Targeted Therapies

Timely Information for Practicing Hematologists and Oncologists

www.tgt-therapies.com

MARCH 2006

 

IMATINIB

Imatinib plus chemotherapy in BCR-ABL–positive acute lymphoblastic leukemia (ALL). Imatinib, a selective inhibitor of BCR-ABL protein kinase, has induced responses in a large proportion of Philadelphia chromosome–positive (Ph+) patients with ALL, but these responses have not been durable. Yanada and colleagues from the Japan Adult Leukemia Study Group (JALSG) conducted a phase II study in which 80 patients with BCR-ABL–positive ALL were treated with oral imatinib 600 mg/day in combination with other anticancer agents (cyclophosphamide, daunorubicin, vincristine, prednisolone, methotrexate, cytosine arabinoside, and dexamethasone) as remission induction, consolidation, and maintenance therapies. Complete remission (CR) was achieved in 96% of patients (n = 77) and associated with polymerase chain reaction negativity of bone marrow cells in 71% of patients. Forty-nine of the CR patients underwent allogeneic hematopoietic stem cell transplantation; relapse occurred in 20 patients after a median CR of 5.2 months. The estimated 1-year event-free and overall survival rates (60% and 76%, respectively) for these patients with ALL were superior to those of JALSG historic controls. (Yanada M, et al. J Clin Oncol. 2006;24:460–466.)

 

Ph+ chronic phase chronic myeloid leukemia (CML). Iacobucci and others from the Italian Cooperative Study Group on CML retrospectively reviewed clinical data obtained from 284 patients with late chronic phase Ph+ CML who had been treated with imatinib 400 mg/day after the failure of interferon-alpha. They found that after 3 to 4 years of treatment the molecular response of late cytogenetic responders (patients for whom a complete cytogenetic response was achieved after 12 months of therapy) was similar to that of early cytogenetic responders (patients for whom a complete cytogenetic response was achieved within 12 months of therapy). Moreover, similar estimated rates were observed for 4-year progression (88% and 100%) and overall survival (92% and 100%) in early and late responders, respectively. In a second study, Jabbour and coworkers from the M.D. Anderson Cancer Center reviewed data from 541 patients with Ph+ chronic phase CML who were treated with imatinib to investigate the rate of sudden blastic transformation (SBT; blastic transformation occurring unexpectedly in patients in complete hematologic remission). Historically, the SBT rate in patients treated with interferon-alpha has been 0.5% to 2.5%. After a median follow-up of 46 months (range, 7 to 54 months), 23 patients (4%) had developed a blast phase. In 4 patients (0.7%) the blast phase was of sudden onset. This finding indicates the need for continuous monitoring of patients with CML who are treated with imatinib. (Iacobucci I, et al. J Clin Oncol. 2006;24:454–459; Jabbour E, et al. Blood. 2006;107:480–482.)

 

THALIDOMIDE

Thalidomide plus dexamethasone in newly diagnosed multiple myeloma. Rajkumar and associates from the Eastern Cooperative Oncology Group (ECOG) conducted a phase III study in which 207 patients with newly diagnosed multiple myeloma were randomized to receive oral thalidomide 200 mg/day plus oral high-dose dexamethasone 40 mg on days 1 through 4, 9 through 12, and 17 through 20 every 4 weeks, or dexamethasone alone. Patients were expected to discontinue the study after four cycles to undergo autologous stem cell transplantation, but treatment beyond four cycles was permitted at the discretion of the treating physician. The response rate in the thalidomide plus dexamethasone arm was greater than that observed in the dexamethasone-alone arm (63% vs 41%). Deep vein thrombosis (DVT) occurred more frequently in patients treated with combination therapy than in patients treated with dexamethasone alone (17% vs 3%). The incidence of DVT of grade 3 or above, neuropathy, rash, bradycardia, and any grade 4 to 5 toxicity was higher in the combination therapy group than in the dexamethasone-alone group (45% vs 21%). These data show that the higher response rate achieved with thalidomide plus dexamethasone compared with dexamethasone alone in newly diagnosed patients with multiple myeloma must be weighed against the greater toxicity associated with the combination. (Rajkumar SV, et al. J Clin Oncol. 2006;24:431–436.)

 

CHRONIC LYMPHOCYTIC LEUKEMIA (CLL)

High-risk genetic features predict poor outcomes. Byrd and others examined the impact of new prognostic factors on outcomes of 88 symptomatic, previously untreated CLL patients who received fludarabine and rituximab in a randomized phase II study. The new prognostic factors predicting rapid CLL disease progression included unmutated IgVH, del 11q, del 17p, and p53 mutations. These factors had not been previously investigated in patients treated with chemoimmunotherapy. Neither IgVH mutational status nor high-risk interphase cytogenetics was found to affect the CR rate. However, median progression-free and overall survival times were shorter in patients with unmutated than mutated IgVH status. In addition, proportional hazards and logistic regression modeling demonstrated that progression-free and overall survival times were longer as the hierarchical classification of Dohner moved from high-risk to low-risk cytogenetic features. These data show that chemoimmunotherapy outcomes are poorer in high-risk CLL patients. (Byrd JC, et al. J Clin Oncol. 2006;24:437–443.)

 

OVARIAN CANCER

Yttrium-90-labeled HMFG1 murine monoclonal antibody therapy. A preliminary study of yttrium-90-labeled murine HMFG1 administered once intraperitoneally (IP) showed prolonged disease-free survival in CR patients with epithelial ovarian cancer (EOC) after surgical debulking and chemotherapy. Verheijen and colleagues conducted a phase III trial in which 447 patients with EOC but no evidence of macroscopic disease following surgery and chemotherapy were randomized to receive IP yttrium-90-labeled murine HMFG1 monoclonal antibody or standard care. At a median follow-up of 3.5 years, no differences in time to relapse or survival were noted between treatment arms. This study showed that consolidation therapy with yttrium-90-labeled murine HMFG1 monoclonal antibody in EOC patients after surgically defined CR was not effective. (Verheijen RH, et al. J Clin Oncol. 2006;24:571–578.) 

 

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