A prospective randomized study of alpha-2b interferon plus hydroxyurea or cytarabine for patients with early chronic phase chronic myelogenous leukemia: the International Oncology Study Group CML1 study

Organic Nanoparticles as Drug Delivery Systems and Their Potential Role in the Treatment of Chronic Myeloid Leukemia

Chronic myeloid leukemia is a myeloproliferative neoplasm that occurs more prominently in the older population, with a peak incidence at ages 45 to 85 years and a median age at diagnosis of 65 years. This disease comprises roughly 15% of all leukemias in adults. It is a clonal stem cell disorder of myeloid cells characterized by the presence of t(9;22) chromosomal translocation, also known as the Philadelphia chromosome, or its byproducts BCR-ABL fusion protein/messenger RNA, leading to the expression of a protein with enhanced tyrosine kinase activity. This fusion protein has become the main therapeutic target in chronic myeloid leukemia therapy, with imatinib displaying superior antileukemic effects, placing it at the forefront of current treatment protocols and displaying great efficacy. Alternatively, nanomedicine and employing nanoparticles as drug delivery systems may represent new approaches in future anticancer therapy. This review focuses primarily on the use of organic nanoparticles aimed at chronic myeloid leukemia therapy in both in vitro and in vivo settings, by going through a thorough survey of published literature. After a brief introduction on the pathogenesis of chronic myeloid leukemia, a description of conventional, first- and second-line, treatment modalities of chronic myeloid leukemia is presented. Finally, some of the general applications of nanostrategies in medicine are presented, with a detailed focus on organic nanocarriers and their constituents used in chronic myeloid leukemia treatment from the literature.

Combination of pegylated IFN-α2b with imatinib increases molecular response rates in patients with low- or intermediate-risk chronic myeloid leukemia

Biologic and clinical observations suggest that combining imatinib with IFN-α may improve treatment outcome in chronic myeloid leukemia (CML). We randomized newly diagnosed chronic-phase CML patients with a low or intermediate Sokal risk score and in imatinib-induced complete hematologic remission either to receive a combination of pegylated IFN-α2b (Peg-IFN-α2b) 50 μg weekly and imatinib 400 mg daily (n = 56) or to receive imatinib 400 mg daily monotherapy (n = 56). The primary endpoint was the major molecular response (MMR) rate at 12 months after randomization. In both arms, 4 patients (7%) discontinued imatinib treatment (1 because of blastic transformation in imatinib arm). In addition, in the combination arm, 34 patients (61%) discontinued Peg-IFN-α2b, most because of toxicity. The MMR rate at 12 months was significantly higher in the imatinib plus Peg-IFN-α2b arm (82%) compared with the imatinib monotherapy arm (54%; intention-to-treat, P = .002). The MMR rate increased with the duration of Peg-IFN-α2b treatment (< 12-week MMR rate 67%, > 12-week MMR rate 91%). Thus, the addition of even relatively short periods of Peg-IFN-α2b to imatinib markedly increased the MMR rate at 12 months of therapy. Lower doses of Peg-IFN-α2b may enhance tolerability while retaining efficacy and could be considered in future protocols with curative intent.

CML Autograft Trials Collaboration. Autologous stem cell transplantation in chronic myeloid leukaemia: a meta-analysis of six randomized trials

RATIONALE

A number of collaborative trial groups developed prospective randomized trials to compare autologous stem cell transplantation (ASCT) with non-transplant therapy (interferon-alpha alone or in combination) for chronic myeloid leukaemia (CML) with the aim of obtaining reliable evidence on the possible benefit of ASCT. With the arrival of tyrosine kinase inhibitors, notably imatinib, these trials closed early without reaching their recruitment targets and no trial was able to address its objectives. Following discussions with the principal investigators, it was agreed that a meta-analysis be performed to attempt to determine the effect of ASCT on the main outcomes.

OBJECTIVES

To establish the effect of ASCT followed by interferon-alphacompared with interferon-alpha only.

FINDINGS

There was no evidence of a difference in survival; odds ratio=0.99 (95% confidence intervals=0.67-1.46). Nor were there statistically significant differences between treatment groups in best haematological or cytogenetic response achieved in the first year. It was not possible to analyse whether autografting with predominantly Philadelphia negative cells early on in the disease resulted in a better outcome.

CONCLUSIONS

The results do not suggest a role for ASCT in initial treatment for CML, but it may still merit investigation in patients resistant to tyrosine kinase inhibitors.

Chronic myelogenous leukemia: elements of conventional chemotherapy and an overview of autografting in the treatment of the chronic phase

Chronic myelogenous leukemia (CML) consists of a clonal malignancy that arises from a pluripotent hematopoietic stem call. In most cases, neoplastic cells are characterized by the formation of a shortened chromosome 22 called the Philadelphia chromosome. It results from a reciprocal translocation between long arms of chromosomes 9 and 22. A rearranged gene (bcr-abl) is the consequence of this translocation, and it may be considered as the first step toward leukemic transformation. Conventional chemotherapy of CML in the chronic phase is unable to suppress the Ph+ leukemic clone. The treatment with the IFNalpha may induce an overall cytogenetic response rate of 40-50% of patients. Autografting for patients with CML in chronic phase may induce a 53% overall cytogenetic response rate with a duration of disease-free time and survival from the autograft ranging, respectively, from 4 to 24 mo and from 8 to 40 mo.

