PMEL is a predictive biomarker for mTORC1 inhibitor treatment of renal angiomyolipoma in tuberous sclerosis complex patients.

BACKGROUND

We aimed to demonstrate the function of premelanosome protein (PMEL) as a biomarker to predict the effectiveness of mammalian target of rapamycin complex 1 (mTORC1) inhibitor treatment in renal angiomyolipomas (RAMLs) in tuberous sclerosis complex (TSC) patients.

METHODS

95 whole blood samples from 49 patients diagnosed with TSC-RAMLs were collected. PMEL, N4BP2, and PCSK1N expression in the plasma samples were tested by quantitative sandwich ELISA. The target tumor volume assessed by maximum cross-sectional area (CSAmax) in CT scans. Correlation analysis was used to determine the relationship between PMEL expression and target tumors, as well as the tumor reduction rate.

RESULTS

The tumor size of TSC-RAMLs positivity correlated with PMEL expression (r = 0.30, p = 0.036) and PCSK1N expression (r = 0.23, p = 0.027), but had no significant relationship with N4BP2 (r = 0.06, p = 0.89). The positive correlation between TSC-RAML tumor volume and PMEL expression still existed in TSC patients before (r = 0.30, p = 0.026) and after mTORC1 inhibitor treatment (r = 0.41, p = 0.0017), but the correlation between tumor volume and PCSK1N expression no longer existed. Further analysis found that PMEL expression negatively correlated with the reduction rate of TSC-RAMLs after mTORC1 inhibitor treatment (r = -0.50, p = 0.0022), both after 3 months (r = -0.47, p = 0.048) and 6 months of treatment (r = -0.52, p = 0.028).

CONCLUSION

PMEL expression positively correlated with the tumor size of TSC-RAMLs, and inversely with the reduction rate of TSC-RAMLs after mTORC1 inhibitor treatment, which may suggest that PMEL may serve as a predictive biomarker for the efficacy of mTORC1 inhibitor treatment.