title: Strong synergy with APR-246 and DNA-damaging drugs in primary cancer cells from patients with TP53 mutant High-Grade Serous ovarian cancer.
abstract: BACKGROUND
  Mutation in the tumor suppressor gene TP53 is an early event in the development of high-grade serous (HGS) ovarian cancer and is identified in more than 96 % of HGS cancer patients. APR-246 (PRIMA-1(MET)) is the first clinical-stage compound that reactivates mutant p53 protein by refolding it to wild type conformation, thus inducing apoptosis. APR-246 has been tested as monotherapy in a Phase I/IIa clinical study in hematological malignancies and prostate cancer with promising results, and a Phase Ib/II study in combination with platinum-based therapy in ovarian cancer is ongoing. In the present study, we investigated the anticancer effects of APR-246 in combination with conventional chemotherapy in primary cancer cells isolated from ascitic fluid from 10 ovarian, fallopian tube, or peritoneal cancer patients, 8 of which had HGS cancer.
  
  
  METHODS
  Cell viability was assessed with fluorometric microculture cytotoxicity assay (FMCA) and Combination Index was calculated using the Additive model. p53 status was determined by Sanger sequencing and single strand conformation analysis, and p53 protein expression by western blotting.
  
  
  RESULTS
  We observed strong synergy with APR-246 and cisplatin in all tumor samples carrying a TP53 missense mutation, while synergistic or additive effects were found in cells with wild type or TP53 nonsense mutations. Strong synergy was also observed with carboplatin or doxorubicin. Moreover, APR-246 sensitized TP53 mutant primary ovarian cancer cells, isolated from a clinically platinum-resistant patient, to cisplatin; the IC50 value of cisplatin decreased 3.6 fold from 6.5 to 1.8 μM in the presence of clinically relevant concentration of APR-246.
  
  
  CONCLUSIONS
  These results suggest that combination treatment with APR-246 and DNA-damaging drugs could significantly improve the treatment of patients with TP53 mutant HGS cancer, and thus provide strong support for the ongoing clinical study with APR-246 in combination with carboplatin and pegylated liposomal doxorubicin in patients with recurrent HGS cancer.
authors.affiliation: Aprea AB, Solna, Sweden.
authors.forename: Åsa
authors.initials: Å
authors.lastname: Fransson
authors.affiliation: Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Daria
authors.initials: D
authors.lastname: Glaessgen
authors.affiliation: Aprea AB, Solna, Sweden.
authors.forename: Jessica
authors.initials: J
authors.lastname: Alfredsson
authors.affiliation: Karolinska Institutet Dept. of Oncology-Pathology, Cancer Center Karolinska (CCK), Stockholm, Sweden.
authors.forename: Klas G
authors.initials: KG
authors.lastname: Wiman
authors.affiliation: Karolinska University Hospital, Stockholm, Sweden.|Karolinska Institutet Dept. of Oncology-Pathology, Cancer Center Karolinska (CCK), Stockholm, Sweden.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Bajalica-Lagercrantz
authors.affiliation: Aprea AB, Solna, Sweden. nina.mohell@aprea.com.
authors.forename: Nina
authors.initials: N
authors.lastname: Mohell
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D018284:Cystadenocarcinoma, Serous / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology*; D004249:DNA Damage / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D004357:Drug Synergism; D005260:Female; D006801:Humans; D020128:Inhibitory Concentration 50; D009154:Mutation; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology*; D011812:Quinuclidines / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D011812:Quinuclidines; D016159:Tumor Suppressor Protein p53; D002945:Cisplatin; C533410:eprenetapopt
keywords: APR-246 (PRIMA-1MET); Cisplatin; DNA-damaging drugs; Doxorubicin; High-Grade Serous (HGS) cancer; Ovarian cancer; Primary cancer cells; Synergy; TP53 mutation; p53 reactivation