Randomized comparison of interferon alpha and hydroxyurea with hydroxyurea monotherapy in chronic myeloid leukemia (CML-study II): prolongation of survival by the combination of interferon alpha and hydroxyurea

The optimum treatment conditions of interferon (IFN) alpha therapy in chronic myeloid leukemia (CML) are still controversial. To evaluate the role of hydroxyurea (HU) for the outcome of IFN therapy, we conducted a randomized trial to compare the combination of IFN and HU vs HU monotherapy (CML-study II). From February 1991 to December 1994, 376 patients with newly diagnosed CML in chronic phase were randomized. In all, 340 patients were Ph/BCR-ABL positive and evaluable. Randomization was unbalanced 1:2 in favor of the combination therapy, since study conditions were identical to the previous CML-study I and it had been planned in advance to add the HU patients of study I (n=194) to the HU control group. Therefore, a total of 534 patients were evaluable (226 patients with IFN/HU and 308 patients with HU). Analyses were according to intention-to-treat. Median observation time of nontransplanted living patients was 7.6 years (7.9 years for IFN/HU and 7.3 years for HU). The risk profile (new CML score) was available for 532 patients: 200 patients (38%) were low, 239 patients (45%) intermediate, and 93 patients (17%) high risk. Complete hematologic response rates were higher in IFN/HU-treated patients (59 vs 32%). Of 169 evaluable IFN/HU-treated patients (75%), 104 patients (62%) achieved a cytogenetic response that was complete in 12% (n=21), major in 14% (n=24), and at least minimal in 35% (n=59). Of the 534 patients, 105 (20%) underwent allogeneic stem cell transplantation in first chronic phase. In the low-risk group, 65 of 200 patients were transplanted (33%), 30 (13%) in the intermediate-risk group, and nine (10%) in the high-risk group. Duration of chronic phase was 55 months for IFN/HU and 41 months for HU (P<0.0001). Median survival was 64 months for IFN/HU and 53 months for HU-treated patients (P=0.0063). We conclude that IFN in combination with HU achieves a significant long-term survival advantage over HU monotherapy. In view of the data of CML-study I, these results suggest that IFN/HU is also superior to IFN alone. HU should be combined with IFN in IFN-based therapies and for comparisons with new therapies.

A randomized study comparing interferon (IFN alpha) plus low-dose cytarabine and interferon plus hydroxyurea (HU) in early chronic-phase chronic myeloid leukemia (CML)

This multicenter randomized phase III study was designed to compare the efficacy and toxicity of IFN alpha-2c (3.5 MU/d) in combination with either araC (10 mg/m(2) d1-10) or hydroxyurea (HU: 25 mg/kg per day) in newly diagnosed CML patients. A total of 114 patients were randomized. Following a median observation period of 36 (range 1-73) months the major cytogenetic response rates were 25 and 27% and the 4-year survival probabilities 62.5 and 63% for the araC and HU group, respectively. While the overall toxicity profile was comparable between both groups, patients in the HU arm exhibited a slightly higher degree of WHO grades 3 and 4 non-hematological toxicities.

AraC-based pharmacotherapy of chronic myeloid leukaemia

In interferon-alpha (IFN) treated chronic phase chronic myeloid leukaemia (CML) patients, survival depends on individual risk profile and achievement of a complete haematological response (CHR) and a major cytogenetic response (MCR) (< 35% Philadelphia-chromosome-positive metaphases). The highest cytogenetic response rates have been achieved with the combination of IFN and low-dose sc. AraC (10 mg daily to 10-20 mg/m2 for 10-14 days/month). Whether the higher cytogenetic response rates are also associated with a significant improvement of survival still remains controversial. The different results obtained from large randomised and observational trials may be due to the numbers of patients enrolled, distribution of risk profiles and the treatment schedule, which is influenced greatly by the haematological and gastrointestinal toxicity of AraC. An oral formulation (YNK01), which is lipophilic and resistant to deamination, is currently under investigation. Clinically, it has similar activity, but toxicity leads to discontinuation of treatment in a considerable proportion of patients. The clinical benefits may therefore be outweighed by the dose-limiting toxicity for both application forms. Combinations with other drugs, e.g., STI571 or homoharringtonine, have shown promising early results in vitro and in vivo.

Current Treatment of Chronic Myeloid Leukemia

We are entering an exciting era in the management of chronic myeloid leukemia (CML). This, in part is related to our considerable understanding of the molecular lesion associated with the disease-arguably the best characterized of any malignancy. Although allogeneic hematopoietic cell transplantation remains the sole potentially curative therapy at present, newer agents such as the tyrosine kinase inhibitor STI571 show promise and may eventually replace less specific cytotoxic therapy. This review focuses on the numerous options currently available for treating CML and includes a treatment algorithm.