BACKGROUND: We report a proof-of-mechanism study of RG7112, a small-molecule MDM2 antagonist, in patients with chemotherapy-naive primary or relapsed well-differentiated or dedifferentiated MDM2-amplified liposarcoma who were eligible for resection. METHODS: Patients with well-differentiated or dedifferentiated liposarcoma were enrolled at four centres in France. Patients received up to three 28-day neoadjuvant treatment cycles of RG7112 1440 mg/m(2) per day for 10 days. If a patient progressed at any point after the first cycle, the lesion was resected or, if unresectable, an end-of-study biopsy was done. The primary endpoint was to assess markers of RG7112-dependent MDM2 inhibition and P53 pathway activation (P53, P21, MDM2, Ki-67, macrophage inhibitory cytokine-1 [MIC-1], and apoptosis). All analyses were per protocol. This trial is registered with EudraCT, number 2009-015522-10. RESULTS: Between June 3, and Dec 14, 2010, 20 patients were enrolled and completed pretreatment and day 8 biopsies. 18 of 20 patients had TP53 wild-type tumours and two carried missense TP53 mutations. 14 of 17 assessed patients had MDM2 gene amplification. Compared with baseline, P53 and P21 concentrations, assessed by immunohistochemistry, had increased by a median of 4·86 times (IQR 4·38-7·97; p=0·0001) and 3·48 times (2·05-4·09; p=0·0001), respectively, at day 8 (give or take 2 days). At the same timepoint, relative MDM2 mRNA expression had increased by a median of 3·03 times (1·23-4·93; p=0·003) that at baseline. The median change from baseline for Ki-67-positive tumour cells was -5·05% (IQR -12·55 to 0·05; p=0·01). Drug exposure correlated with blood concentrations of MIC-1 (p<0·0001) and haematological toxicity. One patient had a confirmed partial response and 14 had stable disease. All patients experienced at least one adverse event, mostly nausea (14 patients), vomiting (11 patients), asthenia (nine patients), diarrhoea (nine patients), and thrombocytopenia (eight patients). There were 12 serious adverse events in eight patients, the most common of which were neutropenia (six patients) and thrombocytopenia (three patients). DISCUSSION: MDM2 inhibition activates the P53 pathway and decreases cell proliferation in MDM2-amplified liposarcoma. This study suggests that it is feasible to undertake neoadjuvant biopsy-driven biomarker studies in liposarcoma. FUNDING: F Hoffmann-La Roche.
"If MDM2 inhibitors are translated to the clinic as part of combination regimens with proteasome inhibitors or immunomodulatory drugs, attention may need to be paid to the potential for additive myelosuppression. This conclusion is based on results from a proof of concept study in patients with liposarcomas of single-agent RG-7112, an inhibitor in the Nutlin family, which induced neutropenia and thrombocytopenia in 30% and 40%, respectively, of patients . "
[Show abstract][Hide abstract] ABSTRACT: Intracellular proteolytic pathways have been validated as rational targets in multiple myeloma with the approval of two proteasome inhibitors in this disease, and with the finding that immunomodulatory agents work through an E3 ubiquitin ligase containing Cereblon. Another E3 ligase that could be a rational target is the murine double minute (MDM) 2 protein, which plays a role in p53 turnover. A novel inhibitor of this complex, MI-63, was found to induce apoptosis in p53 wild-type myeloma models in association with activation of a p53-mediated cell death program. MI-63 overcame adhesion-mediated drug resistance, showed anti-tumor activity in vivo, enhanced the activity of bortezomib and lenalidomide, and also overcame lenalidomide resistance. In mutant p53 models, inhibition of MDM2 with MI-63 also activated apoptosis, albeit at higher concentrations, and this was associated with activation of autophagy. When MI-63 was combined with the BH3 mimetic ABT-737, enhanced activity was seen in both wild-type and mutant p53 models. Finally, this regimen showed efficacy against primary plasma cells from patients with newly diagnosed and relapsed/refractory myeloma. These findings support the translation of novel MDM2 inhibitors both alone, and in combination with other novel agents, to the clinic for patients with multiple myeloma.
