The effectiveness of radioligand therapy is counterintuitive: as tumors shrink and PSMA binding sites decrease, less radiation is delivered to the cancer. The VISION trial showed the first two doses delivered more radiation to the tumor than the subsequent four, questioning the value of a fixed, prolonged treatment schedule.

Even within a single patient, tumor lesions exhibit significant heterogeneity in PSMA expression, with some being "hot" and others "not." This ensures that a standard dose of radioligand therapy will not be delivered uniformly across all disease sites, creating an inherent mechanism for resistance and incomplete response.

In advanced prostate cancer with few options, clinicians retreat patients with radioligand therapy after an initial response, despite a lack of formal data. The rationale is practical: for a patient who previously responded well and has no better alternatives, reusing an effective therapy is a logical clinical decision.

Early in treatment, tumors are "target-rich" with high PSMA expression, creating an ideal window for radioligand therapy. Citing data from the VISION trial, new clinical trials are being designed to accelerate dosing and intensity upfront to maximize impact, then de-escalate as the target diminishes.

The future of advanced prostate cancer treatment is shifting towards therapies that target cell surface markers. This new era will be defined by a growing arsenal of radioligands, T-cell engaging bispecific antibodies (BiTEs), and antibody-drug conjugates (ADCs) aimed at targets like PSMA, B7-H3, and HK2.

Major trials in prostate (PEACE-2), bladder (Keynote B15), and kidney cancer (LITESPARK-022) showcase a common strategy: moving potent systemic therapies into earlier, curative-intent settings. This approach of using the best drugs sooner aims to improve long-term outcomes, though it also raises questions about toxicity and overtreatment.

A surprising number of physicians have already accepted the concept of adaptive radioligand dosing, stopping treatment in high-responding patients. This acceptance is driven by the compelling physics of diminishing returns, even though robust clinical trial data to guide this practice does not yet exist.

Unlike chemotherapy, radioligand therapy's effectiveness wanes as tumors shrink. With less PSMA target for the drug to bind to, less radiation is delivered to the cancer. This physical reality supports "adaptive dosing"—stopping treatment in high-responders to spare healthy tissue and resume later if needed.

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.