HHIP and mesothelioma: Although in a rat mesothelioma model, the SMO inhibitor vismodegib significantly reduced tumor volume and growth, and lowered the expression of HP target genes such as GLI1, HHIP, and PTCH1, the two available Phase I clinical trials of vismodegib and sonidegib failed to demonstrate clinical benefit, potentially due to the lack of genotype‐based patient selection [227, 228, 229, 230].