TCIP1

TCIP1 is the most potent transcriptional/epigenetic CIP (chemical inducers of proximity) and specifically activates BCL6 target genes. TCIP1 kills diffuse large B cell lymphoma cell lines, including chemotherapy-resistant, TP53-mutant lines and exhibits cell-specific and tissue-specific effects. TCIP1 successfully killed large B cell lymphoma cell lines, including chemotherapy-resistant TP53-mutant lines and exhibited cell-specific and tissue-specific effects. The activation of apoptosis to cell death took place in just 72 hours.BCL6 is critical to the lymphatic system, and mice engineered without the BCL6 gene die of complex inflammatory reactions. BRD4 is heavily involved in genome function and stability across many processes. Concerns regarding utilizing these important gene expressions and how they might affect off-target healthy tissues were addressed in the study.TCIP1 acts in a context-specific manner requiring the expression of BRD4 and BCL6 to both be present in order to bind them and operate at a concentration that would occupy only a tiny fraction of the total BCL6 molecules.TCIP1 induced dramatic transcriptomic changes in the spleen, notably with an upregulation of the FOXO3 gene, which mirrored activity in the targeted cancer cells. Despite the significant transcriptomic changes in the spleen, TCIP1 was well tolerated without adverse effects, with no significant differences in mouse body weight and no noticeable abnormalities such as inflammatory infiltrates or apoptotic cells. BCL6-BRD4 TCIP1 (TCIP1) is a potent BCL6-BRD4 transcriptional/epigenetic chemical inducer of proximity (TCIP) by covalently linking BCL6 binder BI-3812 to BRD4 ligand JQ1, selectively kills DLBCL cells with EC50 of 1.3 nM against KARPAS422 cell. TCIP1 rapidly and robustly killed other DLBCL lines with high levels of BCL6, but JQ1 and BI3812 separately or together shows100–1,000-fold less-effective cell killing. TCIP1 is 200–10,000-fold more potent in killing DLBCL cells than the degradation of BRD4 by dBET1 and/or degradation of BCL6 by BI3802. TCIP1 induces a stable, cooperative protein-protein interaction between bromodomain 1 (BD1) of BRD4 and the BTB domain of BCL6. TCIP1 shows affinity for intracellular ternary complex of BRD4 with Kd of 340 nM in TR-FRET assays. TCIP1 induces G1/S and G2/M block in the cell cycle, TCIP1 (10 nM) represses MYC and its targets while activating pro-apoptotic genes in KARPAS422 cells. TCIP1 kills diffuse large B cell lymphoma cell lines, including chemotherapy-resistant, TP53-mutant lines, at EC50 of 1-10 nM in 72 h and exhibits cell-specific and tissue-specific effects, capturing the combinatorial specificity inherent to transcription.