A phase II study of timed sequential therapy of acute myelogenous leukemia (AML) for patients over the age of 60: two cycle timed sequential therapy with topotecan, ara-C and mitoxantrone in adults with poor-risk AML

A Phase 1 Study of the PARP Inhibitor Veliparib in Combination with Temozolomide in Acute Myeloid Leukemia

PURPOSE

In preclinical studies, the PARP inhibitor veliparib enhanced the antileukemic action of temozolomide through potentiation of DNA damage. Accordingly, we conducted a phase 1 study of temozolomide with escalating doses of veliparib in patients with relapsed, refractory acute myeloid leukemia (AML) or AML arising from aggressive myeloid malignancies.

EXPERIMENTAL DESIGN

Patients received veliparib [20-200 mg once a day on day 1 and twice daily on days 4-12 in cycle 1 (days 1-8 in cycle ≥2)] and temozolomide [150-200 mg/m2 daily on days 3-9 in cycle 1 (days 1-5 in cycle ≥2)] every 28 to 56 days. Veliparib pharmacokinetics and pharmacodynamics [ability to inhibit poly(ADP-ribose) polymer (PAR) formation and induce H2AX phosphorylation] were assessed. Pretreatment levels of MGMT and PARP1 protein, methylation of the MGMT promoter, and integrity of the Fanconi anemia pathway were also examined.

RESULTS

Forty-eight patients were treated at seven dose levels. Dose-limiting toxicities were oral mucositis and esophagitis lasting >7 days. The MTD was veliparib 150 mg twice daily with temozolomide 200 mg/m2 daily. The complete response (CR) rate was 17% (8/48 patients). Veliparib exposure as well as inhibition of PAR polymer formation increased dose proportionately. A veliparib-induced increase in H2AX phosphorylation in CD34+ cells was observed in responders. Three of 4 patients with MGMT promoter methylation achieved CR.

CONCLUSIONS

Veliparib plus temozolomide is well tolerated, with activity in advanced AML. Further evaluation of this regimen and of treatment-induced phosphorylation of H2AX and MGMT methylation as potential response predictors appears warranted. Clin Cancer Res; 23(3); 697-706. ©2016 AACR.

All-trans retinoic acid synergizes with topotecan to suppress AML cells via promoting RARα-mediated DNA damage

Background

Chemotherapy is the only therapy option for the majority of AML patients, however, there are several limitations for this treatment. Our aim was to find a new chemotherapy strategy that is more effective and less toxic.

Methods

MTT assays and a xenograft mouse model were employed to evaluate the synergistic activity of all-trans retinoic acid (ATRA) combined with topotecan (TPT). Drug-induced DNA damage and apoptosis were determined by flow cytometry analysis with PI and DAPI staining, the comet assay and Western blots. Short hairpin RNA (shRNA) and a RARα plasmid were used to determine whether RARα expression influenced DNA damage and apoptosis.

Results

We found that ATRA exhibited synergistic activity in combination with Topotecan in AML cells, and the enhanced apoptosis induced by Topotecan plus ATRA resulted from caspase pathway activation. Mechanistically, ATRA dramatically down regulated RARα protein levels and led to more DNA damage and ultimately resulted in the synergism of these two agents. In addition, the increased antitumor efficacy of Topotecan combined with ATRA was further validated in the HL60 xenograft mouse model.

Conclusions

Our data demonstrated, for the first time, that the combination of TPT and ATRA showed potential benefits in AML, providing a novel insight into clinical treatment strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-2010-6) contains supplementary material, which is available to authorized users.

Timed-sequential chemotherapy as induction and/or consolidation regimen for younger adults with acute myelogenous leukemia

Increasing the intensity of induction chemotherapy has generated considerable recent interest in the treatment of acute myeloid leukemia. Achieving complete remission is a sine qua non condition for prolonged disease-free survival and may affect long-term outcome. In this setting, administering a repeat course of induction shortly after completion of the first course, known as timed-sequential chemotherapy (TSC), has been tested and may lead to an improved long-term outcome. Whether these results are due to the biologic recruitment of cell cycle-specific agents is unknown. However, this strategy to intensify induction may lead to more profound myelosuppression and to potential toxicities. Here we review the results of timed-sequential chemotherapy, used as induction regimen in de novo, relapsed or refractory AML or used as post-remission therapy, and compare them with those from other types of regimens.

