High-dose imatinib mesylate therapy in newly diagnosed Philadelphia chromosome-positive chronic phase chronic myeloid leukemia

Imatinib mesylate (STI571) is effective in chronic phase chronic myelogenous leukemia (CML). However, most patients treated with 400 mg imatinib daily have variable levels of residual molecular disease. We treated 114 patients with newly diagnosed chronic phase CML with 400 mg imatinib twice daily. Overall, 109 patients (96%) had a major cytogenetic response (Philadelphia chromosome [Ph] < 35%), and 103 (90%) had a complete response (Ph 0%). With a median follow-up of 15 months, no patient has progressed to accelerated or blastic phase. The estimated 2-year survival rate was 94%. By quantitative polymerase chain reaction (QPCR) studies, 71 (63%) of 112 patients showed BCR-ABL/ABL percentage ratios decrease to less than 0.05%, and 31 (28%) to undetectable levels. Compared with standard-dose imatinib, high-dose imatinib was associated with significantly better complete cytogenetic response (P =.0005), major molecular response (QPRC < 0.05%; P =.00001), and complete molecular response (undetectable BCR-ABL; P =.001). High-dose imatinib was well tolerated but resulted in more frequent myelosuppression; 82% of patients continue to receive 600 mg or more of imatinib daily. In conclusion, high-dose imatinib induced higher rates of complete cytogenetic response and of molecular response in patients with newly diagnosed chronic phase CML.     

Favorable long-term follow-up results over 6 years for response, survival, and safety with imatinib mesylate therapy in chronic-phase chronic myeloid leukemia after failure of interferon-alpha treatment

Imatinib mesylate, a targeted inhibitor of BCR-ABL tyrosine kinase, is the standard of care for chronic myeloid leukemia (CML). A phase 2 trial of imatinib in late chronic-phase (CP) CML after interferon-alpha (IFNalpha) failure enrolled 532 patients, 454 with a confirmed diagnosis of CP CML. Median time from diagnosis was 34 months; median duration of imatinib treatment was 65 months. Cumulative best rates of major cytogenetic response (MCyR) and complete cytogenetic response (CCyR) were 67% and 57%, respectively. At the 5-year landmark, 184 (41%) of the 454 patients are in CCyR. At more than 6 years, 199 (44%) of the 454 patients remain on imatinib. Most responses occurred within 12 months of starting imatinib; however, some patients achieved initial MCyR and CCyR more than 5 years after imatinib initiation. Estimated rates of freedom from progression to accelerated phase (AP) and blastic phase (BP) and overall survival at 6 years were 61% and 76%, respectively. Both freedom from progression to AP/BP and overall survival (OS) were associated with cytogenetic response level at 12 months. No increase in rates of serious adverse events was observed with continuous use of imatinib for up to 6.5 years, compared with earlier time points. Imatinib continues to be an effective and safe therapy for patients with CP CML after failure of IFN.     

Imatinib mesylate therapy for relapse after allogeneic stem cell transplantation for chronic myelogenous leukemia

Twenty-eight adults with chronic myelogenous leukemia (CML) that had relapsed after allogeneic stem cell transplantation (SCT) received imatinib mesylate (400-1000 mg/d). Disease was in chronic phase in 5 patients, accelerated in 15, and blastic in 8 (7 medullary, 1 extramedullary); median time from transplantation to relapse was 9 months (range, 1-137 months). Thirteen patients had undergone salvage donor lymphocyte infusion (DLI) (median time from DLI to imatinib mesylate therapy, 4 months [range, 2-39 months]). The overall response rate was 79% (22 of 28 patients); the complete hematologic response (CHR) rate was 74% (17 of 23 patients), and the cytogenetic response rate was 58% (15 of 26 patients; complete response in 9 [35%] patients). CHR rates were 100% for chronic phase, 83% for accelerated phase, and 43% for blastic phase. The patient with extramedullary blastic disease achieved complete response. Cytogenetic response rates were 63% (12 of 19 patients) for chronic or accelerated phases (complete cytogenetic response in 8) and 43% for blastic phase (3 of 7 patients). At median follow-up of 15 months, 19 patients were alive, 9 with no evidence of disease. The 1-year estimated survival rate was 74%. Five patients had recurrence of grade 3 (3 patients) or grades 1 to 2 (2 patients) graft-versus-host disease (GVHD). Severe granulocytopenia developed in 43% of patients and thrombocytopenia in 27%; both conditions reversed with dose adjustments of imatinib mesylate. We conclude that imatinib mesylate effectively controlled CML that recurred after allogeneic SCT, but it was associated with side effects including myelosuppression and recurrence of severe GVHD.     

