In vivo trafficking of CD19.CAR-VSTs. (A) CD19.CAR-VSTs accumulate at the sites of disease. Immunohistochemistry stain of B-CLL cells (top row) and CD3⁺ T cells (bottom row) from patient 3. (B) Summary table documenting the presence of detectable CD19.CAR-VSTs at the sites of disease as assessed by Q-PCR compared with concomitant PB samples measured as copies per 1000 ng of DNA.