Gilead Pauses KITE-753 Trials Over Safety Concerns

The company is investigating higher rates of severe neurotoxicity seen in later-stage trials compared to initial findings.

Updated on Oct. 30, 2026 in Biotech

Bold flat-color editorial illustration featuring a grid of clinical glass vials against a navy background, evoking medical research and regulatory caution. — Gilead Sciences has placed a partial clinical hold on its KITE-753 trials following reports of increased neurotoxicity in late-stage testing. AI Illustration. Upload story photo >

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Gilead Sciences has placed a partial clinical hold on its phase 2 and phase 3 PALISADES clinical trials for KITE-753. The company initiated the hold in alignment with the FDA to investigate safety discrepancies involving serious neurotoxicity identified between phase 1 and phase 2 data.

Why it matters

The hold highlights the ongoing safety challenges in advancing CAR-T cell therapies from early-stage research into broader clinical applications. Gilead is investigating immune effector cell-associated neurotoxicity syndrome (ICANS) to determine the cause of higher severity rates in later-stage trials compared to initial findings.

While the phase 1 trial for KITE-753 showed a 71% complete response rate, current scrutiny focuses on the increased incidence of grade 3 and 4 ICANS. This syndrome involves neurological side effects triggered by immune cell activation following treatment.

The players

Gilead Sciences

A major biopharmaceutical firm that acquired Kite Pharma to establish a dominant position in the CAR-T cell therapy market.

Kite Pharma

The cell therapy division of Gilead, known for developing the Yescarta CAR-T product.

FDA

The U.S. regulatory body that oversees clinical trial safety standards and aligned with the company on the hold.

The details

ICANS — immune effector cell-associated neurotoxicity syndrome — is a known, potentially severe neurological side effect that can occur after chimeric antigen receptor (CAR) T-cell therapy, where a patient's immune cells are genetically modified to attack cancer. The company is evaluating whether differences in the manufacturing or the administration of the therapy in phase 2 and phase 3 trials contributed to higher toxicity grades than those observed in the initial phase 1 study. No deaths or grade 5 adverse events have been reported in connection with the KITE-753 trials.

2017: Gilead acquired Kite Pharma for $11.9 billion.
Late 2025: Kite revealed phase 1 data for KITE-753.
May 2026: Johnson & Johnson dropped out of the CAR-T race.
Q3 2026: Gilead reported total revenue of $8.3 billion.
October 29, 2026: Gilead announced the partial clinical hold on trials.

The Tech Race

This development follows the May 2026 exit of Johnson & Johnson from the competitive CAR-T field, signaling consolidation in the sector. Gilead faces pressure to stabilize its pipeline as its own cell therapy division reported an 18% sales decline in Q3 2026.

Patients currently enrolled in the PALISADES trials will be subject to the conditions of the partial hold as investigators review safety metrics. There is no timeline for when the company expects to resolve the safety investigation or resume the affected studies.

The takeaway

Gilead faces a critical hurdle in proving that its KITE-753 candidate can be scaled safely outside of early trial parameters. Stakeholders should track future FDA disclosures or company updates regarding the resumption of the PALISADES clinical program.