Efficacy of common salvage chemotherapy regimens in patients with refractory or relapsed acute myeloid leukemia: A retrospective cohort study

To assess treatment response and overall survival (OS) in refractory or relapsed acute myeloid leukemia (R/R AML) patients treated by different common salvage chemotherapy regimens.Medical records data from 142 R/R AML patients were reviewed in this retrospective study. Patients were treated with regimens based on the following drugs: cytarabine, granulocyte colony-stimulating factor (G-CSF), and fludarabine (FLAG) (n = 46); cytarabine and G-CSF in addition to aclarubicin or daunorubicin (CAG/DAG) (n = 30); cytarabine, G-CSF, and cladribine (CLAG) (n = 27); cytarabine, etoposide, and mitoxantrone (MEA) (n = 17); cytarabine plus idarubicin, daunorubicin, or mitoxantrone (IA/DA/MA) (n = 12); and homoharringtonine, cytarabine, and aclarubicin or daunorubicin (HAA/HAD) (n = 10).A total of 43 (35.2%) patients achieved complete remission (CR), 60 (49.2%) patients achieved overall remission rate (ORR), and 18 (14.8%) patients received allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CR. Median OS was 8.0 (95% CI 6.6-9.4) months with a 1-year OS rate of (29.9 ± 3.9)% and 3-year OS rate of (11.1 ± 3.6)%. No difference of CR (P = .621), ORR (P = .385), and allo-HSCT (P = .537) achievement was observed among different chemotherapy regimens. Interestingly, we observed that the CLAG-based regimen did not affect CR (P = .165), while it achieved a numerically higher ORR (P = .093) and was an independent factor for prolonged OS (P = .016). No other regimens were determined to be correlated with CR, ORR, or OS.FLAG-, CAG/DAG-, CLAG-, MEA-, IA/DA/MA- and HAA/HAD-based regimens were found to achieve similar CR rates, while the CLAG-based regimen achieved numerically higher ORR rates and significant favorable OS. Therefore, CLAG-based regimens should be a prioritized treatment option for R/R AML patients.

HAG (Homoharringtonine, Cytarabine, G-CSF) Regimen for the Treatment of Acute Myeloid Leukemia and Myelodysplastic Syndrome: A Meta-Analysis with 2,314 Participants

BACKGROUND

In China, the combination of homoharringtonine, cytarabine, and G-CSF (HAG) has been extensively applied for treatment of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS).

METHODS

We performed a meta-analysis of 2,314 patients (AML, n = 1754; MDS, n = 560) to determine the overall safety and efficacy of this regimen.

RESULTS

The complete response (CR) rate of AML patients (53%) was significantly higher than that of MDS/transformed-AML patients (45%; P = 0.007). The CR rate of patients with newly diagnosed AML (62%) was significantly higher than in patients with relapsed/refractory AML (50%; P = 0.001). There were no significant difference in CR rates between elderly AML patients (54%) and all AML patients (P = 0.721). When compared with non-HAG regimens for AML/MDS induction therapy, the CR rate of patients treated with HAG was significantly higher than in treated with intensive chemotherapy (P = 0.000). No significant differences in CR rates were observed between patients treated with HAG and those treated with CAG (cytarabine, aclarubicin, G-CSF) regimens (P = 0.073). HAG regimen was well tolerated, with early death (ED) in 2%, grade IV myelosurrpression in 52% and infection in 50%. Reports of ED and rates of myelosuppression were reduced as compared with intensive chemotherapy (P = 0.000 and P = 0.000, respectively).

CONCLUSION

The HAG regimen is an effective and safe regimen for the treatment of AML and MDS, and appears to be more effective and better tolerated than intensive chemotherapy. Future randomized controlled trials and further meta-analyses are strongly needed to confirm its efficacy and safety, especially in comparison with intensive chemotherapy.

Homoharringtonine (omacetaxine mepesuccinate) as an adjunct for FLT3-ITD acute myeloid leukemia

An in vitro drug-screening platform on patient samples was developed and validated to design personalized treatment for relapsed/refractory acute myeloid leukemia (AML). Unbiased clustering and correlation showed that homoharringtonine (HHT), also known as omacetaxine mepesuccinate, exhibited preferential antileukemia effect against AML carrying internal tandem duplication of fms-like tyrosine kinase 3 (FLT3-ITD). It worked synergistically with FLT3 inhibitors to suppress leukemia growth in vitro and in xenograft mouse models. Mechanistically, the effect was mediated by protein synthesis inhibition and reduction of short-lived proteins, including total and phosphorylated forms of FLT3 and its downstream signaling proteins. A phase 2 clinical trial of sorafenib and HHT combination treatment in FLT3-ITD AML patients resulted in complete remission (true or with insufficient hematological recovery) in 20 of 24 patients (83.3%), reduction of ITD allelic burden, and median leukemia-free and overall survivals of 12 and 33 weeks. The regimen has successfully bridged five patients to allogeneic hematopoietic stem cell transplantation and was well tolerated in patients unfit for conventional chemotherapy, including elderly and heavily pretreated patients. This study validated the principle and clinical relevance of in vitro drug testing and identified an improved treatment for FLT3-ITD AML. The results provided the foundation for phase 2/3 clinical trials to ascertain the clinical efficacy of FLT3 inhibitors and HHT in combination.

[Homoharringtonine in newly diagnosed acute promyelocytic leukemia treatment: a prospective, randomized controlled trial]

OBJECTIVE

To compare the efficacy and toxicities of combining homoharringtonine (HHT)±daunorubicin (DNR) with all-trans-retinoic acid (ATRA) based therapy and DNR plus ATRA based therapy in newly diagnosed low/intermediate risk acute promyelocytic leukemia (APL).

METHODS

A total of 96 newly diagnosed patients with APL were randomized to HHT group, DNR group and HHT+ DNR group prospectively. The complete remission (CR) rate, the overall survival (OS) and event-free survival (EFS) of three groups were analyzed.

RESULTS

There were 31 patients in HHT group, 33 patients in DNR group and 32 patients in HHT+ DNR group. The baseline characteristics of three groups were similar. No patient died during induction therapy. The morphologic CR rate was 100.0%. The median time to peak WBC counts in HHT+DNR group (4 days, range: 1-23 days) was significantly shorter than that in HHT group (9 days, range: 1-27 days) (P=0.008) and DNR group (7 days, range: 1-27 days) (P=0.240). There was no difference among three groups about the incidence of differentiation syndrome, the median interval to achieve CR, peak WBC counts and transfusions (P >0.05). All patients achieved complete molecular remission (CMR) during consolidation therapy. The interval to achieve CMR was no significantly difference among three groups (P >0.05). The 3-year OS rates for HHT group, DNR group and HHT+DNR group were 95.0%, 100.0% and 91.0%, respectively (P=0.595). The 3-year EFS rates for three groups were 93.0%, 90.0% and 85.0% (P=0.382). No difference was found in the incidence of adverse events among three groups (P >0.05).

CONCLUSIONS

Similar to DNR plus ATRA based therapy, HHT plus ATRA based induction and consolidation therapy should be one of highly-efficient treatment options for newly diagnosed APL. Clinical trial registration Chinese Clinical Trial Registry, ChiCTR-TRC-12002628.

