Molecular relapse in adult standard-risk ALL patients detected by prospective MRD monitoring during and after maintenance treatment: data from the GMALL 06/99 and 07/03 trials.

Although levels of minimal residual disease (MRD) decrease below the detection limit in most adult patients with standard-risk acute lymphoblastic leukemia (ALL) after consolidation treatment, about 30% of these patients will ultimately relapse. To evaluate the power of MRD monitoring as an indicator of impending relapse, we prospectively analyzed postconsolidation samples of 105 patients enrolled in the German Multicenter ALL (GMALL) trial by real-time quantitative polymerase chain reaction (PCR) of clonal immune gene rearrangements. All patients were in hematologic remission, had completed first-year polychemotherapy, and tested MRD negative prior to study entry. Twenty-eight of 105 patients (27%) converted to MRD positivity thereafter, and 17 of 28 (61%) relapsed so far. Median time from molecular (MRD-positive) to clinical relapse was 9.5 months. In 15 of these patients, MRD within the quantitative range of PCR was measured in hematologic remission, and 13 of these patients (89%) relapsed after a median interval of 4.1 months. Of the 77 continuously MRD-negative patients, only 5 (6%) have relapsed. We conclude that conversion to MRD positivity during the early postconsolidation phase in adult standard-risk ALL patients is highly predictive of subsequent hematologic relapse. As a result of the study, as of spring 2006, salvage treatment in the ongoing GMALL trial is intended to be started at the time of recurrence of quantifiable MRD.

Alternating versus concurrent schedules of imatinib and chemotherapy as front-line therapy for Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL).

The best strategy for incorporating imatinib in front-line treatment of Ph+ acute lymphoblastic leukemia (ALL) has not been established. We enrolled 92 patients with newly diagnosed Ph+ ALL in a prospective, multicenter study to investigate sequentially 2 treatment schedules with imatinib administered concurrent to or alternating with a uniform induction and consolidation regimen. Coadministration of imatinib and induction cycle 2 (INDII) resulted in a complete remission (CR) rate of 95% and polymerase chain reaction (PCR) negativity for BCR-ABL in 52% of patients, compared with 19% in patients in the alternating treatment cohort (P = .01). Remarkably, patients with and without a CR after induction cycle 1 (INDI) had similar hematologic and molecular responses after concurrent imatinib and INDII. In the concurrent cohort, grades III and IV cytopenias and transient hepatotoxicity necessitated interruption of induction in 87% and 53% of patients, respectively; however, duration of induction was not prolonged when compared with patients receiving chemotherapy alone. No imatinib-related severe hematologic or nonhematologic toxicities were noted with the alternating schedule. In each cohort, 77% of patients underwent allogeneic stem cell transplantation (SCT) in first CR (CR1). Both schedules of imatinib have acceptable toxicity and facilitate SCT in CR1 in the majority of patients, but concurrent administration of imatinib and chemotherapy has greater antileukemic efficacy.

Outcome of adult patients with T-lymphoblastic lymphoma treated according to protocols for acute lymphoblastic leukemia.

We treated 45 adult patients with T-lymphoblastic lymphoma (T-LBL) (age range 15-61 years) with 2 protocols designed for adult acute lymphoblastic leukemia (ALL). An encouraging cure rate of 90% was recently reported for T-LBL in children treated with a similar approach. In our study, an 8-drug standard induction was administered over 8 weeks including prophylactic cranial (24 Gy) and mediastinal irradiation (24 Gy) followed by consolidation and reinduction therapy. At diagnosis, 91% of the 45 patients showed a mediastinal tumor and 40% had pleural/pericardial effusions; 73% of the patients had stage III/IV disease. Overall, 42 patients (93%) achieved a complete remission (CR), 2 patients (4%) achieved a partial remission, and 1 patient (2%) died during induction. In patients with stage I-III disease (n = 18) the CR rate was 100% compared with 89% in stage IV (n = 27). There were 15 patients who relapsed (36%) within 12 months. The majority of relapses (47%) occurred in the mediastinum (n = 7) despite mediastinal irradiation with 24 Gy in 6 out of 7 patients. The estimates for overall survival, continuous CR, and disease-free survival at 7 years are 51%, 65%, and 62%, respectively. Stage, age, lactate dehydrogenase, and all other parameters had no influence on achievement of CR or outcome. This study demonstrates in a large cohort of patients with adult T-LBL that a high CR rate and a favorable outcome can be achieved with an ALL-type regimen. Mediastinal recurrence was the major obstacle and further improvement by intensification of chemotherapy, increased dose of mediastinal irradiation (36 Gy), and extended indications for stem cell transplantation seem to be required.

Risk-adapted treatment according to minimal residual disease in adult ALL.

The evaluation of minimal residual disease (MRD) is a new diagnostic method which is applicable in various malignant disorders. Acute lymphoblastic leukaemia (ALL) is a somewhat ideal disease in this respect because >90% of the patients show individual clonal markers and because several methods for MRD evaluation are already established. Futhermore, it was demonstrated that level and course of MRD are significantly correlated with relapse risk in childhood and in adult ALL. In clinical practice MRD evaluation may serve for several purposes such as follow-up of individual course of disease, identification of new prognostic factors or evaluation of single treatment elements. We discuss these options as well as general considerations for MRD-based risk stratification and treatment options for risk groups. Practical applications are analysed because prospective MRD-based clinical trials have been recently started. Finally, future options for application of MRD evaluation and also limitations and pitfalls of this method are reviewed.