# Plan the second CAR-T target before the first one is lost

Source: https://onco.cc/ideas/idea-bio1-adaptive-car-antigen-switch/  
OnCo record `idea-bio1-adaptive-car-antigen-switch` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Cell therapies fail when the tumour stops showing the marker they were built to find. Preparing an alternative product in advance would let doctors switch quickly.

## Summary

Antigen-negative relapse accounts for a substantial share of CAR-T failures in B-cell malignancies and is emerging in multiple myeloma. Strategies include dual-target and tandem CARs, sequential products, and adaptor or universal CAR platforms whose specificity is set by a separately dosed molecule. A pragmatic programme would monitor antigen density after infusion and have the alternative product manufactured or an adaptor available before relapse.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Pre-planned antigen switching, triggered by falling antigen density or early molecular relapse rather than by overt relapse, improves durable remission rates compared with reactive switching at relapse.
- Rationale: Antigen loss is detectable before clinical relapse using flow cytometry and MRD assays; the delay in manufacturing a second product is usually what makes switching too late.
- Proposed test: Single-arm study of antigen-density and MRD-triggered pre-emptive switching in relapsed B-cell malignancy, with durable remission at two years compared with historical reactive management.
- Maturity: early-clinical
- Actor: clinic

## Sources

- Bottleneck evidence (Acquired resistance to every therapy): Soria et al., Osimertinib in untreated EGFR-mutated NSCLC (FLAURA, NEJM 2018): https://doi.org/10.1056/NEJMoa1713137

## Connected records

- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [Diffuse large B-cell lymphoma](https://onco.cc/cancers/dlbcl/), [Multiple myeloma](https://onco.cc/cancers/multiple-myeloma/), [Relapsed or refractory multiple myeloma](https://onco.cc/cancers/myeloma-relapsed-refractory/)
- technologies: [Allogeneic (off-the-shelf) cell therapy](https://onco.cc/technologies/allogeneic-cell-therapy/), [CAR-T cell therapy](https://onco.cc/technologies/car-t/), [MRD / molecular residual disease testing](https://onco.cc/technologies/mrd-testing/)
- targets: [BCMA](https://onco.cc/targets/bcma/), [CD19](https://onco.cc/targets/cd19/), [CD20](https://onco.cc/targets/cd20/), [GPRC5D](https://onco.cc/targets/gprc5d/)
- terms: [Minimal / molecular residual disease (MRD)](https://onco.cc/terms/mrd/)
- bottlenecks: [Acquired resistance to every therapy](https://onco.cc/bottlenecks/b-resistance/), [Manufacturing cost and time for living and radioactive medicines](https://onco.cc/bottlenecks/b-manufacturing-cell-therapy/)

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