A Phase II Trial of Imatinib Mesylate as Maintenance Therapy for Patients With Newly Diagnosed C-kit-positive Acute Myeloid Leukemia.

INTRODUCTION: Adults with acute myeloid leukemia (AML) have a high rate of remission; however, more than 50% relapse. C-kit is expressed in approximately 60% of patients with de novo AML and represents a potential therapeutic target. MATERIALS AND METHODS: Patients with newly diagnosed AML received 12 months of imatinib mesylate as maintenance therapy after the completion of post-remission therapy. The primary objective was to determine whether this approach improved progression-free survival (defined as no relapse and no death) compared with historical controls. RESULTS: The median progression-free survival of patients < 60 years of age was 52.1 months (historical control, 13 months) and for patients ≥ 60 years of age was 10.7 months (historical control, 8 months). The median level of AF1q expression was high (9.59), and 84% of patients had moderate or high levels of drug-resistance factors. CONCLUSIONS: Imatinib maintenance therapy may improve the outcome of newly diagnosed patients with AML who are < 60 years of age.

Grade 3 Follicular Lymphoma: Outcomes in the Rituximab Era.

BACKGROUND: Follicular lymphoma (FL) is heterogeneous. Although FL Grade 3B (FL3B) is treated as aggressive FL (aggFL), an optimal approach to FL Grade 3A (FL3A) remains unclear because few data exist on clinical outcomes on the basis of subclassification of FL Grade 3 (FL3) since the introduction of rituximab. We report outcomes of FL3 in the rituximab era. PATIENTS AND METHODS: We identified and analyzed a retrospective cohort of 53 patients with FL3A, 3B, and FL Grade 3 with areas of diffuse large B-cell lymphoma (DLBCL). They were divided into 2 groups: aggFL (n = 21) included patients with FL3B (n = 10) and FL3 (A or B) with concomitant DLBCL (n = 11); indolent lymphoma (n = 32) included only FL3A. RESULTS: Baseline characteristics did not differ between the groups. rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone (R-CHOP) was initial treatment in 15 (79%) of patients with aggFL and 21 (72%) of those with FL3A; rituximab was included in initial therapy in 18 (95%) and 24 (83%), respectively. Comparing aggFL and FL3A, 5-year overall survival was 90% versus 79% (P = .97) and 5-year progression-free survival (PFS) 44% versus 34% (P = .75), respectively. CONCLUSION: We conclude that outcomes for FL3, primarily treated with R-CHOP, do not differ between FL3A and aggFL (FL3B and FL3/DLBCL). The aggFL group showed a plateau in PFS confirming these should be treated with curative intent. FL3A patients, mainly managed with R-CHOP, also show an apparent plateau in PFS. Although longer follow-up and confirmation in other data sets is required, this indicates potential undertreatment of FL3A with less aggressive regimens often used for indolent lymphoma.

Is rituximab sub-optimally dosed in indolent B cell lymphoma?

Rituximab pharmacokinetics are affected by gender, age and weight and can affect outcomes in aggressive B cell lymphoma. Less is known about the pharmacokinetics of rituximab in indolent B cell lymphoma (iNHL). We analysed the effects of gender, age, weight and body surface area on the outcomes of 303 patients treated with first line rituximab-based regimens for iNHL. The patients were divided into 3 treatment cohorts: rituximab only, rituximab + chemotherapy (R-CTX) and R-CTX followed by rituximab maintenance; furthermore, each cohort was subdivided as follicular (FL) or non-FL, based on histology. Older males and patients with higher weight had worse outcomes when treated with R-CTX, probably due to faster rituximab clearance. Our results concur with studies of R-CTX for DLBCL. As this effect was not observed in patients treated with rituximab alone or R-CTX followed by rituximab maintenance, we hypothesize that higher rituximab levels reached with weekly rituximab and/or prolonged exposure achieved with maintenance therapy exceed the therapeutic threshold, even with faster clearance, which nullifies the negative effect of higher weight and male gender. In conclusion, under current practices, a subset of patients with iNHL, i.e., FL treated with R-CTX, may be sub-optimally dosed with rituximab.