Role of Allogeneic Stem Cell Transplantation for Adult Chronic Myeloid Leukemia in the Imatinib Era

Imatinib mesylate and nilotinib decrease synthesis of bone matrix in vitro

Tyrosine kinase inhibitors (TKIs), such as imatinib (IMA) and nilotinib (NIL), are the cornerstone of chronic myeloid leukemia (CML) treatment via the blockade of the oncogenic BCR-ABL1 fusion protein. However, skeletal side effects are commonly observed in pediatric patients receiving long-term treatment with IMA. Additionally, in vitro studies have shown that IMA and NIL alter vitamin D metabolism, which may further impair bone metabolism. To determine whether TKIs directly affect bone cell function, the present study treated the human osteoblastic cell line SaOS-2 with IMA or NIL and assessed effects on their mineralization capacity as well as mRNA expression of receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG), two cytokines that regulate osteoclastogenesis. Both TKIs significantly inhibited mineralization and downregulated osteoblast marker genes, including alkaline phosphatase, osteocalcin, osterix, as well as genes associated with the pro-osteogenic Wnt signaling pathway; NIL was more potent than IMA. In addition, both TKIs increased the RANKL/OPG ratio, which is known to stimulate osteoclastogenesis. The present results suggested that the TKIs IMA and NIL directly inhibited osteoblast differentiation and directly promoted a pro-osteoclastogenic environment through the RANKL-OPG signaling axis. Thus, we propose that future work is required to determine whether the bone health of CML patients undergoing TKI-treatment should be routinely monitored.

Off‑target effect of imatinib and nilotinib on human vitamin D3 metabolism

Prolonged treatment with tyrosine kinase inhibitors (TKI) including imatinib (IMA) or nilotinib (NIL), induces severe disturbances of bone metabolism in patients with chronic myeloid leukaemia. As vitamin D3 (VD3) is involved in the complex cycle of bone remodelling, the present study investigated in vitro, the influence of IMA and NIL on VD3 metabolism i) in HaCaT cells and ii) in cultured outer root sheath keratinocytes (ORS‑KC) from hair follicles of IMA treated children. Cells were incubated in the presence of IMA or NIL. Concomitantly, specific inhibitors were applied to analyze the inhibition of the VD3 processing cytochrome P450 isoenzyme family by TKIs. In vitro, IMA and NIL significantly impaired the production of calcitriol in HaCaT and cultured ORS‑KC cells from hair follicles of IMA treated children. For NIL, this inhibitory effect demonstrated a 4‑fold increase. In HaCaT and ORS‑KC, application of specific CYP450 inhibitors revealed that CYP27B1 was impaired by IMA and NIL leading to an intracellular accumulation of calcidiol. However, during TKI treatment, KC of IMA treated children revealed no differences in calcidiol and calcitriol levels. In conclusion, IMA and NIL interfere with the vitamin D3 cascade due to their metabolism by CYP27B1.

Reduced-intensity allogeneic hematopoietic stem cell transplantation combined with imatinib has comparable event-free survival and overall survival to long-term imatinib treatment in young patients with chronic myeloid leukemia

The relative merits of reduced intensity hematopoietic stem cell transplantation (RIST) for chronic myeloid leukemia (CML) in the first chronic phase (CP) in imatinib era have not been evaluated. The study was designed to compare the outcomes of combination therapy of RIST plus imatinib (RIST + IM) vs. imatinib (IM) alone for young patients with early CP (ECP) and late CP (LCP). Of the patients, 130 were non-randomly assigned to treatment with IM alone (n = 88) or RIST + IM (n = 42). The 10-year overall survival (OS) and event-free survival (EFS) were comparable between RIST + IM and IM groups. LCP, high Sokal score, and no complete cytogenetic response at 3 months were adverse prognostic factors for survival, but only the time from diagnosis to IM was an independent predictor after multivariate analysis. For ECP, IM was similar to RIST + IM, with 10-year EFS rates of 77.2 vs. 81.6% (p = 0.876) and OS rates of 93.8 vs. 87.9% (p = 0.102), respectively. For LCP, both treatments resulted in similar survival, but more patients in the imatinib group experienced events (10-year EFS 40.8 vs. 66.7%, p = 0.047). The patients with higher EBMT risk scores had an inferior survival than those with lower scores (69.2 vs. 92.9%, p = 0.04). We concluded that RIST + IM was comparable to IM in terms of OS and EFS. However, RIST + IM was more affordable than IM alone in a 10-year scale. Thus, RIST + IM could be considered as an alternative treatment option, especially when the patients have low EBMT risk scores and demand a definite cure for CML.

