A study presented during the 2021 ASCO Annual Meeting compared outcomes in patients with Philadelphia-like acute lymphoblastic leukemia (Ph-like ALL) versus those with Ph+ and Ph- ALL, with a specific focus on allogeneic hematopoietic cell transplantation (allo-HCT).
The researchers tested available diagnostic cytogenetic pellets for 365 patients in the Mayo Clinic ALL cohort with a targeted fluorescence in situ hybridization (FISH) panel that included probes able to detect Ph-like–specific rearrangements.
In total, 33 patients (9%) had Ph-like ALL, 132 patients (36%) had Ph+ ALL, and 200 patients (55%) had Ph- ALL. The Ph-like ALL group had a younger median age compared to the Ph+ and Ph- ALL groups (39 vs. 50 vs. 49 years, respectively; P=0.01), as well as a higher median white blood cell count (27.9 vs. 21.5 vs. 4.5 x109/L, respectively; P<0.001). The Ph-like ALL group was less likely to achieve complete response (91% vs. 99% vs. 96%, respectively; P=0.02) and more likely to be minimal residual disease (MRD) positive (64% vs. 34% vs. 36%, respectively; P=0.03); this cohort also had a higher five-year relapse rate (39% vs. 24% vs. 38%, respectively; P=0.01) and lower five-year overall survival (OS; 41% vs. 64% vs. 49%, respectively; P=0.02). MRD negativity was associated with better OS compared to MRD positivity. When analyzing patients who underwent allo-HCT in first complete remission, the groups did not differ in terms of OS or relapse or non-relapse mortality.
“Ph-like ALL is a high-risk subgroup with increased prevalence in younger adults. Allo-HCT appears to offset the poor prognosis associated with this entity. A targeted FISH panel offers timely recognition of this entity in a clinical setting,” the researchers concluded.