9.3 Biotherapy

Biotherapy uses products derived from or designed to act through biologic systems—biologic response modifiers, monoclonal antibodies, antibody-drug conjugates, and related targeted proteins. It is not classic cytotoxic chemotherapy, and it is not cellular therapy. Chimeric antigen receptor T-cell (CAR-T) and other cellular products have their own later chapter (Domain III.B.5). Colony-stimulating factors are biologics used as supportive care; the dedicated colony-stimulating-factor section later in this guide owns dosing and timing. Mention granulocyte colony-stimulating factor (G-CSF, filgrastim) here only as biologic support that shortens neutropenia, then send the details forward.

Historically, interferons and interleukins were the original biologic response modifiers in oncology. They still appear in older teaching and occasional hematologic indications. Contemporary pediatric CPHON items (TCO III.A.2 and III.B.2) are more likely to test monoclonal antibodies and differentiation agents and the nursing setup that keeps a first infusion from becoming an unlabeled emergency.

Targeted antibodies you must be able to nurse

Rituximab is an anti-CD20 monoclonal antibody used on many mature B-cell lymphoma and leukemia pathways. Two toxicities dominate nursing. Infusion reactions—fever, chills, rigors, urticaria, bronchospasm, hypotension—occur most often on the first infusion. Premedicate (commonly acetaminophen and an antihistamine, with a corticosteroid per protocol). Start slowly, stay in the room, and titrate only if vital signs and symptoms allow. Hepatitis B virus (HBV) reactivation can cause fulminant hepatitis. Screen before therapy (HBsAg and anti-HBc at minimum per protocol). A negative conversation about "no jaundice today" is not a screen.

Dinutuximab is an anti-GD2 antibody used in high-risk neuroblastoma. Signature toxicities are neuropathic pain (often requiring opioids and sometimes gabapentinoid co-analgesia during the infusion window) and capillary leak (hypotension, edema, respiratory compromise). Hypersensitivity is common. These infusions run in a monitored setting with a pain plan already written—not "see how they do in clinic chairs." A 4-year-old who screams during dinutuximab is having an expected neuropathic pain syndrome until you prove otherwise; treat the pain and check blood pressure for leak, do not scold the child for "not being brave."

Gemtuzumab (gemtuzumab ozogamicin) is an anti-CD33 antibody-drug conjugate used on selected acute myeloid leukemia protocols. Watch hepatotoxicity and hepatic sinusoidal obstruction syndrome / veno-occlusive disease (SOS/VOD) risk, especially around hematopoietic stem cell transplant. Infusion reactions still apply. Rising bilirubin, tender hepatomegaly, and weight gain after gemtuzumab are not "just after-chemo puffiness."

Blinatumomab is a bispecific T-cell engager (CD19/CD3) used in B-ALL. Keep this section on antibody and biologic administration; deeper cytokine-release-syndrome grading sits with immunotherapy and emergency chapters. Nursing facts that belong here: it is a continuous infusion (multi-day bags with scheduled changes), not an intravenous push. Cytokine release syndrome (CRS) and neurotoxicity (tremor, seizure, confusion, aphasia) are expected risk categories. Premedication (often dexamethasone) and a stop-the-infusion plan are part of setup. Bag hanging, line changes, and pump programming are high-alert. Interrupting the infusion is a clinical event, not a bathroom convenience. Never "catch up" a continuous bag by running it fast.

Differentiation: tretinoin in APL

Tretinoin (all-trans retinoic acid) differentiates acute promyelocytic leukemia (APL) blasts. Priority toxicities are differentiation syndrome (fever, weight gain, respiratory distress, edema—hold per protocol and give dexamethasone when diagnosed), headache, dry skin, hyperleukocytosis, and teratogenicity. This is not a casual vitamin A supplement. It is started urgently for APL coagulopathy (see the AML chapter) and nursed like a high-alert oral or nasogastric hazardous drug. Adolescent girls need pregnancy precautions; caregivers who are pregnant should not handle crushed capsules.

Nursing the infusion: premeds, bedside emergency drugs, vitals, when to stop

Set up before the first drop:

• Protocol premedications on time (acetaminophen, H1 blocker, corticosteroid, hydration as ordered). Do not freelance extra opioids or skip the steroid because the child "did fine last time" if this is a new agent.
• Emergency medications at the bedside: epinephrine, extra antihistamine, corticosteroid, oxygen, suction, and a working intravenous line. For dinutuximab, a pain-rescue plan as well.
• Baseline vital signs and weight (capillary leak and differentiation syndrome are weight diagnoses as much as respiratory diagnoses).
• Informed family: pausing for chills or blood-pressure changes is safety, not failure.

Vital-sign frequency is highest during the first infusion and during any rate increase: commonly every 15 minutes for an initial window, then per policy as the child proves stable. Know your unit's table; the exam concept is more frequent at the start and with titration, not a single national number for every antibody.

When to stop the infusion:

• Anaphylaxis or suspected anaphylaxis (airway, wheeze, hypotension, widespread urticaria)—stop, call for help, give epinephrine per emergency protocol.
• Protocol-defined severe infusion reaction (persistent hypotension, hypoxia, severe dinutuximab pain unresponsive to holds and rate cuts).
• New neurologic change on blinatumomab.
• Capillary-leak crisis (dinutuximab) or differentiation-syndrome respiratory distress (tretinoin is usually oral, but the same notify-and-hold logic applies).

Mild isolated flushing or low-grade fever may be a rate decrease and notify rather than a permanent cancel—follow the protocol grade. Restart only with an order.

Distinguish three sentences for families: chemotherapy kills dividing cells; biotherapy uses antibodies or biologics to mark or modulate disease; cellular therapy later in this guide infuses living immune cells. Mixing those three on a consent conversation is how families leave thinking CAR-T is just another antibody. The CPHON nurse's product is a screened, premedicated child, emergency drugs within reach, vitals on a first-infusion clock, and a stop rule that does not wait for the end of the bag.