Long-term efficacy of reduced-intensity versus myeloablative conditioning before allogeneic haemopoietic cell transplantation in patients with acute myeloid leukaemia in first complete remission: retrospective follow-up of an open-label, randomised phase 3 trial

Background: Secondary or treatment-related acute myeloid leukemia (sAML) is associated with poor outcomes. Although allogeneic hematopoietic cell transplantation (alloHCT) is the treatment of choice, patient eligibility criteria and optimal conditioning regimen remain under study. We have previously shown an advantage of a myeloablative conditioning regimen with reduced toxicity (Fludarabine 150mg/m2, Treosulfan 42g/m2, FluTreo) compared to a reduced intensity regimen. However, the long-term effects of this regimen remain unknown, especially in comparison to patients not receiving alloHCT. Aims: We hypothesized that patients transplanted with FluTreo would have a long-term survival advantage over other treatment alternatives. Methods: We retrospectively studied consecutive patients treated for sAML in our center over the last two decades (1998-2018). Exclusion criteria were: age>70 years, ECOG performance status≥3 at presentation, induction regimens≤2, and autologous or haploidentical HCT because these were performed in individual patients. Since 2013, we have introduced FluTreo for patients with a suitable donor that would have been previously eligible only for reduced intensity conditioning/RIC. The following factors were studied in the whole cohort: age, type of disease (treatment-related or post myelodysplastic syndrome/MDS), previous intensive chemotherapy cycles, cytogenetic risk, overall (OS) and disease-free survival (DFS). In transplant recipients, we also recorded HCT-comorbidity index/CI score, cumulative incidence (CI) of graft-versus-host disease (GVHD), and treatment-related mortality (TRM). Follow-up was calculated from diagnosis in the whole cohort; and from date of transplant in the sub-group analysis of transplant recipients. Results: We studied 19 FluTreo recipients compared to 46 recipients of other conditioning regimens (38 myeloablative and 8 RIC), and 52 patients treated only with chemotherapy. Complete remission (CR) had been achieved in all FluTreo recipients before HCT, compared to 53% of other transplants, and 44% of chemotherapy only patients (p<0.001). As expected, median age was increased in FluTreo and chemotherapy only patients (59 and 58 years respectively), compared to other transplants (48 years, p<0.001). There was no other difference in baseline characteristics. With a median follow-up of 43 (range 13-204) months in surviving patients, 4-year OS was 40.3% in FluTreo versus 31.3% in other transplants and 11.8% in chemotherapy only patients (p<0.001, Figure 1A). In the multivariate analysis, achieving CR (p<0.001) and the FluTreo group (p<0.001) were associated with favorable OS, independently of age and cytogenetic risk. 4-year DFS was 32.3% in FluTreo, versus 29.3% in other transplants and 10.2% in chemotherapy only patients (p=0.001, Figure 1B). Within transplanted patients, there was no significant difference in GVHD, relapse and TRM between FluTreo and other transplants. Within the FluTreo group, acceptable rates of CI in severe acute and extensive chronic GVHD were observed (15.2% and 18.4%, respectively). Similarly, 4-year CI of TRM reached 30.4%, despite a median HCT-CI of 3 (0-7), age of 59 (51-67) years, 4 lines of treatment (3-6), and a majority of matched unrelated donors (13/19). Conclusion: Our real-world study confirms that alloHCT with FluTreo expands the transplant population with similar safety and efficacy to previous transplant modalities in sAML patients. Achievement of CR remains a major predictor of OS in these patients. The choice of alloHCT in this unique patient population of a rather older age and comorbidity index needs to be revisited. Figure 1 Disclosures Gavriilaki: Omeros Pharmaceuticals: Consultancy.

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Clinical Outcomes Following Treatment with Gilteritinib or Quizartinib in Patients with Relapsed/Refractory FLT3-ITD+ Acute Myeloid Leukemia

Blood ◽

10.1182/blood-2020-136118 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 42-43

Author(s):

Alexander E. Perl ◽

Qiaoyang Lu ◽

Alan Fan ◽

Nahla Hasabou ◽

Erhan Berrak ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Complete Remission ◽

