A novel luciferase-based assay for the detection of Chimeric Antigen Receptors.

Chimeric Antigen Receptor-T (CAR-T) cell immunotherapy has produced dramatic responses in hematologic malignancies. One of the challenges in the field is the lack of a simple assay for the detection of CARs on the surface of immune effector cells. In this study, we describe a novel luciferase-based assay, termed Topanga Assay, for the detection of CAR expression. The assay utilizes a recombinant fusion protein, called Topanga reagent, generated by joining the extra-cellular domain of a CAR-target in frame with one of the marine luciferases or their engineered derivatives. The assay involves incubation of CAR expressing cells with the Topanga reagent, a few washes and measurement of luminescence. The assay can detect CARs comprising either immunoglobulin- or non-immunoglobulin-based antigen binding domains. We further demonstrate that addition of epitope tags to the Topanga reagent not only allows its convenient one step purification but also extends its use for detection of CAR cells using flow cytometry. However, crude supernatant containing the secreted Topanga reagent can be directly used in both luminescence and flow-cytometry based assays without prior protein purification. Our results demonstrate that the Topanga assay is a highly sensitive, specific, convenient, economical and versatile assay for the detection of CARs.

Sentinel lymph node biopsy is a reliable method for lymph node evaluation in neoadjuvant chemotherapy-treated patients with breast cancer.

Sentinel lymph node (SLN) mapping in patients with breast cancer treated with neoadjuvant chemotherapy has been debated by surgeons as a result of potential compromise of lymphatic drainage. Whether clinicopathologic variables traditionally associated with SLN positivity differ in patients who have been treated with neoadjuvant chemotherapy has not been well studied. Patients diagnosed with breast carcinoma who underwent neoadjuvant chemotherapy, definitive breast surgery, sentinel node biopsy (SNB), and axillary lymph node dissection (ALND) were retrospectively identified over a 75-month period. Clinicopathologic parameters including age, clinical tumor and node stage, neoadjuvant chemotherapy regimen, pathological tumor and node stage, lymphovascular invasion (LVI), SLN and non-SLN involvement, and extranodal extension were recorded. Ninety-seven patients met inclusion criteria. Ninety-eight per cent had successful SLN mapping. Eight patients with negative SLNs had positive ALND (false-negative rate, 8.3%). Clinicopathological variables associated with SLN status included clinical axillary status (P = 0.038), pathologic tumor size, and nodal status and LVI (P < 0.001). Extranodal extension was significantly associated with non-SLN status (P = 0.004). In patients achieving a pathologic complete response (PCR), SNB remained feasible and accurate (false-negative rate, 11.6%). Successful SLN mapping in patients who have undergone neoadjuvant chemotherapy is highly accurate with a low false-negative rate even in patients who have a PCR.