Homoharringtonine induces apoptosis and inhibits STAT3 via IL-6/JAK1/STAT3 signal pathway in Gefitinib-resistant lung cancer cells

Tyrosine kinase inhibitors (TKIs) are mostly used in non-small cell lung cancer (NSCLC) treatment. Unfortunately, treatment with Gefitinib for a period of time will result in drug resistance and cause treatment failure in clinic. Therefore, exploring novel compounds to overcome this resistance is urgently required. Here we investigated the antitumor effect of homoharringtonine (HHT), a natural compound extracted from Cephalotaxus harringtonia, on Gefitinib-resistant NSCLC cell lines in vitro and in vivo. NCI-H1975 cells with EGFR T790M mutation are more sensitive to HHT treatment compared with that of A549 cells with wild type EGFR. HHT inhibited cells growth, cell viability and colony formation, as well as induced cell apoptosis through mitochondria pathway. Furthermore, we explored the mechanism of HHT inhibition on NSCLC cells. Higher level of interleukin-6 (IL-6) existed in lung cancer patients and mutant EGFR and TGFβ signal requires the upregulation of IL-6 through the gp130/JAK pathway to overactive STAT3, an oncogenic protein which has been considered as a potential target for cancer therapy. HHT reversiblely inhibited IL-6-induced STAT3 Tyrosine 705 phosphorylation and reduced anti-apoptotic proteins expression. Gefitinib-resistant NSCLC xenograft tests also confirmed the antitumor effect of HHT in vivo. Consequently, HHT has the potential in Gefitinib-resistant NSCLC treatment.

Effects of changes in serum endostatin and fibroblast growth factor 19 on the chemotherapeutic sensitivity in acute myeloid leukemia patients

The present study aimed to explore the changes in serum endostatin and fibroblast growth factor 19 (FGF-19) in acute myeloid leukemia patients, and to determine their effects on chemotherapeutic sensitivity. Sixty acute myeloid leukemia patients and 30 healthy controls were included in the study. Patient serum endostatin and FGF-19 levels were measured on admission, and then, standard chemotherapy was administered. The patients were divided into 2 groups according to chemotherapeutic effects: 21 patients in the chemotherapeutic sensitivity group (complete remission + partial remission) and 39 in the chemotherapeutic resistance group (no remission + degradation). A receiver operating characteristic (ROC) curve was used to analyze the relationship of serum endostatin and FGF-19 levels with chemotherapeutic sensitivity in acute myeloid leukemia patients. The levels of serum endostatin and FGF-19 in acute myeloid leukemia patients before chemotherapy were significantly higher than those in the control group. Moreover, these levels significantly decreased after chemotherapy (P < 0.01). The levels of serum endostatin and FGF-19 in the chemotherapeutic sensitivity group were lower than those in the chemotherapeutic resistance group, both before and after chemotherapy (P < 0.05 and P < 0.01, respectively). ROC curve analysis showed that the predictive values of endostatin and FGF-19 were good, and there was no significant difference between these results. In conclusion, serum endostatin and FGF-19 can be used as predictors of chemotherapeutic sensitivity for acute myeloid leukemia patients, and may be important for determining prognosis.

U.S. Food and Drug Administration approval summary: omacetaxine mepesuccinate as treatment for chronic myeloid leukemia

On October 26, 2012, the U.S. Food and Drug Administration (FDA) granted accelerated approval to omacetaxine mepesuccinate (Synribo; Teva Pharmaceuticals USA, Inc., North Wales, PA, http://www.tevausa.com) for the treatment of adult patients with chronic phase (CP) or accelerated phase (AP) chronic myeloid leukemia (CML) with resistance and/or intolerance to two or more tyrosine kinase inhibitors (TKIs). The approval was based on the FDA review of data from 111 patients with CML in CP or in AP who had received two or more prior TKIs, including imatinib. Major cytogenetic response was achieved in 18% of patients with CP, with a median response duration of 12.5 months. Major hematologic response was achieved in 14% of patients with AP, with a median response duration of 4.7 months. The FDA safety evaluation was based on submitted data from 163 patients with CP or AP CML who had received at least one dose of omacetaxine mepesuccinate. The safety evaluation was limited by the single-arm design of the clinical trials as conducted in a small number of previously treated patients. The most common (≥20%) adverse reactions of any grade in enrolled patients included thrombocytopenia, anemia, neutropenia, diarrhea, nausea, fatigue, asthenia, injection site reaction, pyrexia, and infection. The FDA concluded that omacetaxine mepesuccinate has shown activity and a favorable benefit-to-risk profile for the studied population of adult patients with CML (CP or AP) with resistance and/or intolerance to two or more TKIs. Further evidence of response durability to verify clinical benefit is pending.

Homoharringtonine/omacetaxine mepesuccinate: the long and winding road to food and drug administration approval

Homoharringtonine/omacetaxine is a unique agent with a long history of research development. It has been recently approved by the Food and Drug Administration for the treatment of chronic myeloid leukemia after failure of 2 or more tyrosine kinase inhibitors. Research with this agent has spanned over 40 years, with many instructive lessons to cancer research, which are summarized in this review.

[Clinical investigation of homoharringtonine in combination with all-transretinoic acid and arsenic trioxide for acute promyelocytic leukemia]

OBJECTIVE

To study the clinical outcome, adverse effect and treatment cost of homoharringtonine (HHT) in combination with all-trans retinoic acid (ATRA) and arsenic trioxide (AS2O3) for newly diagnosed with patients acute promyelocytic leukemia (APL).

METHODS

Clinical data of treatment of newly diagnosed patients with APL in experimental group (HHT + ATRA + AS2O3, n = 14) and control group \[Idarubicin (IDA) + ATRA + AS2O3, n = 21\] were analyzed retrospectively. The therapeutic effects, side effects and costs during induction therapy were compared between the two groups.

RESULTS

(1) The complete remission (CR) rate were 92.9% (13/14) and 95.2% (20/21) in experimental group and control group, respectively. The time to achieve CR were (28.1 ± 3.8) and (31.7 ± 4.2) days, respectively (P > 0.05). The negative rate of PML-RARα fusion gene at the time of CR were 76.9% (10/13) and 75.0% (15/20), respectively, and that in CR patient at the end of the first cycle treatment were 100.0% (13/13) and 95.0% (19/20), respectively (P > 0.05). (2) 5-year overall survival (OS) rate were (92.6 ± 0.6)% and (89.9 ± 0.5)%, respectively (P > 0.05), 5-year disease free survival (DFS) rate were 100.0% and (86.8 ± 0.6)%, respectively (P > 0.05). (3) During induction therapy, the incidence of infection in experimental and control group were 23.1% (3/13), 60.0% (12/20), respectively (P < 0.05). The amount of platelet transfusion were (54.7 ± 29.6) and (76.5 ± 25.6) units, respectively (P > 0.05), and that of fresh frozen plasma were (1157.1 ± 238.4) and (1423.5 ± 324.6) ml, respectively (P > 0.05). The total medical costs (excluding HHT and IDA) in experimental and control group were (36074.9 ± 1245.6) and (50564.5 ± 3658.4)CNY, respectively (P < 0.05).

CONCLUSION

HHT in combination with ATRA and AS2O3 regimen for newly diagnosed APL has a better efficacy, a higher long-term survival rate, and a lower costs, which is one of the reasonable choice.

