10.1 Immunotherapy

Immunotherapy uses the child's immune system—or laboratory-built antibodies that recruit it—to recognize cancer. CPHON Test Content Outline (TCO) III.A.3 and III.B.3 sit next to biotherapy on purpose. The last chapter taught rituximab, gemtuzumab, and tretinoin as biologics. This section is the immune-toxicity chapter: checkpoint-inhibitor immune-related adverse events (irAEs), anti-GD2 dinutuximab as a full nursing protocol, blinatumomab as a multi-day living infusion, and the difference between systemic and intrathecal (IT) immunotherapy. Children's Oncology Group (COG) and Association of Pediatric Hematology/Oncology Nurses (APHON) practice, not a brand name, is what the Oncology Nursing Certification Corporation (ONCC) tests.

Checkpoint inhibitors: uncommon first-line in young children, still on the exam

Programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) inhibitors (generic exemplars: pembrolizumab, nivolumab, atezolizumab) and cytotoxic T-lymphocyte–associated protein 4 (CTLA-4) inhibitors (ipilimumab) take the brakes off T cells. In adults they are everyday first-line therapy for many solid tumors. In young children they are not typical first-line therapy for the common cooperative-group cancers (acute lymphoblastic leukemia, neuroblastoma, Wilms tumor, osteosarcoma). They appear in relapsed, refractory, and selected solid-tumor or lymphoma settings, on trials, and when a tumor has mismatch-repair deficiency or high mutational burden. Do not teach that every preschooler with a new diagnosis starts a PD-1 inhibitor on day 1. Do teach the toxicity pattern, because when a teenager with relapsed Hodgkin lymphoma or a child with a mismatch-repair–deficient tumor receives one, the nurse who thinks "this is just another antibody infusion reaction" will miss colitis, pneumonitis, and endocrine failure weeks later.

irAEs are the T-cell attack on self. Timing is delayed compared with a classic infusion reaction: dermatitis and colitis can appear during therapy or after the last dose. High-yield organs:

• Colitis: frequent watery stools, cramping, nocturnal diarrhea, blood. This is not "chemo diarrhea" until proven otherwise. Hold the checkpoint inhibitor per protocol, notify, and start the workup for infection versus irAE. High-dose corticosteroids are the typical first-line treatment for moderate-to-severe inflammatory irAEs (colitis, pneumonitis, significant dermatitis) once infection is addressed per the team.
• Pneumonitis: new cough, hypoxia, or infiltrates that are not routine infection. Hold the drug, give oxygen, image, and start steroids as ordered. A pulse-ox drop after pembrolizumab is not automatically "the winter virus."
• Endocrinopathy: hypophysitis, thyroiditis (hyper then hypo), adrenal insufficiency, and hyperglycemia. Fatigue, headache, hypotension, and hyponatremia after a CTLA-4 or PD-1 inhibitor are endocrine emergencies until labs say otherwise. Established hypothyroidism needs hormone replacement (levothyroxine); adrenal crisis needs stress-dose hydrocortisone. Replacement can be lifelong even if the cancer is gone. Steroids treat hypophysitis and inflammatory crisis; they do not replace a missing hormone by themselves.
• Dermatitis: rash and pruritus are common; blistering, mucosal involvement, or rapid progression is a stop-and-notify finding and a steroid-plus-dermatology problem.

The item that holds: inflammatory irAEs are treated with high-dose steroids first-line, not with "push through the infusion." Immunosuppression for irAEs then raises infection risk—teach families that steroids for colitis are treatment, not a contradiction of "boosting immunity." A 15-year-old on pembrolizumab who develops bloody diarrhea at home two weeks after a clinic dose needs same-day evaluation, not a message to wait for the next cycle.

Anti-GD2 dinutuximab: pain, leak, pressure, salt

Dinutuximab is a chimeric anti-GD2 monoclonal antibody used after consolidation in high-risk neuroblastoma. GD2 sits on neuroblastoma cells and on peripheral nerves, which is why the infusion hurts. Nursing is protocol, not optional comfort.

Neuropathic pain is expected. Many protocols protocolize opioids (often a hydromorphone or morphine infusion started before or with the antibody) plus a gabapentinoid (gabapentin or pregabalin) as co-analgesia. A 4-year-old who screams, arches, and says the legs are on fire is having GD2 neuropathy, not "acting out." Treat the pain. Rate holds and extra opioid boluses follow the protocol; do not withhold analgesia because pain "means it is working."

