On June 14, 2024 Autolus Therapeutics plc (Nasdaq: AUTL), a clinical-stage biopharmaceutical company developing next-generation programmed T cell therapies, reported three abstracts to be presented at the European Hematology Association (EHA) (Free EHA Whitepaper) Congress, June 13-16, 2024 (Press release, Autolus, JUN 14, 2024, View Source [SID1234644344]).

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"We are looking forward to presenting longer-term data from adult patients with r/r ALL treated with obe-cel in the FELIX study," said Dr. Christian Itin, Chief Executive Officer of Autolus. "The data indicate that with a median follow up of 21.5 months long-term event free and overall survival are stabilizing at around 40%, suggesting that obe-cel can potentially deliver durable responses as a single agent."

Oral presentation:

Title: obecabtagene autoleucel in adult relapsed/refractory B cell acute lymphoblastic leukemia: Survival and potential impact of CAR T-cell persistence and stem cell transplantation in the FELIX study
Session Title: s419 Acute lymphoblastic leukemia – Clinical 1: Immunotherapy: antibodies and CAR-T cells
Session date and time: Friday, June 14 from 14:45 – 16:00 CEST
Session room: N104
Final Abstract Code: S114
Presenting Author: Dr. Claire Roddie
Summary of Findings: This is an encore presentation of the findings presented at ASCO (Free ASCO Whitepaper) 2024. The overall response rate (ORR) (Complete Response/CRi) in all patients who received obe-cel in the FELIX study was 78% (99/127 patients). At the February 7, 2024, data cut-off date, the majority of ongoing responders showed durable responses. Among the responding patients, at a median follow up of 21.5 months (range: 8.6–41.4), 40% were in ongoing remission without subsequent stem cell therapy (SCT) or other non-protocol specified therapy, while 18% proceeded to subsequent SCT while in remission, 5% started new anti-cancer therapy while in remission and 36% relapsed or died. The median event-free survival (EFS) was 11.9 months and median overall survival (OS) was 23.8 months and the estimated 12-month EFS and OS rates were 49.5% and 61.1% respectively.

These data support the potential of a long-term plateau of survival outcomes in patients receiving obe-cel. Ongoing CAR T persistence and B-cell aplasia were associated with improved EFS. This pattern is consistent with the Phase 1 ALLCAR19 data. Furthermore, SCT consolidation in remission following obe-cel did not appear to improve EFS or OS.
Poster presentations:

Title: obecabtagene autoleucel (obe-cel, AUTO1) for relapsed/refractory adult B-cell acute lymphoblastic leukemia (R/R B-ALL): The impact of inotuzumab (INO)-containing bridging therapy on treatment outcomes
Session Title: Poster session
Session date and time: Friday, June 14 from 18:00 – 19:00 CEST
Final Abstract Code: P418
Presenting Author: Dr. Jae H. Park
Summary of Findings: INO-containing bridging therapies were effective in reducing BM disease prior to lymphodepletion and administration of obe-cel. Our data suggests that reducing BM blasts as much as possible prior to lymphodepletion predicts EFS and OS outcomes; however, patients with high disease burden at screening are still at higher risk of relapse overall. Bridging therapy with INO was utilized in patients with higher disease burden (median 81.5% blasts at screening vs 40% in bridging therapy w/o INO group) and helped minimize the risk of CRS and ICANS without increasing liver toxicity. Choice of bridging therapy prior to obe-cel treatment, though influenced by clinical care variables, may impact outcomes for patients with R/R B-ALL. Further studies comparing bridging with INO-containing therapies or chemotherapy are warranted.

Title: Droplet digital PCR and flow cytometry sensitivity for measuring CAR T-cell kinetics in adult patients with relapsed/refractory B-cell acute lymphoblastic leukemia treated with obecabtagene autoleucel
Session Title: Poster session
Session date and time: Friday, June 14 from 18:00 – 19:00 CEST
Final Abstract Code: P1469
Presenting Author: Dr. Claire Roddie
Summary of Findings: A strong correlation was observed between flow cytometry and ddPCR assays for assessment of CAR T levels in peripheral blood. ddPCR is a more sensitive technology than flow cytometry for monitoring CAR T persistence. Flow cytometry assays developed specifically for CAR T monitoring may be sufficiently sensitive to be of clinical relevance. Our data suggest that loss of CAR T persistence is associated with shorter EFS and may be taken into consideration, together with other parameters such as measurable residual disease (MRD), to help inform clinical monitoring post-obe-cel infusion. A validation cohort using an appropriately developed CAR T marking flow cytometry assay versus a ddPCR assay would be required to conclude on the most appropriate methods to inform clinical outcomes.