[Clinical study on combination of homoharringtonine, Ara-C and idarubicin induction for treatment of newly diagnosed acute myeloid leukemia patients]

The purpose of this study was to assess the efficacy and toxicity of HAI regimen [(homoharringtonine 2.5 mg/(m(2)×d), days 1 - 7; cytarabine 150 mg/(m(2)×d), days 1 - 7; idarubicin 9 mg/(m(2)×d), days 1 - 7)] for induction treatment of newly diagnosed acute myeloid leukemia (AML) (except acute promyelocytic leukemia). 31 patients with newly diagnosed AML, aged 39 (14 - 58) years, were enrolled in this clinical study. The complete remission (CR) rate, especially after one course, the overall survival (OS) rate and relapse free survival (RFS) rate were estimated. The outcomes were compared between different prognostic groups according to World Health Organization (WHO) classification, genetics and initial WBC count. Safety was evaluated using standard WHO criteria. The results showed that 26 patients (84%) achieved CR after 1 course of induction. The CR rate for the patients with favorable, intermediate and unfavorable cytogenetics was 90%, 88% and 60% respectively. All 7 patients with a high initial WBC count (≥ 100×10(9)/L) obtained CR, while 19 out of 24 without a high initial WBC count obtained CR. With a median follow-up of 15(range 2-56) months, the estimated 3-year OS rate for all patients and the patients with CR was 44% and 52% respectively. The 3-year RFS rate was 51%. The patients receiving induction chemotherapy died of the chemotherapy. Profound myelosuppression was seen in all patients after the HAI induction with the median duration of neutropenia (ANC < 0.2×10(9)/L) of 16 (6 - 24) days. As the most common toxicity, severe infections (grade III-IV) involved in all the patients and the duration of febris was 6 (1 - 36) days. The incidence of septemia and invasive fungus infection were 19.4% and 45.2% respectively. The incidence of non-infection fever, increased glutamic-pyruvic transaminase (GPT), diarrhea, increased bilirubin and oral cavity mucositis were 6.5%, 6.5%, 3.2%, 3.2%, 3.2% respectively, as the more frequent severe non-hematological toxicities. It is concluded that HAI regimen is a high efficient induction schedule for the newly diagnosed AML, and archive the higher CR rate after one course than DNR/Ara-C standard induction regimen. Side effects are acceptable, except severe infection.

Intensive induction chemotherapy with regimen containing intermediate dose cytarabine in the treatment of de novo acute myeloid leukemia

To improve long-term outcome of de novo acute myeloid leukemia (AML) patients by intermediate dose of cytarabine integrated in induction therapy and to explore the impact of cytogenetic abnormalities on the prognosis. Eighty-seven AML patients were treated with HAD regimen containing intermediate dose cytarabine (IDAra-C) as induction therapy, 83 from which with karyotype results were divided into three cytogenetic groups according to SWOG criteria. Complete remission (CR) rate, disease-free survival (DFS), and overall survival (OS) among different groups were evaluated. The CR rate of the 87 cases was 80/87 (92%). Median DFS and OS have not reached (NR). DFS rates at 1 and 3 years were 76.3% and 63.4%, respectively. OS rates at 1 and 3 years were 86.0% and 58.7%, respectively. According to SWOG criteria, CR rate, median DFS, and OS were 100%, NR and NR for the favorable group; 88.9%, NR, and 16 months for the intermediate group; 83.3%, 4.5 months, and 7.5 months for the adverse group. The differences among the three groups were statistically significant excepting for CR rate between adverse and intermediate groups. HAD regimen containing IDAra-C as induction chemotherapy regimen is effective in de novo AML of adult patients and can achieve higher CR rate and longer survival than standard dose of cytarabine (SDAra-C) regimen. Most of the patients were able to endure the therapy. Cytogenetics is still an important prognostic factor despite of the incorporation of IDAra-C in induction chemotherapy. The differences among the three groups were statistically significant. Am. J. Hematol., 2009. (c) 2009 Wiley-Liss, Inc.

Prolonged chronic phase in chronic myelogenous leukemia after homoharringtonine therapy

BACKGROUND

Homoharringtonine (HHT) is effective in treating late stage chronic myelogenous leukaemia (CML), but little is known about long term maintenance during complete cytogenetic response. Long term efficacy and toxicity profiles of low dose HHT were evaluated in this study.

METHODS

One hundred and six patients with CML received 1.5 mg/m(2) of HHT alone by continuous daily infusion for seven to nine days every four weeks. Of 79 patients in the control group, 31 were treated with interferon alpha (IFN-alpha) and 48 with hydroxycarbamide. For 17 patients who failed to achieve cytogenetic response within 12 months' treatment of IFN-alpha, HHT was administered. Quantitative RT-PCR was used to detect the BCR-ABL mRNA expression in 36 Philadelphia positive CML patients enrolled after 2007. Haematological and cytogenetic responses were evaluated in all patients at the 12th month of follow-up. Long term efficacy was assessed in a follow-up with a median time of 54 months (12 months-98 months).

RESULTS

After 12 months of therapy, cytogenetic response rate of the HHT, IFN-alpha and hydroxycarbamide groups were 39/106, 14/31 and 3/48, and corresponding molecular cytogenetic response rates 6/18, 3/8 and 0. Of the 17 patients who received HHT as salvage treatment, 6 achieved cytogenetic response (3 major). At the 48 months' follow-up, cytogenetic response was maintained in 32/39 patients treated with HHT. Patients who had cytogenetic response in HHT group or treated with IFN-alpha also showed longer median chronic durations, which were 45 months (12 months-98 months) and 49 months (12 months-92 months) respectively, indicating a longer survival time.

CONCLUSIONS

Low dose HHT alone showed considerable short term and long term efficacy in the treatment of late stage CML. It may also be a good choice for patients who have failed imatinib, IFN-alpha treatment or haematopoietic stem cell transplantation or cannot afford these treatments.

[Efficacy of induction chemotherapy for patients with high-risk myelodysplastic syndrome (MDS) or MDS-transformed acute myeloid leukemia with CHG regimen and its comparison with regimen GAG and HA]

