Balsat, Marie

Abstract Lineage switch (LS), defined as the immunophenotypic transformation of acute leukemia, has emerged as a mechanism of relapse after antigen-targeted immunotherapy, which is associated with dismal outcomes. Through an international collaborative effort, we identified cases of LS after a host of antigen-targeted therapies (eg, CD19, CD22, CD38, and CD7), described how LS was diagnosed, reviewed treatment approaches, and analyzed overall outcomes for this form of postimmunotherapy relapse. Collectively, 75 cases of LS were evaluated, including 53 (70.7%) cases of B-cell acute lymphoblastic leukemia (B-ALL) transforming to acute myeloid leukemia (AML), 17 (22.7%) cases of B-ALL transforming to mixed phenotypic acute leukemia (MPAL)/acute leukemias of ambiguous lineage (ALAL), and 5 (6.7%) cases of rare LS presentation (ie, T-cell ALL to AML). An additional 10 cases with incomplete changes in immunophenotype, referred to as “lineage drift” were also described. With a primary focus on the 70 cases of LS from B-ALL to AML or MPAL/ALAL, LS emerged at a median of 1.5 months (range, 0-36.5) after immunotherapy, with 81.4% presenting with LS within the first 6 months from the most proximal immunotherapy. Although most involved KMT2A rearrangements (n = 45, 64.3%), other rare cytogenetic and/or molecular alterations were uniquely observed. Treatment outcomes were generally poor, with remission rates of <40%. The median overall survival after LS diagnosis was 4.8 months. Outcomes were similarly poor for those with rare immunophenotypes of LS or lineage drift. This global initiative robustly categorizes lineage changes after immunotherapy and, through enhanced understanding, establishes a foundation for improving outcomes of LS.

Outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) for adult acute lymphoblastic leukemia (ALL) have improved over time. Studies have shown that total body irradiation (TBI) is the preferable type of myeloablative conditioning (MAC). However, outcomes based on central nervous system (CNS) involvement, namely CNS-positive versus CNS-negative, have not been compared. Here, we evaluated outcomes of 547 patients (CNS-positive = 96, CNS-negative = 451) who were allografted in the first complete remission (CR1) between 2009 and 2019. Primary endpoint was leukemia-free survival (LFS). Median follow-up was not different between the CNS-positive and CNS-negative groups (79 versus 67.2 months, P = 0.58). The CNS-positive group were younger (median age 31.3 versus 39.7 years, P = 0.004) and were allografted more recently (median year 2012 versus 2010, P = 0.003). In both groups, MAC was the preferred approach (82.3% versus 85.6%, P = 0.41). On multivariate analysis, the CNS-positive group had higher incidence of relapse (RI) (hazard ratio [HR] = 1.58 [95% confidence interval (CI) = 1.06-2.35], P = 0.025), but no adverse effect on LFS (HR = 1.38 [95% CI = 0.99-1.92], P = 0.057) or overall survival (OS) (HR = 1.28 [95% CI = 0.89-1.85], P = 0.18). A subgroup multivariate analysis limited to CNS-positive patients showed that a TBI-based MAC regimen resulted in better LFS (HR = 0.43 [95% CI = 0.22-0.83], P = 0.01) and OS (HR = 0.44 [95% CI = 0.21-0.92], P = 0.03) and lower RI (HR = 0.35 [95% CI = 0.15-0.79], P = 0.01). Another subgroup analysis in CNS-negative patients showed that MAC-TBI preparative regimens also showed a lower RI without a benefit in LFS or OS. While a MAC-TBI allo-HCT regimen may not be suitable to all, particularly for older patients with comorbidities, this approach should be considered for patients who are deemed fit and able to tolerate.

Abstract Background: A recent study from the Acute Leukemia Working Party of EBMT demonstrated that outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) for adults with acute lymphoblastic leukemia (ALL) have improved significantly over time and that total body irradiation (TBI) should be considered as the preferable type of myeloablative conditioning (MAC). This study, however, did not compare outcomes of allo-HCT in patients with CNS involvement (CNS-pos) vs. those without CNS disease (CNS-neg). Study population: Here, we evaluate post allo-HCT outcomes of 547 patients (CNS-pos at initial presentation=96, CNS-neg=451) who underwent the procedure in first complete remission (CR1) between 2009 and 2019 at an EBMT participating transplant center. The distribution of ALL subtypes were as follows: CNS-pos (Ph-neg B ALL=28%, Ph-pos B ALL=27%, and T-cell ALL=45%) and for CNS-neg (Ph-neg B ALL=21%, Ph-pos B ALL=44%, and T-cell ALL=35%), p=0.01. The primary endpoint was leukemia-free survival (LFS). Results: The median follow up was not statistically different between the CNS-pos (78.7 months) and the CNS-neg group (67.2 months), p=0.58. Patients in the CNS-pos group were younger (median age 31.3 vs. 39.7 years, p=0.004), received the procedure more recently (median year 2012 vs. 2010, p=0.003), were less likely to have a Karnofsky score of equal or higher than 90 (70.8% vs. 81.9%, p=0.017), or to have received peripheral blood stem cells (PBSC) (61.5% vs. 72.7%, p=0.028). The groups did not differ in regards to donor source (URD, 50% vs. 56.5%, p=0.24) or the intensity of the preparative regimen (MAC, 82.3% vs. 85.6%, p=0.41). In multivariate analysis, CNS-pos were associated with higher cumulative incidence of relapse (HR=1.58 (95%CI=1.06-2.35), P=0.025) and a trend for an inferior leukemia-free survival (LFS) (HR=1.38 (95%CI=0.99-1.92), p=0.057), but did not adversely impact overall survival (OS) (HR=1.28 (95%CI=0.89-1.85), p=0.18). A subgroup multivariate analysis limited to patients with CNS-pos showed that prescribing a TBI MAC regimen (vs. others) results in a lower cumulative incidence of relapse (HR=0.35 (95%CI=0.15-0.79), p=0.012) and better LFS (HR=0.43 (95%CI=0.22-0.83), p=0.01) and OS (HR=0.44 (95%CI=0.21-0.92), p=0.03). Use of PBSC (vs. BM) was also independently associated with better OS (HR=0.53 (95%CI=0.29-0.99), p=0.046). Conclusion: Notwithstanding the inherent limitations of registry data, particularly ascertaining the absence of CNS involvement in the CNS-neg group, our results show CNS involvement as an independent risk factor for relapse following allo-HCT. Our data support, nonetheless, the choice of a TBI-based MAC regimen in this group of patients but stresses the need for close monitoring of relapse after allo-HCT. Disclosures Labopin: Jazz Pharmaceuticals: Honoraria. Bazarbachi: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hikma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees. Mielke: Immunicum: Other: Data safety monitoring board; DNA Prime SA: Speakers Bureau; Gilead/KITE: Other: Travel support, Expert panel ; Miltenyi: Other: Data safety monitoring board; Novartis: Speakers Bureau; Celgene/BMS: Speakers Bureau. Socie: Alexion: Research Funding. Huynh: Jazz Pharmaceuticals: Honoraria. Yakoub-Agha: Jazz Pharmaceuticals: Honoraria. Giebel: Janssen: Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy, Honoraria, Speakers Bureau. Peric: Therakos, Servier, MSD, Astellas, Novartis, Abbvie, Pfizer: Honoraria. Mohty: Sanofi: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Adaptive Biotechnologies: Honoraria.