Astrid Dempfle

Dual Topoisomerase Inhibitor Is Highly Potent and Improves Antitumor Response to Radiotherapy in Cervical Carcinoma

Despite advances in vaccination and early detection, the total number of cases and deaths from cervical cancer has risen steadily in recent decades, making it the fourth most common type of cancer in women worldwide. Low-income countries in particular struggle with limited resources and treatment limitations for cervical cancer. Thus, effective medicines that are simple to manufacture are needed. The newly developed dual topoisomerase inhibitor P8-D6, with its outstanding ability to induce apoptosis, could be a promising option. In this study, the efficacy of P8-D6 in combination with radiochemotherapy against cervical carcinoma was investigated in established cell lines and in a translational approach in ex vivo patient cells by measuring the cytotoxicity, cell viability and caspase activity in vitro in 2D and 3D cell cultures. Treatment with P8-D6 resulted in significantly greater cytotoxicity and apoptosis induction compared to standard therapeutic cisplatin in both 2D and 3D cell cultures. Specifically, a considerably stronger anti-proliferative effect was observed. The treatment also led to morphological changes and a loss of membrane integrity in the 3D spheroids. Radiotherapy also benefited greatly from P8-D6 treatment. In fact, P8-D6 was a more potent radiosensitizer than cisplatin. Simple synthesis, favorable physicochemical properties and high potency make P8-D6 a promising cervical cancer drug candidate.

Combined PARP and Dual Topoisomerase Inhibition Potentiates Genome Instability and Cell Death in Ovarian Cancer

Although ovarian cancer is a rare disease, it constitutes the fifth leading cause of cancer death among women. It is of major importance to develop new therapeutic strategies to improve survival. Combining P8-D6, a novel dual topoisomerase inhibitor with exceptional anti-tumoral properties in ovarian cancer and compounds in preclinical research, and olaparib, a PARP inhibitor targeting DNA damage repair, is a promising approach. P8-D6 induces DNA damage that can be repaired by base excision repair or homologous recombination in which PARP plays a major role. This study analyzed benefits of combining P8-D6 and olaparib treatment in 2D and 3D cultures with ovarian cancer cells. Measurement of viability, cytotoxicity and caspase activity were used to assess therapy efficacy and to calculate the combination index (CI). Further DNA damage was quantified using the biomarkers RAD51 and γH2A.X. The combinational treatment led to an increased caspase activity and reduced viability. CI values partially show synergisms in combinations at 100 nM and 500 nM P8-D6. More DNA damage accumulated, and spheroids lost their membrane integrity due to the combinational treatment. While maintaining the same therapy efficacy as single-drug therapy, doses of P8-D6 and olaparib can be reduced in combinational treatments. Synergisms can be seen in some tested combinations. In summary, the combination therapy indicates benefits and acts synergistic at 100 nM and 500 nM P8-D6.