Potential predictive patterns of minimal residual disease detected by immunohistochemistry on bone marrow biopsy specimens during a long-term follow-up in patients treated with cladribine for hairy cell leukemia.
BACKGROUND
Minimal residual disease (MRD) in patients treated for hairy cell (HC) leukemia as assessed by immunohistochemistry has not been included routinely in evaluation of treatment results.


OBJECTIVE
To assess the presence of persistent HCs after treatment, as detected by immunohistochemistry, and to evaluate the correlation between the level of MRD and clinical outcome.


METHODS
Percentages of DBA.44-positive HCs were assessed on 116 biopsy specimens from 17 patients. The patients had a median follow-up of 55.4 months.


RESULTS
Minimal residual disease was seen in 3 patterns. Group 1 (7 patients) had MRD levels ranging from "rare scattered suspicious HCs" to less than 1%. The MRD levels were stable throughout follow-up, and all patients remained in complete remission. Group 2 (6 patients) had MRD levels ranging from 1% to 5%, and 3 patients were in complete remission at 77.9, 63.8, and 108.0 months. Another patient showed evidence of disease activity (partial remission) at 47.6 months. Two other patients relapsed at 12.3 months and at 25.7 months, respectively, with greater than 1% HCs. Group 3 (4 patients) had MRD levels greater than 5%. Three patients relapsed at 11.3, 12.1, and 29.6 months, respectively, with greater than 5% HCs. The fourth patient had MRD levels of 5% at 14.6 months and 2% at 20.0 months but was subsequently lost to follow-up.


CONCLUSIONS
Quantitative assessment of MRD may be of value in identifying patients at risk for relapse of hairy cell leukemia.
Mhawech-Fauceglia
Paulette
P
Department of Pathology, Geneva University Hospital, Geneva, Switzerland. paulette.mhawech-fauceglia@roswellpark.org
Oberholzer
Martin
M
Aschenafi
Senait
S
Baur
Audrey
A
Kurrer
Michael
M
Von Rohr
Albert
A
Hsu-Schmitz
Shu-Fang
SF
Wagner
Beatrice
B
Delacretaz
Francoise
F
Hurwitz
Nina
N
D000970:Antineoplastic Agents / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000378:metabolism; D001706:Biopsy; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology*; D017338:Cladribine / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D007279:Injections, Subcutaneous; D007943:Leukemia, Hairy Cell / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D018365:Neoplasm, Residual / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D011237:Predictive Value of Tests; D012074:Remission Induction; D012189:Retrospective Studies
D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D017338:Cladribine