Journal of Clinical Oncology, Vol 8, 1830-1838, Copyright © 1990 by American Society of Clinical Oncology
Trimetrexate in prostatic cancer: preliminary observations on the use of prostate-specific antigen and acid phosphatase as a marker in measurable hormone-refractory disease
HI Scher, T Curley, N Geller, C Engstrom, DD Dershaw, SY Lin, K Fitzpatrick, J Nisselbaum, M Schwartz and L Bezirdjian
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
Thirty-one patients with bidimensionally measurable hormone-refractory
prostatic cancer received trimetrexate (TMTX). Serial values of
prostate-specific antigen (PSA) and acid phosphatase (SAP) were correlated
with response. Five patients (17%; 95% confidence interval, 3% to 30%)
achieved a partial remission for a median of 3 months (range, 3 to 7.5
months). Marker levels showed large variations with no discernible
patterns. Serial PSA and SAP in 19 patients with abnormal baseline values
showed a correlation with measurable disease response in only 68% (13 of
19) and 47% (nine of 19) of patients, respectively. Values were then
smoothed using an exploratory data analysis technique of running medians
and averages. Trends in marker changes were much more apparent. Several
"decision rules" were evaluated for use of markers as indices of disease
progression. A 50% increase from the patient's minimum value in either PSA
or SAP on two successive determinations correlated with progression in 90%
of cases in this trial. TMTX has modest activity in prostatic cancer, and
further trials are not warranted. Biochemical markers do not uniformly
reflect disease activity in hormone-refractory disease, and changes in
biochemical markers must be interpreted cautiously when used as the sole
end point to assess efficacy in clinical trials.
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