Prognostic significance of cytogenetic clonal evolution in patients with chronic myelogenous leukemia on imatinib mesylate therapy

Cytogenetic clonal evolution (CE) is a known poor prognostic factor in Philadelphia chromosome-positive chronic myelogenous leukemia (Ph-positive CML). However, its prognostic relevance in the era of imatinib therapy is unknown. We investigated the independent prognostic relevance of CE in 498 patients with Ph-positive CML treated with imatinib for chronic or accelerated phases. One hundred twenty-one patients had CE alone (n = 70) or with other accelerated phase criteria (n = 51). Patients were compared in 4 categories: chronic phase (n = 295), CE only (n = 70), accelerated phase without CE (n = 82), and accelerated phase with CE (n = 51). Statistical methods used established methodologies for univariate and multivariate analyses. In chronic and accelerated phases of CML, CE was not associated with significant differences in major or complete cytogenetic response rates, but it was an independent poor prognostic factor for survival by multivariate analyses in both chronic (P =.005) and accelerated phase (P =.03). Multivariate analyses conducted at the 3-month landmark (including the 3-month cytogenetic response) identified the lack of cytogenetic response at 3 months to be a stronger independent poor prognostic factor for survival than CE for both chronic (major cytogenetic response versus other) and accelerated phase (any cytogenetic response versus other). We conclude that cytogenetic CE is not an important factor for achieving major or complete cytogenetic response with imatinib mesylate therapy, but it is an independent poor prognostic factor for survival in both chronic and accelerated phases of CML. The 3-month cytogenetic response to imatinib mesylate refined the prognostic relevance of such studies in patients on imatinib mesylate therapy.     

Survival benefit with imatinib mesylate versus interferon-alpha-based regimens in newly diagnosed chronic-phase chronic myelogenous leukemia

A survival benefit for imatinib mesylate versus interferon-alpha therapy could not be demonstrated in the randomized study in newly diagnosed Philadelphia chromosome (Ph)-positive chronic-phase chronic myelogenous leukemia (CML) due to the high rate of crossover (90%) from interferon-alpha to imatinib mesylate within a year of study entry. We compared survival in 279 patients with newly diagnosed CML treated with imatinib mesylate at our institution (2000-2004) to 650 patients treated with interferon-alpha (1982-1997). The complete cytogenetic response rates were 87% with imatinib mesylate and 28% with interferon-alpha (P < .001). The estimated 3-year survival rates were 96% with imatinib mesylate and 81% with interferon-alpha (P < .01). Survival rates with imatinib mesylate were significantly better than with interferon-alpha within each of the CML prognostic risks groups. By multivariate analysis, imatinib mesylate therapy was identified as an independent favorable prognostic factor, after accounting for the impact of pretreatment factors (hazard ratio, 0.44; P < .01). By landmark analysis at 12 months, survival within each cytogenetic response category was similar with imatinib mesylate or interferon-alpha, suggesting that the survival benefit of imatinib mesylate (versus interferon-alpha in newly diagnosed CML) is through improving cytogenetic response.     

