BRAF-AXL-PD-L1 Signaling Axis as a Possible Biological Marker for RAI Treatment in the Thyroid Cancer ATA Intermediate Risk Category

The use of radioiodine therapy (RIT) is debated in intermediate-risk differentiated thyroid cancer (DTC) patients. The understanding of the molecular mechanisms involved in the pathogenesis of DTC can be useful to refine patient selection for RIT. We analyzed the mutational status of BRAF, RAS, TERT, PIK3 and RET, and the expression of PD-L1 (as a CPS score), the NIS and AXL genes and the tumor-infiltrating lymphocytes (TIL, as the CD4/CD8 ratio), in the tumor tissue in a cohort of forty-six ATA intermediate-risk patients, homogeneously treated with surgery and RIT. We found a significant correlation between BRAF mutations and a less than excellent (LER, according to 2015 ATA classification) response to RIT treatment (p = 0.001), higher expression of the AXL gene (p = 0.007), lower expression of NIS (p = 0.045) and higher expression of PD-L1 (p = 0.004). Moreover, the LER patient group had a significantly higher level of AXL (p = 0.0003), a lower level of NIS (p = 0.0004) and a higher PD-L1 level (p = 0.0001) in comparison to patients having an excellent response to RIT. We also found a significant direct correlation between the AXL level and PD-L1 expression (p < 0.0001) and a significant inverse correlation between AXL and NIS expression and TILs (p = 0.0009 and p = 0.028, respectively). These data suggest that BRAF mutations and AXL expression are involved in LER among DTC patients and in the higher expression of PD-L1 and CD8, becoming new possible biomarkers to personalize RIT in the ATA intermediate-risk group, as well as the use of higher radioiodine activity or other possible therapies.

Cytoplasmic Expression of AXL Is Associated With High Risk of Postoperative Relapse of Conventional Renal Cell Carcinoma

BACKGROUND/AIM

Despite early detection by widespread use of abdominal imaging more than 40% of patients with conventional renal cell carcinoma (RCC) will die due to metastatic disease. Small kinase inhibitors for AXL receptor tyrosine kinase may delay the progression of metastatic cRCC.

PATIENTS AND METHODS

We analysed AXL expression by immunohistochemistry on tissue multi arrays of 691 conventional RCC without metastasis at the time of nephrectomy.

RESULTS

The Kaplan-Meier survival analysis indicated a poor disease-specific survival rates for patients with tumour showing cytoplasmic AXL staining, whereas expression on the cell membrane is associated with excellent disease outcome. Multivariate Cox regression analysis identified cytoplasmic AXL expression as an independent prognostic factor indicating a five-times higher risk of postoperative tumour progression (RR=5.048; 95% CI=2.391-10.657; p<0.001).

CONCLUSION

Detecting cytoplasmic expression of AXL can be used to define a subset of conventional RCC with high risk of progression, thus identifying patients for more aggressive surveillance and adjuvant AXL inhibitor treatment as early as possible.