Treatment with Everolimus and PD-901 in combination in the NF1-asssociated mouse model extended lifespan and dramatically reduced tumor burden, although all tumors that were analyzed at necropsy were grade 2, as assessed by H & E, S100, and Ki67 as described above (Figure 2A, 2C, 3A, 4A). The gene discussed is S100B; the disease is neoplasm.