Treatment (Rx) patterns and attrition rates in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC).
Authors: Gebrael Georges , Jo Yeonjung , Hage Chehade Chadi , Ozay Zeynep Irem , Sayegh Nicolas , Ostrowski Micah , Campbell Patrick , Anderson Ethan , Nordblad Blake , Galarza Fortuna Gliceida M , Mathew Thomas Vinay , Riaz Irbaz Bin , Graf Ryon P , Guha Avirup , Maughan Benjamin L. , Roy Soumyajit , Antonarakis Emmanuel S. , Agarwal Neeraj , Swami Umang 
Published: February 2025

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Background:
The Rx landscape of pts with mCRPC has recently evolved with the approval of lutetium-177-PSMA-617 (Lu-177) and poly(ADP) ribose polymerase inhibitors (PARPi) either as single agents or as combinations with an androgen receptor pathway inhibitor (ARPI) [PMID: 37442702]. However, real-world data on the uptake of these agents are lacking. Herein, we sought to assess the Rx patterns and attrition rates of pts with mCRPC in the era of newly approved therapies.
Methods:
The de-identified nationwide Flatiron Health Electronic-Health Record (EHR)-derived database was used to extract pt-level data. Eligibility criteria: diagnosis of mCRPC and Rx line (L) information. The data cut-off date was 5/31/2024. Rx patterns in each line of therapies were summarized using frequency and percentages. All analysis was done using R version 4.2.3.
Results:
Of the overall cohort of 24,105 pts with metastatic prostate cancer, 12,333 pts diagnosed with mCRPC between 1/1/2013 and 5/9/2024 met the eligibility criteria and were included. Rx trends are summarized (Table). Of pts receiving 1L Rx, 61% of pts received 2L therapy, and 35% received 3L therapy. Androgen receptor pathway inhibitor (ARPI) was the most common Rx in the 1L setting (73.7%), followed by taxane (10%) and sipuleucel-T (3.8%). In 2L, ARPI was again the most frequent Rx (46.8%), followed by taxane (23.6%). In 3L, taxane became the most frequent Rx (35.4%), followed by ARPI (26.2%) and radium-223 (4.9%). Rx trends per year will be presented in the meeting.
Conclusions:
In the current era,a high proportion of pts with mCRPC receiving 1L Rx do not receive a subsequent line of Rx (39% of pts do not receive 2L, and 65% do not receive 3L Rx). ARPIs and taxanes remain the most frequently used Rx options in most L of therapy. These findings highlight the need for better tolerated Rx, therapies with a novel mechanism of action, and improved access to care for our pts. Rx trends per year will be presented in the meeting.

Rx patterns in pts with mCRPC.

Rx
1L, n (%)N = 12,333
2L, n (%)N = 7475
3L, n (%)N = 4316
4L, n (%)N = 2339
5L, n (%)N = 1225

ARPI
9085 (73.7)
3503 (46.8)
1130 (26.2)
356 (15.2)
157 (12.8)

PARPi-based therapies
93 (0.8)
185 (2.5)
142 (3.3)
98 (4.2)
47 (3.9)

Platinum-based therapy
127 (1)
216 (2.9)
198 (4.6)
148 (6.3)
130 (10.6)

Lu-177-based therapies
50 (0.4)
109 (1.5)
169 (3.9)
143 (6.3)
103 (8.4)

Radium-223
183 (1.5)
241 (3.2)
213 (4.9)
125 (5.3)
79 (6.4)

Sipuleucel-T
474 (3.8)
94 (1.3)
53 (1.2)
18 (0.8)
8 (0.7)

Taxane
1240 (10)
1763 (23.6)
1526 (35.4)
935 (40)
393 (32)

Pembrolizumab
24 (0.2)
41 (0.5)
36 (0.8)
27 (1.2)
29 (2.4)

Other*/not-applicable**
665 (5.4)/392 (3.2)
1000 (13.4)/323 (4.3)
602 (14)/247 (5.7)
320 (13.7)/169 (7.2)
162 (13.3)/117 (9.5)

*Includes drugs approved for mCRPC in combination with unapproved agents or clinical trial drugs.

**Includes agents not approved for prostate cancer.