Plasma cyclic nucleotide levels in monitoring acute leukemia patients.

To verify the clinical usefulness of plasma cyclic nucleotide determination as a tumor marker, levels were measured in 52 normal subjects and in 106 acute leukemia patients. In untreated patients plasma cyclic GMP (cGMP) levels were markedly elevated, whereas cyclic AMP levels did not significantly differ from those of normal subjects. Plasma cGMP levels normalized in all patients who attained complete remission and remained in the normal range during all the remission period. In the patients who relapsed, an early increase in cGMP levels to the pretreatment values was observed, thus suggesting that their determination may be of clinical relevance in monitoring the patients' response to treatment.