10.2 Cellular Therapies including CAR-T

Cellular therapy infuses living immune cells that have been collected, modified, or selected to attack cancer. CPHON TCO III.B.5 is not the hematopoietic stem cell transplant (HSCT) section (III.B.7). Autologous CD19 chimeric antigen receptor T-cell (CAR-T) therapy for relapsed or refractory B-ALL—and some B-cell lymphomas—is the high-yield pediatric product. Use the generic name CD19 CAR-T. Do not treat one commercial brand as the only 2026 ONCC product; several licensed and protocol products share the CD19 target, the lymphodepletion backbone, and the same two toxicities: cytokine release syndrome (CRS) and immune effector cell–associated neurotoxicity syndrome (ICANS).

This is not transplant

HSCT replaces marrow with donor or autologous stem cells after high-dose conditioning; engraftment reconstitutes all blood lines, graft-versus-host disease is an allogeneic-donor-cell problem, and the product is hematopoietic progenitors. CAR-T is a targeted immune-cell drug. The child keeps native marrow (already damaged by prior therapy) and receives T cells that carry an artificial receptor against CD19. Autologous CD19 CAR-T does not cause classic graft-versus-host disease from an allogeneic graft. It does kill healthy CD19-positive B cells, which causes prolonged B-cell aplasia. Mixing the two on a consent conversation is how families pack for "another transplant" and miss CRS teaching.

Other pediatric cellular products exist (virus-specific T cells, investigational solid-tumor CARs). CPHON items still orbit autologous CD19 CAR-T for B-ALL. A 9-year-old in second marrow relapse after intensive chemotherapy is the classic candidate picture; a newly diagnosed standard-risk preschooler on day 4 of induction is not.

The sequence: apheresis → lymphodepletion → infusion → expansion

Leukapheresis collects T cells through a large-bore or apheresis catheter. Collection-day nursing is counts, ionized calcium (citrate binding causes perioral tingling and tetany), and line thrombosis or bleeding. The product ships to a manufacturing lab. The child may receive bridging chemotherapy to hold the leukemia while cells are grown; bridging is not the CAR-T itself. Manufacturing turnaround is days to weeks—teach the concept, not an invented ONCC-mandatory day count.

Lymphodepleting chemotherapy, classically fludarabine plus cyclophosphamide, makes immunologic space and homeostatic cytokines so the CAR-T cells can expand. Expect cytopenias, infection risk, and hemorrhagic-cystitis precautions with cyclophosphamide (hydration; mesna if the protocol uses it). This chemo is a means to expansion, not the curative intent by itself.

Infusion is a blood-product-style cell bag: two-identifier check, vital signs, emergency drugs at the bedside. Premedicate per protocol (commonly acetaminophen and an antihistamine). Avoid routine high-dose corticosteroids at infusion that might blunt CAR-T function unless a protocol exception exists—this is the opposite instinct from checkpoint-inhibitor irAE treatment in the last section. Do not filter away the cells with an inappropriate filter. Stay in the room.

Expansion over the following days is when CAR-T cells proliferate, kill CD19-positive blasts, and release cytokines. CRS and ICANS declare themselves here, often in the first one to two weeks, with product-specific windows. Fever is the opening move, not a reason to send the child to the playroom unmonitored. A 9-year-old who looks well on the evening of infusion and spikes 39.2°C on day 4 is in the expansion window until proven otherwise.

CRS: mechanism and first-line nursing

Activated CAR-T cells and macrophages pour out interleukin-6 (IL-6) and other cytokines. Clinically, CRS is a spectrum. Fever is the grade-defining start in most systems. Hypotension and capillary leak follow. Hypoxia and pulmonary edema mark higher grades. Grading language—fever alone versus hypotension that responds to fluids versus hypoxia or shock needing intensive care—is the exam concept. Do not memorize one society's exact numeric table as if ONCC published it. The dedicated cytokine-release-syndrome emergency section later in this guide owns staging algorithms. This section's job is mechanism and first-line nursing.

• Notify the cellular-therapy team early. CRS can climb in hours.
• Supportive care: antipyretics as allowed, oxygen, fluid boluses with caution for leak, cultures, and broad-spectrum antibiotics for febrile neutropenia per protocol because infection and CRS coexist.
• Tocilizumab, an IL-6 receptor antagonist, is the targeted first-line drug for CRS that meets protocol treatment criteria (typically hypotension, hypoxia, or a rapid grade rise—not every isolated low-grade fever). Give it as ordered; do not wait for a code.
• Intensive-care unit (ICU) transfer for refractory hypotension, high oxygen need, or rapid evolution. Vasopressors and ventilatory support are ICU tools; the floor nurse's job is not to "tough out" high-grade CRS in a regular room.
• Steroids are used for severe or refractory CRS and for ICANS. For many CRS protocols they come after tocilizumab because they can dampen CAR-T activity. Follow the product protocol, not a general oncology steroid habit.

ICANS: the brain after the fever

ICANS is neurotoxicity from immune-effector cells: delirium, tremor, aphasia (cannot name objects or write), depressed consciousness, seizures, and, at the extreme, cerebral edema. It may follow CRS or appear on its own. ICE-style neurologic checks (Immune Effector Cell–Associated Encephalopathy: orientation, naming, following commands, writing, attention) run on a clock, not only when a parent says the child "seems off." Adapt the tasks for younger children (follow a command, name a familiar toy, track, speak). A 12-year-old who cannot write her name the morning after fever is ICANS until proven otherwise.

Nursing: serial ICE-style exams and a low threshold to call; seizure prophylaxis when the protocol requires it (often levetiracetam in higher-risk windows); corticosteroids as first-line treatment for significant ICANS on most product protocols; airway protection and head-of-bed positioning as ordered; treat cerebral edema as a neuro-emergency, not as "chemo fog." Do not assume every headache is ICANS; do not assume every aphasia is anxiety. Tocilizumab treats CRS; it is not the automatic first drug for isolated ICANS without CRS.

After the cells: B-cell aplasia, infection, cytopenias, HLH-like illness

Because CD19 CAR-T also kill normal B cells, hypogammaglobulinemia and prolonged B-cell aplasia are expected on-target toxicities. Intravenous immunoglobulin (IVIG) replacement is used when IgG is low or infections accumulate. Teach families that IVIG is not optional "extra immunity" and that live vaccines wait until B-cell recovery and team clearance.

Cytopenias can last weeks: transfusion support, growth factors per protocol, and bleeding precautions. Infection (bacterial, viral, fungal) is the leading late killer after the CRS window. Hemophagocytic lymphohistiocytosis (HLH)–like or macrophage-activation pictures (ferritin surge, cytopenias, organ failure) overlap with severe CRS—notify; do not invent a home ferritin cutoff as ONCC fact.

A 9-year-old with second-relapse B-ALL who receives CD19 CAR-T, spikes fever on day 4, and then cannot name a watch is the CPHON picture: fever is CRS until dual-worked, tocilizumab is the IL-6 move, ICE-style checks catch ICANS, steroids treat the brain, and IVIG waits in the after-care folder because B cells are gone.