Heat-induced BRCA2 degradation in human tumours provides rationale for hyperthermia-PARP-inhibitor combination therapies

Purpose: Hyperthermia (40–44 °C) effectively sensitises tumours to radiotherapy by locally altering tumour biology. One of the effects of heat at the cellular level is inhibition of DNA repair by homologous recombination via degradation of the BRCA2-protein. This suggests that hyperthermia can expand the group of patients that benefit from PARP-inhibitors, a drug exploiting homologous recombination deficiency. Here, we explore whether the molecular mechanisms that cause heat-mediated degradation of BRCA2 are conserved in cell lines from various origins and, most importantly, whether, BRCA2 protein levels can be attenuated by heat in freshly biopted human tumours. Experimental design: Cells from four established cell lines and from freshly biopsied material of cervical (15), head- and neck (9) or bladder tumours (27) were heated to 42 °C for 60 min ex vivo. In vivo hyperthermia was studied by taking two biopsies of the same breast or cervical tumour: one before and one after treatment. BRCA2 protein levels were measured by immunoblotting. Results: We found decreased BRCA2-levels after hyperthermia in all established cell lines and in 91% of all tumours treated ex vivo. For tumours treated with hyperthermia in vivo, technical issues and intra-tumour heterogeneity prevented obtaining interpretable results. Conclusions: This study demonstrates that heat-mediated degradation of BRCA2 occurs in tumour material directly derived from patients. Although BRCA2-degradation may not be a practical biomarker for heat deposition in situ, it does suggest that application of hyperthermia could be an effective method to expand the patient group that could benefit from PARP-inhibitors

Postoperative outcomes of primary and interval cytoreductive surgery for advanced ovarian cancer registered in the Dutch Gynecological Oncology Audit (DGOA)

Objectives: The challenge when performing cytoreductive surgery (CRS) is to balance the benefits and risks. The aim of this study was to report short term postoperative morbidity and mortality in relation to surgical outcome in patients undergoing primary debulking surgery (PDS) or interval debulking (IDS) surgery in the Netherlands. Methods: The Dutch Gynecological Oncology Audit (DGOA) was used for retrospective analysis. Patients undergoing PDS or IDS between January 1st, 2015 - December 31st, 2018 were included. Outcome was frequency of postoperative complications. Median time to adjuvant chemotherapy and severity of complications were related to outcome of CRS. Complications with Clavien-Dindo ≥3 were analyzed per region and case mix corrected. Statistical analysis was performed with R.Studio. Results: 1027 patients with PDS and 1355 patients with IDS were included. Complications with re-invention were significantly higher in PDS compared to IDS (5.7% vs. 3.6%, p = 0.048). Complete cytoreduction was 69.7% in PDS and 62.1% IDS, p &lt; 0.001. Time to adjuvant chemotherapy was 49 days in patients with complete CRS and a complication with re-intervention. Regional variation for severe complications showed one region outside confidence intervals. Conclusions: Higher complete cytoreduction rate in the PDS group indicates that the correct patients have been selected, but is associated with a higher percentage of complication with re-intervention. As result, time to start adjuvant chemotherapy is longer in this group. Maintaining a balance in aggressiveness of surgery and outcome of the surgical procedure with respect to severe complications is underlined. Bench marked data should be discussed nationally to improve this balance.</p