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.

Related Insights

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.

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 investigator-led PLUTO trial found docetaxel chemotherapy provided a better overall survival benefit than lutetium in first-line mCRPC. This result directly confronts the common clinical bias against chemotherapy ("chemophobia"), proving that older treatments can still outperform newer targeted agents and should not be prematurely abandoned.

Beyond efficacy, new therapies like bispecifics require significant institutional support. Clinicians need training for unfamiliar side effects like CRS, and facilities need resources like observation units and admission protocols, creating a steep implementation curve for clinical practice.

The panel reviews advanced, second-line ADC trials in China using novel targets and payloads. An expert remarks that these are the drugs and questions the US and Europe may only begin to study in two to three years, signaling a significant shift in the global oncology R&D landscape.

The rapid advancement of ARPIs wasn't just a scientific breakthrough. It was a rare convergence of FDA interest in new endpoints, a deeper biological understanding of castration resistance, and intense industry and academic collaboration that created a uniquely fertile ground for innovation.

Developers often test novel agents in late-line settings because the control arm is weaker, increasing the statistical chance of success. However, this strategy may doom effective immunotherapies by testing them in biologically hostile, resistant tumors, masking their true potential.

Experts believe molecular tests like Decipher and PTEN status are superior to simply counting bone lesions for guiding treatment. While not yet standard practice for all decisions, this represents a significant shift towards using underlying tumor biology to determine therapy, like adding docetaxel.

In the AMPLITUDE trial, only 16% of high-risk metastatic prostate cancer patients received docetaxel, despite it being allowed and indicated by disease characteristics. This suggests a real-world "chemophobia" or physician bias towards newer targeted therapies, even within a clinical trial setting.

An antibody-drug conjugate's (ADC) effectiveness is capped by its chemotherapy payload. In prostate cancer, topoisomerase inhibitors have a poor track record. Therefore, ADCs using this payload face an uphill battle compared to those with proven payloads like microtubule inhibitors (taxanes).