Autoimmunity to SOX2, clinical phenotype and survival in patients with small-cell lung cancer.

Objective: Autoantibodies to SOXB1 antigens are commonly found in patients with small-cell lung cancer (SCLC). It has not been established whether the presence of circulating SOX antibodies is associated with a specific paraneoplastic clinical phenotype, or if a tumour immune response to SOX antigens can affect prognosis in patients with SCLC in relation to other established prognostic factors.

Methods: Using recombinant SOX2 in an ELISA, we analysed sera in a prospective study from 212 unselected SCLC patients, which included 35 patients with neurological paraneoplastic disorders, or other well characterised onconeural antibodies.

Results: Overall, SOX2 antibodies were detected in 70 SCLC patients, with a sensitivity of 33% (95% CI 27-40%) and specificity of 97% (95% CI 94-99%) compared to controls matched for age, gender and smoking history. No single clinical phenotype was seen in relation to the presence of SOX2 antibodies in isolation. Multivariate analysis showed that the presence of SOX2 antibodies in SCLC patients without evidence of neurological paraneoplastic disorders or onconeural antibodies did not have a significant effect on survival when known prognostic factors were accounted for.

Conclusions: SOX2 antibodies are very specific markers for SCLC compared to matched non-tumour controls, but their presence does not seem to alter prognosis in this tumour type.