Low-dose rituximab in adult patients with primary immune thrombocytopenia.
BACKGROUND
Rituximab 375 mg/m(2) weekly for 4 wks has significant activity in adults with primary immune thrombocytopenia (ITP). In this setting, several evidences support the possible use of lower doses of rituximab.


OBJECTIVE
To investigate the activity of low-dose rituximab as salvage therapy in previously treated symptomatic ITP.


METHODS
Forty-eight adult patients were treated prospectively with rituximab 100 mg weekly for 4 wks.


RESULTS
Overall and complete responses (CR) (platelet level ≥ 50 and 100 × 10(9) /L) were 60.5% and 39.5%, respectively. In responders, the median time to response was 35 d (range: 7-112 d). The median time of observation was 18 months (range 3-49 months). Sixteen of 29 responding patients (55%) relapsed and 14 needed further treatments. The 12- and 24-month cumulative relapse-free survival was 61% and 45%, respectively. In univariate analysis, CR rate was in inverse relation with weight OR=0.95, CI(95%) [0.91; 0.99] (P=0.019) and age OR=0.96, CI(95%) [0.93; 0.99] (P=0.047). Cox regression model showed that relapse probability increases as weight (HR=1.06, CI(95%) [1.0031; 1.111]) and period between diagnosis and rituximab therapy (HR=1.01, CI(95%) [1.002; 1.017]) increase. One patient developed an interstitial pneumonia 1 month after the end of rituximab treatment. No other infectious, hematologic or extra-hematologic complications were documented during follow-up.


CONCLUSIONS
Low-dose rituximab is active in ITP but has moderate long-term effect. A comparative study with standard dose is warranted.
Zaja
Francesco
F
Clinica Ematologica, DIRM, Azienda Ospedaliero Universitaria S. Maria Misericordia, Udine, Italy. zaja.francesco@aoud.sanita.fvg.it
Vianelli
Nicola
N
Volpetti
Stefano
S
Battista
Marta Lisa
ML
Defina
Marzia
M
Palmieri
Salvatore
S
Bocchia
Monica
M
Medeot
Marta
M
De Luca
Stefano
S
Ferrara
Felicetto
F
Isola
Miriam
M
Baccarani
Michele
M
Fanin
Renato
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000009:adverse effects; D058846:Antibodies, Monoclonal, Murine-Derived; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000188:drug therapy* / Q000503:physiopathology; D012008:Recurrence; D012044:Regression Analysis; D012074:Remission Induction; D000069283:Rituximab; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D007155:Immunologic Factors; D000069283:Rituximab