Characteristics predicting outcomes of allogeneic stem-cell transplantation in relapsed acute myelogenous leukemia

Analysis of Subset Chimerism for MRD-Detection and Pre-Emptive Treatment in AML

Allogeneic hematopoietic stem cell transplantation (alloHCT) represents the only potentially curative treatment in high-risk AML patients, but up to 40% of patients suffer from relapse after alloHCT. Treatment of overt relapse poses a major therapeutic challenge and long-term disease control is achieved only in a minority of patients. In order to avoid post-allograft relapse, maintenance as well as pre-emptive therapy strategies based on MRD-detection have been used. A prerequisite for the implementation of pre-emptive therapy is the accurate identification of patients at risk for imminent relapse. Detection of measurable residual disease (MRD) represents an effective tool for early relapse prediction in the post-transplant setting. However, using established MRD methods such as multicolor flow cytometry or quantitative PCR, sensitive MRD monitoring is only applicable in about half of the patients with AML and advanced MDS undergoing alloHCT. Donor chimerism analysis, in particular when performed on enriched leukemic stem and progenitor cells, e.g. CD34+ cells, is a sensitive method and has emerged as an alternative option in the post alloHCT setting. In this review, we will focus on the current strategies for lineage specific chimerism analysis, results of pre-emptive treatment using this technology as well as future developments in this field.

Joint regression analysis for survival data in the presence of two sets of semi-competing risks

In many clinical trials, multiple time-to-event endpoints including the primary endpoint (e.g., time to death) and secondary endpoints (e.g., progression-related endpoints) are commonly used to determine treatment efficacy. These endpoints are often biologically related. This work is motivated by a study of bone marrow transplant (BMT) for leukemia patients, who may experience the acute graft-versus-host disease (GVHD), relapse of leukemia, and death after an allogeneic BMT. The acute GVHD is associated with the relapse free survival, and both the acute GVHD and relapse of leukemia are intermediate nonterminal events subject to dependent censoring by the informative terminal event death, but not vice versa, giving rise to survival data that are subject to two sets of semi-competing risks. It is important to assess the impacts of prognostic factors on these three time-to-event endpoints. We propose a novel statistical approach that jointly models such data via a pair of copulas to account for multiple dependence structures, while the marginal distribution of each endpoint is formulated by a Cox proportional hazards model. We develop an estimation procedure based on pseudo-likelihood and carry out simulation studies to examine the performance of the proposed method in finite samples. The practical utility of the proposed method is further illustrated with data from the motivating example.

Acute Myeloid Leukemia in Young Adults: Does Everyone Need a Transplant?

With the exception of the minority of patients with acute myelocytic leukemia who are considered potentially cured by chemotherapy, hematopoietic cell transplantation (HCT) has traditionally been the recommended approach for those patients achieving complete remission who meet the criteria for HCT and have an appropriate stem-cell donor. This decision has become more complex with the discovery of new risk factors, such as genomic abnormalities and minimal residual disease, especially in younger populations. Patients younger than age 60 years who are considered fit and who do not harbor poor prognostic features are felt still to have a high likelihood of cure without having to undergo HCT. Here, we discuss the role that these emerging risk factors play in the decision to undergo transplantation, but emphasize that this remains a decision made jointly by the patient, the treating hematologist, and the transplant physician.

Quizartinib versus salvage chemotherapy in relapsed or refractory FLT3-ITD acute myeloid leukaemia (QuANTUM-R): a multicentre, randomised, controlled, open-label, phase 3 trial

BACKGROUND

Patients with relapsed or refractory FLT3 internal tandem duplication (FLT3-ITD)-positive acute myeloid leukaemia have a poor prognosis, including high frequency of relapse, poorer response to salvage therapy, and shorter overall survival than those with FLT3 wild-type disease. We aimed to assess whether single-agent quizartinib, an oral, highly potent and selective type II FLT3 inhibitor, improves overall survival versus salvage chemotherapy.

METHODS

QuANTUM-R is a randomised, controlled, phase 3 trial done at 152 hospitals and cancer centres in 19 countries. Eligible patients aged 18 years or older with ECOG performance status 0-2 with relapsed or refractory (duration of first composite complete remission ≤6 months) FLT3-ITD acute myeloid leukaemia after standard therapy with or without allogeneic haemopoietic stem-cell transplantation were randomly assigned (2:1; permuted block size of 6; stratified by response to previous therapy and choice of chemotherapy via a phone-based and web-based interactive response system) to quizartinib (60 mg [30 mg lead-in] orally once daily) or investigator's choice of preselected chemotherapy: subcutaneous low-dose cytarabine (subcutaneous injection of cytarabine 20 mg twice daily on days 1-10 of 28-day cycles); intravenous infusions of mitoxantrone (8 mg/m² per day), etoposide (100 mg/m² per day), and cytarabine (1000 mg/m² per day on days 1-5 of up to two 28-day cycles); or intravenous granulocyte colony-stimulating factor (300 μg/m² per day or 5 μg/kg per day subcutaneously on days 1-5), fludarabine (intravenous infusion 30 mg/m² per day on days 2-6), cytarabine (intravenous infusion 2000 mg/m² per day on days 2-6), and idarubicin (intravenous infusion 10 mg/m² per day on days 2-4 in up to two 28-day cycles). Patients proceeding to haemopoietic stem-cell transplantation after quizartinib could resume quizartinib after haemopoietic stem-cell transplantation. The primary endpoint was overall survival in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02039726, and follow-up is ongoing.

