The future of advanced prostate cancer treatment may involve combining ADCs with bispecific T-cell engagers. This strategy could use ADCs for a short duration to deliver a potent hit, followed by immunotherapy to achieve durable remission, potentially reducing toxicity and enabling earlier use.

The rationale for combining the PPAR-gamma inhibitor FX-909 with other agents goes beyond simple synergy. It's a strategic approach to address intratumoral heterogeneity, where a single tumor can contain both target-positive (luminal) and target-negative (basal-like) cell populations, requiring a multi-pronged attack.

Instead of replicating the ADC and checkpoint inhibitor combination successful in other cancers, experts suggest a more "sophisticated" approach for prostate cancer. The next step should be combining ADCs with T-cell engagers, which have shown greater single-agent efficacy in this specific disease, potentially leapfrogging a less effective strategy.

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.

Unlike bladder cancer, prostate cancer has highly effective androgen-pathway inhibitors (ARPIs) that extend survival. This success has pushed chemotherapy and, by extension, ADC development to later treatment lines as clinicians prioritize other novel mechanisms of action first.

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.

For antibody-drug conjugates (ADCs) to make a meaningful impact in prostate cancer, the clinical development bar is exceptionally high. Merely showing activity in late-line settings is insufficient; the true measure of success is demonstrating superiority over the established chemotherapy standard, docetaxel.

Initial ADCs targeting PSMA in prostate cancer were hampered by the neurotoxicity of MMAE payloads and inefficient linker technology. This limited deliverable dosage, causing trials to fail for technical reasons rather than a flawed biological target, paving the way for newer, better-designed ADCs.

Counterintuitively, data suggests that prostate cancer patients who progressed on PSMA-targeted radioligand therapy can still achieve deep responses to a PSMA-targeting ADC. This may be because resistant tumors become more proliferative, increasing their sensitivity to the ADC's cytotoxic topoisomerase payload, which has a different mechanism of action.