This study was aimed to investigate the efficacy of moderate intensity regimen, CHG (homoharringtonine, cytarabine and granulocyte colony-stimulating factor (G-CSF)) on the patients with high-risk MDS or MDS-transformed acute myeloid leukemia. 30 newly diagnosed adult patients with high-risk MDS or MDS-transformed AML were enrolled in this clinical trial to evaluate the efficacy of sequential low-dose homoharringtonine/cytarabine chemotherapy combined with G-CSF priming. Homoharringtonine and Ara-C were injected intravenously at doses of 1 mg and 25 mg daily for 14 consecutive days respectively, G-CSF was injected subcutaneously once daily at a dose of 300 microg on 12 hours prior to chemotherapy and continued given until the end of chemotherapy or when the peripheral WBC count reached > 20 x 10(9)/L. This regimen was given only for one course, and followed by conventional chemotherapy as maintenance or consolidation therapy when CR achieved. 33 patients with high- risk MDS and MDS-transformed AML were injected aclarubicin/Ara-C intravenously at doses of 10 mg and 25 mg for 8 and 14 consecutive days respectively, G-CSF was used at the same dose and the same way as the CHG regimen. 33 patients with high-risk MDS and MDS-transformed AML were treated with HHT/Ara-C intravenously at doses of 2 - 3 mg and 100 - 150 mg daily for 7 consecutive days respectively, G-CSF was injected when WBC count was below 4 x 10(9)/L, and it was stopped to be used when WBC count was > 4 x 10(9)/L. The results showed that (1) 14 patients achieved complete remission (CR) (46.67 %) and 7 patients achieved partial remission (PR) (23.33 %) with one course of CHG regimen, total effective rate was 70%; 14 patient achieved CR (42.4%) and 9 patients achieved PR (27.3%) with one course of CAG regimen, total effective rate was 69.7%; 7 patient achieved CR (33.3%) and 3 patients achieved PR (9.1%) with one course of HA regimen, total effective rate was 42.4%. There was no statistical difference between the effective rate of CHG and CAG, but difference was significant between CHG and HA. (2) Agranulocytosis (neutrophil < 0.5 x 10(9)/L) occurred in 12 cases (40%) of CHG-treated patients with a mean 8 days of agranulocytic period, so the infectious complications were less serious and tolerable without treatment-related death. (3) Among 14 out of 30 patients with CR, 9 relapsed, the mean duration from CR to replace was 8.2 months. All relapsed patients reusing CHG regimen did not achieved CR again. (4) Among 13 cases with CR, 6 patients just received HA or DA regimens as consolidatory and intensive chemotherapy after CR have relapsed, the mean CR time was only 6.1 months. Otherwise, the mean CR time of 7 CR patients received alternative succeeded chemotherapy containing mitoxantrone/idarubicin/THP/homoharringtonine/daunorubicin/aclarubicin after CR was 10.6 months; and among them 4 are still in continuous CR. It is concluded that the CHG chemotherapy regimen has a similar effect with CAG but better than HA, and in a saft chemotherapy regimen with slight myelosuppression in clinical application, strong and alternative succeeded chemotherapy is necessary for CR patients to keep longer CR and survival.

[Efficiency of GHA priming chemotherapy on patients with refractory acute myeloid leukemia and myelodysplastic syndrome and its relationship with expression of costimulatory molecule B7.1]

This study was purposed to explore the clinical efficiency and side effects of GHA (G-CSF, homoharringtonine and low-dose cytarabine) priming chemotherapy for patients with refractory acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), and its relationship with B7.1 expression. 79 cases of refractory AML and 21 cases of MDS were treated with GHA standard priming chemotherapy. Clinical efficiency, side effects, and therapy-relevant mortality were observed in comparison with MA therapy. Expression of costimulatory molecule B7.1 was detected by immunofluorescence and its relationship with clinical efficiency was explored. The results showed that the remission rate in AML was 60.7% (complete remission rate was 43% and partial remission rate was 17.7%), and that was 52.4% in MDS. The incidence of granulocyte deficiency was 25% during 3.5 days. The severe infection rate was 3%, without severe bleeding, with mild digest effect, and slight damage of function in heart, liver, and kidney. The therapy-related mortality was zero. The higher CR rate was in AML-M(2) and AML-M(5) (60.9%, 61.9%), and the longest remission period was 4 years; expression rate of costimulatory molecule B7.1 displayed large variance (0% - 66.7%) and had positive correlation with efficiency of priming chemotherapy. The rate of B7.1 expression was higher in AML-M(2) and AML-M(5) and lower in other AML groups and normal control. It is concluded that GHA priming chemotherapy can be used to treat refractory AML and MDS, without severe side effects, toxicity and therapy-related mortality. It is a new chemotherapy protocol with better effect and low toxicity. Efficiency of GHA priming chemotherapy may be correlated with B7.1 expression. Its mechanism is worthy to be further explored.

Novel agents in CML therapy: tyrosine kinase inhibitors and beyond

The emergence of resistance to imatinib has become a significant problem despite the remarkable clinical results achieved with this tyrosine kinase inhibitor in the treatment of chronic myeloid leukaemia. The most common cause of imatinib resistance is the selection of leukemic clones with point mutations in the Abl kinase domain. These mutations lead to amino acid substitutions and prevent the appropriate binding of imatinib. Genomic amplification of BCR-ABL, modulation of drug efflux or influx transporters, and Bcr-Abl-independent mechanisms also play important roles in the development of resistance. Persistent disease is another therapeutic challenge and may in part, be due to the inability of imatinib to eradicate primitive stem cell progenitors. A multitude of novel agents have been developed and have shown in vitro and in vivo efficacy in overcoming imatinib resistance. In this review, we will discuss the current status of the ATP-competitive and non-ATP-competitive Bcr-Abl tyrosine kinase inhibitors. We will also describe inhibitors acting on targets found in signaling pathways downstream of Bcr-Abl, such as the Ras-Raf-mitogen-activated protein kinase and phosphatidylinositol-3 kinase-Akt-mammalian target of rapamycin pathways, and targets without established links with Bcr-Abl.

[Analysis on prognosis and correlative factors of acute nonlymphocytic leukemia]

To analyze the prognosis and risk factors of acute nonlymphocytic leukemia (ANLL), 94 patients with acute nonlymphocytic leukemia were enrolled in this study, while survival rate and risk factors of prognosis were analyzed. The results indicated that the complete remission (CR) ratio was 51.1%. Overall survival and event-free survival rates of month 6, 12, 18, 24 were 68.6%, 55.8%, 53.8%, 46.4%, 21.3% and 57.9%, 38.6%, 33.3%, 31.6%, 0% respectively. The factors such as age<40 years, WBC<10.0x10(9)/L before chemotherapy, WBC in the period of bone marrow suppression<1.0x10(9)/L, chemotherapy within 1 month after occurrence of leukemia, blood transfusion before chemotherapy of APL had favourable influence on remission and survival rates of ANLL patients. CR1, the time to get CR, length of CR and relapse significantly correlated with prognosis (p<0.05). It is concluded that the individualized therapy concerning the risk factors should be applied to ANLL patients for improving the remission, survival rate and prognosis.

Effect of cantharidin, cephalotaxine and homoharringtonine on "in vitro" models of hepatitis B virus (HBV) and bovine viral diarrhoea virus (BVDV) replication

The effect as antiviral agents versus viral hepatitis B and C of three compounds purified from natural products commonly used as remedies in traditional Chinese medicine, cantharidin, cephalotaxine and homoharingtonine, was investigated. To assess the activity of these compounds against flavivirus, we used bovine viral diarrhoea virus (BVDV) as a surrogate for hepatitis C virus (HCV). Anti-BVDV activity was determined by reduction in BVDV-RNA production and protection of infected embryonic bovine trachea (EBTr) cells against the cytopathic effect of BVDV. The effect versus hepatitis B virus (HBV) was investigated by measuring HBsAg and HBV-DNA release from hepatoblastoma HepG2 2.2.15 cells infected with HBV. As positive control we used the standard anti-HBV and anti-HCV drugs, lamivudine and ribavirin, respectively. Up to 100 microM lamivudine and ribavirin did not induce cell toxicity, whereas they induced dose-dependent anti-HBV and anti-BVDV effects, respectively. In the same range, cantharidin, cephalotaxine and homoharringtonine induced toxicity in EBTr cells and had no protective effect against BVDV. In contrast, they were able to inhibit HBV production at concentrations 10- to 100-fold lower than those inducing cell toxicity, which suggests that they are useless for the treatment of infection by flaviviruses, but potentially useful in combined therapy against hepatitis B.

Phase I/II study of subcutaneous homoharringtonine in patients with chronic myeloid leukemia who have failed prior therapy

BACKGROUND

Homoharringtonine (HHT) is a cephalotaxus alkaloid that inhibits the synthesis of proteins leading to apoptosis. Intravenous HHT has demonstrated activity in patients with chronic myeloid leukemia (CML) after failure with interferon.

