Telomerase inhibitors TMPyP4 and BIBR 1532 show synergistic antitumor activity in combination with chemotherapeutic drugs

We investigated the in vitro pharmacodynamic interactions of telomerase inhibitors (TMPyP4 and BIBR1532) with three anticancer drugs (cisplatin, doxorubicin, and paclitaxel) on a broad range of human cancer cell lines (MCF-7, MDA-MB-231, HeLa, U-118 MG, OVCAR-3, MCF-12A), selected based on the basal level of hTERT. The drug combination approach was performed using a combination index (CI), the Chou-Talalay method. The HeLa cells show the highest level of hTERT among the studied cell lines, and the second level was noted in the MCF-7 cells. Almost all used combinations in this line revealed a synergistic effect, with the lowest CI for BIBR1532 and cisplatin. Interestingly, the highest synergistic effect, compared to other combinations, was shown by BIBR1532 and doxorubicin in U118 MG cells. Additionally, the highest effect of TMPyP4, compared to all combinations, was noted in conjunction with cisplatin in HeLa cells. The most impactful results were achieved by combining inhibitors with drugs that interact directly with DNA strands. Moreover, the different hTERT levels influence the response to treatments. This underscores the need for in vitro optimization to maximize the synergistic interaction of compounds. Combining genome-based medicine and drug screening using personalized models may fulfill the promise of precision medicine for every cancer type.