False-positive HIV-1 RNA detection after CAR-T cell therapy in a multiple myeloma patient: multi-assay comparison confirms dual-target cross-reactivity.
Stefano Brusa, Daniela D'Angelo, Giuseppe D'Ambrosio et al.
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Case in brief
A patient with multiple myeloma undergoing CAR-T cell therapy tested positive for HIV-1 RNA using two dual-target assays, showing low copy numbers. However, a single-target assay consistently returned negative results, and serological tests for HIV remained non-reactive. This discrepancy underscores the need for careful interpretation of HIV RNA results in the context of CAR-T therapy.
What made this case unusual
The false-positive HIV-1 RNA detection was attributed to cross-reactivity with vector-derived sequences from the CAR-T therapy, highlighting a specific challenge in assay design.
Diagnostic / clinical pearl
Clinicians should be aware that CAR-T cell therapy can lead to false-positive HIV-1 RNA results due to assay cross-reactivity, necessitating the use of serological tests for accurate diagnosis.
Why it matters
This case emphasizes the critical role of assay design in the interpretation of viral load tests, particularly in patients receiving advanced therapies like CAR-T.