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Donor CAR-T cells face two barriers to expansion in lymphoma patients

A study of donor-derived CAR-T treatment for large B-cell lymphoma separates two reasons the cells may fail to expand after infusion: the recipient's immune system can reject them, and the infused cells differ in their capacity to multiply. The findings point to questions for patient screening and cell-product design, while the small main cohort does not establish a new treatment strategy.

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Blue donor immune cells face other cells in a microscopy-inspired treatment illustration.

Immune rejection limits donor-cell expansion

Off-the-shelf CAR-T therapy uses immune cells from a healthy donor, unlike approved treatments manufactured from each patient’s own cells. The donor approach could shorten the wait for a product, but those cells must survive and expand after infusion. A study in people with relapsed or treatment-resistant large B-cell lymphoma found very different expansion even though the main group received the same cema-cel product lot. In patients whose donor cells did not expand, pre-existing recipient CD8 T cells that recognised the foreign cells were more frequent. Those immune cells could reject the infusion before it had time to grow. The finding separates a patient-side barrier from differences within the manufactured CAR-T cells.[1], [2]

Effector-like cells grow more strongly

Among patients whose donor cells did expand, effector-like cell features tracked stronger clonal growth than stem-like or central-memory programmes. The authors saw a similar expansion pattern in two separate cohorts given another cema-cel lot or a donor anti-BCMA CAR-T product. That points to cell fitness as a second variable, beyond whether the patient rejects the donor cells.[1], [2]

Small cohort leaves treatment choices open

The main analysis covered 11 patients treated with one product lot. Its molecular measurements distinguish mechanisms associated with expansion; they do not show that screening recipients or selecting a different donor cell population improves outcomes. Researchers suggest using the two factors to guide future donor selection and manufacturing studies. MD Anderson institutional funds and Allogene Therapeutics supported the work.[1], [2]

References

  1. News sourceCancer DiscoveryCancer Discovery split rejection from cell fitness in off-the-shelf CAR-T↩1↩2↩3
  2. News sourceUT MD AndersonImmune rejection and cell fitness shape donor CAR-T expansion↩1↩2↩3
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