesting its findings. Spokesperson Sarah Singleton said the company takes the FDA's warning "very seriously" and plans to "work cooperatively with the agency to address the matters raised in the letter." The FDA gave ImmunityBio 15 days to respond and either explain why the promotional materials do not violate the agency's rules or offer a plan to discontinue and correct any misleading statements.

Not all market observers read the warning as a threat to the company's fundamentals. Piper Sandler analyst Edward Tenthoff said the firm believes "ImmunityBio can comply with these requests and are not changing our Anktiva revenue forecast." Anktiva generated $113 million in global sales in 2025, and analysts tracked by LSEG expect that figure to climb to $217.60 million in 2026, projections that assume the company can resolve the regulatory dispute without material disruption to prescribing. Whether those forecasts hold may depend on how quickly ImmunityBio can satisfy the FDA's demand for corrective action, and on whether the agency concludes the pattern of misleading promotion has been broken.