Bosutinib efficacy and safety in chronic phase chronic myeloid leukemia after imatinib resistance or intolerance: Minimum 24‐month follow‐up

Bosutinib is an orally active, dual Src/Abl tyrosine kinase inhibitor for treatment of chronic myeloid leukemia (CML) following resistance/intolerance to prior therapy. Here, we report the data from the 2‐year follow‐up of a phase 1/2 open‐label study evaluating the efficacy and safety of bosutinib as second‐line therapy in 288 patients with chronic phase CML resistant (n = 200) or intolerant (n = 88) to imatinib. The cumulative response rates to bosutinib were as follows: 85% achieved/maintained complete hematologic response, 59% achieved/maintained major cytogenetic response (including 48% with complete cytogenetic response), and 35% achieved major molecular response. Responses were durable, with 2‐year estimates of retaining response >70%. Two‐year probabilities of progression‐free survival and overall survival were 81% and 91%, respectively. The most common toxicities were primarily gastrointestinal adverse events (diarrhea [84%], nausea [45%], vomiting [37%]), which were primarily mild to moderate, typically transient, and first occurred early during treatment. Thrombocytopenia was the most common grade 3/4 hematologic laboratory abnormality (24%). Outcomes were generally similar among imatinib‐resistant and imatinib‐intolerant patients and did not differ with age. The longer‐term results of the present analysis confirm that bosutinib is an effective and tolerable second‐line therapy for patients with imatinib‐resistant or imatinib‐intolerant chronic phase CML. ClinicalTrials.gov Identifier: NCT00261846. Am. J. Hematol. 89:732–742, 2014. © 2014 The Authors American Journal of Hematology Published by Wiley Periodicals, Inc.     

Imatinib mesylate (STI571) therapy for Philadelphia chromosome-positive chronic myelogenous leukemia in blast phase

Molecular abnormalities caused by the hybrid Bcr-Abl gene are causally associated with the development and progression of Philadelphia chromosome-positive (Ph(+)) chronic myelogenous leukemia (CML). Imatinib mesylate (STI571), a specific Bcr-Abl tyrosine-kinase signal-transduction inhibitor, has shown encouraging activity in phase I and II studies of CML. Here, we describe the use of imatinib mesylate to treat 75 patients in blast-phase CML (median age, 53 years; 65 with nonlymphoid and 10 with lymphoid blasts), and compare the results with those of a historical control group treated with standard cytarabine-based therapy. Imatinib mesylate was given as oral doses at 300 to 1000 mg per day and was the first salvage therapy for 47 patients. The objective response rate was 52% (39 of 75 patients: 16 had complete and 3 had partial hematologic response; 12 had hematologic improvement; 7 returned to second chronic phase; and 1 had a complete response in extramedullary blastic disease). Response rates were not different between nonlymphoid and lymphoid groups. The cytogenetic response rate was 16% (12 patients: 5 complete, 3 partial [Ph(+) below 35%], and 4 minor [Ph(+), 34% to 90%]). The estimated median overall survival was 6.5 months; the estimated 1-year survival was 22%. Response to therapy (landmark analysis at 8 weeks) was associated with survival prolongation. Compared with standard cytarabine combinations, imatinib mesylate therapy was less toxic and produced a higher response rate (55% versus 29%, P =.001), longer median survival (7 versus 4 months, P =.04), and lower 4-week induction mortality (4% versus 15%, P =.07). Imatinib mesylate is currently being tested in combination with other drugs to improve the prognosis for blast-phase CML.     

Imatinib improves but may not fully reverse the poor prognosis of patients with CML with derivative chromosome 9 deletions

Deletions of the derivative chromosome 9 occur in a subset of patients with Philadelphia chromosome-positive chronic myeloid leukemia (CML) and are associated with a poor prognosis on standard drug therapy. However, it is currently unknown if the presence of deletions influences the response to imatinib, an Abl-specific tyrosine kinase inhibitor, that has recently shown excellent hematologic and cytogenetic responses in patients with CML. We, therefore, compared hematologic and cytogenetic responses with imatinib in 397 patients with CML, and survival and progression in 354 of these patients, according to deletion status and disease phase. We found no difference in survival between patients with and without deletions, contrasting with previous reports in cohorts with a lower proportion of patients treated with imatinib. However, the time to disease progression on imatinib treatment was significantly shorter for patients with deletions, both in chronic phase (P =.02) and advanced phases (P =.02). Moreover, both in chronic phase and more advanced phases of CML, hematologic and cytogenetic responses were uniformly lower in patients with deletions, with significant differences seen for hematologic response (P =.04), for major cytogenetic response (P =.008) in chronic phase, and for hematologic response in advanced phases (P =.007) of CML. This finding suggests that differences in survival may become apparent with longer follow-up.     

Long-term follow-up of patients with chronic myeloid leukemia having received autologous stem cell transplantation

Prior to introduction of imatinib mesylate, the median survival of chronic myeloid leukemia (CML) patients was approximately 60?months and the standard treatment with interferon-alpha (IFN-α) resulted in major cytogenetic responses of 20-25%. As an alternative treatment approach besides allogeneic transplantation, intensive chemotherapy followed by autologous hematopoietic stem cell transplantation (autoHSCT) was investigated at that time with the rationale of debulking disease burden and mobilization and transplantation of Philadelphia chromosome-negative (Ph-) stem cells. In the era of tyrosine kinase inhibitors as state-of-the-art therapy for CML, the concept of autoHSCT has attracted only little interest and long-term follow-up and outcome data after autoHSCT in CML patients is scarce. In this long-term analysis, we report on 21 CML patients, mobilized in early chronic phase and transplanted with largely Ph- grafts, who received IFNα as maintenance therapy. Imatinib mesylate was administered upon cytogenetic relapse or disease progression while on IFN-α. The 10-year survival was 61% and 11 patients (52%) were alive at a median follow-up of 12.5?years (range 0.3-13.8) with eight patients in complete hematologic remission (CHR) and three of eight in major molecular remission (MMR). While all patients in MMR and two of five patients in CHR received imatinib, it is noteworthy that three patients remaining in CHR only received IFN-α maintenance after autoHSCT. With the limitations of a small patient population, this is the longest follow-up analysis demonstrating that autoHSCT in CML is very efficient to debulk the disease, restore Ph-negative hematopoiesis, and is able to induce major and sustained molecular responses in the majority of patients with substantial long-term survival rates.     

Evaluation of Long-Term Outcomes, Cytogenetic and Molecular Responses with Imatinib Mesylate in Early and Late Chronic-Phase Chronic Myeloid Leukemia: A Report from a Single Institute

Here we compare the management and survival outcomes of chronic myeloid leukemia (CML) patients who had early or late imatinib mesylate (IM) therapy. The cytogenetic and molecular responses of 189 CML patients were analyzed. Of this group, 121 patients were classified as the early chronic phase (ECP) group and started IM within 12 months of diagnosis. The other 68 patients were classified as the late chronic phase (LCP) group who had been treated with interferon (IFN)-alpha-2 and crossed over to IM more than 12 months after diagnosis. The overall rates of complete cytogenetic response (CCyR) and major molecular response (MMR) at last follow-up were 83.6 and 78.1% in the ECP and LCP groups, respectively. The CCyR rates were 89.3 (for ECP patients) versus 73.5% (for LCP patients; p < 0.0001). At last follow-up, 82.4% ECP and 64.2% LCP patients had achieved an MMR (p < 0.0001). No significant differences were noted between the two groups with regard to survival outcomes. Our experience reveals that IM is an effective rescue therapy in most CML LCP patients who are intolerant or in whom IFN-alpha therapy fails. Such therapeutic options should be considered in LCP patients, particularly in countries where IM may not be available.     

Predictive factors for outcome and response in patients treated with second-generation tyrosine kinase inhibitors for chronic myeloid leukemia in chronic phase after imatinib failure

We assessed the predictive factors for outcome and response in 123 patients with chronic myeloid leukemia in chronic phase treated with second-generation tyrosine kinase inhibitors (TKIs) after imatinib failure. Better event-free survival rates with second-generation TKI therapy were associated with a previous cytogenetic response to imatinib (P < .001) and a performance status of 0 (P = .001). Patients with 0, 1, or 2 adverse factors had 2-year event-free survival rates of 78%, 49%, and 20% (P < .001), respectively; 2-year overall survival rates of 95%, 85%, and 40%, (P = .002), respectively; and a 12-month probability of achieving a major cytogenetic response of 64%, 36%, and 20% (P = .007), respectively. In conclusion, patients with poor performance status and no previous cytogenetic response to imatinib therapy have a low likelihood of responding to second-generation TKI with poor event-free survival and therefore should be offered additional treatment options. This scoring system could serve to advise patients of their prognosis and treatment options, as well as to evaluate the benefit of newer alternate options.     

Excellent outcomes of children with CML treated with imatinib mesylate compared to that in pre-imatinib era

Allogeneic hematopoietic stem cell transplantation (HSCT) and tyrosine kinase inhibitor have revolutionized the treatment of patients with chronic myeloid leukemia (CML). In this study, the clinical impact of HSCT and imatinib mesylate (IM) was retrospectively analyzed in 28 children with CML treated in our institutes from 1984 to 2008. Twelve patients were given oral IM. At 36?months after initiation of IM therapy, the complete cytogenetic response rate was 90.9%, and the major molecular response rate was 36.4%. Sixteen children received allogeneic HSCT without administration of IM. The stage of disease at transplantation was: first chronic phase (n?=?10), second chronic phase (n?=?2), accelerated phase (n?=?2), and blastic crisis (n?=?2). The progression rate was significantly lower in patients treated with IM than in those treated without IM (0 vs. 28.6%, p?=?0.006). In summary, the survival outcomes of pediatric patients with CML were dramatically improved by treatment with IM compared to HSCT.     

Imatinib for newly diagnosed chronic-phase chronic myeloid leukemia: results of a prospective study in Japan

Although imatinib has become the current standard treatment for chronic myeloid leukemia (CML), there is limited information regarding its efficacy and safety among Japanese patients. We therefore conducted a prospective multi-center open-label study of imatinib for Japanese patients with newly diagnosed chronic-phase CML (CP-CML). A total of 107 patients were enrolled and treated with imatinib at an initial daily dose of 400 mg. Eighty-three patients completed 3 years of study treatment. The cumulative rates of major cytogenetic response and complete cytogenetic response (CCyR) were 90.9 and 90.2% at 3 years, respectively. The safety profile was not very different from that reported in the IRIS study, although grade ≥3 neutropenia occurred relatively frequently (31.8 vs. 14.3%). Only seven patients discontinued the study due to adverse events, as did four patients due to insufficient efficacy. The 3-year probabilities of overall survival and progression-free survival were 93.2 and 91.4%, respectively. Higher average daily doses (i.e., ≥350 mg) were significantly associated not only with higher rates of achieving CCyR, but also with longer duration of CCyR. These findings confirm the clinical utility of imatinib in Japanese patients with newly diagnosed CP-CML, and suggest detrimental effect of low average daily dose on treatment results.     

Result of high-dose imatinib mesylate in patients with Philadelphia chromosome-positive chronic myeloid leukemia after failure of interferon-alpha

Imatinib at 400 mg daily is effective in chronic-phase chronic myeloid leukemia (CML) after interferon failure, although only a few patients achieve a molecular remission. We investigated whether higher doses of imatinib may be more effective. Thirty-six patients with chronic-phase CML after failure on interferon-alpha were treated with 400 mg imatinib twice daily. Median time from diagnosis was 25 months (range, 10-135 months); 4 patients (11%) had clonal evolution. All 11 patients with active disease achieved complete hematologic response. Excluding patients with fewer than 35% Ph-positive metaphases before the start of therapy, 19 (90%) of 21 evaluable patients achieved a major cytogenetic response. Of 27 evaluable patients, 24 (89%) achieved a complete cytogenetic response. Quantitative polymerase chain reaction was performed in bone marrow every 3 months. Of 32 evaluable patients, 18 (56%) showed BCR-ABL/ABL percentage ratios lower than 0.045%, including 13 (41%) with undetectable levels. With a median follow-up of 15 months, all patients were alive in chronic phase. Toxicities were similar to those reported with standard dose; 71% of patients continue to receive 600 mg or more of imatinib daily. In conclusion, high-dose imatinib induces complete cytogenetic responses in most patients with chronic-phase CML after interferon failure. This is accompanied by a high rate of molecular remission.     

Imatinib Mesylate in the Treatment of Chronic Myelogenous Leukemia

Imatinib mesylate binds to the inactive conformation of BCR-ABL tyrosine kinase, suppressing the Philadelphia chromosome-positive clone in chronic myelogenous leukemia (CML). Clinical studies of imatinib have yielded impressive results in the treatment of all phases of CML. With the higher rates of complete cytogenetic response with imatinib, molecular monitoring of disease has become mandatory in assessing response and determining prognosis. The practical aspects of the treatment of CML with imatinib are discussed. The emergence of imatinib resistance, albeit in a small percentage of patients, has prompted an evaluation of innovative treatment strategies.     

Imatinib mesylate in Philadelphia chromosome-positive, chronic-phase myeloid leukemia after failure of interferon alpha

Imatinib mesylate (STI 571; Glivec) is a potent and selective tyrosine kinase inhibitor. The introduction of imatinib has chanced the philosophy of mechanisms of cancer therapy and already changed current management of patients with chronic myeloid leukemia (CML). A total of 49 patients with later chronic phase CML in whom previous therapy with interferon alpha had failed were treated with 400 mg of oral imatinib daily. Patients were evaluated for hematologic and cytogenetic responses. Time to progression, survival, and toxic effects were also evaluated. Complete hematologic responses were reported for 48 of 49 patients studied (98 percent). The median time to a complete hematologic response was 1.2 month; 89% of patients who had a response did so within 4 months. Imatinib induced major cytogenetic responses in 73%; 62% had a complete responses. After a median follow-up of 18 months, CML had not progressed to the accelerated or blast phases in an estimated 98% of patients, and 100 percent of the patients were alive. Grade 3 or 4 nonhematologic toxic effects were manageable. No one of patients discontinued treatment due to of drug-related adverse events, and no treatment-related deaths occurred. The results of current study indicate that imatinib has a significant therapy benefit in CML patients in whom treatment with IFN alpha had failed. Therefore, has favorably changed the prognosis for patients with chronic myelogenous leukemia.     

The long-term durability of cytogenetic responses in patients with accelerated phase chronic myeloid leukemia treated with imatinib 600 mg: the GIMEMA CML Working Party experience after a 7-year follow-up

Background

Imatinib mesylate is the first line treatment for chronic myeloid leukemia. The advent of imatinib increased survival significantly in patients in an advanced phase of the disease. However, few long-term data on the outcome of these patients based on large, prospective and controlled trials are available.

Design and Methods

A phase 2 multicenter trial of the use of imatinib 600 mg/daily in patients with accelerated phase chronic myeloid leukemia was sponsored and promoted by the Italian Cooperative Study Group on Chronic Myeloid Leukemia in 2001.

Results

One hundred and eleven patients were enrolled; the median follow-up of the 41 living patients is 82 months (range, 73–87). One hundred and seven patients (96%) returned to chronic phase and 79 patients (71%) achieved a complete hematologic response. Cumulative best rates of major cytogenetic response and complete cytogenetic response were 30% and 21%, respectively. All responses were maintained for a minimum of 4 weeks. At last follow-up, four patients were alive in complete remission after allogeneic transplant, 16 patients (14%) had switched to a second generation tyrosine kinase inhibitor and 21 patients (19%) were alive on imatinib therapy. No late toxicities were observed. Progression-free survival and event-free survival rates were 36.5% and 15%, respectively, at 7 years. The median survival time was 37 months, and was significantly associated with the achievement of a complete hematologic response or a complete cytogenetic response.

Conclusions

Imatinib may induce durable responses, associated with prolonged survival, in patients with accelerated phase chronic myeloid leukemia