High-dose imatinib induction followed by standard-dose maintenance in pre-treated chronic phase chronic myeloid leukemia patients--final analysis of a randomized, multicenter, phase III trial

BACKGROUND

Previous data suggest that the response of chronic myeloid leukemia cells to imatinib is dose-dependent. The potential benefit of initial dose intensification of imatinib in pre-treated patients with chronic phase chronic myeloid leukemia remains unknown.

DESIGN AND METHODS

Two hundred and twenty-seven pre-treated patients with chronic myeloid leukemia in chronic phase were randomly assigned to continuous treatment with a standard dose of imatinib (400 mg/day; n=113) or to 6 months of high-dose induction with imatinib (800 mg/day) followed by a standard dose of imatinib as maintenance therapy (n=114).

RESULTS

The rates of major and complete cytogenetic responses were significantly higher in the high-dose arm than in the standard-dose arm at both 3 and 6 months (major cytogenetic responses: 36.8% versus 21.2%, P=0.01 and 50.0% versus 34.5%, P=0.018; complete cytogenetic responses: 22.8% versus 6.2%, P<0.001 and 40.4% versus 16.8%, P<0.001) on the basis of an intention-to-treat analysis. At 12 months, the difference between treatment arms remained statistically significant for complete cytogenetic responses (40.4% versus 24.8%, P=0.012) but not for major cytogenetic responses (49.1% versus 44.2%, P=0.462). The rate of major molecular responses was also significantly better at 3 and 6 months in the high-dose arm (month 3: 14.9% versus 3.5%, P=0.003; month 6: 32.5% versus 8.8%, P<0.001). Overall and progression-free survival rates were comparable between arms, but event-free survival was significantly worse in the high-dose arm (P=0.014).

CONCLUSIONS

Standard-dose imatinib remains the standard of care for pre-treated patients with chronic phase chronic myeloid leukemia (Clinicaltrials.gov identifier: NCT00327262).

High-dose imatinib improves cytogenetic and molecular remissions in patients with pretreated Philadelphia-positive, BCR-ABL-positive chronic phase chronic myeloid leukemia: first results from the randomized CELSG phase III CML 11 "ISTAHIT" study

BACKGROUND

Imatinib 400 mg/day is the standard treatment for patients with chronic phase chronic myeloid leukemia. Recent reports suggested higher and more rapid cytogenetic and molecular responses with higher doses of imatinib.

DESIGN AND METHODS

In this prospective international, multicenter phase III study, 227 patients with pre-treated Philadelphia chromosome-positive, BCR-ABL-positive chronic myeloid leukemia were randomized to a standard-dose imatinib arm (400 mg/day) or a high-dose imatinib arm (800 mg/day for 6 months followed by 400 mg/day as maintenance therapy). In this planned interim analysis hematologic, cytogenetic and molecular responses as well as toxicity were evaluated.

RESULTS

Compared to the standard-dose, high-dose imatinib led to higher rates of major and complete cytogenetic responses at both 3 months (major: 21% versus 37%, P=0.01; complete: 6% versus 25%, P<0.001) and 6 months (major: 34% versus 54%, P=0.009; complete: 20% versus 44%, P<0.001). This was paralleled by a significantly higher major molecular response rate at 6 months in the high-dose imatinib arm (11.8% versus 30.4%; P=0.003). At 12 months, the rates of major cytogenetic response (the primary end-point) were comparable between the two arms (57% versus 59%). In contrast to non-hematologic toxicities, grade 3/4 hematologic toxicities were more common in the high-dose arm. Cumulative complete cytogenetic response rates were higher in patients without dose reduction in the high-dose arm (61%) than in the patients with no dose reduction in the standard-dose arm (36%) (P=0.014).

CONCLUSIONS

This is the first randomized phase III trial in patients with pre-treated chronic phase chronic myeloid leukemia demonstrating improvements in major cytogenetic response, complete cytogenetic response and major molecular response rates with high-dose imatinib therapy (ClinicalTrials.gov Identifier: NCT00327262).

Phase-I/II study to evaluate dose limiting toxicity, maximum tolerated dose, and tolerability of bendamustine HCl in pre-treated patients with B-chronic lymphocytic leukaemia (Binet stages B and C) requiring therapy

PURPOSE

Bendamustine hydrochloride, an anti-neoplastic agent with unique mechanism of action, is known to cause impressive remissions in relapsed non-Hodgkin's lymphoma and chronic lymphocytic leukaemia (CLL). Optimal bendamustine dosing for CLL patients had not been finally established and a phase I/II study was conducted to determine the maximum tolerated dose (MTD) and dose limiting toxicity (DLT) of bendamustine.

METHODS

The open-label, single-centre phase I/II study was conducted from March 2001 to September 2002 in Sofia, Bulgaria. The 15 study patients were extendedly pre-treated, but fludarabine-naive (3 female, 12 male, 47-72 years of age, 61 years on average). Bendamustine was given at a starting dose of 100 mg/m2 on days 1 and 2 every 3 weeks based on the previous results in lymphoma.

RESULTS

Bendamustine was well tolerated in spite of heavy pre-treatment of the study participants. Toxicity corresponded to the known safety profile of bendamustine, with the exception of bilirubin elevation. The level of 110 mg/m2 was established as MTD. A bendamustine dose of 100 mg/m2 is the recommended dose for further clinical investigations. A 4-week interval is recommended to allow for sufficient recovery. Efficacy results confirmed powerful anti-neoplastic activity of bendamustine even in extendedly pre-treated CLL patients. Based on the remission criteria, nine patients were defined as responders (four CRs, two PR, three NC) and two patients as nonresponders to therapy. Four patients were not evaluable for response, because they had received less than three courses bendamustine. After a follow-up period of 15 months, the four patients with CR were still in remission. One patient with PR had relapsed, the other had ongoing response.

CONCLUSIONS

Bendamustine is a very active and well-tolerated drug in patients with pre-treated and refractory CLL. Fludarabine-naivity of patients appears to markedly improve their bendamustine tolerability. First-line use of bendamustine is a safe option for CLL-patients requiring treatment, because bendamustine-owing to its unique pharmacodynamics-(1) is highly effective, (2) reasonably safe, and (3) does hardly produce cross-resistance against other anti-neoplastic drugs effective in this indication.