Efficacy of these two analogues is equivalent with biochemical control represented by a GH <2.5 μg/L and a normal IGF-I level in 30–40% of individuals.8–11 Notably, similar biochemical outcomes are observed whether the iSRLs are used as primary or secondary therapy following TSS.12 First-generation iSRL also have remarkable inhibitory effects on tumour growth to the extent that <2% of individuals show tumour enlargement during long-term treatment.12,13. The gene discussed is IGF1; the disease is neoplasm.