Abstract CT190: Latin American patient subgroup analysis of the phase 3 TITAN study: Apalutamide plus ADT in metastatic Hormone-Sensitive Prostate Cancer (mHSPC)
Authors: Juarez Alvaro , Chi Kim N. , Pereira Andrea J. , Chowdhury Simon , Triantos Spyros , McCarthy Sharon , Bhaumik Amitabha , Mundle Suneel , Velasquez Esteban , Rosas Sara , Fabricio Vanessa , Agarwal Neeraj 
Published: July 2021

Background: Apalutamide (APA) is an approved treatment in various countries of Latin America to treat patients with metastatic hormone-sensitive prostate cancer (mCSPC) patients based on the TITAN study interim analysis, which demonstrated an improved overall survival (HR 0.48; 95% CI 0.39-0.60) and radiographic progression-free survival (HR 0.67; 95% CI 0.51-0.89) for patients receiving APA + androgen deprivation therapy (ADT) compared to placebo (PBO) + ADT (KN Chi, et al. N Engl J Med 2019; 381:13-24). As there can be geographical differences in disease presentation and management, we undertook a post-hoc analysis of the Latin American (LATAM) patients enrolled to TITAN.

Methods: mCSPC patients were randomly assigned 1:1 to receive APA (240 mg per day) plus ADT or PBO plus ADT. Patients previously treated for localized disease were eligible and treatment with prior docetaxel was permitted. Radiographic progression-free survival (rPFS) and overall survival (OS) were TITAN's dual primary endpoints.

Results: In total, 177 LATAM patients from Argentina, Brazil and Mexico were recruited (16.8% of the study population). Of the 177 patients, 94 were assigned to the APA-ADT arm and 83 randomized to PBO-ADT arm. The LATAM APA and PBO patients were similar with a median age of 69, 64% of the patients had an ECOG Performance Status of 0, and the majority of patients had a high-volume disease, 57% , which was comparable to the TITAN intention to treat (ITT) population. Prior docetaxel was used in 4% of the LATAM population versus 10.7% in the TITAN ITT population. At the first interim analysis of OS with a median follow-up of 22.7 months, the 2 year OS rate was 84% in the APA group versus 79% in the PBO group (HR for death 0.77; 95% CI of 0.38-1.55; p=0.4567). Median rPFS was not reached in the APA group versus 22.0 months for PBO (HR for radiographic progression or death 0.44; 95% CI of 0.26-0.75; p=0.0019). The benefit of APA-ADT for the LATAM patients appeared consistent to the overall ITT population for the primary, secondary and exploratory efficacy endpoints. The frequency of grade 3 or 4 adverse events was 48.9% in the APA group and 42.2% in the placebo group; discontinuation due to adverse events were more frequent in the APA arm than in the placebo group (11.7% vs. 2.4%).

Conclusion: This analysis of the LATAM patients with mCSPC enrolled in the TITAN study confirms the benefit of the addition of APA to ADT with a safety profile that was consistent with the results shown in the ITT population.

Citation Format: Alvaro Juarez, Kim N. Chi, Andrea J. Pereira, Simon Chowdhury, Spyros Triantos, Sharon McCarthy, Amitabha Bhaumik, Suneel Mundle, Esteban Velasquez, Sara Rosas, Vanessa Fabricio, Neeraj Agarwal. Latin American patient subgroup analysis of the phase 3 TITAN study: Apalutamide plus ADT in metastatic Hormone-Sensitive Prostate Cancer (mHSPC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT190.