Olaparib and temozolomide in desmoplastic small round cell tumors: a promising combination in vitro and in vivo

Abstract

Purpose Desmoplastic small round cell tumors (DSRCTs) are highly malignant and very rare soft tissue sarcomas with a high unmet need for new therapeutic options. Therefore, we examined poly(ADP-ribose) polymerase 1 (PARP1) and Schlafen-11 (SLFN11) expression in DSRCT tumor tissue and the combination of PARP inhibitor olaparib with the alkylating agent temozolomide (TMZ) in a preclinical DSRCT model. Methods PARP1 and SLFN11 have been described as predictive biomarkers for response to PARP inhibition. Expression of PARP1 and SLFN11 was assessed in 16 and 12 DSRCT tumor tissue samples, respectively. Effects of single-agent olaparib, and olaparib and TMZ combination treatment were examined using the preclinical JN-DSRCT-1 model. In vitro, single-agent and combination treatment effects on cell viability, the cell cycle, DNA damage and apoptosis were examined. Olaparib and TMZ combination treatment was also assessed in vivo. Results PARP1 and SLFN11 expression was observed in 100% and 92% of DSRCT tumor tissues, respectively. Olaparib treatment reduced cell viability and cell migration in a dose-dependent manner in vitro. Drug synergy between olaparib and TMZ was observed in vitro and in vivo. Combination treatment led to a cell-cycle arrest and induction of DNA damage and apoptosis, even when combined at low dosages. Conclusion We show high PARP1 and SLFN11 expression in DSRCT tumor material and antitumor effects following olaparib and TMZ combination treatment in a preclinical DSRCT model. This suggests that olaparib and TMZ combination treatment could be a potential treatment option for DSRCTs.Keywords Desmoplastic small round cell tumor (DSRCT) · Poly(ADP-ribose) polymerase (PARP) · Schlafen-11 (SLFN11) · Olaparib · Temozolomide · Combination treatment Abbreviations DSRCT Desmoplastic small round cell tumor ES Ewing sarcoma PARP Poly(ADP-ribose) polymerase SLFN11 Schlafen-11 SSB Single-stranded breaks STS Soft tissue sarcoma TMZ Temozolomide Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s0043 2-020-03211 -z) contains supplementary material, which is available to authorized users.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

SLFN11 informs on standard of care and novel treatments in a wide range of cancer models

“…We were also surprised by the limited impact of SLFN11 in our in vitro and in vivo models treated with the PARP inhibitor olaparib, particularly in light of other reports of a correlation of SLFN11 with PARPi. 3,4,6,22 There could be several reasons for this. Firstly, we have used olaparib, while most of the published preclinical observations have been generated using talazoparib, an extreme PARP "trapper", where even low concentrations are known to cause DNA damage.…”

“…In vitro, independent analyses have identified Schlafen 11 (SLFN11) as the strongest predictor of sensitivity to DNAdamaging agents (DDA), such as topoisomerase I (e.g., irinotecan), topoisomerase II (e.g., etoposide), DNA synthesis inhibitors (e.g., gemcitabine) and DNA cross-linkers and alkylating agents (e.g., cisplatin). 1,2 In addition to DDA, SLFN11 has been also associated with sensitivity to PARP inhibitors (PARPi), [3][4][5][6] which belong to the class of DNA damage-response inhibitors (DDRi). For the aforementioned agents, and in multiple cancer cell line panels, the presence of SLFN11 has been shown to correlate with sensitivity, whereas the low or absent expression has been associated with resistance.…”

Desmoplastic Small Round Cell Tumor: A Review of Main Molecular Abnormalities and Emerging Therapy

“…Since poly(ADP-ribose) polymerases (PARPs) perform an important role in DDR, specifically in the base excision repair of single-strand DNA breaks, PARP inhibitors recently emerged as new treatment for cancer based on synthetic lethality concept, particularly in BRCA-mutant cancers defective in homologous repair [105,106]. DSRCT has high level of PARP1, the most abundant enzyme of PARP family, and combination of olaparib and temozolamide has demonstrated enhanced antitumor effects in vitro and in vivo [70,107,108]. [110,111].…”

“…The cell has tumorigenic capacity and the histology of heterotransplanted tumors in SCID mice maintains the characteristics of the original DSRCT, including the expression of immunohistochemical markers (vimentin, desmin, CD57, among others), a t(11; 22) translocation (p13; q12 ) and presence of EWS-WT1 fusion[69]. JN-DSRCT-1 cells are being used in a several studies that help to unveil DSRCT biology, specially the role of EWS-WT1 fusion protein and also to identify targets for therapeutic interventions[12,70] As mentioned before, EWS-WT1 translocation is the major driver in DSRCT and plays many roles in tumor biology that have the potential to be used as therapeutic targets. As already described in other studies, EWS-WT1 gene underwent RNA splicing and one variant lacks three amino-acids and was named EWS-WT1(-KTS) due the absence of Lys-Thr-Ser residues[71].…”

“…This activity is also observed in EWS-WT1 fusion protein, trabectedin reduces its binding on its target gene promoters and, thus, affects EWS-WT1-dependent gene expression in JN-DSRCT-1 cells[80]. Recently, the combination of PARP inhibitor olaparib with the alkylating agent temozolomide was tested in JN-DSRCT-1 cells in vitro and in vivo and the results indicates that the combination have synergistic effects upon cell viability, inducing cell cycle arrest which progress to apoptosis induction, causing tumor reduction[70].Additionally to JN-DSRCT-1 cells, Markides and collaborators established more DSRCT cell lines, including BER lineage that also presents EWS-WT1 fusion protein and have similar behavior of JN-DSRCT-1[12,82]. Together, this evidence shows the importance of obtaining tumor models to accelerate preclinical research, bring possibilities for investigating new therapeutic approaches for this rare but lethal malignancy.…”