Adaptive BAT

Hormone-sensitive disease is a different problem.

Most published BAT trials treat castration-resistant cancer. Adaptive BAT for HSPC is the book’s proposed use earlier: oscillate androgens while the tumor is still AR-addicted, so continuous ADT does not quietly select AR-V7, neuroendocrine, and other CRPC clones. This is not NCCN first-line care.

Why HSPC is not just earlier CRPC

HSPC cells still depend on AR. A sudden SPA pulse can stall replication and recruit TOP2B, producing double-strand breaks.
Continuous ADT ± long ARSI is the selection pressure that favors splice variants and lineage plasticity.
The DNA-damage response is usually less wrecked than in late CRPC, which is why the book discusses pairing short SPA pulses with repair pressure (PARPi) as a research idea, not a standard recipe.
Classic teaching still holds outside a protocol: do not raise testosterone in untreated hormone-sensitive disease on a whim.

What “adaptive” means here

Cycle length and SPA pulse width are not locked at 28 days forever. HSPC often wants shorter high poles (hours–days) so T− clones do not get a vacation.
ARSIs, if used, sit in the low-T window as short pulses (about 1–14 days). They are withheld during the testosterone peak.
Type can change. A man who starts Type 1 (T+ dominant) can drift toward Type 3. ctDNA, PSMA PET, and symptoms move the cycle; PSA alone does not.
If the ecosystem becomes Type 4 (T− dominant / NEPC), BAT is the wrong tool.

Four-type ecosystem

Type 1 — T+ dominant

Classic AR-high HSPC. SPA is most lethal here. Goal: shrink this population without converting it.

Type 2 — Cooperative

T+ plus TP clones. Real peaks and real troughs can still suppress both.

Type 3 — Mixed-resistant frontier

T− emerging while T+/TP remain. Imaging and ctDNA matter more than PSA. This is where cycle length gets shortened or partners get added.

Type 4 — T− dominant

Lineage-plastic / NEPC biology. Think platinum, PARPi if HRR, RLT, or a trial — not more testosterone.

What the clinic data actually is

BATMAN is the only completed dedicated HSPC BAT study. ADT lead-in, then oscillating BAT. Primary endpoint met: 59% (17/29) reached PSA <4 ng/mL at 18 months. Later writeups describe high objective response and long ADT-PFS in responders. Still investigational.

SPIDERMAN (NCT07142551) is the registered first-line oscillation study: ADT + darolutamide lead-in, then alternating BAT cycles and darolutamide cycles in metastatic hormone-sensitive disease. That is the prospective test of the idea, not proof yet.

The book is explicit: using aBAT to delay HSPC→CRPC is mechanistic plus early-clinical. It is not a completed phase III substitution for ADT + ARPI.

Monitoring if someone is on a protocol

Signal	Why
Peak and trough testosterone	Confirm a real high pole (book target often ≥1,500 ng/dL) and a real trough.
PSA	Reporter for AR-high cells. A bounce on the high pole is not automatic failure.
ctDNA / AR-V7 / HRR	Watch the Type 3 drift.
Scans	Call progression. PCWG3 for bone-scan flare.
Hematocrit, BP, pain, obstruction	Same safety frame as CRPC BAT.

Trials, including BATMAN and SPIDERMAN