Gilead partly pauses lymphoma cell therapy trials over nerve side effects

Two trials of an experimental cancer treatment from Kite, the cell therapy arm of drugmaker Gilead Sciences, have been placed on a partial clinical hold after some patients developed serious nerve and brain side effects.¹ The treatment, called KITE-753, is being tested in people with large B-cell lymphoma, an aggressive blood cancer, whose disease came back or did not respond to earlier treatment.¹ Gilead disclosed the hold during its third-quarter earnings call on October 29, 2026.¹

A partial clinical hold limits parts of a trial while a safety question is looked into, rather than stopping everything. According to CancerNetwork, the hold lets Gilead and Kite investigate why the rate of severe neurotoxicity differed between the earlier and later stages of the program.¹ The company said it will give updates as more information becomes available.¹

What happened

The two affected studies are known as PALISADES-1 and PALISADES-2.¹ CancerNetwork reported that grade 3 and grade 4 neurotoxicity in patients prompted the hold.¹ Grades are how doctors rate side effects; grades 3 and 4 are the more serious levels.

The side effect in question has a long name: immune effector cell–associated neurotoxicity syndrome, or ICANS.¹ In plain terms, it is a set of nerve and brain problems that can follow immune cell therapies of this kind. Gilead’s chief medical officer, Dietmar Berger, said on the call that the developers paused the two trials to investigate safety differences between the findings from the early (phase 1) and later (phase 2) parts of testing.¹

The public reports do not say how many patients were affected, how severe each case was, or how the cases turned out. That detail had not been released when this article was written.

What the therapy is

KITE-753 is a CAR-T therapy. That means it is made from a patient’s own immune cells (T cells), which are changed in a lab so they can find and attack cancer, then given back to the same patient.¹ This one is designed to recognize two markers, CD19 and CD20, which sit on the surface of B cells. CD20 in particular is found on B cells that have turned into lymphoma cells.² Kite’s existing approved CAR-T therapy for this cancer, axicabtagene ciloleucel (sold as Yescarta, often shortened to axi-cel), targets CD19 only.²

KITE-753 has a near twin, KITE-363. According to Cindy Perettie, who heads Kite, the two are structurally identical. The difference is how they are made: KITE-753 uses a 3-day manufacturing process, while KITE-363 is made the conventional way.¹ The faster process is meant to keep the T cells in better working shape.¹ Kite’s early trials of KITE-363 in autoimmune diseases affecting the joints and the nervous system do not use the rapid process and are continuing, Perettie said.¹

The two trials on hold

PALISADES-1 is an early-to-mid-stage study (phase 1/2) of KITE-363 or KITE-753 in adults whose B-cell lymphoma relapsed or did not respond to treatment.³ It started in October 2021 and plans to enroll about 247 people, according to its registry record.³ Its first goals were to measure serious side effects that limit the dose in the first 28 days, and then how many patients’ tumors shrink.³ People who receive either therapy move into a separate follow-up study for up to 15 years.⁴

PALISADES-2 is a phase 3 trial, the large late-stage test that usually comes before a company seeks approval.⁵ It compares KITE-753 directly with Yescarta in adults whose large B-cell lymphoma came back or did not respond after one earlier line of treatment.⁵ Patients are assigned by chance to one treatment or the other, and both they and their doctors know which they got.⁵ It started in May 2026 and plans to enroll about 550 people.⁵ Its main measures are how many patients have no detectable cancer at six months and how long they go without the disease getting worse or needing new treatment.⁵

Both registry records list the studies as active but not recruiting.³⁵ A UK patient charity’s listing, which is undated, had named recruiting sites for PALISADES-2 in Cardiff, London and Newcastle.²

The evidence so far

The earlier picture looked different. At the American Society of Hematology meeting in December 2025, Kite presented early data on 30 patients who received KITE-753.¹ At the third dose level, 11 of 14 patients who had never had CAR-T before (79%) showed no detectable cancer, after a median follow-up of 2.9 months.¹ Across all dose levels, 14 of 20 such patients had that response.¹ No dose-limiting side effects were seen, and at the third dose level there were no cases of grade 3 or higher ICANS or of cytokine release syndrome, a whole-body inflammatory reaction common with these therapies.¹ Investigators said at the time that the data supported further development.¹

The slower-made twin, KITE-363, had data presented at the American Society of Clinical Oncology meeting in 2025 covering 37 treated patients.¹ Among 23 patients new to CAR-T at the third dose level, 87% saw their cancer shrink and 78% had no detectable cancer.¹ Two patients (8%) at that dose had grade 3 ICANS, lasting 1 and 2 days; there were no grade 4 or 5 cases.¹

These are small, early studies with short follow-up and no comparison group, so they cannot show how the therapy stacks up against existing treatment. That is what PALISADES-2 was designed to test.

What the hold does not show yet

The hold does not mean the therapy has failed, and it does not mean it is unsafe in every setting. It means a safety signal appeared that the company wants to understand. The key open question, as described on the call, is why serious nerve side effects showed up at a different rate in the later stage of testing than in the earlier one.¹ Whether the fast manufacturing process plays a role has not been stated; the company only drew a line between the paused fast-made product and the continuing conventionally made one.¹

For context, nerve side effects are a known risk across CAR-T therapies. In Kite’s earlier ZUMA-7 trial of Yescarta in the same second-line setting, 21% of participants had grade 3 or higher neurological effects, according to a 2021 report.⁶ How the new cases compare with that has not been made public.

Who is behind it

Both trials are sponsored by Kite, a Gilead company.³⁵ The US Food and Drug Administration cleared Kite to begin testing KITE-363 in people in 2021, and the PALISADES-1 study was registered that year.⁶ The positive early results described above were released by Gilead in a company news release and presented at medical meetings; they have been reported in a meeting abstract rather than as a full peer-reviewed paper, based on the references CancerNetwork listed.¹ The news of the hold itself came from the company’s earnings call.¹

What to watch next

• Whether Gilead releases details on the number and severity of the serious nerve side effects.¹
• Whether the hold is lifted, changed or extended, and whether trial rules such as dosing or patient selection change as a result.
• Whether the 3-day manufacturing process is linked to the difference, given that the conventionally made twin’s autoimmune trials continue.¹
• Updates to the registry records for PALISADES-1 and PALISADES-2.³⁵

Biohack will follow this thread as Kite shares more.