METHODS

A Phase I study was completed of subcutaneous (s.c.) HHT in patients with CML in accelerated or blast phases and demonstrated efficacy and good tolerance at the same doses used by intravenous (i.v.) administration. The maximal tolerated dose (MTD) was 1.25 mg/m(2) s.c. twice daily. The cohort was then expanded to treated at the MTD to include patients in late chronic phase CML after imatinib failure. Therapy consisted of an i.v. loading dose of HHT 2.5 mg/m(2) over 24 hours, followed by 1.25 mg/m(2) s.c. twice daily for 14 days every 28 days until remission, then for 7 days every 28 days. Six patients (median age, 53 years) who had failed imatinib were treated and 5 were evaluable. Patients received a median of 4.5 courses of s.c. HHT.

RESULTS

Complete hematologic remission was obtained in all 5 evaluable patients and 3 had cytogenetic (CG) responses: 1 complete and 2 minor. The 2 patients with BCR-ABL kinase domain mutations at the start of therapy with HHT had a CG response and in both instances the mutations became undetectable. All patients developed myelosuppression and 3 had their HHT dose reduced due to prolonged neutropenia. Nonhematologic toxicity was mild and manageable.

CONCLUSIONS

Subcutaneous HHT is well tolerated and may have clinical activity in patients with CML after imatinib failure.

New Strategies in Chronic Myeloid Leukemia

Most patients with chronic myeloid leukemia (CML) achieve clinically relevant hematologic and cytogenetic responses to imatinib. Patients who show resistance to imatinib need new therapeutic options. A range of options are being developed to treat imatinib-resistant patients who have CML. Promising results of early-phase clinical trials have been reported for new tyrosine kinase inhibitors, farnesyl transferase inhibitors, decitabine, homoharringtonine, and vaccines. Further clinical trials are needed to characterize the efficacy and safety profile of these new agents and to determine which agents improve the long-term prognosis for patients with CML who have shown resistance to imatinib.

[The diagnosis and treatment of polycythemia rubra vera manifesting as acute cerebral stroke]

OBJECTIVE

To analyze the particularities of diagnosis and treatment of acute cerebral stroke secondary to polycythemia vera (PV).

METHODS

To track and evaluate the clinical parameters, the manifestations of CT/MRI, the data of laboratory examinations, the therapeutic responses and the prognosis of acute cerebral stroke secondary to PV. Twenty-two cases of PV with initial presentation as acute stroke were analyzed.

RESULTS

(1) 55.0% of the patients with stroke as the initial presentation of to PV had multiple lacuna infarction. (2) 37.5% of the patients had a temporary symptom aggravation after receiving a therapeutic regimen of blood-letting and chemotherapy, whereas, the stroke symptoms improved and became stable when treated with blood-letting combined with hemodilution and chemotherapy simultaneously. (3) Six cases received homoharringtonine treatment and all of them reached complete remission (CR). However, 3 of them showed ST segment and T-wave changes in electrocardiogram and 2 of them had bone marrow depression. Four cases received arsenic trioxide and obtained CR, but the relapse rate reached 50.0%. Nine cases were treated with hydroxycarbamide and all of them obtained CR.

CONCLUSIONS

(1) Stroke secondary to PV should be treated with stroke regimen as well as PV therapy, and hydroxycarbamide might have stable benefit and few side effects. (2) Hematocrit assay should be used as a routine item in stroke patients with frequently relapsed.

[Protection of mdr1 transfected cord blood mononuclear cell graft against anticancer agents in vivo]

OBJECTIVE

To explore the myelo-protection effect of mdr1 transfected cord blood cells (CBMNCs) graft against high-dose homoharringtonine leukemia-bearing severe combined immunodeficient (SCID) mice model.

METHODS

Multidrug resistant (mdr1)gene was transferred into CBMNCs by a retrovirus vector, containing full-length cDNA of human mdr1 gene. CBMNCs and high-titer retrovirus supernatant were cocultured with cytokine combinations for 5 - 6 days. The SCID mouse models bearing human HL-60 cell leukemia were divided into three groups. Group A received tail vein injection of 2 x 10(6) mdr1 gene transduced CBMNCs at day 1 and 3, groups B and C 2 x 10(6) un-transduced CBMNCs and same volume of normal saline, respectively. The 3 groups of the mouse model were treated with weekly escalated doses of homoharringtonine. The peripheral white blood cell (WBC) counts, the human leukemia cells percentage in peripheral blood, the histological findings of main organs were assayed. The CD33 positive HL-60 cells in bone marrow were determined by flow cytometry. The function and expression of mdr1 gene were examined by PCR, immunochemistry (IC) and DNR extrusion test in vivo.

RESULTS

(1) mdr1 gene was transferred into CBMNCs successfully and the transfection frequency was 30%. (2) Leukemia SCID mice were xenotransplanted with mdr1-transfected BMMNCs by a programmed procedure and could be used as a valuable model for in vivo evaluating myelo-protection effects. (3) The transfected mice could tolerate homoharringtonine 5 approximately 6 folds higher than conventional dose and kept peripheral WBC count at a mean of 3 x 10(9)/L, with the peripheral human myeloid leukemia cells percentage decreasing to less than 5%. Histological examination showed that there was no leukemia infiltration in the main organs, the CD33 positive HL-60 cells in bone marrow were less than 5%. (4) The repopulation frequency of the transfected CBMNs in marrow were 9.13%. DNR extrusion test confirmed that the P-gp product maintained its biological function in the marrow.

CONCLUSION

mdr1 transferred-human CBMNC can xenotransplanted and repopulated in leukemia-bearing SCID mouse and are protected from chemotherapy-induced myelosuppression.

Investigational strategies in chronic myelogenous leukemia

Imatinib is the cornerstone of therapy in chronic myelogenous leukemia (CML) and a model for the development of novel agents directed at specific targets. The results of imatinib therapy continue to improve with approaches such as higher doses of imatinib and, possibly, with combinations of imatinib and interferon-alpha with or without cytarabine. There are multiple targets with agents directed to them that may prove to be synergistic with imatinib. These approaches are attractive, particularly when dealing with imatinib resistant CML, to prevent resistance and improve the probability of cure. The continued understanding of the biology of CML and mechanisms of resistance to imatinib and the ability to develop target-specific therapies should lead to the increased probability of cure for most patients who have CML.

Combinatorial treatment of ovarian cancer cells with harringtonine and cisplatin results in increased cisplatin-DNA adducts

The current studies represent the first step in assessing the utility of harringtonine in combination with cisplatin as an improved approach for treating ovarian cancer. Three ovarian cancer cell lines, platinum-sensitive A2780, and platinum-resistant A2780/CP70 and OvCar-3, were exposed to their respective IC(50) dose of cisplatin for 1 h with or without a 24-h pretreatment with harringtonine. The level of platinum-DNA adducts was determined by atomic absorption spectrometry (AAS). These studies show for the first time that harringtonine pretreatment significantly increased the amount of platinum-DNA adducts in all ovarian cancer cell lines by 2-4 fold, immediately following 1-h exposure to cisplatin. Moreover, the level of cisplatin-DNA adducts in harringtonine-pretreated cells remained elevated by 3-4.7-fold for at least 6 h after cisplatin was removed, relative to cells only exposed to cisplatin. In all three cell lines the removal (repair) of platinum-DNA adducts was not significantly altered by harringtonine. In addition, the extent to which harringtonine altered the expression of select DNA damage response genes (p53, P16, ERCC1 and XPB) was determined using RT-PCR and Southern hybridization in A2780 and A2780/CP70 cells. The expression of ERCC1 and XPB RNAs were only modestly altered by harringtonine, consistent with a lack of effect of harringtonine on repair of cisplatin-DNA damage. However, harringtonine altered expression of p53 and P16 RNAs in both cell lines, although the down-regulation of p53 and P16 RNAs by harringtonine were more pronounced in A2780 cells. The novel observation that harringtonine augments platinum-DNA adducts in both platinum-sensitive and -resistant ovarian cancer cells indicates this combination of drugs may have utility in treating ovarian cancer and may be especially useful in managing platinum-resistant cancers. Additional studies are required to determine which sequence of these drugs is most beneficial, as well as the mechanism by which harringtonine increases cisplatin-DNA damage in ovarian cancer cells.

