Instructor Notes — Chapter 27

Peptides in Oncology: Hormone-Axis Blockade, Somatostatin Analogs, and Radioligand Therapy Part 5 · advanced · prerequisites: Chapters 3, 26, 5

What this chapter is actually doing

On the surface this is a survey of peptide drugs used in cancer treatment. It is not. It is the chapter where the book's central thesis stops being an argument and becomes a receipt.

Everywhere else, the book asks readers to evaluate claims about compounds with thin evidence. Here it shows them a therapeutic area where peptides have been guideline-level standard of care since the mid-1980s — and where, crucially, the successful peptides all share a structural feature that the compounds in Part III conspicuously lack. Students should leave surprised by how old and boring this material is, not by how new it is. If they leave impressed by radioligand therapy and unimpressed by the fact that leuprolide has been routine since before they were born, the chapter has under-delivered and §27.8 will not land.

Budget your time accordingly. §27.5 and §27.6 are the fun ones and will teach themselves. §27.1 and §27.8 are the load-bearing ones and need active facilitation.

Prerequisite check

Do not start until students can state Chapter 3 §3.5's pulsatility principle from memory. §27.2 is unteachable without it, and students who half-remember it will read the flare as a side effect and miss the entire point.

A two-minute opener that works: ask the room "if you wanted to shut down a hormone axis, would you give more of the hormone or less?" Let the wrong answer sit for a moment, then run §27.2.

Section-by-section teaching notes

§27.1 — Peptides have been standard care for decades. The temptation is to skim this as introduction. Don't. This is the chapter's thesis and the empirical foundation for §27.8. Spend real time on the four reasons for invisibility, particularly the fourth (the consumer peptide market has an interest in not mentioning it). Students who work in or near the wellness industry sometimes find that fourth reason uncomfortable; that discomfort is productive and should be surfaced, not smoothed.

§27.2 — The flare. This is the best teaching moment in the chapter and possibly in Part 5. The key move is getting students to see that the therapy and the complication are the same mechanism at different times, not a mechanism plus an unrelated adverse effect. The diagram does most of the work; make sure everyone can redraw it.

Common misconception to pre-empt: students often assume the flare is an allergic or immunological phenomenon because that is what "reaction" usually means in a drug context. It is not.

§27.3 — Antagonists and the naming rule. Two things here. First, the -relin / -relix payoff, which Chapter 1 explicitly promised — call back to it out loud so students feel the debt being paid. Second, the relugolix precision note. Some instructors are tempted to cut this because it complicates the story. Do not cut it. A student who understands why the oral drug is not a peptide understands peptide pharmacology better than one who memorized ten peptide drugs.

§27.4 — Somatostatin analogs. The chemistry is a preview of Chapter 33; treat it as a worked example rather than a systematic treatment. The critical content is the split between the symptom-control claim and the antiproliferative claim. Students who can articulate why those need separate ratings have internalized Chapter 5's rule; students who cannot have merely memorized it.

§27.5 — PRRT. Highest engagement in the chapter. The single sentence to make sure everyone leaves with: the peptide's job is not to be a drug — it is to be an address. Then immediately generalize with "the peptide is not always the drug," including the target and substrate variants. Students consistently find this reframe useful in later chapters.

§27.6 — Theranostics and PSMA. Two moves. The theranostic loop (image → treat only if positive → re-image) is genuinely elegant and worth dwelling on as the strongest form of patient selection in the book. Then the honesty clause: most PSMA ligands are not peptides. Point out that the chapter volunteers a fact that weakens its own headline. That is worth naming explicitly as a modeling behavior.

§27.7 — PDCs. Keep it short. Its purpose is (a) to complete the addressing family and (b) to introduce the accelerated-approval-then-withdrawal pattern via melphalan flufenamide, which the Dossier section then uses.

§27.8 — The pattern. The payoff. Do not rush it and do not let it become a lecture. The empty fourth box should be derived by the class, not announced. See Discussion Guide prompt 5.

§27.9 and the Dossier. Six ✅ ratings in one chapter is a data point about the book's method, not just about oncology. Say so. The Field 7 work is best done as a live exercise with a real label pulled up on screen.

Sensitivity

Assume at least one person in any room of reasonable size has personal experience of cancer treatment, their own or a family member's. Two working rules:

Do not soften the toxicity content. Underselling ADT's burden or PRRT's delayed hematologic risk is its own kind of disrespect, and patients generally know better anyway.

Always name the comparator. The chapter is explicit that evaluating oncology toxicity without a comparator is a category error. Model that in discussion, and correct it gently when a student says "that sounds awful" without finishing the sentence.

Avoid asking students to disclose personal experience. Some will volunteer; that is fine. Do not create an expectation.

Assessment guidance

• The quiz's key is published in the student file. Exercises are published without answers; see _scratch/answers/ch27.md.
• Ten exercise items are marked †. Grade those on reasoning quality, not on reaching a particular conclusion. Several have no settled answer.
• Best single summative item: exercise U (rewrite the inaccurate NETTER-1 headline). It tests endpoint discipline, population qualifiers, and the ability to write accurately for a general audience, all at once.
• Best single formative check: ask students to sort three named drugs into §27.8's three boxes. Takes ninety seconds and reveals immediately who has the frame.