Drug Repositioning Based on the Reversal of Gene Expression Signatures Identifies TOP2A as a Therapeutic Target for Rectal Cancer

Rectal cancer is a common disease with high mortality rates and limited therapeutic options. Here we combined the gene expression signatures of rectal cancer patients with the reverse drug-induced gene-expression profiles to identify drug repositioning candidates for cancer therapy. Among the predicted repurposable drugs, topoisomerase II inhibitors (doxorubicin, teniposide, idarubicin, mitoxantrone, and epirubicin) presented a high potential to reverse rectal cancer gene expression signatures. We showed that these drugs effectively reduced the growth of colorectal cancer cell lines closely representing rectal cancer signatures. We also found a clear correlation between topoisomerase 2A (TOP2A) gene copy number or expression levels with the sensitivity to topoisomerase II inhibitors. Furthermore, CRISPR-Cas9 and shRNA screenings confirmed that loss-of-function of the TOP2A has the highest efficacy in reducing cellular proliferation. Finally, we observed significant TOP2A copy number gains and increased expression in independent cohorts of rectal cancer patients. These findings can be translated into clinical practice to evaluate TOP2A status for targeted and personalized therapies based on topoisomerase II inhibitors in rectal cancer patients.

DNA-PK inhibitor peposertib enhances p53-dependent cytotoxicity of DNA double-strand break inducing therapy in acute leukemia

Peposertib (M3814) is a potent and selective DNA-PK inhibitor in early clinical development. It effectively blocks non-homologous end-joining repair of DNA double-strand breaks (DSB) and strongly potentiates the antitumor effect of ionizing radiation (IR) and topoisomerase II inhibitors. By suppressing DNA-PK catalytic activity in the presence of DNA DSB, M3814 potentiates ATM/p53 signaling leading to enhanced p53-dependent antitumor activity in tumor cells. Here, we investigated the therapeutic potential of M3814 in combination with DSB-inducing agents in leukemia cells and a patient-derived tumor. We show that in the presence of IR or topoisomerase II inhibitors, M3814 boosts the ATM/p53 response in acute leukemia cells leading to the elevation of p53 protein levels as well as its transcriptional activity. M3814 synergistically sensitized p53 wild-type, but not p53-deficient, AML cells to killing by DSB-inducing agents via p53-dependent apoptosis involving both intrinsic and extrinsic effector pathways. The antileukemic effect was further potentiated by enhancing daunorubicin-induced myeloid cell differentiation. Further, combined with the fixed-ratio liposomal formulation of daunorubicin and cytarabine, CPX-351, M3814 enhanced the efficacy against leukemia cells in vitro and in vivo without increasing hematopoietic toxicity, suggesting that DNA-PK inhibition could offer a novel clinical strategy for harnessing the anticancer potential of p53 in AML therapy.

Prognostic Impact of the Latency Time from the Administration of Cytotoxic Therapy to the Development of Therapy-Related Myeloid Neoplasms

Introduction: Among Therapy-Related Myeloid Neoplasms (t-MNs), there are two large groups depending on the cytotoxic trigger. A first group arises after exposure to alkylating agents and / or radiation in the previous 5-10 years and it is associated with unbalanced chromosomal abnormalities, frequently with alterations in Cr 5, 7, complex karyotype and mutated TP53. The second arises after exposure to topoisomerase II inhibitors in the previous 1-5 years, and it is characterized by frequent balanced translocations and KMT2A rearrangement. In those cases with a latency time from cytotoxic exposure to T-MNs diagnosis greater than 10 years, there is doubt about whether they should be considered T-MNs or de novo leukemias. Material and methods: We performed a retrospective analysis of 34 patients with diagnosis of T-MNs treated in our center between 2013 and 2019. We have reviewed the cytogenetic alterations at diagnosis and alterations in TP53 and / or 17p and rearrangements in KMT2A. We divided the cohort into two groups based on the latency time of ≤10 years or> 10 years. The comparison between both groups was carried out using the chi2 test for qualitative variables and the t-student for quantitative variables. The Kaplan Meier method has been used for the calculation of Overall Survival (OS) and Event Free Survival (EFS) and the Cox regression model for the univariate and multivariate analysis. Results: The median follow-up of the global cohort was 8.5 months (0-74). The median OS of the global cohort was 10 months and the EFS was 8 months. In patients with a latency time ≤10 years the median OS was 12 months vs 9 months in those with latency >10 years, with a Hazard Ratio (HR) of 0.6 [95% CI (0.2-1.7), p = 0.3] and the EFS was 7 months vs 9 months respectively [HR 0.3, 95% CI (0.3-1.8), p = 0.7]. The baseline characteristics of the population are reflected in Table 1. A similar percentage of patients with complex or monosomal karyotype at diagnosis is observed in both groups, as well as alterations in TP53 and/or 17p. In the >10-year latency subgroup, there were no patients with prior exposure to Topoisomerase II Inhibitors. Within the <10-year latency group, we divided the cohort into two groups: 1 to 5 years and 5 to 10 years of latency. No differences were found for OS [HR 1.5 95% CI (0.4-5), p = 0.4] or for EFS [HR 2.1 95% CI (0.7-6.2), p = 0.1]. A univariate analysis was performed including the characteristics reflected in Table 2. The variables with a significant HR for OS and EFS were to present a monosomic karyotype at diagnosis and alterations in TP53 and/or 17p. In the multivariate analysis, only the alterations in TP53 and/or 17p maintained a significant HR. Conclusions: Patients with a latency time from exposure to cytotoxic therapy to the diagnosis of T-MNs > 10 years, presented cytogenetic and molecular characteristics similar to those with an exposure time ≤10 years, as well as a similar OS and EFS. Regarding the cytogenetic characteristics at diagnosis of the general cohort, patients with monosomic karyotype and especially those with TP53 and/or 17p alterations had a worse prognosis. Disclosures Garcia-Gutiérrez: Incyte:Consultancy, Other: Travel, Accommodation, Expenses, Research Funding;Novartis:Consultancy, Other: Travel, Accommodation, Expenses, Research Funding;Bristol-Myers Squibb:Consultancy, Other: Travel, Accommodation, Expenses, Research Funding;Pfizer:Consultancy, Other: Travel, Accommodation, Expenses, Research Funding.