FINDINGS

Between May 7, 2014, and Sept 13, 2017, 367 patients were enrolled, of whom 245 were randomly allocated to quizartinib and 122 to chemotherapy. Four patients in the quizartinib group and 28 in the chemotherapy group were not treated. Median follow-up was 23·5 months (IQR 15·4-32·3). Overall survival was longer for quizartinib than for chemotherapy (hazard ratio 0·76 [95% CI 0·58-0·98; p=0·02]). Median overall survival was 6·2 months (5·3-7·2) in the quizartinib group and 4·7 months (4·0-5·5) in the chemotherapy group. The most common non-haematological grade 3-5 treatment-emergent adverse events (within ≤30 days of last dose or >30 days if suspected to be a treatment-related event) for quizartinib (241 patients) and chemotherapy (94 patients) were sepsis or septic shock (46 patients [19%] for quizartinib vs 18 [19%] for chemotherapy), pneumonia (29 [12%] vs eight [9%]), and hypokalaemia (28 [12%] vs eight [9%]). The most frequent treatment-related serious adverse events were febrile neutropenia (18 patients [7%]), sepsis or septic shock (11 [5%]), QT prolongation (five [2%]), and nausea (five [2%]) in the quizartinib group, and febrile neutropenia (five [5%]), sepsis or septic shock (four [4%]), pneumonia (two [2%]), and pyrexia (two [2%]) in the chemotherapy group. Grade 3 QT prolongation in the quizartinib group was uncommon (eight [3%] by central reading, ten [4%] by investigator report); no grade 4 events occurred. There were 80 (33%) treatment-emergent deaths in the quizartinib group (31 [13%] of which were due to adverse events) and 16 (17%) in the chemotherapy group (nine [10%] of which were due to adverse events).

INTERPRETATION

Treatment with quizartinib had a survival benefit versus salvage chemotherapy and had a manageable safety profile in patients with rapidly proliferative disease and very poor prognosis. Quizartinib could be considered a new standard of care. Given that there are only a few available treatment options, this study highlights the value of targeting the FLT3-ITD driver mutation with a highly potent and selective FLT3 inhibitor.

FUNDING

Daiichi Sankyo.

Influence of FLT3-ITD and NPM1 status on allogeneic hematopoietic cell transplant outcomes in patients with cytogenetically normal AML

OBJECTIVE

In individuals with cytogenetically normal (CN) AML, disease risk is estimated using molecular features such as the status of NPM1 and FLT3-ITD genes. However, data regarding the impact of NPM1 and FLT3-ITD status on hematopoietic stem cell transplant (HCT) outcomes are limited. We examined the effect of NPM1 and FLT3-ITD status on transplant outcomes in 131 CN AML patients transplanted at Princess Margaret Hospital between 2006 and 2017.

METHODS

Overall survival (OS) was calculated using Kaplan-Meier analysis and multivariable Cox proportional hazards regression. Cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were calculated using competing risk regression.

RESULTS

There was no difference in 3-year OS among NPM1⁺ /FLT3-ITD^- , NPM1^- /FLT3-ITD^- , NPM1⁺ /FLT3-ITD⁺ and NPM1^- /FLT3-ITD⁺ patients: 56% (95% CI, 29%-76%), 61% (95% CI, 46%-73%), 53% (95% CI, 34%-70%) and 52% (95% CI, 17%-78%), respectively. CIR at 3-years was similar among NPM1^- /FLT3-ITD^- , NPM1⁺ /FLT3-ITD⁺ and NPM1^- /FLT3-ITD⁺ patients-14% (95% CI, 6%-26%), 13% (95% CI, 4%-28%) and 19% (95% CI, 4%-41%), respectively-while there were no relapses in the NPM1⁺ /FLT3-ITD^- group. NRM at 3 years for NPM1⁺ /FLT3-ITD^- , NPM1^- /FLT3-ITD^- , NPM1⁺ /FLT3-ITD⁺ and NPM1^- /FLT3-ITD⁺ patients was similar at 44% (95% CI, 19%-67%), 38% (95% CI, 25%-50%), 43% (95% CI, 25%-59%) and 44% (95% CI, 14%-71%), respectively.

CONCLUSION

NPM1 and FLT3-ITD status may provide limited prognostic information about transplant outcomes in CN AML patients.