Allogeneic Transplantation in Chronic Myeloid Leukemia and the Effect of Tyrosine Kinase Inhibitors on Survival: A Quasi-Experimental Study

Objective:

Tyrosine kinase inhibitors (TKIs) have changed the indications for allogeneic hematopoietic stem cell transplantation (allo-HSCT) in chronic myeloid leukemia (CML). Therefore, we aimed to evaluate the effect of TKIs on allo-HSCT in CML.

Materials and Methods:

In this quasi-experimental study, we compared patient, disease, and transplantation characteristics as well as allo-HSCT outcomes between the pre-TKI era (before 2002) and the post-TKI era (2002 and later) in patients with CML. A total of 193 allo-HSCTs were performed between 1989 and 2012.

Results:

Patients in the post-TKI era had more advanced disease (>chronic phase 1) at the time of transplant and more frequently received reduced-intensity conditioning compared to patients in the pre-TKI era. Relapse/progression occurred more frequently in the year ≥2002 group than in the year <2002 group (48% vs. 32% at 5 years, p=0.01); however, overall survival (OS) was similar in these two groups (5-year survival was 50.8% vs. 59.5%, respectively; p=0.3). TKIs (with donor lymphocyte infusions or alone) for treatment of relapse after allo-HSCT were available in the post-TKI era and were associated with improved OS. While the rates of hematologic remission at 3 months after allo-HSCT were similar between TKI eras, patients having remission had better disease-free survival (DFS) [relative risk (RR): 0.15, confidence interval (CI) 95%: 0.09-0.24, p<0.001] and OS (RR: 0.14, CI 95%: 0.09-0.23, p<0.001). Male allo-HSCT recipients had worse DFS (RR: 1.7, CI 95%: 1.2-2.5, p=0.007) and OS (RR: 1.7, CI 95%: 1.1-2.6, p=0.02) than females.

Conclusion:

TKIs are an effective option for the treatment of relapse after allo-HSCT in CML. Hematologic remission after allo-HSCT is also an important factor for survival in CML patients.

The evolution of treatment strategies for patients with chronic myeloid leukemia relapsing after allogeneic bone marrow transplant: can tyrosine kinase inhibitors replace donor lymphocyte infusions?

The optimal treatment for chronic myeloid leukemia (CML) relapsing following allogeneic bone marrow transplant (alloBMT) is unknown. We performed a single-center retrospective analysis of 71 consecutive patients undergoing alloBMT for CML from 1995 to 2008. A multi-state model was used to quantify cumulative incidences of complete molecular response (CMR) and death following alloBMT. The primary analysis was comparison of three treatment interventions (tyrosine kinase inhibitor: TKI, donor lymphocyte infusion: DLI, and TKI + DLI) for relapsed disease post-alloBMT. Forty-five (63%) patients relapsed post-alloBMT (molecular relapse: n = 16, cytogenetic relapse: n = 20, hematologic relapse: n = 2, advanced phase relapse: n = 7) and 40 patients underwent one of three treatments: TKI-only (n = 13), DLI-only (n = 11) or TKI + DLI (n = 16). Although not statistically significant, the TKI-only group had the highest cumulative incidence of CMR and lowest cumulative incidence of death compared to DLI and TKI + DLI. These data support the finding that TKI therapy is active in the post-alloBMT setting.

