Refractory testicular germ cell tumors are highly sensitive to the second generation DNA methylation inhibitor guadecitabine

Abstract

Testicular germ cell tumors (TGCTs) are the most common cancers of young males. A substantial portion of TGCT patients are refractory to cisplatin. There are no effective therapies for these patients, many of whom die from progressive disease. Embryonal carcinoma (EC) are the stem cells of TGCTs. In prior in vitro studies we found that EC cells were highly sensitive to the DNA methyltransferase inhibitor, 5-aza deoxycytidine (5-aza). Here, as an initial step in bringing demethylation therapy to the clinic for TGCT patients, we evaluated the effects of the clinically optimized, second generation demethylating agent guadecitabine (SGI-110) on EC cells in an animal model of cisplatin refractory testicular cancer. EC cells were exquisitely sensitive to guadecitabine and the hypersensitivity was dependent on high levels of DNA methyltransferase 3B. Guadecitabine mediated transcriptional reprogramming of EC cells included induction of p53 targets and repression of pluripotency genes. As a single agent, guadecitabine completely abolished progression and induced complete regression of cisplatin resistant EC xenografts even at doses well below those required to impact somatic solid tumors. Low dose guadecitabine also sensitized refractory EC cells to cisplatin in vivo. Genome-wide analysis indicated that in vivo antitumor activity was associated with activation of p53 and immune-related pathways and the antitumor effects of guadecitabine were dependent on p53, a gene rarely mutated in TGCTs. These preclinical findings suggest that guadecitabine alone or in combination with cisplatin is a promising strategy to treat refractory TGCT patients.

Epigenetic treatment combinations to effectively target cisplatin‐resistant germ cell tumors: past, present, and future considerations

“…A major drawback of this study was presumably the high 5AC dose used (150 mg/m 2 per day, days 1-5, every 3 weeks), which most likely induced unspecific cytotoxicity rather than an epigenetic reprogramming (Roth et al, 1993). The data from cell line and animal models have shown that low nanomolar HMA doses were sufficient to induce GCT cell apoptosis, to lose expression of pluripotency genes, re-expression of tumor suppressor genes, and to re-sensitize resistant phenotypes towards cisplatin treatment (Beyrouthy et al, 2009;Albany et al, 2017;Oing et al, 2018d). Supporting this approach, two clinical studies assessing the combination of either DAC or GDAC with carboplatin yielded promising response rates in heavily pre-treated patients with platinum-refractory ovarian cancers (Matei et al, 2012(Matei et al, , 2018.…”

“…The activity of DAC and GDAC has been closely linked to an overexpression of DNMT3B and an intact p53dependent apoptosis induction (Beyrouthy et al, 2009;Biswal et al, 2012;Wongtrakoongate et al, 2014;Albany et al, 2017). Moreover, pre-treatment with DAC or GDAC resulted in a remarkable re-sensitization towards cisplatin in mouse models using cisplatin-resistant GCT or ovarian cancer cells lines (Steele et al, 2009;Albany et al, 2017). In line with these findings, treatment of cisplatin-resistant seminoma and non-seminoma cell lines with 5AC led to a significant cisplatin re-sensitization in vitro, which seemed to be irrespective of p53-mutation status (Wermann et al, 2010;Oing et al, 2018d).…”

“…The first clinical trial evaluating 5AC among 17 refractory GCT patients failed to induce responses but was associated with remarkable toxicity. The data from cell line and animal models have shown that low nanomolar HMA doses were sufficient to induce GCT cell apoptosis, to lose expression of pluripotency genes, re-expression of tumor suppressor genes, and to re-sensitize resistant phenotypes towards cisplatin treatment (Beyrouthy et al, 2009;Albany et al, 2017;Oing et al, 2018d). The data from cell line and animal models have shown that low nanomolar HMA doses were sufficient to induce GCT cell apoptosis, to lose expression of pluripotency genes, re-expression of tumor suppressor genes, and to re-sensitize resistant phenotypes towards cisplatin treatment (Beyrouthy et al, 2009;Albany et al, 2017;Oing et al, 2018d).…”

“…Mechanistically, the anti-neoplastic effect of HMAs is thought to mainly result from a global DNA demethylation allowing for re-expression of silenced genes, including tumor suppressor genes and testis cancer antigens (Steele et al, 2009;Pleyer & Greil, 2015). The activity of DAC and GDAC has been closely linked to an overexpression of DNMT3B and an intact p53dependent apoptosis induction (Beyrouthy et al, 2009;Biswal et al, 2012;Wongtrakoongate et al, 2014;Albany et al, 2017). Moreover, pre-treatment with DAC or GDAC resulted in a remarkable re-sensitization towards cisplatin in mouse models using cisplatin-resistant GCT or ovarian cancer cells lines (Steele et al, 2009;Albany et al, 2017).…”

“…The Indiana study with guadecitabine has shown some substantial responses of tumours, sometimes with complete response both radiologically and with tumour markers (Albany et al, 2017). This is promising but the trial is on hold at present while doses are being adjusted.…”