Unique dual targeting of thymidylate synthase and topoisomerase1 by FdUMP[10] results in high efficacy against AML and low toxicity

Acute myeloid leukemia (AML) is an aggressive malignancy that leads to marrow failure and death. There is a desperate need for new therapies. The novel fluoropyrimidine, FdUMP[10], was highly active against both human AML cell lines, (IC(50) values, 3.4nM-21.5nM) and murine lines (IC(50) values, 123.8pM-131.4pM). In all cases, the IC(50) of FdUMP[10] was lower than for cytarabine and ∼ 1000 times lower than 5-fluorouracil (5-FU). FdUMP[10] remained effective against cells expressing the Flt3 internal tandem duplication, BCR-ABL, MN1, and an shRNA against p53. It had activity against patient samples at concentrations that did not affect normal hematopoietic cells. FdUMP[10] inhibited thymidylate synthase (TS) and trapped topoisomerase I cleavage complexes (Top1CCs), leading to DNA damage and apoptosis. All cell lines and nearly all primary AML samples examined expressed both TS and Top1. In vivo, FdUMP[10] was active against a syngeneic AML model with a survival advantage equivalent to doxorubicin plus cytarabine. 5-FU treatment was toxic and did not improve survival. FdUMP[10] was better tolerated than 5-FU or cytarabine plus doxorubicin and did not affect normal HSCs, while 5-FU dramatically impaired their ability to engraft. In summary, FdUMP[10] was highly efficacious and better tolerated than standard therapies.

Acute myeloid leukaemia: optimal management and recent developments

The current treatment of patients with acute myeloid leukaemia yields poor results, with expected cure rates in the order of 30-40% depending on the biological characteristics of the leukaemic clone. Therefore, new agents and schemas are intensively studied in order to improve patients' outcomes. This review summarizes some of these new paradigms, including new questions such as which anthracycline is most effective and at what dose. High doses of daunorubicin have shown better responses in young patients and are well tolerated in elderly patients. Monoclonal antibodies are promising agents in good risk patients. Drugs blocking signalling pathways could be used in combination with chemotherapy or in maintenance with promising results. Epigenetic therapies, particularly after stem cell transplantation, are also discussed. New drugs such as clofarabine and flavopiridol are reviewed and the results of their use discussed. It is clear that many new approaches are under study and hopefully will be able to improve on the outcomes of the commonly used '7+3' regimen of an anthracycline plus cytarabine with daunorubicin, which is clearly an ineffective therapy in the majority of patients.

The role of timed sequential chemotherapy in adult acute myelogenous leukemia

Consecutive trials of timed sequential chemotherapy (TSC) have been conducted in adults with acute myelogenous leukemia. The rationale for TSC was based on the observation that leukemic cells can be recruited synchronously into the cell cycle after initial intensive therapy, at which time they may become more susceptible to killing by chemotherapeutic agents. Achieving complete remission is essential for prolonged disease-free survival and may affect long-term outcome. TSC has led to higher rates of complete remission and has improved long-term outcomes. This article reviews the results of important trials in which TSC was used as an induction regimen in de novo, relapsed, or refractory acute myelogenous leukemia or as postremission therapy.

Development of farnesyltransferase inhibitors for clinical cancer therapy: focus on hematologic malignancies

Farnesyltransferase inhibitors (FTIs) target and inhibit the peptide prenylating enzyme farnesyltransferase. This new class of signal transduction inhibitors is being tested clinically in diverse malignancies, with encouraging results in hematololgic malignancies and breast cancer in particuarl. Critical questions have yet to be answered, for example, optimal dose and schedule, disease subgroups most likely to respond, and appropriate combinations with standard cytotoxics and new biologics. Gene profiling studies of malignant target cells obtained during FTI clinical trials will help to identify patients who are likely to respond to FTIs and to develop mechanisms for overcoming FTI resistance. Clinical trials and correlative laboratory studies in progress and under development will define the optimal roles of FTIs in cancer patients.

Therapeutic efficacy of NSC606985, a novel camptothecin analog, in a mouse model of acute promyelocytic leukemia

Nanomolar concentrations of NSC606985, a novel camptothecin (CPT) analog, effectively induces apoptosis in vitro in acute myeloid leukemic (AML) cells. Here we investigated the potential therapeutic effects of NSC606985 on the mice model with acute promyelocytic leukaemia (APL), a unique subtype of AML. The results showed that NSC606985 at single dose rapidly eliminated the infiltration with apoptosis induction of leukemic cells in peripheral blood and tissues. Treatment of NSC606985 with two regimens, continuous monotherapy and intermittent long-term therapy, significantly prolonged the survival of leukemic mice with tumor regression. These results propose that NSC606985 warrants further preclinical and clinical investigations for AML treatment.

Flexible low-intensity combination chemotherapy for elderly patients with acute myeloid leukaemia: a multicentre, phase II study

OBJECTIVE

To evaluate the efficacy of a flexible low-intensity combination chemotherapy (FLICC) protocol in a multicentre, phase II study of elderly patients with acute myeloid leukaemia (AML).