Case-matched comparison with standard versus reduced intensity conditioning regimen in chronic myeloid leukemia patients

This retrospective case-matched study evaluated the efficacy of reduced intensity conditioning (RIC) regimen on early and late allogeneic transplant outcome in chronic myeloid leukemia (CML) patients. Twenty-eight patients conditioned with RIC regimen were matched to 56 patients who received a myeloablative conditioning (MAC) regimen. The main criteria for case matching among our CML allotransplant cohort were the Gratwohl scoring system. The median score was 2 (1-4) in each group. The pretransplant disease status was first chronic phase (CP1, n = 20), CP2 (n = 2), and advanced phase (n = 6) in RIC, and CP1 (n = 46), CP2 (n = 3), and advanced phase (n = 7) in MAC. The duration of neutropenia and thrombocytopenia was shorter in RIC than MAC. The grade and duration of mucositis were less in RIC. The need for total parenteral nutrition (21% vs. 77%, p < 0.0001) and febrile neutropenic episodes (50% vs. 95%, p < 0.0001) were observed less frequently in RIC compared with MAC-given patients. Acute or chronic graft versus host diseases (GvHD) were not affected by the intensity of conditioning regimen. The incidence of transplant-related mortality was higher in MAC (7% vs. 14%, p = 0.01). Although more relapse/progression was observed in the RIC group, the probability of 5- and 10-year leukemia-free- and overall survival were similar regardless of conditioning regimen intensity (p > 0.05). In early first CP, the pair of female donor-male recipient and the development of chronic GvHD prolonged both leukemia-free survival and overall survival in multivariate analysis. According to our single-center matched-pair analysis, the use of RIC regimens in patients with low-risk CML results with toxicities less, responses later, and relapses more frequent than the MAC regimens.

Dasatinib in the treatment of chronic myeloid leukemia in accelerated phase after imatinib failure: the START a trial

PURPOSE Patients with chronic myelogenous leukemia in accelerated phase (CML-AP) that is resistant or intolerant to imatinib have limited therapeutic options. Dasatinib, a potent inhibitor of BCR-ABL and SRC-family kinases, has efficacy in patients with CML-AP who have experienced treatment failure with imatinib. We now report follow-up data from the full patient cohort of 174 patients enrolled onto a phase II trial to provide a more complete assessment of the efficacy and safety of dasatinib in this population. PATIENTS AND METHODS Patients with imatinib-resistant (n = 161) or -intolerant (n = 13) CML-AP received dasatinib 70 mg orally twice daily. Results At a median follow-up of 14.1 months (treatment duration, 0.1 to 21.7 months), major and complete hematologic responses were attained by 64% and 45% of patients, respectively, and major and complete cytogenetic responses were achieved in 39% and 32% of patients, respectively. Responses were achieved irrespective of imatinib status (resistant or intolerant), prior stem-cell transplantation, or the presence of prior BCR-ABL mutation. The 12-month progression-free survival and overall survival rates were 66% and 82%, respectively. Dasatinib was generally well tolerated; the most frequent nonhematologic severe treatment-related adverse event was diarrhea (52%; grade 3 to 4, 8%). Cytopenias were common, including grade 3 to 4 neutropenia (76%) and thrombocytopenia (82%). Pleural effusion occurred in 27% of patients (grade 3 to 4, 5%). CONCLUSION Dasatinib is effective in patients with CML-AP after imatinib treatment failure.

First-line therapy for chronic myeloid leukemia: Past, present, and future

The development of Bcr-Abl tyrosine kinase inhibitors has dramatically changed the prognosis of patients with newly diagnosed chronic myeloid leukemia (CML). Standard-dose imatinib (400 mg/day in chronic phase, 600 mg/day in advanced CML) now dominates the management of this disease, producing considerably higher hematologic, cytogenetic, and molecular response rates than seen with previous drug therapies. However, although many patients respond well to standard-dose imatinib initially, some patients do not achieve adequate levels of response or discontinue therapy because of resistance. One approach to improving treatment response with first-line imatinib may be to increase the imatinib dose (800 mg/day), although recent trial data indicate that overall increases in response rates may be modest. Newer Bcr-Abl tyrosine kinase inhibitors can induce responses in patients with all phases of imatinib-resistant CML, even those with imatinib-resistant mutations in the BCR-ABL gene. Furthermore, in initial studies, first-line dasatinib or nilotinib treatment has produced response rates that compare favorably with historical controls treated with imatinib, although confirmation is required from head-to-head clinical trials. Future clinical approaches may include drug combinations, which may allow quiescent leukemia stem cells to be eradicated. Further improvements in drug treatment for first-line CML are expected during the next few years.