[Expression and significance of apoptosis protein inhibitor survivin and XIAP, in patients with myelodysplastic syndromes and in the cell line MUTZ-1]

OBJECTIVE

To investigate the expression of apoptotic protein inhibitors, survivin and XIAP, in patients with myelodysplastic syndromes (MDS) and in the cell line MUTZ-1, as well as to explore the possible mechanisms of homoharringtonine (HHT) in the treatment of MDS.

METHODS

Bone marrow samples from 47 patients with de novo MDS at diagnosis were examined and bone marrow samples from 15 normal donors were used as control. A MDS-RAEB cell line MUTZ-1 was used as in vitro model. Detection of apoptotic cells and cell cycle analysis were performed with flow cytometry (FACS). The expression of apoptotic protein inhibitor survivin and XIAP in the MDS cells were detected by RT-PCR technique. MUTZ-1 were treated with antisense oligodeoxynucleotide (AS-ODNs) of survivin and or HHT, the effects were evaluated by cell viability and cell apoptosis.

RESULTS

Survivin mRNA positive rate in MDS were significantly higher than that in normal controls (38.3% and 0, respectively, P < 0.01), and the positive rate in high risk group (RAEB, RAEBT and CMML) was significantly higher than that in RA/RAS group (53.6% and 16.7%, respectively, P < 0.05). XIAP was expressed in all untreated MDS and healthy controls. XIAP mRNA expression in high risk group was significantly higher than that in RA/RAS subtypes and healthy controls (1.55 +/- 0.34, 0.74 +/- 0.24, and 1.01 +/- 0.28, respectively, P < 0.01). However, XIAP mRNA expression was significantly lower in RA/RAS subtypes than in healthy control (0.74 +/- 0.24 and 1.01 +/- 0.28, P < 0.054). Apoptosis peak detected by FACS analysis and positive Annexin V FITC staining on cell membrane indicated that HHT could induce MUTZ-1 cell undergoing apoptosis in dose- and time-dependent manners. Treatment of MUTZ-1 cells with HHT revealed that HHT could significantly down-regulate survivinexpression but had no significant effect on XIAP expression in the cells. AS-ODNs of survivin could inhibit MUTZ-1 cells growth, induce them to apoptosis and sensitize them to HHT.

CONCLUSION

The expression levels of survivin; Institute of Hematology, Oncology and Tumor Immunology, Robert Roessle Clinic, Humboldt University, Berlin, Germany (Wolf Dieter Ludwig, Christian Wuchter) and XIAP vary in different subtypes of MDS patients, suggesting that the proteins may play an important role in the pathogenesis of the disease. Down-regulation of survivin in MUTZ-1 cells may be one of the mechanisms that HHT induces apoptosis of MDS cells.

[Quantitative analysis of Sokal's risk index in relation to 2 therapy protocols: their respective impact on clinical remission of chronic myeloid leukemia]

OBJECTIVE

To quantitatively evaluate the impact of Sokal's risk index and that of 2 therapy protocols on the clinical outcome of patients with chronic myeloid leukemia (CML).

METHODS

With the assistance of Access 2000 database of CML, 94 patients with CML were grouped on the basis of either different therapy protocols utilizing harringtonine plus Ara-C (HA) vs hydroxyurea (Hu) or Sokal scores, and the impact of therapy protocol and risk profile were quantitatively evaluated respectively.

RESULT

Treatment protocol utilizing HA was incapable of lengthening the duration of chronic phase (DCP) of CML, regardless of its better short-term effect than that of Hu. The impact of risk profile of the patients on clinical remission rate and DCP was more significant than that of the therapy protocols.

CONCLUSION

HA should not be used as the first-line protocol in the treatment of CML patients in chronic phase who have not received any previous medical intervention. Patients should be categorized according to the risk profile for choosing appropriate treatment protocol and making better clinical judgement.

[Chemotherapy and radiation therapy]

Stem cell transplantation and interferon-based treatment are major strategies in chronic phase CML and chemotherapy is one of limited therapeutic options when they are not available or ineffective. Hydroxyurea is superior to busulfan in better effect and lesser side effects. Homoharringtonine, a plant alkaloid, has shown cytogenetic response in one third of patients who were resistant to interferon therapy, and a better response rate in combination with cytarabine and interferon alfa. There have been no improvement of clinical outcome in treatment of accelerated phase and blastic crisis although many trials including decitabine are going on.

Homoharringtonine: history, current research, and future direction

BACKGROUND

Cephalotoxine esters, including homoharringtonine (HHT), have shown encouraging activity in leukemia in initial studies in China and in later studies in the U.S.

METHODS

The authors conducted a review of the literature to examine the studies pertinent to HHT in relation to preclinical studies and Phase I-II trials in patients with hematologic malignancies and solid tumors.

RESULTS

HHT and analogues appear to induce differentiation and apoptosis. Studies from China reported high response rates in patients with leukemia. Trials in the U.S. using short HHT infusions (3-4 mg/m(2) daily for 5 days) resulted in a high incidence of cardiovascular complications that were reduced using continuous infusion schedules of 3-7 mg/m(2) daily for 5-7 days initially, and later lower dose schedules of 2.5 mg/m(2) daily for 7-14 days. Results in solid tumors were negative. However encouraging results were reported in patients with acute myeloid leukemia, myelodysplastic syndrome, acute promyelocytic leukemia, and, most important, chronic myeloid leukemia (CML). In CML patients, HHT has been investigated alone and in combination with interferon-alpha and low-dose cytarabine in late and early chronic phases, with positive results. Additional areas of interest include the potential use of HHT for the treatment of central nervous system leukemia, polycythemia vera, and other nonmalignant conditions such as malaria. New semisynthetic preparations and HHT derivatives that bypass multidrug resistance may improve the efficacy and toxicity profiles, and broaden the range of antitumor efficacy.

CONCLUSIONS

HHT and its derivatives appear to have promising activity in hematologic malignancies, a finding that needs to be pursued.

Homoharringtonine and low-dose cytarabine in the management of late chronic-phase chronic myelogenous leukemia

PURPOSE

: To evaluate the efficacy and toxicity profiles of a combination regimen of homoharringtonine (HHT) and low-dose cytarabine (ara-C) in patients with Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia (CML) who had experienced treatment failure with interferon alfa (IFNalpha) therapy.