METHOD

Twenty-five patients aged 61-78 years (median 70 years) with de novo (n = 17) or secondary (n = 8) AML (cytogenetic risk: favourable 2, intermediate 18, adverse 2, unknown 3) from eight Australian centres were enrolled. Treatment comprised mitoxantrone 6 mg/m(2) intravenously daily for 3 days, cytarabine 10mg/m(2) subcutaneously every 12 hours for 7-14 days and etoposide 100mg orally for 7-14 days.

RESULTS

The treatment was generally well tolerated, and 13 patients (52%) achieved a complete remission (CR). One patient achieved a partial remission but died on day 28 due to pneumonia. Five patients (20%) had no response, whilst six (24%) died on or before day 30 and so were not evaluable. The median overall survival (OS) was 6.5 months, and the median remission duration was 7.7 months. Estimated 1-year survival was 32%, but patients achieving CR had an estimated 1-year survival of 64%, whereas none in the non-CR group survived to 1 year. Two of the CR patients have survived beyond 2 years. OS was significantly shorter in the adverse cytogenetic risk group of patients compared with the favourable- and intermediate-risk groups, with the rates of death relative to the adverse group being 0.02 and 0.08 in the favourable- and intermediate-risk groups, respectively. There was no significant association between CR rate and pre-existing myelodysplasia or the presence of multilineage dysplasia. The median durations of significant neutropenia (<0.5 x 10(9)/L) and thrombocytopenia (<20 x10(9)/L) with the first course of treatment in the 19 evaluable patients were 19 days (range 12-26) and 11 days (range 1-25), respectively. The median duration of stay in the hospital was 27 days (range 14-42). These values were much shorter for the second course of treatment: 6 days, 5 days and 15 days, respectively.

CONCLUSION

The findings of this multicentre, phase II study validate the previously reported single-institution experience with the FLICC protocol in elderly patients with AML. The clinical outcome with this protocol is comparable to those reported with more aggressive anti-leukaemia protocols.

Development of the farnesyltransferase inhibitor tipifarnib for therapy of hematologic malignancies

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 doing so, interdict multiple pathways involved in proliferation and survival of diverse malignant cell types. Tipifarnib is an orally bioavailable, nonpeptidomimetic methylquinolone FTI that is being tested clinically in diverse hematologic malignancies, in particular myeloid malignancies and myeloma. FTI therapy is accompanied by a relatively low toxicity profile, thereby providing an important alternative to traditional cytotoxic approaches for elderly patients who are not likely to tolerate or even benefit from aggressive chemotherapy. Current laboratory and clinical studies continue to define the determinants of FTI antitumor activity and resistance. The full development of FTIs for the therapy of hematologic malignancies will require the design and testing of rational combinations of cytotoxic, biologic and immunomodulatory agents in the laboratory and the clinic.

Nanomolar concentration of NSC606985, a camptothecin analog, induces leukemic-cell apoptosis through protein kinase Cδ–dependent mechanisms

As a promising new class of anticancer drugs, camptothecins have advanced to the forefront of several areas of therapeutic and developmental chemotherapy. In the present study, we report that NSC606985, a rarely studied camptothecin analog, induces apoptosis in acute myeloid leukemia (AML) cells NB4 and U937 and inhibits the proliferation without cell death in breakpoint cluster region–Abelson murine leukemia (bcr-abl) kinase-carrying leukemic K562 cells. For apoptosis induction or growth arrest, nanomolar concentrations of NSC606985 are sufficient. At such low concentrations, this agent also significantly inhibits the clonogenic activity of hematopoietic progenitors from patients with AML. For apoptosis induction, NSC606985 rapidly induces the proteolytic activation of protein kinase Cδ (PKCδ) with loss of mitochondrial transmembrane potential (ΔΨm) and caspase-3 activation. Cotreatment with rottlerin, a PKCδ-specific inhibitor, completely blocks NSC606985-induced mitochondrial ΔΨm loss and caspase-3 activation, while the inhibition of caspase-3 by z-DEVD-fluoromethyl ketone (Z-DEVD-fmk) only partially attenuates PKCδ activation and apoptosis. These data indicate that NSC606985-induced PKCδ activation is an early event upstream to mitochondrial ΔΨm loss and caspase-3 activation, while activated caspase-3 has an amplifying effect on PKCδ proteolysis. In addition, NSC606985-induced apoptosis by PKCδ also involves caspase-3–independent mechanisms. Taken together, our results suggest that NSC606985 is a potential agent for the treatment of AML.