Suboptimal response to or failure of imatinib treatment for chronic myeloid leukemia: what is the optimal strategy?

Treatment responses to imatinib vary among patients with chronic myeloid leukemia (CML), and definitions of treatment failure and suboptimal response have been published. This article discusses monitoring and treatment of patients with CML after failure of or suboptimal response to imatinib therapy. We reviewed articles listed on PubMed from January 1, 2002, to July 31, 2008, and abstracts from the 2007 Annual Meeting of the American Society of Hematology. Search terms used were chronic myeloid/myelogenous leukemia, imatinib, and BCR-ABL. To enable early recognition of suboptimal responses, patients should be frequently monitored according to published guidelines, including cytogenetic analysis every 6 months until a complete response is achieved and molecular monitoring every 3 months from the start of therapy or monthly if an increasing BCR-ABL1 transcript level is detected. Mutational analysis of BCR-ABL1 may assist with treatment selection. A recent survey suggests that a notable proportion of physicians do not follow treatment guidelines and that broader communication is required. Recent recommendations state that, in patients whose response to imatinib at 400 mg/d is suboptimal, the dose should be increased, whereas alternative therapies, such as dasatinib, nilotinib, and allogeneic stem cell transplant (in eligible patients), and imatinib dose escalation should be considered after imatinib failure. However, clinical data are lacking to confirm this sequence of treatments, and introducing alternative therapies at an earlier stage of treatment, for example, after a suboptimal response, may produce better long-term outcomes in a higher proportion of patients. Patient and disease characteristics should be carefully considered to optimize treatment strategy for CML.

Suboptimal response to or failure of imatinib treatment for chronic myeloid leukemia: what is the optimal strategy?

Treatment responses to imatinib vary among patients with chronic myeloid leukemia (CML), and definitions of treatment failure and suboptimal response have been published. This article discusses monitoring and treatment of patients with CML after failure of or suboptimal response to imatinib therapy. We reviewed articles listed on PubMed from January 1, 2002, to July 31, 2008, and abstracts from the 2007 Annual Meeting of the American Society of Hematology. Search terms used were chronic myeloid/myelogenous leukemia, imatinib, and BCR-ABL. To enable early recognition of suboptimal responses, patients should be frequently monitored according to published guidelines, including cytogenetic analysis every 6 months until a complete response is achieved and molecular monitoring every 3 months from the start of therapy or monthly if an increasing BCR-ABL1 transcript level is detected. Mutational analysis of BCR-ABL1 may assist with treatment selection. A recent survey suggests that a notable proportion of physicians do not follow treatment guidelines and that broader communication is required. Recent recommendations state that, in patients whose response to imatinib at 400 mg/d is suboptimal, the dose should be increased, whereas alternative therapies, such as dasatinib, nilotinib, and allogeneic stem cell transplant (in eligible patients), and imatinib dose escalation should be considered after imatinib failure. However, clinical data are lacking to confirm this sequence of treatments, and introducing alternative therapies at an earlier stage of treatment, for example, after a suboptimal response, may produce better long-term outcomes in a higher proportion of patients. Patient and disease characteristics should be carefully considered to optimize treatment strategy for CML.

