The PSMA Addition study, adding lutetium in metastatic hormone-sensitive prostate cancer, showed an RPFS benefit. However, initial data suggested adverse quality of life scores. Upcoming results on pain and skeletal events are critical to determine if the toxicity profile undermines its clinical utility in this earlier disease setting.

Despite two positive Phase 3 trials showing an overall survival benefit, Radium-223 is not widely used. A key reason is its failure to produce dramatic PSA declines or clear scan improvements. This lack of a satisfying, immediate feedback signal, or "firework display," makes clinicians less likely to prescribe it, even with proven efficacy.

Lutetium faces criticism for its fixed 6-cycle regimen, which may be suboptimal as the PSMA target diminishes with ADT. However, this critique is rarely applied to other drugs like PARP inhibitors, which are given until progression. This highlights a double standard and the tension between using a fixed regimen for regulatory approval versus finding the optimal dose in practice.

While Pluvicto (lutetium) is approved for six cycles, clinicians are retreating relapsed patients who previously responded well. This common practice occurs in a "data-free zone," driven by the lack of better options and the logic that a previously effective drug may work again in a patient selected for prior response.

The current standard of care for hormone-sensitive prostate cancer is so effective—with half of patients alive at 8 years in some trials—that new additions must clear an exceptionally high bar. Unlike in refractory settings, an incremental improvement in radiographic progression-free survival may not be enough to warrant adoption without a transformative overall survival benefit.

Clinicians may be biased towards lutetium-PSMA because it causes significant PSA drops, which radium-223 does not. This observable metric may not reflect superior overall efficacy, as radium's survival benefit is proven and it may even have unique synergistic potential with drugs like enzalutamide through different biological pathways.

An expert expressed disappointment with Lutetium's efficacy in the metastatic hormone-sensitive setting, suggesting its benefit is lower than expected. A potential flaw in trial design was starting hormonal agents first, which can lower PSMA expression, thereby potentially reducing the radioligand's target and diminishing its therapeutic effect.

Instead of administering all six planned doses of PSMA Lutetium upfront in the hormone-sensitive setting, a novel "sandwich" strategy is being considered. This involves giving a few doses, re-imaging, and reserving subsequent doses for later, potentially optimizing efficacy and managing long-term toxicity.

While Lutetium shows promise in hormone-sensitive prostate cancer, experts raise concerns about potential late-effect toxicities for patients surviving many years. This contrasts with docetaxel, where toxicity is acute and resolves after treatment, highlighting an unknown long-term risk-benefit profile for new radioligand therapies.