STAT3 and glioblastoma: Concerns about in vivo stability, immunogenicity, and low potency led to the design of non-peptide mimetics, such as LLL12 and STX-0119, which have been found to induce apoptosis in GBM cell lines or TMZ-resistant xenografts via inhibition of downstream STAT3 targets, such as survivin Bcl-2 and Bcl-xL [223,224,225,226].