Lovotibeglogene Autotemcel Gene Therapy for Sickle Cell Disease: 60 Months Follow-up

Abstract Presentation Date: 6/8/2024 Presentation Start Time: 8:45:00 AM Background Lovotibeglogene autotemcel (lovo-cel) gene therapy uses autologous transplantation of hematopoietic stem and progenitor cells (HSPC) transduced with the BB305 lentiviral vector encoding a modified β-globin gene, which produces an anti-sickling hemoglobin (Hb), HbAT87Q. The phase 1/2 HGB-206 (NCT02140554) and phase 3 HGB-210 (NCT04293185) studies of lovo-cel are the largest clinical trials of gene therapy in sickle cell disease (SCD) to date. We report efficacy and safety from these studies, including the first data from adult and pediatric patients (age 12 to 18 years) in HGB-210, and HRQOL data from HGB-206. Methods This analysis includes patients from HGB-206 Group C and HGB-210 who received lovo-cel using the current HSPC mobilization and manufacturing process. Patients with SCD and recurrent severe vaso-occlusive events (VOEs) or history of overt stroke underwent plerixafor mobilization and apheresis followed by myeloablative busulfan conditioning and lovo-cel infusion. After 24 months of follow-up post lovo-cel infusion, patients enrolled in the long-term study LTF-307 (NCT04628585). Lab evaluations, SCD-related outcomes (eg, resolution of VOEs), globin response (a composite endpoint evaluating HbAT87Q percentage and total Hb), and safety are reported up to 60 months. An independent Event Adjudication Committee confirmed VOEs met protocol criteria. HRQOL data from Patient-Reported Outcomes Measurement Information System (PROMIS)-57 domains of pain interference, fatigue, and pain intensity are reported up to 48 months. Results This analysis includes 47 patients (HGB-206 Group C, n = 36; HGB-210, n = 11; male, 59.6%; median range age, 23 y 12-38) who received a lovo-cel infusion as of Feb 13, 2023. Median (range) follow-up was 35.5 months (0.3-61.0). Median (range) time to neutrophil and platelet engraftment was 20 days (12-35) and 35 days (19-136). Peripheral blood vector copy number remained stable (median 1 c/dg through follow-up). Median HbAT87Q levels were ≥4.5 g/dL from 6 months post infusion to last study visit. Median (range) total Hb level increased from 8.7 g/dL (6.1-12.5) at relative baseline to 11.8 g/dL (8.4-15.0) at last visit; median percent HbAT87Q of nontransfused total Hb was ≈40% or more (Figure 1). Of 34 evaluable patients (ie, ≥18 months follow-up and ≥4 VOEs in the 2 years before enrollment), 30 (88.2%) and 32 (94.1%) had complete resolution of VOEs and severe VOEs during the 6-18 months post infusion, vs a median (range) of 3.5 (1.5-16.5) and 3.0 (0.5-13.0) events/year in the 2 years before enrollment. Additional efficacy analyses in subgroups (eg, stroke history, α-globin genotype) will be presented. Among patients who had globin response or who had ≥18 months follow-up (n = 38), 33 (86.8%) achieved globin response. Hemolysis markers (eg, reticulocytes, total bilirubin, lactate dehydrogenase) approached normal levels. Among all 47 patients, 44 (93.6%) had ≥1 AE of grade ≥3 after lovo-cel infusion; the most common of which were stomatitis (33 70.2% patients) and thrombocytopenia (28 59.6%). Serious AEs were reported for 26 (55.3%) patients, the most common of which was chronic pain/acute exacerbation of chronic pain (3 6.4%; 2 chronic neuropathic pain and 1 chronic pain associated with anxiety). One patient with -α3.7/-α3.7 genotype diagnosed with myelodysplastic syndrome had stable complete blood counts 30 months post infusion. No veno-occlusive liver disease, graft failure, replication-competent lentivirus, or vector-mediated insertional oncogenesis was observed. Lovo-cel treatment regimen largely reflected known side effects of HSPC collection and busulfan conditioning regimen. A total of 25 patients (all from HGB-206 Group C; age ≥18 y) had evaluable HRQOL data. Mean scores for PROMIS-57 domains of pain intensity, pain interference, and fatigue improved (ie, decreased) over time up to 48 months (Figure 2). Conclusions One-time treatment with lovo-cel resulted in sustained HbAT87Q production and near-complete resolution of VOEs and severe VOEs up to 18 months post treatment; the safety profile was consistent with underlying SCD and myeloablative conditioning. Patients reported sustained improvements in pain intensity, pain interference, and fatigue. Ongoing long-term follow-up will continue to provide important information on efficacy, safety, and patient experience post lovo-cel treatment.