In its prior Phase 3 program, KYZATREX achieved normal 24-hour mean total testosterone levels in 88% of treated hypogonadal men by Day 90, with increased blood pressure reported in 2.6% of patients as the most common adverse event. Building on that dataset, Marius Pharmaceuticals is initiating a six-month, open-label post-marketing study in 50 men aged 65–80 with confirmed hypogonadism, positioning the effort as groundwork for a potential label expansion and a simplified once-daily dosing option.
The single-site study will track quality of life and a suite of aging-relevant measures, including cardiovascular parameters, body composition, strength-related metrics, and inflammatory markers. Importantly, investigators will compare KYZATREX’s labeled titration protocol with a streamlined once-daily regimen, probing whether adherence and operational simplicity can be improved without compromising hormonal control. Enrollment has begun following IRB approval, and the design skews pragmatic: ambulatory assessments, routine labs, and functional endpoints that map closely to real-world management in endocrine and urology clinics.
Strategically, this is an expansion play aimed at two pressure points in the testosterone therapy market. First is the long-running regulatory hesitation around treating “age-related” hypogonadism, which has constrained labeling to classical etiologies despite large unmet demand in older men. Generating targeted data in a 65–80 cohort—especially around cardiovascular signals and functional outcomes—may be intended to soften that stance or at least open a path to more explicit use in older patients who meet diagnostic criteria beyond simple age-related decline. Second is a competitive bid on usability. Oral testosterone undecanoate products have struggled with dose titration complexity and blood pressure labeling; demonstrating acceptable hormonal control and neutral-to-manageable cardiovascular trends on a once-daily schedule could differentiate KYZATREX on adherence, monitoring burden, and prescriber confidence.
For sites and CROs, the operational footprint is minimal and tailored to a population that can be difficult to retain. A once-daily arm, if validated, would reduce monitoring intensity tied to dose adjustments and might lower dropout tied to regimen complexity. The single-site setup trades speed and control for generalizability; sponsors and regulators will discount site-specific practice effects and demographic skew, but the approach should deliver a clean operational read on titration versus simplification. For payers and clinicians, the inclusion of quality-of-life and functional measures could resonate more than biochemical normalization alone, provided the signals are robust enough to influence coverage policies and practice patterns in older men where safety scrutiny is highest.
The core tension is that an open-label, N=50, single-site study is unlikely to be sufficient for a true indication expansion into older or “late-onset” populations given FDA’s conservative posture and the class’s blood pressure concerns. More plausibly, positive findings could underpin a supplemental filing focused on dosing flexibility and support a larger, multi-center, randomized follow-on designed around cardiovascular neutrality, hematologic safety, prostate parameters, and durability of functional gains. Watch how inclusion criteria are framed to avoid the age-related labeling trap, the magnitude and variability of testosterone exposure on once-daily dosing, and any clinically meaningful shifts in ambulatory blood pressure and inflammation. If the signal holds and operational simplicity is borne out, expect Marius to seek broader dosing language first, while using these data to scope a registrational path in older men that regulators will accept.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
