ASH 2024 | Updated results of the ALLELE trial: tabelecleucel for Epstein–Barr virus-driven PTLD

So tab-cel, or the actual name for it is tabelecleucel, but for, you know, it is difficult to say it, so for abbreviation, I’m just going to say tab-cel, but the way that you say it is tabelecleucel, tabelecleucel, so we’ll call it tab-cel. We actually presented our updated outcome of the Phase III ALLELE study as a large multi-center Phase III global study using tab-cel in patients with EBV-positive PTLD post allogeneic hematopoietic stem cell transplantation or solid organ transplantation failing rituximab with or without chemotherapy. We’re reporting the outcome of 75 patients here, 26 patients after allogeneic stem cell transplantation, 49 patients after solid organ transplantation. 

A little bit about tab-cel. So tab-cel is an off-the-shelf, non-genetically modified, allogeneic, EBV-specific immunotherapy that can eliminate EBV-positive cells. And the way that it eliminates the EBV-positive target is still through T-cell receptor, MHC class one, and the surface of basically infected cells, malignant cells, presenting EBV associated antigen to the tab-cel through the natural pathway. Normal T-cells from EBV positive normal donors are used to manufacture tab-cel. And because we need to have the tab-cel product needs to be matched to a restricted HLA of patient so you need to have multiple cell lines to cover the populations. A diverse group of donors have been used to manufacture a wide variety of basically tab-cel lines with the goal of covering 90 percent of populations. So that’s the tab-cel product. How we choose a product for the patient? You use a HLA from the recipient and a donor and a transplant and based on those and a restricted HLA, you find the tab-cel line for the patients. 

75 patients enrolled, 26 post-allo, 49 post-solid organ transplant. In terms of safety, it was very safe. No death related to this was reported. In terms of adverse events of special interest, no cytokine release syndrome, no ICANS, no tumor flare, there were two transient GvHD that were treated. In term of graft failure, post-solid organ transplant, we had three that two of them were completely treated and reversed. In term of efficacy, in the second line setting, these patients as a standard of care, they don’t have really good options. If you are primary refractory or relapsed, most patients, they have median survival ranging from one to four months. And most patients die of this. So we saw overall response rate of close to 50% with complete response rate close to 30% and partial response close to 20% with the median progression-free survival of close to 24 months and one-year estimated PFS close to 75%. Another important thing about overall survival, for responders, one-year estimated overall survival was close to 80% and that is impressive for these patients. The product actually is already approved in Europe. It was approved in December of 2022 based on the preliminary result from the same study. Based on this updated larger cohort here, BLA is filed and under priority review at the FDA with the PDUFA date of January 15, 2025.

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