Standard first-line therapy of chronic myeloid leukemia is treatment with imatinib. In the randomized German Chronic Myeloid Leukemia-Study IV, more potent BCR-ABL inhibition with 800 mg ('high-dose') imatinib accelerated achievement of a deep molecular remission. However, whether and when a de-escalation of the dose intensity under high-dose imatinib can be safely performed without increasing the risk of losing deep molecular response is unknown. To gain insights into this clinically relevant question, we analyzed the outcome of imatinib dose reductions from 800 mg to 400 mg daily in the Chronic Myeloid Leukemia-Study IV. Of the 422 patients that were randomized to the 800 mg arm, 68 reduced imatinib to 400 mg after they had achieved at least a stable major molecular response. Of these 68 patients, 61 (90%) maintained major molecular remission on imatinib at 400 mg. Five of the seven patients who lost major molecular remission on the imatinib standard dose regained major molecular remission while still on 400 mg imatinib. Only two of 68 patients had to switch to more potent kinase inhibition to regain major molecular remission. Importantly, the lengths of the intervals between imatinib high-dose treatment before and after achieving major molecular remission were associated with the probabilities of maintaining major molecular remission with the standard dose of imatinib. Taken together, the data support the view that a deep molecular remission achieved with high-dose imatinib can be safely maintained with standard dose in most patients. Study protocol registered at clinicaltrials.gov 00055874.
PURPOSE Combined-modality treatment (CMT) with 2× ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) and small-field radiotherapy is standard of care for patients with early-stage favorable Hodgkin lymphoma (HL). However, the role of radiotherapy has been challenged. Positron emission tomography (PET) after 2× ABVD (PET-2) might help to predict individual outcomes and guide treatment. METHODS Between November 2009 and December 2015, we recruited patients age 18 to 75 years with newly diagnosed, early-stage favorable HL for this international randomized phase III trial. Patients were assigned to standard CMT of 2× ABVD and 20-Gy involved-field radiotherapy or PET-guided treatment, omitting involved-field radiotherapy after negative PET-2 (Deauville score < 3). Primary objectives were to exclude inferiority of 10% or more in 5-year progression-free survival (PFS) of ABVD alone compared with CMT in a per-protocol analysis among PET-2–negative patients (noninferiority margin for hazard ratio, 3.01) and to confirm PET-2 positivity (Deauville score ≥ 3) as a risk factor for PFS among CMT-treated patients. RESULTS We enrolled 1,150 patients. Median follow-up was 45 months. Among 628 PET-2–negative, per-protocol–treated patients, 5-year PFS was 93.4% (95% CI, 90.4% to 96.5%) with CMT and 86.1% (95% CI, 81.4% to 90.9%) with ABVD (difference 7.3% [95% CI, 1.6% to 13.0%]; hazard ratio, 1.78 [95% CI, 1.02 to 3.12]). Five-year overall survival was 98.1% (95% CI, 96.5% to 99.8%) with CMT and 98.4% (95% CI, 96.5% to 100.0%) with ABVD. Among 693 patients who were assigned to CMT, 5-year PFS was 93.2% (95% CI, 90.2% to 96.2%) among PET-2–negative patients and 88.4% (95% CI, 84.2% to 92.6%) in PET-2–positive patients ( P = .047). When using the more common liver cutoff (Deauville score, 4) for PET-2 positivity, the difference was more pronounced (5-year PFS, 93.1% [95% CI, 90.7% to 95.5%] v 80.9% [95% CI, 72.2% to 89.7%]; P = .0011). CONCLUSION In early-stage favorable HL, a positive PET after two cycles ABVD indicates a high risk for treatment failure, particularly when a Deauville score of 4 is used as a cutoff for positivity. In PET-2–negative patients, radiotherapy cannot be omitted from CMT without clinically relevant loss of tumor control.
