Abstract 3612: Elevated TGFa levels in chronic mylogenous leukemia (CML) patient plasma measured by a highly sensitive single molecule array immunoassay

Abstract

Abstract Introduction: Recent reports suggest that cytokine and growth factor profiling are prognostic in myelodisplasias and CML. TGF-α and IL-6 plasma levels selectively identified CML patients failing to achieve an early molecular response (EMR), or progressed on imatinib therapy (Nievergall et al, 2016). In patients failing to achieve EMR, the median TGFα concentrations were in the low pg/mL range while IL-6 levels were sub-pg/mL or undetectable. Thus, to accurately and reproducibly measure TGFα and IL-6 levels in blood as prognostic or predictive markers of imatinib response, there is a need for highly sensitive immunoassays. Here we demonstrate the utility of using a digital immunoassay to measure sub-pg/mL levels of TGFα and IL-6 in CML plasma samples assessed for BCR-ABL fusion transcripts. Methods: Single molecule array immunoassays (Simoa) for TGFα and IL-6 were performed on the HD-1 platform (Quanterix), qualified based on precision, reproducibility, linearity, sensitivity according to kit specifications. CML blood samples were obtained from CMBP, LabCorp, Inc, following BCR-ABL e1b2, b2b2, and b3b2 transcript fusion testing by RT-PCR. Results: TGFα and IL-6 concentrations in the plasma of 77 CML patients were determined and compared to levels in healthy controls. TGFα in CML plasma was elevated and ranged ~20-fold (6.13-118.6 pg/mL), in contrast to the low levels and narrow range in healthy controls (range = 1.11-3.17 pg/mL). Median TGFα levels were 10-fold higher in CML patient plasma (median = 18.8 pg/mL) relative to healthy controls (median = 1.8 pg/mL; p <0.0001). IL-6 levels ranged broadly in CML plasma (0.12-12.6 pg/mL) relative to healthy controls (0.3-1.04pg/mL), though median levels were not significantly different (CML = 0.61 vs 0.69, p = 0.873). TGFα and IL-6 concentrations were not significantly correlated. TGFα levels appear elevated in CML samples expressing all 3 BCR-ABL transcripts, however, a larger number of samples enriched in fusion transcripts are being assessed to confirm possible correlations. Conclusions: We have qualified novel highly sensitive single molecule array immunoassays to measure TGFα and IL-6 in the plasma of CML patients and healthy controls, and found significantly elevated levels of TGFα in CML plasma. These results support further investigation of TGFα and IL-6, using sensitive immunoassays, as potential prognostic and predictive markers of CML disease progression and treatment outcome. Citation Format: Ahmed Chenna, Li Cai, Christos Petropoulos, John W. Winslow. Elevated TGFa levels in chronic mylogenous leukemia (CML) patient plasma measured by a highly sensitive single molecule array immunoassay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3612.