PATIENTS AND METHODS

One hundred five patients were treated: 100 in chronic phase (15 with cytogenetic clonal evolution) and five in accelerated phase. Their median age was 52 years; all had been treated unsuccessfully with IFNalpha; 94% were in late chronic phase; 43% had been exposed to ara-C and 11% had been exposed to HHT. Patients received HHT 2.5 mg/m(2) by continuous infusion daily for 5 days and ara-C 15mg/m(2) daily in two subcutaneous injections for 5 days every 4 weeks. The outcome of the 100 patients in chronic phase was compared with a previous study group of 73 patients treated with HHT alone.

RESULTS

Overall, the complete hematologic response (CHR) rate in chronic phase was 72%; the cytogenetic response rate was 32% (major response, 15%; complete response, 5%). Toxicities were acceptable, mostly related to moderate diarrhea (3%), headaches (3%), cardiovascular events (3%),and myelosuppression-associated complications (3% to 14%). With a median follow-up period of 25 months, the estimated 4-year survival rate was 55%. Response rates were identical with HHT plus ara-C versus HHT alone, but the survival was significantly longer with the combination after accounting for differences in the study groups and by multivariate analysis.

CONCLUSION

The combination regimen of HHT and ara-C is effective and safe in patients with CML who have experienced treatment failure with IFNalpha and needs to be investigated together with IFNalpha as part of front-line CML therapy. The addition of ara-C did not improve the response rates but may have improved survival, perhaps through suppression of clones related to disease transformation.

A phase II trial of homoharringtonine and caracemide in the treatment of patients with advanced large bowel cancer

Twenty-four previously untreated, ambulatory patients with advanced colorectal carcinoma were treated with either caracemide (11 patients) or homoharringtonine (13 patients). No objective responses were observed in any of the treatment cohorts. Caracemide was well tolerated with the exception of one death due to sepsis. On the homoharringtonine arm one patient died of pulmonary sepsis, one patient experienced grade 4 leukopenia requiring more than 4 weeks of recovery, and an additional patient developed grade 4 renal failure. These severe and unexpected complications caused early termination of accrual to the homoharringtonine arm of the study. These agents have no activity in the treatment of advanced colorectal carcinoma.

[A randomized control clinical trial of glaucoma filtering surgery with homoharringtonine]

OBJECTIVE

To study the antiproliferative effects of homoharringtonine (Hh) on glaucoma filtering surgery.

METHODS

In a randomized control clinical trial, 78 patients (88 eyes) with refractory glaucoma underwent trabeculectomy with and without Hh. In the Hh-treated eyes (n = 46), the therapeutic dose of Hh was: intraoperative application of Hh 0.4 mg and postoperative subconjunctival injections of Hh 0.62 +/- 0.20 mg (ranged 0.53 - 0.75 mg). In the control eyes (n = 42), Hh was not used. The follow-up period was 18 to 48 months, and the data were analyzed by using the life-table method of Kaplan-Meier.

RESULTS

The cumulative success probability in Hh group was 84.5% and that in control group was 50.9%, the difference being significant (P < 0.05). The cumulative percentage of functioning bleb in Hh group was 84.2% and that in control group was 52.9% (P < 0.05). The rates of corneal erosion were 23.9% and 7.1%, and the rates of conjunctival wound leak were 6.5% and 2.4% in Hh and control group respectively. There was no significant change in corneal endothelial density following the use of Hh (P > 0.05).

CONCLUSION

The study indicates that Hh is a safe and effective antiproliferative agent for the use in glaucoma filtering surgery, it not only can increase the success probability considerably, but also maintain at least the postoperative IOP at relatively low normal level for 3 years.

Standard and low-dose chemotherapy for the treatment of myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are a heterogeneous group of disorders with an invariably fatal outcome. Other than bone marrow transplantation, no treatment has been able to alter the natural history of MDS. As a result, there has been an interest in identifying new and more effective chemotherapeutic agents. Many of the drugs that have been evaluated in an attempt to increase remissions and prolong survival were selected because of their activity in acute myeloid leukemia. Thus cytarabine has been the most widely studied drug. Although numerous studies suggested activity for low-dose cytarabine (LoDAC), a careful analysis of the data identified a complete remission (CR) rate of less than 20%, without meaningful clinical benefit. The issue of LoDAC was finally put to rest by a randomized trial in which survival was no better than with supportive care. 5-Azacytidine induces cellular differentiation by hypomethylation of DNA. Phase II trials noted CRs in fewer than 10% of patients, with response rates under 30%, although additional patients appeared to experience hematologic and clinical benefit. A randomized trial of 5-azacytidine versus supportive care failed to demonstrate a survival benefit. One of the most promising new agents is the topoisomerase inhibitor topotecan, which achieves CRs in more than 30% of patients. Combinations of this drug with other active agents are in development. Obviously, new treatment strategies are needed to improve the outcome of MDS patients. Combination approaches incorporating new, active agents should have sound scientific rationale, targeting biological differences among the various MDS subtypes.

Chronic myelogenous leukemia: a review

Chronic myelogenous leukemia (CML) is a chronic myeloproliferative disorder with an initially chronic course lasting for 3-5 years. It eventually transforms into accelerated and blastic phases, which are generally fatal. CML was one of the first diseases in which a specific chromosomal abnormality was identified, a t(9;22)(q34;q11) or Philadelphia chromosome. CML had been traditionally treated with conventional chemotherapy with hydroxyurea or busulfan. Although these agents can achieve hematologic remissions in most patients, no evidence of sustained disappearance of the chromosomal abnormality was evident. Interferon alpha (IFN-alpha) has been able to achieve hematologic and cytogenic remissions in a significant number of patients, and recent studies show a survival advantage for patients treated with IFN-alpha compared with those treated with conventional chemotherapy. The results of these studies are discussed, and the reasons for discordance among different investigators analyzed in this review. Allogeneic bone marrow transplantation (BMT) may be curative in some patients with CML. The benefits and limitations of this approach in the treatment of CML are also discussed and the results of different alternatives compared. Other alternatives of therapy, including newer chemotherapeutic agents, combinations of IFN-alpha with other agents, and autologous BMT, are presented. The availability of very sensitive techniques for detection of the Philadelphia chromosome at the molecular level has allowed the detection of minimal residual disease. The information available on these measurements is also analyzed. Finally, we discuss the alternatives for patients with accelerated and blastic phase CML, as well as the clinical characteristics and prognosis for patients with Philadelphia-chromosome-negative CML.

Sequential emergence of MRP- and MDR1-gene over-expression as well as MDR1-gene translocation in homoharringtonine-selected K562 human leukemia cell lines

To investigate the mechanism of resistance to an antineoplastic natural product homoharringtonine (HHT) in leukemic cells, we have established 5 sub-lines of human myeloid leukemia K562 cells, designated as K-H30, K-H100, K-H200, K-H300 and K-H400, which showed progressive resistance to different concentrations of HHT. These sub-lines were cross-resistant to daunorubicin, vincristine, etoposide and mitoxantrone, but not to melphalan. Immunofluorescence with monoclonal anti-Pgp antibody MRK16 and Northern-blot analysis demonstrated that resistance to HHT is related to the sequential emergence of MRP- and MDR1-gene over-expression. In the low-level-resistant K-H30 sub-line, the MDR1 gene was not over-expressed, but the MRP gene was over-expressed 2.1-fold. In the intermediate-level-resistant K-H100 and K-H200 sublines, both the MRP and the MDR1 genes were over-expressed. However, in the high-level-resistant K-H300 and K-H400 sublines, MDR1-gene over-expression predominated (20- and 21-fold respectively). On the other hand, GST pi-gene expression was decreased in all 5 sub-lines. Southern-blot analysis revealed no MRP-gene amplification in any of the 5 sub-lines, whereas the MDR1 gene was amplified in the high-level-resistant K-H300 and K-H400 sub-lines. The most interesting observation is a homogeneously staining region (HSR) found in chromosome 2 of the K-H300 and K-H400 sub-lines. Chromosome painting and in situ hybridization demonstrated that this HSR was translocated from chromosome 7 and consisted of the amplified MDR1 gene, suggesting that there is a relationship between MDR1-gene, translocation and MDR1-gene amplification.