Chronic myeloid leukaemia: the evolution of gene-targeted therapy

Chronic myeloid leukaemia (CML) was the first human cancer linked to an acquired chromosomal abnormality, subsequently shown to be a reciprocal translocation between chromosomes 9 and 22. The resulting fusion gene product, BCR-ABL, was shown to be the causative agent of the disease. CML has an incidence of around 1-2 cases per 100,000; in Australia, there are probably more than 200 new cases per year and more than 1300 prevalent cases. Treatment of CML with imatinib has been a powerful vindication of the concept of rational, gene-targeted drug design. Five-year published experience with imatinib at 400 mg orally daily demonstrates 89% overall survival and an estimated 93% freedom from disease progression. Adverse effects are mostly mild and transient. Higher doses of imatinib may be more efficacious and will be studied in upcoming clinical trials in Australia; however, imatinib is almost certainly not curative. Up to 28% of patients may have to stop imatinib because of intolerance or disease resistance, mostly due to point mutations of BCR-ABL. In this situation, many patients will respond to second- and third-generation tyrosine kinase inhibitors. Management of CML patients should involve close monitoring, especially in the first 2 years, with regular cytogenetics and quantitative polymerase chain reaction to optimise response and identify suboptimal responders as early as possible. Bone marrow transplantation remains the only known cure, but is reserved for patients whose kinase inhibitor therapy has failed, or who have advanced disease (accelerated phase or blastic transformation).

Complete molecular responses are achieved after reduced intensity stem cell transplantation and donor lymphocyte infusion in chronic myeloid leukemia

Patients with newly diagnosed chronic phase chronic myeloid leukemia were treated with imatinib mesylate (IM) for 6 to 12 months to establish disease control, before reduced intensity stem cell transplantation (RISCT). Escalating doses of donor lymphocyte infusions were given from 6 months after transplantation to eradicate residual disease. A total of 18 patients entered the study and 15 received RISCT (median follow-up, 31 months). RISCT was well tolerated with rapid engraftment, short inpatient stays, and few readmissions. Viral reactivation was common, although extensive graft-versus-host disease occurred infrequently. Donor lymphocyte infusions were given as part of the RISCT protocol in 13 of 15 patients. BCR-ABL transcripts continued to decrease after RISCT, and 8 (53%) patients achieved sustained undetectable levels. All patients are currently off IM. Although IM is now established as first-line therapy for chronic phase chronic myeloid leukemia, this protocol is a safe, well-tolerated, and effective strategy in these patients. This study is registered at http://www.controlled-trials.com as ISRCTN86187144.

HLA-mismatched/haploidentical hematopoietic stem cell transplantation without in vitro T cell depletion for chronic myeloid leukemia: improved outcomes in patients in accelerated phase and blast crisis phase

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only proven curative therapy for chronic myeloid leukemia (CML), but lack of human leukocyte antigen (HLA)-matched sibling or unrelated donors has restricted its application. Recently, we developed an effective method for haploidentical allo-HSCT achieving comparable outcomes to HLA-identical transplantation.

AIM

To evaluate the outcomes of CML patients who underwent haploidentical allo-HSCT.

METHODS

Ninety-three patients were treated with a modified busulfan (BU)/cyclophosphamide (CY) 2 regimen, including antithymocyte globulin followed by unmanipulated blood and marrow transplantation.

RESULTS

Our data showed that the cumulative incidence of acute graft-versus-host disease (GVHD) was 64.52%, and grade III-IV was 26.45%, 61.79% had chronic GVHD, and 28.93% had extensive chronic GVHD. Non-relapse mortality varied at 8.72% (100 days), 20.72% (1 year) and 20.72% (2 years). Probability of 1-year and 4-year leukemia-free survival was similar in chronic phase (CP) 1, CP2/CR2, accelerated phase, and blast crisis patients. Probability of 4-year overall survival varied as 76.5% (CP1), 85.7% (CP2/CR2), 73.3% (accelerated phase), and 61.5% (blast crisis). Multivariate analysis indicated that factors affecting transplantation outcomes were HLA-B+DR mismatches versus others for II-III acute GVHD and III-IV acute GVHD, the stage of disease at transplantation for relapse, and the time from diagnosis to transplantation for leukemia-free survival, overall survival, and transplantation-related mortality. In our protocol, survival of HSCT for advanced CML was similar to stable stage.

CONCLUSIONS

For patients lacking an HLA-identical related donor, haploidentical relatives are alternative HSCT donors.

