Periodic Reporting for period 1 - TRIPLECON (Triple negative breast cancer control through synergistic inhibition of EGFR and CDK9 signaling)
Reporting period: 2017-10-01 to 2018-09-30
Indeed within this PoC project, we have provided additional support for our hypothesis. First, before initiating in vivo studies in mice, we have shown in collaboration with prof. Shudong Wang (Univ. Southern Australia) that the CDK9 inhibitor I-73 is the most optimal CDK9 inhibitor to be combined with lapatinib. Second, we have revealed that this combination therapy is effective not only in TNBC cell lines but also in TNBC organo-typic cultures derived from patient derived xenografts (PDX). Third, we showed that the combination treatment effectively targets TNBC cell cultures not only when these were grown in 2D but also in 3D cultures. Finally, we have provided evidence that this drug combination can also be effective in EGFR dependent cancers beyond TNBC (e.g. in colorectal and lung cancer). With regard to planned in vivo experiments in mice, we have shown that next to both treatments (lapatinib and CDK I-73) as monotherapy their combination treatment is safe in healthy mice. Secondly and importantly, we have determined in mice baring suitable TNBC xenograft models that the combination treatment was effectively inhibiting RNAPOL2 activity the direct target leading to downregulation of downstream target MCL1. This effect was not seen by treatment with either monotherapies. Currently, final in vivo experiments in mice bearing TNBC xenografts are on-going to show that this drug combination is an effective drug combination.
In conclusion, while we still have to complete the final in vivo experiments we can conclude that the PoC has broad this new combination treatment closer to the clinic since we have found that the combination treatment is effective and safe. Moreover we also provide evidence that combining two independent pathways which converge on the p-TEFb complex is effective not only in TNBC but also in other cancer type making this an effective strategy beyond breast cancer.