Capillary leak produces edema, rapid weight gain, pulmonary crackles, and hypoxia. Hypotension rides with leak and with the antibody itself. Have fluid-bolus orders, hold parameters, and a monitored setting that can escalate. Electrolyte wasting—hyponatremia, hypokalemia, and hypoalbuminemia-associated shifts—belongs on the chemistry panel, not only on the blood-pressure sheet. Weigh every shift. A 1-kg overnight gain in a 15-kg child is leak until proven otherwise.

Hypersensitivity (urticaria, bronchospasm, anaphylaxis) still occurs. Premeds commonly include an antihistamine, antipyretic, and sometimes a corticosteroid per protocol. First cycles run where you can escalate—not an unsupervised clinic chair.

Blinatumomab: the bag is the treatment

Blinatumomab is a CD19/CD3 bispecific T-cell engager used in B-ALL (measurable residual disease, relapsed/refractory disease, and selected front-line arms). It is not chimeric antigen receptor T-cell therapy and it is not a five-minute push. It is a continuous intravenous infusion lasting days, with scheduled bag changes. The pump, the tubing, and central-line security are the drug.

• Prime and change bags on the pharmacy clock. An empty bag or an unrecognized disconnection is a missed dose and a clinical event.
• Never bolus to "catch up" if the infusion ran behind. Restart at the ordered rate.
• Line security: Luer-lock, lumen discipline so a toddler cannot tug the continuous bag off, no unapproved Y-site drugs, protection during showers and play. A disconnected blinatumomab line on the playroom floor is both a hazardous-drug problem and lost T-cell engagement.
• Cytokine release syndrome (CRS) (fever, hypotension, hypoxia) and neurotoxicity (tremor, seizure, confusion, aphasia, facial palsy) are expected risk categories. Premedication often includes dexamethasone. Deeper CRS grading with tocilizumab lives with cellular therapy and the later emergency chapter; here the antibody-specific rule is stop or hold per protocol, do not speed the bag.

A 7-year-old whose parent "just disconnected the pump for a bath" has interrupted therapy. Assess the child for CRS and neuro change, secure a new closed system, and notify—do not run the next bag at twice the rate to make up the hour.

Intrathecal versus systemic immunotherapy

Systemic immunotherapy (checkpoint inhibitors, dinutuximab, blinatumomab) circulates, causes whole-body irAEs or CRS, and is given intravenously. Intrathecal immunotherapy delivers an agent into cerebrospinal fluid for sanctuary-site disease. Families sometimes lump IT antibodies and IT chemotherapy together as "immune shots in the back." The differences CPHON tests:

IT product must be preservative-free and labeled for IT use. The same timeout used for IT methotrexate applies: two-nurse route check, no vinca on the tray. Do not assume an "immune" syringe is automatically safe for the spine.

Premeds and emergency stop parameters

Set up before the first drop: protocol premedications on time (antihistamine, acetaminophen, corticosteroid, hydration; opioids and gabapentinoids for dinutuximab); emergency medications at the bedside (epinephrine, extra antihistamine, corticosteroid, oxygen, suction, a working IV, and a dinutuximab pain-rescue plan); baseline weight, vitals, and neurologic exam for blinatumomab; and family teaching that pausing is safety.

Stop the infusion (or hold the continuous bag per protocol) for anaphylaxis (airway, wheeze, hypotension, widespread urticaria)—give epinephrine, do not finish the bag first; protocol-defined severe dinutuximab pain unresponsive to holds, rate cuts, and opioid rescue; capillary-leak crisis (refractory hypotension, hypoxia, or rapid weight gain with respiratory compromise); and new neurologic change on blinatumomab (seizure, aphasia, severe confusion). Mild isolated flushing or low-grade fever may be a rate decrease and notify. Restart only with an order.

The CPHON product is a nurse who can tell a family that checkpoints are not first-line for most toddlers, that steroids treat inflammatory irAEs, that dinutuximab pain is protocolized, that blinatumomab lives in a locked bag, and that IT immune products follow the same route timeout as IT methotrexate.