PROGNOSTIC IMPORTANCE OF SERUM-SOLUBLE CD23 LEVEL IN CHRONIC LYMPHOCYTIC-LEUKEMIA

Prognosis of B-cell chronic lymphocytic leukemia (CLL) is based on cli nical staging whose limitation is the failure to assess whether the di sease will progress or remain stable in early stage (Binet A, or Rai 0 , I, II) patients. We previously reported that soluble CD23 (sCD23), a protein derived from the B-cell membrane CD23 Ag, is selectively elev ated in the serum of CLL patients. This prospective study assessed the predictive value of serum sCD23 level measured at study entry on the overall survival of all CLL patients and on disease progression of sta ge Binet A patients. Prognostic value of repeated measurements of sCD2 3 over time in stage A patients was also analyzed. One hundred fifty-t hree CLL patients were prospectively followed with a median follow-up of 78 months. Eight clinical or biological parameters were collected f rom the date of the first sCD23 measurement. At study entry. by Cox mo del, Binet staging (P = .0001) and serum sCD23 level (P = .03) appeare d as prognostic factors for survival. Patients with sCD23 level above median value (>574 U/mL) had a significantly worse prognosis than thos e with lower values (median survival of 53 v 100(+) months, P = .0001) . During follow-up, sCD23 doubling time increased by 3.2 the risk of d eath (P = .001). Among stage A patients In = 100), sCD23 determination at study entry was the sole variable predictive of disease progressio n, patients with sCD23 level above 574 U/mL had a median time progress ion of 42 months versus 88 months for those with lower levels (P = .00 01). Stage A patients who doubled their sCD23 level exhibited a 15-fol d increased risk of progression (P = .0001) and, in addition, the sCD2 3 increase preceded by 48 months disease progression. We conclude that in CLL patients, serum sCD23 level provides significant additional pr ognostic information in terms of overall survival. Most interestingly, among early stage patients, sCD23 determination at diagnosis and duri ng the course of the disease may help to the early identification of p atients who will rapidly progress to upper stages. (C) 1996 by The Ame rican Society of Hematology.