Immune response and survival of refractory cancer patients who received TGF-ß2 antisense/GM-CSF gene modified autologous tumor cell (TAG) vaccine.

TAG vaccine is a novel 'triad vaccine' that involves transfection of autologous tumor with a dual plasmid, TGFß2 antisense gene and GM-CSF gene. Patients with advanced cancer who failed standard therapy were treated. IFN-γ ELISPOT analysis (Enzyme-Linked Immunospot Assay for Interferon Gamma) using TAG autologous vaccine target cells was performed prior to vaccination and at week 12 after the third vaccination. The purpose of this assessment was to correlate the IFN-γ ELISPOT immune response with long-term survival of advanced cancer patients who received TAG vaccination. Twenty-three of 28 patients received ≥ 3 TAG vaccinations (two patients withdrew consent and three had disease progression prior to the third vaccination). Eleven patients demonstrated a positive ELISPOT response (>10 spots and ≥ 2 × baseline) at week 12 and 12 patients did not (P=0.002). Median survival from time of treatment between ELISPOT-positive and -negative groups was significantly different (550 vs 159 days, P=0.036), as was median survival from the time of procurement (627 vs 257 days, respectively, P=0.043). In conclusion, the IFN-γ ELISPOT assay may provide an effective measure of immune response following treatment with 'triad vaccines', but additional patient numbers and/or other immune modulatory parameters are necessary for future testing.

Enhanced target gene knockdown by a bifunctional shRNA: a novel approach of RNA interference.

RNA interference (RNAi) is a natural cellular regulatory process that inhibits gene expression by transcriptional, post-transcriptional and translational mechanisms. Synthetic approaches that emulate this process (small interfering RNA (siRNA), short hairpin RNA (shRNA)) have been shown to be similarly effective in this regard. We developed a novel 'bifunctional' RNAi strategy, which further optimizes target gene knockdown outcome. A bifunctional construct (bi-sh-STMN1) was generated against Stathmin1, a critical tubulin modulator that is overexpressed in human cancers. The bifunctional construct is postulated to concurrently repress the translation of the target mRNA (cleavage-independent, mRNA sequestration and degradation) and degrade (through RNase H-like cleavage) post-transcriptional mRNA through cleavage-dependent activities. Bi-sh-STMN1 showed enhanced potency and durability in parallel comparisons with conventional shRNA and siRNAs targeting the same sequence. Enhanced STMN1 protein knockdown by bi-sh-STMN1 was accompanied by target site cleavage at the mRNA level showed by the rapid amplification of complementary DNA ends (RACE) assay. Bi-sh-STMN1 also showed knockdown kinetics at the mRNA level consistent with its multieffector silencing mechanisms. The bifunctional shRNA is a highly effective and advantageous approach mediating RNAi at concentrations significantly lower than conventional shRNA or siRNA. These results support further evaluations.