Harvard Medical School and Massachusetts General Hospital, Boston, MA
Matthew R. Smith , Shannon Matheny , Fred Saad , Dana E. Rathkopf , Peter F.A. Mulders , Johann Sebastian De Bono , Eric Jay Small , Neal D. Shore , Karim Fizazi , Thian San Kheoh , Jinhui Li , Mary Beth Todd , Thomas W. Griffin , Margaret K. Yu , Charles J. Ryan
Background: In study COU-AA-302 of men with mCRPC and no prior chemotherapy, AA plus prednisone (hereafter AA) significantly increased radiographic progression-free survival. There is limited information about response to subsequent AS-directed therapies following AA. In this post hoc analysis of pts who received AA during study COU-AA-302, we evaluated clinical response to subsequent AA or enzalutamide (ENZ). Methods: In COU-AA-302, 546 pts were randomized and received AA. Subsequent response and discontinuation data from 88 pts receiving AS-directed therapy after study were collected retrospectively, source verified, and entered into the database. Median time to prostate-specific antigen (PSA) progression with 95% confidence intervals was estimated using the Kaplan-Meier method. Results: As of May 2013, following AA on study, 55 pts received subsequent AA and 33 received subsequent ENZ. 69% (38/55) of pts in the AA then AA group and 67% (22/33) pts in the AA then ENZ group received intervening chemotherapy. Baseline patient characteristics were similar across both groups and to the overall COU-AA-302 population. Median (range) exposure to subsequent therapy was 4 (1-20) months for AA and 5 (1-12) months for ENZ. Response to subsequent AA or ENZ is summarized in the Table. Conclusions: In this post hoc analysis, pts previously treated with AA experienced modest clinical response on subsequent treatment with either AA or ENZ. These data support further studies of subsequent AS-targeted drugs following treatment with AA for mCRPC. Clinical trial information: NCT00887198.
AA then AA | AA then ENZ | |
---|---|---|
n | 55 | 33 |
Median time to PSA progression on subsequent therapy, months |
3.9 (2.6, NE) | 2.8 (1.8, NE) |
Positive response during subsequent therapya [n (%)] |
27 (49) | 22 (67) |
Clinical symptoms | 10 (18) | 4 (12) |
CT/MRI/bone scans | 1 (2) | 1 (3) |
PSA values | 24 (44) | 22 (67) |
Other | 0 | 1 (3) |
Reason for discontinuation during subsequent therapya [n (%)] |
||
Radiographic progression | 10 (18) | 5 (15) |
Clinical progression | 17 (31) | 9 (27) |
PSA progression | 28 (51) | 13 (39) |
Adverse event | 3 (6) | 0 |
Therapy ongoing | 6 (11) | 11 (33) |
Other | 14 (26) | 6 (18) |
a More than one reason allowed.
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