What are the endpoints of therapy for acute leukemias? Old definitions and new challenges

Developing an instrument to assess patient preferences for benefits and risks of treating acute myeloid leukemia to promote patient-focused drug development

Objective Acute myeloid leukemia (AML) is a progressive blood cancer with few effective treatment options. As part of a patient-focused drug development (PFDD) initiative led by the Leukemia and Lymphoma Society (LLS), this study sought to use a community-centered approach to develop and pilot an instrument to measure patient preferences for the benefits and risks of treating AML. Methods Instrument development was informed by a literature review, engagement with expert stakeholders (n = 12), engagement with community stakeholders, and pre-testing. A discrete-choice experiment (DCE), in which participants made choices between 16 pairs of hypothetical treatments, was developed with five attributes: event-free survival, complete remission, time in hospital, short-term side-effects, and long-term side-effects. A pilot test was conducted and analyzed using conditional logistic regression. Results are presented using relative attribute importance (RAI) scores. Results Patients with AML and caregivers were engaged in developing (n = 15), pre-testing (n = 13), and pilot testing (n = 26) the instrument. The pilot included patients with AML (n = 18) and caregivers of living or deceased patients with AML (n = 8). Participants had a mean age of 50 years (range =24-81), and were mostly college educated (n = 22), privately insured (n = 21), and employed (n = 13). Based on the DCE, complete remission was identified as the most important attribute (RAI =10), followed by event-free survival (3.7), time in hospital (2.8), long-term side-effects (2.3), and short-term side-effects (2.1). Conclusion The mixed-methods approach to PFDD was welcomed by all stakeholders and there was strong endorsement to implement this DCE as part of a national survey. Key points for decision makers The Leukemia and Lymphoma Society (LLS) initiated an independent effort to promote patient-focused drug development (PFDD). This study presents the development and piloting of a preference study as a first step in this initiative. Results of this pilot study were used to guide a PFDD meeting to discuss the lived experience of patients and caregivers affected by AML. Productive engagement by all patients, caregivers, and stakeholders throughout the process resulted in strong endorsement of the project's approach and recognition of the need to conduct a national study.

Minimal Residual Disease Evaluation in Childhood Acute Lymphoblastic Leukemia: A Clinical Evidence Review

BACKGROUND

Leukemia accounts for nearly a third of childhood cancers in Canada, with acute lymphoblastic leukemia (ALL) comprising nearly 80% of cases. Identification of prognostic factors that allow risk stratification and tailored treatment have improved overall survival. However, nearly a quarter of patients considered standard risk on the basis of conventional prognostic factors still relapse, and relapse is associated with increased morbidity and mortality. Relapse is thought to result from extremely low levels of leukemic cells left over once complete remission is reached, termed minimal residual disease (MRD). Poor event-free survival (EFS) as well as overall survival for those who are classified as MRD-positive have been substantiated in seminal studies demonstrating the prognostic value of MRD for EFS in the past few decades. This review sought to further elucidate the relationship between MRD and EFS by looking at relapse, the primary determinant of EFS and the biological mechanism through which MRD is thought to act. This evidence review aimed to ascertain whether MRD is an independent prognostic factor for relapse and to assess the effect of MRD-directed treatment on patient-important outcomes in childhood ALL.

METHODS

Large prospective cohort studies with a priori multivariable analysis that includes potential confounders are required to draw confirmatory conclusions about the independence of a prognostic factor. Data on the prognostic value of MRD for relapse measured by molecular methods (polymerase chain reaction [PCR] of immunoglobulin or T-cell receptor rearrangements) or flow cytometry for leukemia-associated immunophenotypes or difference-from-normal approach were abstracted from included studies. Relevant data on relapse, EFS, and overall survival were abstracted from randomized controlled trials (RCTs) evaluating the effect of MRD-directed treatment.

RESULTS

A total of 2,832 citations were reviewed, of which 12 studies were included in this review. All cohort studies evaluating MRD as a prognostic factor for relapse found significant independent value when added to various existing prognostic factors. Seven studies showed prognostic value of MRD measured at the end of induction therapy and two at the end of consolidation therapy in de novo ALL, one study in relapsed ALL after re-induction therapy, and three studies before hematopoietic stem cell transplant. One large RCT in standard-risk patients found no compromise to outcomes when reducing treatment in MRD-negative patients, and also showed a 45% reduction in relapse risk and nearly 40% benefit in EFS when escalating treatment in MRD-positive patients.

CONCLUSIONS

Minimal residual disease is an independent prognostic factor for relapse in childhood ALL. Relapse is a key determinant of EFS and patients' quality of life. Treatment selected on the basis of MRD status appears to improve outcomes.

Finding the optimal combination therapy for the treatment of newly diagnosed AML in older patients unfit for intensive therapy

There is no standard of care for older patients with newly diagnosed acute myeloid leukemia (AML) unfit for intensive therapy, and prognosis with currently recommended low-intensity therapies (decitabine, azacitidine, and low-dose cytarabine [LDAC]) remains poor. One promising strategy is to combine low-intensity treatments with novel agents. Gemtuzumab ozogamicin, tipifarnib, and barasertib have been investigated in phase 2/3 or 3 trials combined with LDAC, and phase 3 trials are currently investigating sapacitabine plus decitabine, and volasertib plus LDAC in AML. This review discusses current treatment recommendations and the development of combination therapies for older patients unfit for intensive therapy.

New considerations in the design of clinical trials for the treatment of acute leukemia

There is great need for improved therapy for patients with acute leukemia. The current systems of clinical drug development and delivery of leukemia care are imperfectly adapted to the optimal identification and testing of future regimens. Novel clinical trial design with increased enrolment and appropriate end point selection would facilitate more efficient validation of candidate therapies. Clinical outcomes registries and biological sample storage would allow patient and leukemic factor substratification for the development of the next generation of targeted personalized therapy. We believe that the standard of care for patients in the USA diagnosed with acute leukemia, if treated with curative intent, is referral to a specialized center where an appropriate clinical trial can be offered.