Serum alkaline phosphatase levels and and survival of patients with mCRPC
Posted Oct 27 2010 12:00am
The ability to monitor and predict outcomes of patients in treatment for metastatic castration-resistant prostate cancer (mCRPC) is becoming increasingly important as better treatments for such patients start to become available or enter clinical trials.
To date, patients’ PSA levels and decreases in their levels of circulating T cells (CTCs) have been seen as two of the better options for monitoring of risk for progression. However, a new paper by Sonpavde et al. has now established the serum alkaline phosphatase level (serum APL) as another potential marker for early response to treatment or disease progression. And it should be noted that measuring serum APL is a very simple laboratory test, available without any need for the sophisticated equipment necessary to assess CTC levels.
Sonpavde et al. used data from patients enrolled in the TAX 327 clinical trial, in which men with mCRPC were treated with either docetaxel + prednisone or mitoxantrone + prednisone Their goal was to establish whether changes in serum APL within 90 days of treatment with chemotherapy were associated with the patients’ overall survival (OS). In addition to other factors for trial eligibility, patients included in this study needed to have a baseline APL ≥ 120 units/l (the upper limit of normal) and at least two post-therapy measurements of APL.
The results of their analysis showed the following:
601 patients met all eligibility criteria.
By day 90
Changes in serum APL did not meet criteria required to act as a surrogate endpoint for OS.
For men treated with docetaxel + prednisone or mitoxantrone + prednisone, who have mCRPC and a serum APL > 120 units/l at time of treatment, it appears that:
Normalization of serum APL by day 90 is predictive of better survival independent of a decline of ≥ 30 percent in PSA level.
An increase in serum ALP by day 90 is predictive of poor survival independent of an increase of ≥ 50 percent in PSA level.
These results will clearly need to be validated based on other available data, which may be available from recently reported or ongoing clinical trials of cabazitaxe,. abiraterone actetate and MDV3100.