Comparison of myeloablative and nonmyeloablative hematopoietic stem cell transplantation for treatment of chronic myeloid leukemia

This retrospective study compared outcomes for 81 chronic myeloid leukemia patients who underwent myeloablative or nonmyeloablative allogeneic hematopoietic stem cell transplantation (HSCT). Sixty-five patients received myeloablative HSCT, and 16 patients received fludarabine (Fd), low-dose busulfan (Bu), and antithymocyte globulin (ATG) in nonmyeloablative HSCT. We determined overall survival (OS) and disease-free survival (DFS), as well as the occurrence of acute and chronic graft-versus-host disease (GVHD). The incidences of acute GVHD of grades II to IV were 14.0% and 18.7% for the myeloablative and nonmyeloablative groups, respectively. The incidence of chronic GVHD was significantly higher in the nonmyeloablative group (80% versus 66%). Five-year OS and DFS rates were significantly higher in nonmyeloablative group (70% for both), compared with 56% and 54%, respectively, for the myeloablative group. A univariate analysis, however, revealed a strong but statistically insignificant trend for enhanced overall OS and DFS in the nonmyeloablative group (P = .1 and .07, respectively). A multivariate analysis with the factors of treatment, age, sex, acute and chronic GVHD, and disease status at the time of transplantation revealed that both OS and DFS were significantly higher in the nonmyeloablative group than in the myeloablative group. These findings suggest that nonmyeloablative Fd/Bu/ATG treatment is at least not inferior (and quite probably superior) in terms of patient outcome compared with standard myeloablative therapy. Further larger-scale randomized clinical trials are warranted to clarify the efficacy of this treatment regimen.

Current and emerging treatment options in chronic myeloid leukemia

Treatments for chronic myeloid leukemia (CML) represent a success story in molecular medicine. The development of imatinib, a tyrosine kinase inhibitor (TKI) targeted against the causative Bcr-Abl oncoprotein in CML, has resulted in hematologic and cytogenetic remissions in all phases of CML. A significant proportion of patients are resistant to imatinib or develop resistance during treatment. This is often a result of mutated forms of the Bcr-Abl oncoprotein to which imatinib is unable to bind. Several strategies have been developed to overcome the problem of imatinib resistance, including high-dose imatinib, novel targeted agents, and combination treatments. Novel agents include dasatinib, a potent TKI that inhibits several critical oncogenic proteins and which has recently been approved for patients with CML who are resistant or intolerant to imatinib; and nilotinib, a potent selective Bcr-Abl kinase inhibitor currently in clinical development. Other agents in development include SKI-606 and INNO-406. Stem cell transplantation remains a useful option, although it is not generally used as first-line treatment. Overall, there are an increasing number of treatment options available for patients with CML.

Diagnosis and management of chronic myeloid leukemia

BACKGROUND

The success of imatinib therapy for chronic myeloid leukemia (CML) has brought new challenges; these include optimizing disease monitoring, imatinib resistance, and use of novel, more potent tyrosine kinase inhibitors. Thus, there is a need to establish new best practices for CML management in the post-imatinib era.

METHODS

An internet-based questionnaire, consisting of 26 multiple choice questions, was developed to assess hematologists' and oncologists' self-reported treatment strategies for CML.

RESULTS

Between November 2005 and January 2006, 956 eligible physicians responded to the survey; 727 from the US and 229 from Europe. Most US respondents (60%) practiced in the community setting, whereas European respondents were primarily academic (44%) and hospital-based (40%). Physicians' responses were generally in line with current recommendations, although differences were identified. Confusion existed among respondents over optimal timing of treatment decisions, with a notable proportion of physicians focusing on a single timepoint rather than consistent monitoring, as currently advocated. Some respondents were unaware of new molecular monitoring techniques, when to monitor for BCR-ABL mutations (and the impact on treatment decisions), and the benefit of new tyrosine kinase inhibitors.

CONCLUSIONS

Responses to the survey suggest that treatment practices in some areas of CML management are not in line with current recommendations. Identified areas of need should be targeted in future educational activities for the CML community.