Five Australian Clinicians Set Out When to Escalate, Pause and Restart 177Lu-PSMA Rather Than Run Six Fixed Cycles

The imaging bar the guide starts from

The authors begin with molecular imaging, because the radiation payload lands only where target expression has been confirmed. VISION established the criteria most programs adopted: one PSMA-positive lesion exceeding liver uptake, and no PSMA-negative disease. TheraP and ENZA-p set a higher bar, using stricter avidity thresholds keyed to maximum standardized uptake value. Those two entry bars select two different populations, and the guide leaves the choice to the treating team without naming a settled standard.

Androgen deprivation moves what the scan measures

Louise Emmett's serial 68Ga-PSMA-11 imaging work, cited as the first of the guide's 13 references, showed that starting androgen blockade rapidly drives PSMA expression down in hormone-sensitive and castration-resistant disease alike. The authors carry that into sequencing: a PSMA-PET read after androgen deprivation has begun measures a suppressed target. They pair it against evidence of improved radiographic progression-free survival when LuPSMA is combined with an androgen receptor pathway inhibitor, and against the sequential approach tested in UpFrontPSMA, where 177Lu-PSMA-617 preceded docetaxel in hormone-sensitive disease.

PSA50 and the first 12 weeks

The guide frames on-treatment assessment as a stratification tool, with PSA kinetics giving the early signal and PSA50 responses associated with better radiographic progression-free and overall survival. The authors are explicit that biochemical progression alone, in the absence of radiographic progression and particularly inside the first 12 weeks, is not grounds to discontinue LuPSMA, while adding that close clinical monitoring still matters because some of those patients do go on to progress. SPECT/CT gets its own section as the imaging that makes on-treatment adjustment possible.

When less and when more

The adaptive dosing section rests on the tumor sink effect: high tumor volume sequesters radioactivity in disease and spares healthy tissue, which the authors argue may permit personalized dose escalation in exactly the patients who look least suited to it. Fractionated schedules run the other direction, allowing more intensive radiation early in the course with limited added toxicity. Both are presented as hypotheses awaiting prospective dose optimization trials. Elsevier gates the article. Readable from outside were the published abstract, the section previews the publisher displays and the reference list. The numeric thresholds for escalation are not among them.

Why This Matters to the APO|APE Reader

The guide never lays out a division of labor across nuclear medicine, urology, medical oncology and pathology, which leaves the scheduling problem it creates unowned: if androgen deprivation suppresses PSMA within days, the PET that decides eligibility has to be booked against the date hormonal therapy started, and that date usually lives in a urology record rather than a nuclear medicine one. Escalation, fractionation and retreatment each add a SPECT/CT read that a six-cycle protocol never budgeted for. A theranostics program built on the VISION criteria and a fixed schedule will need a different imaging calendar to run the version of treatment these authors describe.