(UroToday.com) The 2023 European Society of Medical Oncology (ESMO) Annual Congress held in Madrid, Spain between October 20th and 24th, 2023 was host to a prostate cancer abstracts poster session. Dr. Lisa Horvath presented the results of a secondary analysis of ENZAMET (ANZUP 1304) evaluating the effects of enzalutamide +/- early docetaxel on overall survival (OS) in participants aged <70 years versus those ≥ 70 years.
In 2019, we saw the emergence of data for enzalutamide in patients with metastatic castrate sensitive that randomized patients to receive testosterone suppression plus either open-label enzalutamide or a standard nonsteroidal antiandrogen therapy (standard-care group). The primary end point was overall survival. We highlight that ENZAMET utilized an active comparator (non-steroidal anti-androgen), in contrast to many other trials in this space. Concurrent use of docetaxel was permitted at the discretion of the treating physician (16% had prior docetaxel and 45% with planned use of early docetaxel). 53% of patients had CHAARTED high volume disease, and 39% had prior local therapy. Interim analysis after a median follow-up of 34 months showed a significant survival benefit in the enzalutamide group versus those receiving standard nonsteroidal anti-androgens (hazard ratio 0.67, 95% confidence interval 0.52 to 0.86).1
Despite these observed benefits, there are often reservations about extending doublet and/or triplet therapy treatment intensification to older patients. It is thus important to understand the benefits of these agents in older patients, who may be frailer and have more co-morbidities. In this post-hoc analysis, Dr. Horvath and colleagues assessed the efficacy of enzalutamide in patients with mHSPC ≥70 years versus <70 years of age.
Of 1,125 patients randomised, 46% were ≥70 years. The proportion of docetaxel usage was lower in patient aged ≥70 years (35% versus 52% in those <70 years of age).
The beneficial effects of enzalutamide on OS seen in the whole cohort were maintained in patients aged ≥70 years, regardless of planned use of early docetaxel. Patients aged ≥70 years treated with enzalutamide significantly improved OS, consistent with that observed in younger patients.
Patients in the oldest quartile had similar rates of G3-5 AEs with enzalutamide compared to younger patients. However, patients aged 69-74 had higher rates of toxicity, probably reflecting higher rates of docetaxel use compared to the oldest quartile. Similarly, the rates of adverse events of interest (fatigue, cognitive disturbance, memory impairment, fall, generalised muscle weakness, seizure and hypertension) were highest in ages 69-74 years. AEs leading to enzalutamide treatment discontinuation were almost twice as likely in ages 69-74 and 74-96 years compared to younger quartiles.
Dr. Horvath concluded that this post-hoc analysis demonstrates that patients aged ≥70 years treated with enzalutamide/testosterone suppression +/- docetaxel derive similar beneficial treatment effects to the overall cohort. These data suggest enzalutamide is a suitable option for older men with mCSPC fit for enzalutamide.
Presented by: Lisa G. Horvath, MBBS, FRACP, PhD, Director of Research, Conjoint Chair of Medical Oncology (Genitourinary Cancers), Chris O’Brein Lifehouse, Syndey, Australia
Written by: Rashid K. Sayyid, MD, MSc – Society of Urologic Oncology (SUO) Clinical Fellow at The University of Toronto, @rksayyid on Twitter during the 2023 European Society of Medical Oncology (ESMO) Annual Meeting, Madrid, Spain, Fri, Oct 20 – Tues, Oct 24, 2023.
References: