Christopher Arthur

Multicenter, Randomized, Open-Label, Phase III Trial of Decitabine Versus Patient Choice, With Physician Advice, of Either Supportive Care or Low-Dose Cytarabine for the Treatment of Older Patients With Newly Diagnosed Acute Myeloid Leukemia

PURPOSE This multicenter, randomized, open-label, phase III trial compared the efficacy and safety of decitabine with treatment choice (TC) in older patients with newly diagnosed acute myeloid leukemia (AML) and poor- or intermediate-risk cytogenetics. PATIENTS AND METHODS Patients (N = 485) age ≥ 65 years were randomly assigned 1:1 to receive decitabine 20 mg/m(2) per day as a 1-hour intravenous infusion for five consecutive days every 4 weeks or TC (supportive care or cytarabine 20 mg/m(2) per day as a subcutaneous injection for 10 consecutive days every 4 weeks). The primary end point was overall survival (OS); the secondary end point was the complete remission (CR) rate plus the CR rate without platelet recovery (CRp). Adverse events (AEs) were recorded. RESULTS The primary analysis with 396 deaths (81.6%) showed a nonsignificant increase in median OS with decitabine (7.7 months; 95% CI, 6.2 to 9.2) versus TC (5.0 months; 95% CI, 4.3 to 6.3; P = .108; hazard ratio [HR], 0.85; 95% CI, 0.69 to 1.04). An unplanned analysis with 446 deaths (92%) indicated the same median OS (HR, 0.82; 95% CI, 0.68 to 0.99; nominal P = .037). The CR rate plus CRp was 17.8% with decitabine versus 7.8% with TC (odds ratio, 2.5; 95% CI, 1.4 to 4.8; P = .001). AEs were similar for decitabine and cytarabine, although patients received a median of four cycles of decitabine versus two cycles of TC. The most common drug-related AEs with decitabine were thrombocytopenia (27%) and neutropenia (24%). CONCLUSION In older patients with AML, decitabine improved response rates compared with standard therapies without major differences in safety. An unplanned survival analysis showed a benefit for decitabine, which was not observed at the time of the primary analysis.

Safety and efficacy of imatinib cessation for CML patients with stable undetectable minimal residual disease: results from the TWISTER study

Most patients with chronic myeloid leukemia (CML) treated with imatinib will relapse if treatment is withdrawn. We conducted a prospective clinical trial of imatinib withdrawal in 40 chronic-phase CML patients who had sustained undetectable minimal residual disease (UMRD) by conventional quantitative polymerase chain reaction (PCR) on imatinib for at least 2 years. Patients stopped imatinib and were monitored frequently for molecular relapse. At 24 months, the actuarial estimate of stable treatment-free remission was 47.1%. Most relapses occurred within 4 months of stopping imatinib, and no relapses beyond 27 months were seen. In the 21 patients treated with interferon before imatinib, a shorter duration of interferon treatment before imatinib was significantly associated with relapse risk, as was slower achievement of UMRD after switching to imatinib. Highly sensitive patient-specific BCR-ABL DNA PCR showed persistence of the original CML clone in all patients with stable UMRD, even several years after imatinib withdrawal. No patients with molecular relapse after discontinuation have progressed or developed BCR-ABL mutations (median follow-up, 42 months). All patients who relapsed remained sensitive to imatinib re-treatment. These results confirm the safety and efficacy of a trial of imatinib withdrawal in stable UMRD with frequent, sensitive molecular monitoring and early rescue of molecular relapse.

Patients with chronic myeloid leukemia who maintain a complete molecular response after stopping imatinib treatment have evidence of persistent leukemia by DNA PCR

Around 40–50% of patients with chronic myeloid leukemia (CML) who achieve a stable complete molecular response (CMR; undetectable breakpoint cluster region-Abelson leukemia gene human homolog 1 (BCR–ABL1) mRNA) on imatinib can stop therapy and remain in CMR, at least for several years. This raises the possibility that imatinib therapy may not need to be continued indefinitely in some CML patients. Two possible explanations for this observation are (1) CML has been eradicated or (2) residual leukemic cells fail to proliferate despite the absence of ongoing kinase inhibition. We used a highly sensitive patient-specific nested quantitative PCR to look for evidence of genomic BCR–ABL1 DNA in patients who sustained CMR after stopping imatinib therapy. Seven of eight patients who sustained CMR off therapy had BCR–ABL1 DNA detected at least once after stopping imatinib, but none has relapsed (follow-up 12–41 months). BCR–ABL1 DNA levels increased in all of the 10 patients who lost CMR soon after imatinib cessation, whereas serial testing of patients in sustained CMR showed a stable level of BCR–ABL1 DNA. This more sensitive assay for BCR–ABL1 provides evidence that even patients who maintain a CMR after stopping imatinib may harbor residual leukemia. A search for intrinsic or extrinsic (for example, immunological) causes for this drug-free leukemic suppression is now indicated.

Impact of early dose intensity on cytogenetic and molecular responses in chronic- phase CML patients receiving 600 mg/day of imatinib as initial therapy

We conducted a trial in 103 patients with newly diagnosed chronic phase chronic myeloid leukemia (CP-CML) using imatinib 600 mg/day, with dose escalation to 800 mg/day for suboptimal response. The estimated cumulative incidences of complete cytogenetic response (CCR) by 12 and 24 months were 88% and 90%, and major molecular responses (MMRs) were 47% and 73%. In patients who maintained a daily average of 600 mg of imatinib for the first 6 months (n = 60), MMR rates by 12 and 24 months were 55% and 77% compared with 32% and 53% in patients averaging less than 600 mg (P = .037 and .016, respectively). Dose escalation was indicated for 17 patients before 12 months for failure to achieve, or maintain, major cytogenetic response at 6 months or CCR at 9 months but was only possible in 8 patients (47%). Dose escalation was indicated for 73 patients after 12 months because their BCR-ABL level remained more than 0.01% (international scale) and was possible in 45 of 73 (62%). Superior responses achieved in patients able to tolerate imatinib at 600 mg suggests that early dose intensity may be critical to optimize response in CP-CML. The trial was registered at www.ANZCTR.org.au as #ACTRN12607000614493.

Imatinib produces significantly superior molecular responses compared to interferon alfa plus cytarabine in patients with newly diagnosed chronic myeloid leukemia in chronic phase

We analyzed molecular responses in 55 newly diagnosed chronic-phase chronic myeloid leukemia (CML) patients enrolled in a phase 3 study (the IRIS trial) comparing imatinib to interferon-alfa plus cytarabine (IFN+AraC). BCR-ABL/BCR% levels were measured by real-time quantitative RT-PCR and were significantly lower for the imatinib-treated patients at all time points up to 18 months, P<0.0001. The median levels for imatinib-treated patients continued to decrease and had not reached a plateau by 24 months. A total of 24 IFN+AraC-treated patients crossed over to imatinib. Once imatinib commenced, the median BCR-ABL/BCR% levels in these patients were not significantly different to those on first-line imatinib for the equivalent number of months. The incidence of progression in imatinib-treated patients, defined by hematologic, cytogenetic or quantitative PCR criteria, was significantly higher in the patients who failed to achieve a 1 log reduction by 3 months or a 2 log reduction by 6 months, P=0.002. A total of 49 patients were screened for BCR-ABL kinase domain mutations. Mutations were detected in two imatinib-treated patients who crossed over from IFN+AraC and both lost their imatinib response. In conclusion, first-line imatinib-treated patients had profound reductions in BCR-ABL/BCR%, which significantly exceeded those of IFN+AraC-treated patients and early measurements were predictive of subsequent response.

BCR-ABL messenger RNA levels continue to decline in patients with chronic phase chronic myeloid leukemia treated with imatinib for more than 5 years and approximately half of all first-line treated patients have stable undetectable BCR-ABL using strict sensitivity criteria.

Purpose: In the first years of imatinib treatment, BCR-ABL remained detectable in all but a small minority of patients with chronic myeloid leukemia. We determined whether BCR-ABL continues to decline with longer imatinib exposure and the incidence and consequence of undetectable BCR-ABL. Experimental Design: BCR-ABL levels were measured in a subset of 53 imatinib-treated IRIS trial patients for up to 7 years (29 first-line, 24 second-line). Levels were deemed undetectable using strict PCR sensitivity criteria. Results: By 18 months, the majority achieved a 3-log reduction [major molecular response (MMR)]. BCR-ABL continued to decline but at a slower rate (median time to 4-log reduction and undetectable BCR-ABL of 45 and 66 months for first-line). The probability of undetectable BCR-ABL increased considerably from 36 to 81 months of first-line imatinib {7% [95% confidence interval (95% CI), 0-17%] versus 52% (95% CI, 32-72%)}. Undetectable BCR-ABL was achieved in 18 of 53 patients and none of these 18 lost MMR after a median follow-up of 33 months. Conversely, MMR was lost in 6 of 22 (27%) patients with sustained detectable BCR-ABL and was associated with BCR-ABL mutations in 3 of 6. Loss of MMR was recently defined as suboptimal imatinib response. There was no difference in the probability of achieving molecular responses between first- and second-line patients but first-line had a significantly higher probability of maintaining MMR [P = 0.03; 96% (95% CI, 88-100%) versus 71% (95% CI, 48-93%)]. Conclusions: With prolonged therapy, BCR-ABL continued to decline in most patients and undetectable BCR-ABL was no longer a rare event. Loss of MMR was only observed in patients with sustained detectable BCR-ABL.

Randomized dose-finding study of darbepoetin alfa in anaemic patients with lymphoproliferative malignancies

Summary. Darbepoetin alfa is a novel erythropoiesis‐stimulating protein with a prolonged serum half‐life. This randomized, double‐blind, placebo‐controlled, dose‐finding study investigated the efficacy and safety of darbepoetin alfa in anaemic patients with lymphoproliferative malignancies who were receiving chemotherapy. Patients were randomized in a 1:2:2:1 ratio to receive darbepoetin alfa 1·0 μg/kg (n = 11), 2·25 μg/kg (n = 22), 4·5 μg/kg (n = 22) or placebo (n = 11), administered subcutaneously once weekly for 12 weeks. No dose increases were allowed during the study. A higher proportion of patients achieved a haemoglobin response (defined as a ≥ 2·0 g/dl increase from baseline) in the darbepoetin alfa 1·0 μg/kg (45%), 2·25 μg/kg (55%) and 4·5 μg/kg (62%) groups than in the placebo group (10%; P < 0·01). The mean change in haemoglobin from baseline to week 13 was 1·56 g/dl in the 1·0 μg/kg group, 1·64 g/dl in the 2·25 μg/kg group and 2·46 g/dl in the 4·5 μg/kg group, compared with a mean change of 1·00 g/dl in the placebo group. The overall safety profile of darbepoetin alfa in this study was similar to that of placebo. These results show that darbepoetin alfa effectively and safely increased haemoglobin concentrations in patients with lymphoproliferative malignancies. Confirmative studies at doses of 2·25 and/or 4·5 μg/kg/week in this population are warranted.

Factors affecting the outcome of allogeneic bone marrow transplantation for adult patients with refractory or relapsed acute leukaemia

We evaluated the outcome of allogeneic bone marrow transplantation (BMT) for advanced acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL) in 383 adult patients in nine Australian adult BMT centres between 1981 and 1997. The median overall survival for the group was 4.8 months, with an estimated 5‐year survival of 18%. 28% of patients died of transplant‐related toxicities within the first 100 d. Progressive disease was responsible for 48% of deaths. Multi‐factor analysis demonstrated that AML (v ALL), disease status (second complete remission [CR2] v others), age (< 40 years) and duration of prior first complete remission (CR1) (> 6 months) were pre‐transplant variables significantly associated with improved survival. Acute graft‐versus‐host disease (GVHD) of any grade reduced the rate of relapse in both AML and ALL, but only grades I–II were associated with improved survival. Both limited and extensive chronic GVHD were associated with increased survival. Only patients with AML in untreated first relapse or CR2, with a duration of CR1 > 6 months, or patients with T ALL, had a 5‐year survival > 20%. Transplants for AML in induction failure or pre‐B ALL in untreated first relapse or CR2 had an intermediate outcome, with 5‐year survival of 10–20%. A 5‐year survival of < 10% was observed for patients transplanted for ALL in induction failure or for pre‐B ALL or AML in refractory first relapse or beyond CR2. These results suggest that for most adult patients with advanced acute leukaemia an allograft offers only a small chance of cure.

