The development of SERDs for adjuvant therapy was stalled for two decades not by efficacy concerns, but by logistics. Fulvestrant, the first SERD, required monthly intramuscular injections, a pragmatically unfeasible strategy for a 5-year adjuvant trial, a problem only solved with the advent of oral SERDs.
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.
A common assumption that older patients may prefer simpler, continuous medication regimens is often incorrect. Clinical experience shows that the vast majority of patients, regardless of age, are interested in a time-limited therapy option, provided it can be delivered conveniently without infusions.
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.
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.
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.
Contrary to the norm where real-world outcomes are worse than in controlled trials, real-world data for the oral SERD elacestrant shows efficacy as good as, or even better than, the pivotal EMERALD study. This unusual finding significantly bolsters confidence in the drug's broad clinical utility across a less-selected patient population.
In a crowded field, GSK's CSO explains their choice of the FGF21 molecule "Effie" was driven by three specific technical advantages: a longer half-life enabling monthly dosing for sicker patients, easier manufacturing via mammalian systems, and the lowest immunogenicity profile compared to competitors.
Despite being a pill, oral Wegovy requires an empty stomach, only 4oz of water, and a 30-minute post-dose fast. This difficult regimen is a major impediment to its uptake, particularly in the U.S. where patients prioritize the maximum efficacy of injectables over the supposed convenience of a cumbersome pill.
Using a second CDK4/6 inhibitor after progression on a first showed disappointing results in trials like post-MONARCH. However, the EMBER-3 trial's success, combining abemaciclib with the novel SERD imlunestrant, demonstrated robust efficacy. This suggests the choice of endocrine partner is the critical factor for making this sequencing strategy viable.
The PSMA edition trial's fixed six-cycle Lutetium regimen, designed nearly a decade ago, is now seen as suboptimal. This illustrates how the long duration of clinical trials means their design may not reflect the latest scientific understanding (e.g., adaptive dosing) by the time results are published and debated.