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- Castell, Alina, et al.
(author)
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MYCMI-7 : A Small MYC-Binding Compound that Inhibits MYC: MAX Interaction and Tumor Growth in a MYC-Dependent Manner
- 2022
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In: Cancer Research Communications. - : American Association For Cancer Research (AACR). - 2767-9764. ; 2:3, s. 182-201
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Journal article (peer-reviewed)abstract
- Deregulated expression of MYC family oncogenes occurs frequently in human cancer and is often associated with aggressive disease and poor prognosis. While MYC is a highly warranted target, it has been considered "undruggable," and no specific anti-MYC drugs are available in the clinic. We recently identified molecules named MYCMIs that inhibit the interaction between MYC and its essential partner MAX. Here we show that one of these molecules, MYCMI-7, efficiently and selectively inhibits MYC:MAX and MYCN:MAX interactions in cells, binds directly to recombinant MYC, and reduces MYC-driven transcription. In addition, MYCMI-7 induces degradation of MYC and MYCN proteins. MYCMI-7 potently induces growth arrest/apoptosis in tumor cells in a MYC/MYCN-dependent manner and downregulates the MYC pathway on a global level as determined by RNA sequencing. Sensitivity to MYCMI-7 correlates with MYC expression in a panel of 60 tumor cell lines and MYCMI-7 shows high efficacy toward a collection of patient-derived primary glioblastoma and acute myeloid leukemia (AML) ex vivo cultures. Importantly, a variety of normal cells be- come G1 arrested without signs of apoptosis upon MYCMI-7 treatment. Finally, in mouse tumor models of MYC-driven AML, breast cancer, and MYCN-amplified neuroblastoma, treatment with MYCMI-7 downregu- lates MYC/MYCN, inhibits tumor growth, and prolongs survival through apoptosis with few side effects. In conclusion, MYCMI-7 is a potent and selective MYC inhibitor that is highly relevant for the development into clinically useful drugs for the treatment of MYC-driven cancer.Significance: Our findings demonstrate that the small-molecule MYCMI-7 binds MYC and inhibits interaction between MYC and MAX, thereby ham- pering MYC-driven tumor cell growth in culture and in vivo while sparing normal cells.
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- Ingelshed, Katrine, et al.
(author)
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The MDM2 Inhibitor Navtemadlin Arrests Mouse Melanoma Growth In Vivo and Potentiates Radiotherapy
- 2022
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In: Cancer Research Communications. - : American Association For Cancer Research (AACR). - 2767-9764. ; 2:9, s. 1075-1088
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Journal article (peer-reviewed)abstract
- The tumor suppressor protein p53 is mutated in close to 50% of human tumors and is dysregulated in many others, for instance by silencing or loss of p14ARF. Under steady-state conditions, the two E3 ligases MDM2/MDM4 interact with and inhibit the transcriptional activity of p53. Inhibition of p53–MDM2/4 interaction to reactivate p53 in tumors with wild-type (WT) p53 has therefore been considered a therapeutic strategy. Moreover, studies indicate that p53 reactivation may synergize with radiation and increase tumor immunogenicity. In vivo studies of most MDM2 inhibitors have utilized immunodeficient xenograft mouse models, preventing detailed studies of action of these molecules on the immune response. The mouse melanoma cell line B16-F10 carries functional, WT p53 but does not express the MDM2 regulator p19ARF. In this study, we tested a p53-MDM2 protein–protein interaction inhibitor, the small molecule Navtemadlin, which is currently being tested in phase II clinical trials. Using mass spectrometry–based proteomics and imaging flow cytometry, we identified specific protein expression patterns following Navtemadlin treatment of B16-F10 melanoma cells compared with their p53 CRISPR-inactivated control cells. In vitro, Navtemadlin induced a significant, p53-dependent, growth arrest but little apoptosis in B16-F10 cells. When combined with radiotherapy, Navtemadlin showed synergistic effects and increased apoptosis. In vivo, Navtemadlin treatment significantly reduced the growth of B16-F10 melanoma cells implanted in C57Bl/6 mice. Our data highlight the utility of a syngeneic B16-F10 p53+/+ mouse melanoma model for assessing existing and novel p53-MDM2/MDM4 inhibitors and in identifying new combination therapies that can efficiently eliminate tumors in vivo.Significance:The MDM2 inhibitor Navtemadlin arrests mouse tumor growth and potentiates radiotherapy. Our results support a threshold model for apoptosis induction that requires a high, prolonged p53 signaling for cancer cells to become apoptotic.
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- Mirza, Mansoor Raza, et al.
(author)
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Ad hoc Analysis of the Phase III ENGOT-OV16/NOVA Study: Niraparib Efficacy in Germline BRCA Wild-type Recurrent Ovarian Cancer with Homologous Recombination Repair Defects
- 2022
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In: Cancer Research Communications. - : AMER ASSOC CANCER RESEARCH. - 2767-9764. ; 2:11, s. 1436-1444
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Journal article (peer-reviewed)abstract
- In this analysis, we examined the relationship between progression-free survival (PFS) and mutation status of 18 homologous recombination repair (HRR) genes in patients in the non-germline BRCA-mutated (non-gBRCAm) cohort of the ENGOT-OV16/NOVA trial (NCT01847274), which evaluated niraparib maintenance therapy for patients with recurrent ovarian cancer. This post hoc exploratory biomarker analysis was performed using tumor samples collected from 331 patients enrolled in the phase III ENGOT-OV16/NOVA trial's non-gBRCAm cohort. Niraparib demonstrated PFS benefit in patients with either somatic BRCA-mutated (sBRCAm; HR, 0.27; 95% confidence interval, CI, 0.08–0.88) or BRCA wild-type (BRCAwt; HR, 0.47; 95% CI, 0.34–0.64) tumors. Patients with BRCAwt tumors with other non-BRCA HRR mutations also derived benefit from niraparib (HR, 0.31; 95% CI, 0.13–0.77), as did patients with BRCAwt/HRRwt (HRR wild-type) tumors (HR, 0.49; 95% CI, 0.35–0.70). When patients with BRCAwt/HRRwt tumors were further categorized by genomic instability score (GIS), clinical benefit was observed in patients with homologous recombination–deficient (GIS ≥ 42; HR, 0.33; 95% CI, 0.18–0.61) and in patients with homologous recombination–proficient (HRp; GIS < 42; HR, 0.60; 95% CI, 0.36–0.99) disease. Although patients with sBRCAm, other non-BRCA HRR mutations, or GIS ≥ 42 benefited the most from niraparib treatment, PFS benefit was also seen in HRp (GIS < 42) patients without HRR mutations. These results support the use of niraparib in patients with recurrent ovarian cancer regardless of BRCA/HRR mutation status or myChoice CDx GIS.Significance:We retrospectively evaluated the mutational profile of HRR genes in tumor samples from 331 patients from the non-germline BRCA-mutated cohort of the phase III NOVA trial of patients with platinum-sensitive high-grade serous ovarian cancer. Patients with non-BRCA HRR mutations generally benefited from second-line maintenance treatment with niraparib compared with placebo.
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