Myeloid Leukemia ◽

Research Funding ◽

Phase 3 ◽

Hematopoietic Stem ◽

Travel Costs ◽

Baseline Characteristics ◽

Acute Myeloid

Background: Gilteritinib is approved for patients (pts) with relapsed/refractory (R/R) FLT3-mutated acute myeloid leukemia (AML), based on findings from the phase 3 ADMIRAL trial (Perl AE, et al. N Engl J Med. 2019). A phase 3 trial, QuANTUM-R, demonstrated the benefit of quizartinib in pts with R/R AML with FLT3 internal tandem duplication (FLT3-ITD) mutations (Cortes JE, et al. Lancet Oncol. 2019). Although eligibility criteria across both studies were similar, QuANTUM-R was more stringent as to prior therapy intensity and remission duration, which potentially enriched for higher-risk pts. We sought to describe outcomes from ADMIRAL among pts who otherwise met eligibility for QuANTUM-R. Methods: In this post-hoc analysis, a subset of pts from ADMIRAL were matched with R/R FLT3-ITD+ AML pts from QuANTUM-R on the basis of baseline characteristics and prior treatment criteria. Matched pts were either refractory to initial anthracycline-based chemotherapy or had relapsed ≤6 mos after achieving composite complete remission (CRc) with an anthracycline-based regimen. Results: Overall, 218 pts with R/R FLT3-ITD+ AML in the ADMIRAL trial (gilteritinib, n=140; salvage chemotherapy [SC], n=78) were matched with the QuANTUM-R intention-to treat (ITT) population (N=367; quizartinib, n=245; SC, n=122). Proportions of pts preselected for high-intensity SC were 66% (n=143/218) in the matched ADMIRAL ITT population and 77% (n=281/367) in the QuANTUM-R ITT populations. Demographic and baseline characteristics of the matched ADMIRAL ITT population and QuANTUM-R ITT population were similar. Median durations of exposure to gilteritinib and quizartinib were 3.8 mos and 3.2 mos, respectively, and median number of treatment cycles received were five and four, respectively. Rates of hematopoietic stem cell transplantation (HSCT) were similar in pts treated with gilteritinib (35%; n=49/140) or quizartinib (32%; n=78/245), as were the proportions of pts who resumed gilteritinib (23%; n=32/140) or quizartinib (20%; n=48/245) therapy post-HSCT. Median overall survival (OS) in pts treated with gilteritinib or quizartinib was longer than that observed with SC. After a median follow-up of 17.4 mos, median OS was 10.2 mos with gilteritinib versus 5.6 mos with SC (hazard ratio [HR]=0.573 [95% CI: 0.403, 0.814]; one-sided nominal P=0.0008). After a median follow-up of 23.5 mos, median OS with quizartinib was 6.2 mos versus 4.7 mos with SC (HR=0.76 [95% CI: 0.58-0.98]; one-sided P=0.02). After censoring for HSCT, median OS was 9.3 mos with gilteritinib versus 5.5 mos with SC (HR=0.525 [95% CI: 0.356-0.775]; nominal one-sided P=0.0005), and 5.7 mos versus 4.6 mos with quizartinib versus SC, respectively (HR=0.79 [95% CI: 0.59, 1.05]; one-sided P=0.05). In both QuANTUM-R and matched ADMIRAL populations, the survival benefits of quizartinib and gilteritinib compared with SC were maintained across multiple subgroups, including high FLT3-ITD allelic ratio subsets. Compared with SC, high CRc rates were observed in pts treated with either gilteritinib (57%; n=80/140) or quizartinib (48%; n=118/245). The complete remission (CR) rate with gilteritinib was 23% (n=32/140), whereas the CR rate with quizartinib was 4% (n=10/245) (Table). Median time to achieve CRc was 1.8 mos with gilteritinib and 1.1 mos with quizartinib, median duration of CRc was 5.5 mos with gilteritinib and 2.8 mos with quizartinib. The safety profiles of gilteritinib and quizartinib were generally similar, though aspartate or alanine aminotransferase elevations (any grade) were more frequent with gilteritinib (41-44%) than quizartinib (≤13%), whereas neutropenia (14% vs 34%, respectively), fatigue (24% vs 39%, respectively), and prolonged QT intervals (9% vs 27%, respectively) were more frequent with quizartinib. Conclusions: In pts with R/R FLT3-ITD+ AML and similar baseline characteristics, both gilteritinib and quizartinib were generally well tolerated and associated with improved survival and treatment response compared with SC. Responses to gilteritinib and quizartinib, as measured by CRc, were similar; blood count recovery varied between the two FLT3 inhibitors. Although cross-study comparisons have substantial limitations, the findings suggest that while remission is achieved faster with quizartinib, response may be more durable and survival potentially longer with gilteritinib. Disclosures Perl: Syndax: Consultancy, Honoraria; Leukemia & Lymphoma Society, Beat AML: Consultancy; Novartis: Honoraria, Other, Research Funding; Agios: Consultancy, Honoraria, Other; Jazz: Honoraria, Other; FORMA Therapeutics: Consultancy, Honoraria, Other; Daiichi Sankyo: Consultancy, Honoraria, Other: Writing/editorial support, travel costs for meetings, Research Funding; FUJIFILM Pharmaceuticals USA, Inc: Research Funding; New Link Genetics: Honoraria, Other; Arog Pharmaceuticals Inc: Other: uncompensated consulting, travel costs for meetings; Actinium Pharmaceuticals Inc: Consultancy, Honoraria, Research Funding; Biomed Valley Discoveries: Research Funding; Astellas: Consultancy, Honoraria, Other: writing/editorial support, travel costs for meeting presentations related to study, Research Funding; Bayer HealthCare Pharmaceuticals: Research Funding; AbbVie Inc: Consultancy, Honoraria, Other, Research Funding; Takeda: Honoraria, Other: Travel costs for meeting; Loxo Oncology Inc, a wholly owned subsidiary of Eli Lilly & Company: Consultancy, Honoraria, Other. Lu:Astellas: Current Employment. Fan:Astellas Pharma: Current Employment. Hasabou:Astellas Pharma: Current Employment. Berrak:Astellas: Current Employment. Tiu:Eli Lilly & Company: Current equity holder in publicly-traded company, Ended employment in the past 24 months; Astellas Pharma Global Development: Current Employment.

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