PTCH1 and skin basal cell carcinoma: For example, hedgehog signaling pathway inhibitor small molecules (vismodegib, sonidegib) may be most effective in BCC patients with PTCH1 mutations who are not exposed to high As, whereas the same therapy may show the least or no response in BCC patients without PTCH1 somatic mutations exposed to high As (see Table 4 and Figure 8).