A phase I/II study of oral etoposide and idarubicin in elderly patients with high-risk acute myeloid leukemia unable to undergo intensive chemotherapy

Tipifarnib in the treatment of newly diagnosed acute myelogenous leukemia

Farnesyltransferase inhibitors (FTIs) represent a new class of signal transduction inhibitors that block the processing of cellular polypeptides that have cysteine terminal residues and, by so doing, interdict multiple pathways involved in proliferation and survival of diverse malignant cell types. Tipifarnib is an orally bioavailable, nonpeptidomimetic methylquinolone FTI that has exhibited clinical activity in patients with myeloid malignancies including elderly adults with acute myelogenous leukemia (AML) who are not candidates for traditional cytotoxic chemotherapy, patients with high-risk myelodysplasia, myeloproliferative disorders, and imatinib-resistant chronic myelogenous leukemia. Because of its relatively low toxicity profile, tipifarnib provides an important alternative to traditional cytotoxic approaches for elderly patients who are not likely to tolerate or even benefit from aggressive chemotherapy. In this review, we will focus on the clinical development of tipifarnib for treatment of newly diagnosed AML, both as induction therapy for elderly adults with poor-risk AML and as maintenance therapy following achievement of first complete remission following induction and consolidation therapies for poor-risk AML. As with all other malignancies, the optimal approach is likely to lie in rational combinations of tipifarnib with cytotoxic, biologic and/or immunomodulatory agents with non-cross-resistant mechanisms of action. Gene expression profiling has identified networks of differentially expressed genes and gene combinations capable of predicting response to single agent tipifarnib. The clinical and correlative laboratory trials in progress and under development will provide the critical foundations for defining the optimal roles of tipifarnib and in patients with AMl and other hematologic malignancies.

Active oral regimen for elderly adults with newly diagnosed acute myelogenous leukemia: a preclinical and phase 1 trial of the farnesyltransferase inhibitor tipifarnib (R115777, Zarnestra) combined with etoposide

The farnesyltransferase inhibitor tipifarnib exhibits modest activity against acute myelogenous leukemia. To build on these results, we examined the effect of combining tipifarnib with other agents. Tipifarnib inhibited signaling downstream of the farnesylated small G protein Rheb and synergistically enhanced etoposide-induced antiproliferative effects in lymphohematopoietic cell lines and acute myelogenous leukemia isolates. We subsequently conducted a phase 1 trial of tipifarnib plus etoposide in adults over 70 years of age who were not candidates for conventional therapy. A total of 84 patients (median age, 77 years) received 224 cycles of oral tipifarnib (300-600 mg twice daily for 14 or 21 days) plus oral etoposide (100-200 mg daily on days 1-3 and 8-10). Dose-limiting toxicities occurred with 21-day tipifarnib. Complete remissions were achieved in 16 of 54 (30%) receiving 14-day tipifarnib versus 5 of 30 (17%) receiving 21-day tipifarnib. Complete remissions occurred in 50% of two 14-day tipifarnib cohorts: 3A (tipifarnib 600, etoposide 100) and 8A (tipifarnib 400, etoposide 200). In vivo, tipifarnib plus etoposide decreased ribosomal S6 protein phosphorylation and increased histone H2AX phosphorylation and apoptosis. Tipifarnib plus etoposide is a promising orally bioavailable regimen that warrants further evaluation in elderly adults who are not candidates for conventional induction chemotherapy. These clinical studies are registered at www.clinicaltrials.gov as #NCT00112853.

Intensive chemotherapy is not recommended for patients aged >60 years who have myelodysplastic syndromes or acute myeloid leukemia with high-risk karyotypes

BACKGROUND

It is unclear whether intensive chemotherapy is beneficial to patients with high-risk myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) if they are aged >/=60 years.

METHODS

The authors studied 160 patients with a median age of 67 years who received intensive chemotherapy for MDS or AML with cytosine arabinoside and an anthracycline.

RESULTS

At diagnosis, cytogenetic analysis was available in 146 patients. Karyotype was normal in 78 patients and abnormal in 68 patients. Of the abnormal karyotypes, 32 belonged to the high-risk category, ie, they involved either >/=3 chromosomes or chromosome 7. Complete remission (CR) was achieved by 94 patients (56%). CR rates were 70% among the patients who had a normal karyotype, 69% among the patients who had an abnormal (noncomplex) karyotype, but only 46% among the patients ho had a high-risk karyotype. The median survival was 9.5 months in the entire group, 18 months in patients with normal karyotype, 6 months in patients with abnormal, and 4 months in patients with a high-risk karyotype. A poor prognosis was attributable to low rates of CR and a high risk of early recurrence.

CONCLUSIONS

According to the current data, elderly patients with AML or advanced MDS do not benefit from intensive chemotherapy if they show karyotype anomalies, especially those in the high-risk category.