Characteristics of Medicare patients with relapsed/refractory acute lymphoblastic leukemia initiating treatment with inotuzumab ozogamicin, blinatumomab, or other agents.

e19009 Background: B-cell precursor acute lymphoblastic leukemia (ALL) represents the majority of ALL cases. The INO-VATE and TOWER trials demonstrated that adult patients with relapsed/refractory (RR) B-cell precursor ALL treated with inotuzumab ozogamicin (ino, anti-CD22 monoclonal antibody [mAb]) and blinatumomab (blin, CD19-directed CD3 T-cell engager mAb), respectively, had improved clinical outcomes over chemotherapy. Real-world data on older RR ALL patients initiating CD-targeted therapy is limited. We describe characteristics, healthcare resource utilization (HRU), costs for Medicare beneficiaries with RR ALL initiating ino, blin, or other (chemotherapeutic, tyrosine kinase inhibitor [TKI], or mAb) therapies. Methods: Retrospective study utilizing Medicare enrollment/claims data. Eligible study patients diagnosed with RR ALL 1/1/2017-6/30/2019 and initiated ino, blin, or other at/after diagnosis (first observed treatment = index date). Claims for ino/other patients only visible in outpatient/pharmacy settings; proportion who received inpatient administration prior to outpatient unknown. Blin identifiable in inpatient + outpatient settings. B/T-cell status not captured; patients receiving T-ALL therapy (nelarabine) excluded. Measures included characteristics/HRU during 6 months pre-index and HRU/costs per patient per month (PPPM; costs in 2021 USD) during variable follow-up period (≥3 months until death, disenrollment, or study end). Results: Of 15,586 Medicare beneficiaries with RR ALL, 2,306 (< 15%) initiated an ALL treatment; 1,329 qualified for study inclusion: 55 (4%) received ino, 209 (16%) blin (73% initiated blin during hospital stay), 1,065 (80%) other. Mean age of ino/blin was 62; other 66. Larger proportion of ino cohort qualified for Medicare with non-age-related factors (disability) than blin/other. Treatment groups comparable by sex/race. Ino cohort had higher prevalence of congestive heart, pulmonary, and renal diseases (35%, 31%, 38%) than blin (19%, 25%, 19%), other (23%, 30%, 21%), respectively; diabetes prevalence was lower for ino than for blin/other (20%, 34%, 36%, respectively). Over 6 months pre-index, there was variability in exposure to cytotoxic chemotherapies, mAbs, TKIs by cohort;76% each of ino/blin cohorts, 66% of other cohort were hospitalized for any reason. Follow-up time (months) varied by cohort: 8.0 ino, 12.8 blin, 17.8 other, during which blin patients had higher PPPM rates of hospital stays, longer stays (9.3 days blin, 6.0 ino, 3.9 other), and higher mean (SD) total cost of care: $65,437 ($155,664) blin, $55,995 ($36,688) ino, $17,520 ($22,720) other. Conclusions: During 2017-2019, < 15% of Medicare beneficiaries with RR ALL received ALL treatment, of which 1 in 5 received CD-targeted therapy. Costs were highest for blin followed by ino then other.