Measurement of In Vivo BCR-ABL Kinase Inhibition to Monitor Imatinib-Induced Target Blockade and Predict Response in Chronic Myeloid Leukemia

PURPOSE Intrinsic sensitivity to imatinib, based on measurement of inhibitory concentration 50% for imatinib, is variable in untreated patients with chronic myeloid leukemia (CML). This suggests that patient-tailored dosing may be more rational than a fixed dose for all. Dose optimization potentially could be based on accurate measurement of the level of BCR-ABL kinase inhibition achieved in vivo. PATIENTS AND METHODS In vivo kinase inhibition was measured by calculating the reduction in protein (p)--Crkl level in mononuclear blood cells taken from 49 CML patients at weekly intervals after imatinib therapy was commenced. RESULTS Greater than 50% inhibition (> 50% reduction in p-Crkl from baseline) was achieved by 21% of patients by days 7 to 14 (and maintained in all patients on days 21 to 28) and an additional 24% of patients achieved more than 50% inhibition by days 21 to 28. Thus, overall 45% of patients achieved more than 50% inhibition. All of these patients achieved major molecular responses by 24 months compared with 56% of the patients who failed to achieve 50% kinase inhibition (P < .001). Patients with less than 50% kinase inhibition were also more likely to have suboptimal responses. CONCLUSION In vivo BCR-ABL kinase inhibition can be assessed in the first month of imatinib therapy and may provide a valuable guide to optimization of dosage. The extent of BCR-ABL kinase inhibition is an excellent predictor of cytogenetic and molecular response. These observations suggest that dose adjustment based on in vivo measurements of drug-induced target inhibition could be applied in settings beyond imatinib and may be a more effective approach than using one dose for all patients in targeted anticancer therapy.

Combined Interferon Alfa-2a and Cytosine Arabinoside as First-Line Treatment for Chronic Myeloid Leukemia

Thirty patients with chronic myeloid leukemia in chronic phase and less than 1 year from diagnosis were treated with a combination of interferon alfa-2a (IFN) 9 million units daily continuously and intermittent low-dose cytosine arabinoside (Ara-C) 20 mg/m2 daily for 21 days every 42 days. The leukemia was controlled initially with hydroxyurea prior to commencing IFN and Ara-C. The treatment was continued for at least 12 months after which time nonresponders were withdrawn from the trial and responders continued on IFN alone. The median duration of follow-up is 14 months (range 10-53 months). Hematological response was assessed by clinical and laboratory parameters and cytogenetic response was assessed by regular bone marrow chromosome analysis. A complete hematological response occurred in 28/30 patients (93%). A complete cytogenetic response (no detectable Philadelphia chromosome-positive metaphases) was present on at least one occasion in 9/30 (30%), a partial cytogenetic response (between 1 and 34% Philadelphia chromosome-positive metaphases) in 7/30 (23%) and a minor response in 4/30 (13%), giving an overall cytogenetic response rate of 67%. Significant side effects included mucositis, nausea, cytopenia and depression. Side effects could be managed by dose reduction or temporary cessation and were tolerable in most patients, but in 1 patient this led to withdrawal from the trial due to severe depression. Two patients have transformed, 1 to acute lymphoblastic leukemia and 1 to accelerated phase. Two patients have died after exiting the study, both from complications of allogeneic bone marrow transplantation. In conclusion, these results are superior to the results using IFN alone and indicate the need for a randomized study.