PLoS ONE 09/2014; 9(9):e103015. DOI:10.1371/journal.pone.0103015 · 3.23 Impact Factor
"As elderly patients do not tolerate the intensive chemotherapy and stem cell transplantation of current treatment regimes , the development of less toxic and more specific targeted therapy is necessary. Small-molecule MDM2 inhibitors like nutlin-3 have emerged as a potent and promising treatment option for cancers harboring wild type TP53, including AML [3-5], and the oral formulation of nutlin-3, RG7112, has completed the first early phase clinical trials for both solid cancers and hematological malignancies [6-8]. Intriguingly, these small-molecule p53 activators have demonstrated selective toxicity for cancer cells versus normal cells [4,9], and may also induce reversible cell cycle arrest of normal cells to protect them from adverse effects of conventional chemotherapy . "
[Show abstract][Hide abstract] ABSTRACT: Background
The small-molecule MDM2 antagonist nutlin-3 has proved to be an effective p53 activating therapeutic compound in several preclinical cancer models, including acute myeloid leukemia (AML). We and others have previously reported a vigorous acetylation of the p53 protein by nutlin-treatment. In this study we aimed to investigate the functional role of this p53 acetylation in nutlin-sensitivity, and further to explore if nutlin-induced protein acetylation in general could indicate novel targets for the enhancement of nutlin-based therapy.
Nutlin-3 was found to enhance the acetylation of p53 in the human AML cell line MOLM-13 (wild type TP53) and in TP53 null cells transfected with wild type p53 cDNA. Stable isotope labeling with amino acids in cell culture (SILAC) in combination with immunoprecipitation using an anti-acetyl-lysine antibody and mass spectrometry analysis identified increased levels of acetylated Histone H2B, Hsp27 and Hsp90 in MOLM-13 cells after nutlin-treatment, accompanied by downregulation of total levels of Hsp27 and Hsp90. Intracellular levels of heat shock proteins Hsp27, Hsp40, Hsp60, Hsp70 and Hsp90α were correlated to nutlin-sensitivity for primary AML cells (n = 40), and AML patient samples with low sensitivity to nutlin-3 tended to express higher levels of heat shock proteins than more responsive samples. Combination therapy of nutlin-3 and Hsp90 inhibitor geldanamycin demonstrated synergistic induction of apoptosis in AML cell lines and primary AML cells. Finally, TP53 null cells transfected with a p53 acetylation defective mutant demonstrated decreased heat shock protein acetylation and sensitivity to nutlin-3 compared to wild type p53 expressing cells.
Altogether, our results demonstrate that nutlin-3 induces acetylation of p53, histones and heat shock proteins, and indicate that p53 acetylation status and the levels of heat shock proteins may participate in modulation of nutlin-3 sensitivity in AML.
Molecular Cancer 05/2014; 13(1):116. DOI:10.1186/1476-4598-13-116 · 4.26 Impact Factor
"As a result, this class of molecules has shown promising anti-cancer efficacy in cancer cell line xenograft assays. Examples include Nutlin-3 and its pharmacologically optimized form, RG7112, which are currently undergoing phase I clinical trials for the treatment of retinoblastoma and liposarcomas, and haematological malignancies, respectively [141,142]. Owing to their selective nature, Nutlin-3 and RG7112 are expected to have less deleterious effects on healthy tissues, although the real scenario will only be clear once the results of the clinical trials are published. "
[Show abstract][Hide abstract] ABSTRACT: The ability of cullin 4A (CUL4A), a scaffold protein, to recruit a repertoire of substrate adaptors allows it to assemble into distinct E3 ligase complexes to mediate turnover of key regulatory proteins. In the past decade, a considerable wealth of information has been generated regarding its biology, regulation, assembly, molecular architecture and novel functions. Importantly, unravelling of its association with multiple tumours and modulation by viral proteins establishes it as one of the key proteins that may play an important role in cellular transformation. Considering the role of its substrate in regulating the cell cycle and maintenance of genomic stability, understanding the detailed aspects of these processes will have significant consequences for the treatment of cancer and related diseases. This review is an effort to provide a broad overview of this multifaceted ubiquitin ligase and addresses its critical role in regulation of important biological processes. More importantly, its tremendous potential to be exploited for therapeutic purposes has been discussed.
Open Biology 02/2014; 4(2):130217. DOI:10.1098/rsob.130217 · 5.78 Impact Factor
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