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MINI 27 - Biology and Other Issues in SCLC (ID 152)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Small Cell Lung Cancer
- Presentations: 1
MINI27.01 - Investigation of Chimeric Antigen Receptor T Cells as a Novel Immunotherapy for SCLC (ID 2901)
16:45 - 18:15 | Author(s): W.L. Denning
Small cell lung cancer (SCLC) is an aggressive malignancy with an average of 20,000 new cases per year and 16,000 deaths per year. SCLC accounts for about 10-15% of newly diagnosed lung cancers. Even in the face of extensive research, the standard of care- platinum-based combination chemotherapy- has not changed in decades. Yet even with modern chemotherapy formulations, the two year survival rate for advanced disease stages is less than 5%. Complicating treatment is that often at the time of diagnosis, SCLC as already metastasized to the patient’s surrounding lymph nodes. Therefore, a novel therapeutic strategy will have address three disease aspects: (1) reduce primary tumor growth and eliminate metastatic spread; (2) avoid resistance mechanisms used by SCLC to escape radio- and chemotherapies; (3) synergize with or supersede current therapeutic strategies. Chimeric antigen receptor T cells, little explored in SCLC, is well suited to address these aspects.
Human SCLC cell lines were analyzed using a 90 gene signature to establish immunological targets. Western blot analysis confirmed the expression of CD56 and other targets on SCLC cell lines. For CAR T cell generation, PBMC were electroporated with the Sleeping Beauty transposase and a transposon containing a CD56R chimeric antigen receptor. CD56R-CAR transduced T cells were cultured for 4 weeks in the presence of K562 cells expressing CD56 and the cytokines IL-2/IL-21 to expand CD56R-CAR T cells. CAR T cells were tested in vitro for killing ability in the presence of three SCLC cell lines using a chromium release assay. CAR T cells were also analysed via FACS to assess CAR expression, T cell phenotype, and memory status.
An analysis of immune markers in SCLC cell lines revealed that, compared to NSCLC lines, there is a reduction in the expression of suppressive ligands and co-stimulatory ligands, antigen presentation, and natural killer ligands. SCLC cell lines, however, express high levels of CD56. When two CD56-positive and one CD56-negative cell line was tested, CD56-CAR T cells could kill efficiency CD56 expressing cell lines, however there was little killing of the CD56-negative cell line. An analysis of PBMCs cultured after electroporation revealed that a large percentage of CD3+ T cells expressed the CD56 CAR and even after 4 weeks in culture, the CAR T cells displayed a memory phenotype.
An interrogation of SCLC cell lines versus NSCLC cell lines revealed that SCLC cell lines had reduced expression of checkpoint ligands, NK cell killing ligands, antigen presentation, but consistent with their origin, high expression of CD56. Our conclusion from this analysis is that expansion of SCLC-specific immune responses in vivo or elicitation of de novo responses in vivo will be hindered. Therefore, immunotherapies centered around adoptive transfer of T cell that can kill in an HLA-independent manner maybe better suited for SCLC. In that vein, CD56R-CAR T cells effectively targeted CD56-positive SCLC in vitro, but was unable to kill CD56-negative cells- which indicates a possible escape variant. Our lab is now moving toward testing CD56R-CAR T cell in vivo in both xenograph models and spontaneous ones.
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