Homoharringtonine in patients with myelodysplastic syndrome (MDS) and MDS evolving to acute myeloid leukemia

Current anti-leukemic chemotherapy in patients with myelodysplastic syndromes (MDS) and MDS evolving to acute myeloid leukemia (AML) is associated with low response rates and high treatment-related toxicity. Homoharringtonine (HHT) is a novel cephalotaxime alkaloid with reported efficacy in relapsed and de novo AML and more recently, chronic myeloid leukemia. Although its mechanism(s) of action is not completely understood, in vitro studies have demonstrated both cytotoxic and differentiating activity in leukemic cells, as well as intra-cellular changes suggestive of apoptotic cell death. In a phase II trial, HHT was administered at a dose od 5 mg/m2 by 24-h continuous infusion daily for 9 days to patients with MDS and MDS evolving to AML (MDS/AML). Twenty-eight patients (MDS 16, MDS/AML 12) with a median age of 67 years (range 23-83) were entered. A complete remission was achieved in seven patients, a partial remission was achieved in one patient for an overall response rate of 28% (8/28). There were four of 13 responders in MDS/AML patients and four of 15 in patients with MDS. The median duration of complete response was 7 months (range 2-10). Significant myelosuppression was universal and resulted in a high incidence of induction deaths (13/28) due to neutropenic-related infections. Extramedullary toxicity was mild and consisted of hypo-tension, fluid retention, hypoglycemia, diarrhea, nausea and vomiting. HHT given in this dose and schedule demonstrated limited activity in MDS and MDS/AML and was associated with prolonged pancytopenia and marrow hypoplasia in many patients. Administration of HHT at a lower dose or in combination with hematopoietic growth factors may lead to better results, but treatment with HHT as single agent at this dose and schedule is not currently recommended for these patients.

Homoharringtonine: an effective new natural product in cancer chemotherapy

Homoharringtonine (HHT) is a cytotoxic alkaloid isolated from the evergreen tree cephalotaxus harringtonia native to the southern provinces of China. The principal mechanism of action of HHT is the inhibition of protein synthesis in a dose- and time-dependent manner by acting on the ribosomes of cancer cells. It blocks the progression of cells from G1 phase into S phase and from G2 phase into M phase. It is synergestic or additive in vitro with AraC, amsacrine, actinomycin D and dexamethasone. Clinical studies have indicated that HHT is effective in treating acute myeloid leukemia (AML), chronic myeloid leukemia (CML) and myelodysplastic syndrome (MDS), but not acute lymphoblastic leukemia (ALL) and solid tumors. The dose limiting toxicities are hypotention and myelosuppression. Homoharringtonine has relatively mild extramedullary toxicities and no anthracycline-like cardiac toxicity, which make it a suitable candidate for the treatment of aged patients. Pharmacological studies indicate that HHT belongs to the category of multidrug resistance (MDR)-related drugs. The cells resistant to HHT are cross-resistant to anthracycline, vinca alkaloids, mitoxantrone, but not cis-platine and AraC. Multiple mechanisms, including the sequential emergence of overexpression of multidrug resistance-associated protein (MRP) and MDR1 genes, are involved in the cross-resistance of tumor cells to HHT.

Homoharringtonine therapy induces responses in patients with chronic myelogenous leukemia in late chronic phase

Homoharringtonine (HHT) is a plant alkaloid with potent myelosuppressive activity and little toxicity when used in a continuous infusion schedule. The antileukemic efficacy of HHT has been shown in acute myeloid leukemia, but has not been investigated in chronic myelogenous leukemia (CML). Seventy-one patients with Philadelphia chromosome-positive (Ph+) CML in late chronic phase (time from diagnosis to therapy longer than 12 months) were treated with a continuous infusion of HHT at a daily dose of 2.5 mg/m2 for 14 days for remission induction and for 7 days every month for maintenance. The median number of courses given was 6 (range, 1 to 35) and 21 patients (30%) continue on treatment. Forty-two of 58 patients (72%) evaluable for hematologic response achieved a complete hematologic remission, and 9 (16%) had a partial hematologic remission. Twenty-two of 71 patients (31%) developed a cytogenetic response; it was major (Ph+ cells less than 35%) in 11 (15%) and complete (Ph+ cells 0%) in 5 (7%). Significant myelosuppression occurred in 39% of induction courses and 9% of maintenance courses. Fever or documented infection was present in 26% of induction courses and in only 8% of maintenance courses. Nonmyelosuppressive toxicity was minimal. Homoharringtonine produced hematologic remissions in the majority of patients with advanced chronic-phase CML. Cytogenetic response occurred in some patients without an association with myelosuppression, and these responses may be prolonged. Future studies investigating homoharringtonine in combination with other active agents in CML, such as interferon, are warranted.

[An experimental study on homoharringtonine and glaucoma surgery]

PURPOSE

To test the inhibiting effect of a Chinese herbal drug. Homoharringtonine (HH) on the wound healing process at the filtering site in an experimental model.

METHODS

Posterior sclerectomies were performed in 20 rabbits. Postoperatively one eye of each rabbit received subconjunctival injections of HH and fellow eye received saline injections in a randomized masked fashion.

RESULTS

14 days after operation, intraocular pressure decreased significantly compared with that of control (P < 0.05). The number of filtration blebs was greater than that of control (14/6). On pathological examination, the number of fibroblasts per square measure of cross section of tissue cut from filtration region that was diminished significantly compared with that of control (P < 0.01). There were no serious and permanent ocular toxic and side effects.

CONCLUSIONS

The study suggests that the HH can inhibit cicatrization at the glaucoma filtering site, promote the formation of filtering blebs and provide a sufficient evidence for the further clinical use of HH.

[Studies on the anticancer effect of HH07A, a derivative of hainanensine]

The effect of HH07A on the growth of tumor cells in vitro was investigated using the techniques of cell growth curve determination and soft-agar colony-forming assay. The result showed that HH07A inhibited the growth of L1210 cells and HL-60 cells at a concentration of 1.5 micrograms.ml-1 and 4.0 micrograms.ml-1, respectively. Among the cells tested, L1210 cells were shown to be the most sensitive, followed by KB cells and HL-60 cells (with IC50 of 2.29, 4.13 and 4.36 micrograms.ml-1, respectively). Normal mouse granulocyte-macrophage progenitor cells (GM-CFC) were less sensitive to the drug (with IC50 of 11.15 micrograms.ml-1) as compared with the tumor cells. As they were exposed to HH07A 3.5 micrograms.ml-1 for 5 days, HL-60 cells did not show NBT reductive ability. Intraperitoneal injection of HH07A exerted inhibitory effect on the ascitic tumors of L1210 and S180 in mice. Oral or ip administration of HH07A also showed some effect on S180 solid tumors in mice.