Ratio-Dependent Synergism of a Doxorubicin and Olaparib Combination in 2D and Spheroid Models of Ovarian Cancer

Abstract

Ovarian cancer is the fourth leading cause of death in women in developed countries. Even though patients with the most lethal form of the disease (HGSOC; high grade serous ovarian cancer) respond well to initial treatment, they often relapse with progressively resistant disease. Inhibitors of the poly(ADP-ribose) polymerase (PARP) enzymes are a relatively new class of molecularly targeted small molecule drugs that show promise in overcoming resistance. The present study explores the combination of a DNA damaging agent, doxorubicin (DOX), with the PARP inhibitor, olaparib (OLP), in order to achieve optimal synergy of both drugs in serous ovarian cancer. This drug combination was evaluated and optimized in 2D monolayers and 3D multicellular tumor spheroids (MCTS) using a genetically and histologically characterized panel of nine OC cell lines with or without BRCA1 or BRCA2 mutations. Combination index (CI) values of DOX and OLP were determined using the Chou and Talalay method. The potency of this drug combination was found to rely heavily on the molar ratios at which the two drugs are combined. In general, MCTS growth inhibition was reflective of the patterns predicted by the CI values obtained in monolayers. Promising combination ratios identified in this study warrant further preclinical and clinical investigation.

Carboplatin sensitivity in epithelial ovarian cancer cell lines: The impact of model systems

“…Fig). Therefore, carboplatin sensitivity was evaluated in 3D spheroids formed in the PDMS microfluidic device and the Matrigel-assisted ULA plate since the latter is widely used for drug sensitivity assays [11,18,19,45,50].…”

“…In the particular case of ovarian cancer, 3D spheroids are clinically relevant models since in advanced disease EOC cells can spread to the peritoneum as aggregates/spheroids [52,53]. In the literature, several EOC cell lines have been studied by different spheroid generating methods, including hanging-droplets [16, 22, 27-29, 41, 54, 55], biomimetic hydrogels [23], plastic wells coated with matrix scaffolds [20,46,56], and more recently by microfluidics [33,34,37,38,42,44] and commercially available round-bottom ULA plates [18,45,50,57]. In the present study we first compared the ability of four EOC cell lines to form spheroids using these ULA 96-well plates (in the absence or presence of Matrigel) with that of hanging-droplets and PDMS-based microfluidic chips.…”

“…It is also 10 times higher than the 2D IC 50 (by clonogenic assay) of the most resistant cell lines OV90 and OV866(2) (see Table 1). Then, the effect of carboplatin on our EOC cell lines was evaluated by measuring the size of the spheroids, as is commonly used in the literature [18,19,45,51], and by measuring live/apoptotic/dead cells by flow cytometry using Annexin V/7-AAD staining of the dissociated spheroids. For the spheroids grown in the PDMS-based microfluidic chips, we observed a significant decrease in the percentage of live cells following treatment with 300 μM carboplatin for the OV90 and OV866(2) spheroids, but not for the TOV3041G and TOV112D cells, the latter being the most resistant in this assay (Fig 4B).…”

“…Although several studies have compared the chemosensitivity of ovarian cancer cell lines grown as monolayers with 3D-spheroid cultures [18,41,45,46], little is known about the impact that different 3D spheroid model systems have on their sensitivity. In the present study, we investigated the ability of four different EOC cell lines to form 3D spheroids following different methodologies (hanging-droplets, ULA plates and microfluidic chips), and their carboplatin sensitivity in monolayer culture versus spheroids formed within microfluidic devices or round-bottom ULA plates (the latter using Matrigel as an ECM) (Fig 1).…”

GEICO1601-ROLANDO: A Multicentric Single Arm Phase II Clinical Trial to Evaluate the Combination of Olaparib and Pegylated Liposomal Doxorubicin for Platinum-Resistant Ovarian Cancer

“…Recently, a preclinical study demonstrated a synergism of the combination of olaparib with doxorubicin in 2D and spheroid models of ovarian cancer [14]. This study showed that DNA damage was increased at a molar concentration of doxorubicin: olaparib of 50:1 in both BRCA mutant and BR CA wild type cell lines UWB1-289.…”