CAR T-Cell Therapy Emergencies: Delayed Recognition of CRS and Neurotoxicity

After CAR T-cell therapy, a fever or a new problem with speech can signal a serious treatment complication.

Cytokine release syndrome, or CRS, causes a widespread inflammatory response. Immune effector cell-associated neurotoxicity syndrome, or ICANS, affects the nervous system.

Both can occur despite appropriate care. A possible malpractice claim concerns the response to warning signs and whether a departure from appropriate care caused additional harm.

Why CAR T-Cell Therapy Can Cause These Reactions

CAR stands for chimeric antigen receptor. In this treatment, a patient’s T cells are collected and genetically modified to recognize a target on cancer cells. The cells are then infused back into the patient.

The American Cancer Society explains how CAR T-cell therapy treats certain blood cancers, including some leukemias, lymphomas, and multiple myeloma. Eligibility depends on the particular product and diagnosis.

As the modified cells activate and multiply, they release cytokines, chemical signals that coordinate immune activity. An excessive inflammatory response can produce CRS. Neurological toxicity can develop alongside it or separately, so improvement in one complication does not establish that the other has resolved.

These are specific risks of this form of immunotherapy. They should not be managed by automatically applying the same instructions used for other cancer treatments.

Fever After CAR T Requires Assessment for CRS and Infection

CRS can begin with fever and progress to low blood pressure, low oxygen levels, and organ dysfunction. Its timing and severity vary by product and patient.

Infection can produce the same findings. Some patients also have low neutrophil counts, which reduces their ability to fight infection.

An infection workup is appropriate. The problem would be failing to assess possible CRS at the same time when the treatment history and findings call for it. Infection and CRS can coexist, and antibiotics do not treat the inflammatory process driving CRS.

If you develop a fever after CAR T-cell therapy, follow the treatment center’s emergency instructions and contact the team immediately. Do not assume it is an expected reaction that can wait until the next appointment.

How CRS Severity Guides the Response

The 2019 ASTCT consensus grading system classifies CRS using fever, low blood pressure, and the respiratory support required. The American Society for Transplantation and Cellular Therapy developed this system to standardize assessment.

Fever of at least 38°C, or 100.4°F, not explained by another cause is required at the onset. Grade 1 has no associated low blood pressure or oxygen requirement. Higher grades reflect increasing needs for blood-pressure medication or respiratory support.

The more severe blood-pressure or respiratory finding determines the grade. Organ dysfunction matters clinically but does not independently determine the ASTCT CRS grade.

Once fever has been suppressed by treatment such as tocilizumab or corticosteroids, its absence does not automatically mean CRS is over.

Treatment Must Match the Clinical Situation

Tocilizumab blocks the receptor for interleukin-6, one of the inflammatory signals involved in CRS. It is an important treatment when indicated. Corticosteroids may also be used, depending on severity, persistence, and the product-specific approach.

Patients may need fluids, oxygen, blood-pressure support, and intensive care. Treatment requires reassessment as the condition changes. A grade recorded earlier in the day cannot substitute for evaluating a patient whose blood pressure or breathing is worsening.

The question in a review is when the findings called for treatment or escalation under the applicable protocol, and what happened next.

Neurotoxicity Can Begin With Changes in Speech or Writing

ICANS can cause difficulty finding words, confusion, altered alertness, and seizures. Changes in handwriting may be an early sign.

The 2022 EBMT nursing guidelines for CAR T-cell therapy describe neurological monitoring and escalation. They also explain that neurotoxicity can follow CRS, including after the inflammatory syndrome has improved.

A patient who is newly confused needs assessment for other possible causes as well, including infection, metabolic disturbances, medication effects, and stroke. A CAR T history adds an important possibility; it does not eliminate those emergencies.

An ICE Score Is One Part of the Examination

The Immune Effector Cell-Associated Encephalopathy assessment, called ICE, evaluates orientation, naming objects, following a command, writing, and attention.

The overall ICANS grade also considers consciousness, seizures, motor weakness, and brain swelling. A serious finding in one of those areas can require escalation even when a bedside score does not capture the full problem. Younger children may need a different assessment tool.

CRS Treatment Does Not Replace Neurotoxicity Treatment

Tocilizumab may be indicated for CRS occurring alongside ICANS, but it is not an adequate treatment for isolated ICANS. Corticosteroids and supportive care are central to managing significant neurotoxicity. Seizures and impaired consciousness may require urgent neurological assessment and intensive care.

A review must therefore examine both complications separately. Giving medication for CRS does not establish that worsening neurological symptoms were appropriately managed.

The Federal Safety Program Changed in 2025

In June 2025, the FDA eliminated REMS requirements for six CAR T-cell products. REMS means Risk Evaluation and Mitigation Strategy, a formal drug safety program.

The change removed those programs’ special certification requirements and their requirement for immediate on-site access to tocilizumab. Related labeling changes revised monitoring and certain post-treatment restrictions. Boxed warnings for CRS and neurological toxicity remained.

The removal of a federal program did not eliminate the need to recognize and treat these complications. A review must identify the product, treatment date, applicable labeling, and clinical circumstances. Historical REMS requirements should not be described as universal current rules.

When Delayed Recognition May Become Malpractice

A New York malpractice claim requires evidence of a departure from accepted medical practice and injury caused by that departure.

For a CAR T emergency, the review may ask:

• Were changes in temperature, blood pressure, oxygen needs, and neurological function recognized and reassessed?

• Were concerning findings communicated to a clinician able to act?

• Were infection and treatment toxicity evaluated together when appropriate?

• Did medication administration and transfer to a higher level of care occur when indicated?

• Did discharge instructions provide a usable emergency plan?

These questions do not establish negligence by themselves. They identify what the records and qualified medical assessment must address.

Causation is a separate requirement. The review must explain what additional injury is attributed to the alleged delay, rather than assuming that an ICU admission, seizure, or death proves preventable harm.

Informed Consent Requires a Separate Analysis

For nonemergency treatment, New York Public Health Law 2805-d addresses disclosure of reasonably foreseeable risks, benefits, and alternatives.

An informed-consent claim also requires showing that a reasonably prudent person in the patient’s position would have declined the treatment if fully informed, and that the lack of informed consent proximately caused the injury.

Instructions about symptoms and emergency contact arrangements also need review. An inadequate discharge plan and inadequate consent are different alleged failures, even when both concern the same complication.

The Certificate of Merit Is an Attorney’s Certificate

For represented malpractice actions, CPLR 3012-a’s certificate-of-merit provision generally calls for an attorney’s certificate based on review and consultation with a physician knowledgeable about the relevant issues.

It is not a physician-signed affidavit proving negligence. The statute includes alternatives and timing exceptions, including provisions addressing an approaching deadline or requested records that have not been produced.

New York Filing Deadlines for CAR T Treatment Claims

Under CPLR 214-a, the ordinary medical malpractice period is two years and six months from the alleged act or omission. Qualifying continuous treatment for the same illness, injury, or condition can affect that calculation.

Follow-up appointments do not automatically establish continuous treatment. The nature of the care and its relationship to the alleged failure matter.

The statute’s special cancer discovery provision concerns negligent failure to diagnose cancer or a malignant tumor. Delayed recognition of CRS or ICANS does not qualify merely because it happened during cancer care.

If the patient died, EPTL 5-4.1 generally gives the estate’s personal representative two years from death to bring a wrongful death action. Death does not automatically revive an already time-barred underlying claim.

Public-entity claims can have earlier notice requirements and different lawsuit deadlines. Where General Municipal Law 50-e applies, notice is generally due within 90 days after the claim arises.

For wrongful death, that notice period runs from appointment of the estate representative. The defendant’s identity and governing law must be checked before calculating a deadline.

Talk With a New York Cancer Lawyer About a CAR T Emergency

If you have questions about how fever, confusion, or other changes were handled after CAR T-cell therapy, you can contact Porter Law Group’s New York cancer lawyers about a possible claim.

The review would examine the treatment history, the response to warning signs, and whether an alleged departure caused additional harm. Medical care should proceed independently of a legal inquiry.

Call 833-888-LATE, email info@porterlawteam.com, or request a free case evaluation.

This article is for informational and educational purposes only. It is not a substitute for medical advice from a qualified healthcare provider or legal advice based on your specific circumstances.

Attorney advertising. Contacting Porter Law Group does not create an attorney-client relationship.

Frequently Asked Questions

Does a fever after CAR T-cell therapy mean CRS?

Not necessarily. Fever can reflect CRS, infection, or another cause, and infection can occur alongside CRS. The treatment history and accompanying findings guide the evaluation. Contact the CAR T team immediately and follow its emergency instructions rather than deciding at home which explanation is most likely.

Can ICANS appear after CRS has improved?

Yes. Neurological toxicity can develop after CRS improves, so a lower temperature does not establish that the neurological risk has passed. New difficulty speaking, confusion, unusual sleepiness, or seizures needs prompt assessment. Follow the treatment center’s instructions, and seek emergency care for sudden or severe neurological changes.

Does tocilizumab treat both CRS and ICANS?

Tocilizumab is used for CRS when indicated, but it is not an adequate treatment for isolated ICANS. When both conditions occur, clinicians must address each one. Significant neurological toxicity may require corticosteroids, seizure treatment, and supportive care. Improvement in blood pressure or fever does not establish that neurological symptoms are controlled.

Did the 2025 REMS removal end CAR T monitoring requirements?

No. The FDA removed formal REMS requirements for six products and revised related labeling, but the risks of CRS and neurological toxicity remained. Patients still need the monitoring and follow-up appropriate to their product and condition. The applicable instructions depend on the treatment and the date of care.

Can a known CAR T complication still support a malpractice claim?

Possibly. A disclosed risk can still require appropriate monitoring, investigation, and treatment. A claim needs evidence that the care departed from accepted practice and that the departure caused additional harm. The review must account for complications that can occur despite appropriate care, rather than treating the outcome alone as proof.