MDM2 antagonists synergize with PI3K/mTOR inhibition in well-differentiated/dedifferentiated liposarcomas.

BACKGROUND: Well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) are characterized by a consistent amplification of the MDM2 gene. The PI3K/AKT/mTOR pathway has been suggested to play also an important role in their tumorigenesis. Our goal was to determine whether combined MDM2 and PI3K/AKT/mTOR targeting is associated with higher anti-tumor activity than single agent alone in preclinical models of WDLPS/DDLPS. METHODS: WDLPS/DDLPS cells were exposed to RG7388 (MDM2 antagonist) and BEZ235 (PI3K/mTOR dual inhibitor) after which apoptosis and signaling/survival pathway perturbations were monitored by flow cytometry and Western blot analysis. Xenograft mouse models were used to assess tumor growth and animal survival. Western blotting, histopathology, and tumor volume evolution were used for the assessment of treatment efficacy. RESULTS: The PI3K/AKT/mTOR was upregulated in up to 81% of the human WDLPS/DDLPS samples analysed. Treatment with RG7388 and BEZ235 resulted in a greater tumor activity than either drug alone with a significant difference in terms of cell viability after 72h of treatment with RG-73888 alone, BEZ235 alone and a combination of both agents. Consistent with these observations, we found a significant increase in apoptosis with the combination versus the single agent treatment alone. We then analysed the in vivo antitumor activity of RG7388 and BEZ235 in a xenograft model of DDLPS. The combination regimen significantly reduced tumor growth rate in comparison with single agent alone. CONCLUSIONS: Our results represent the first in vivo evidence of synergy between MDM2 and PI3K/AKT/mTOR antagonists and represent a strong rationale to evaluate the therapeutic potential of such a combination in WDLPS/DDLPS.

Activity of trabectedin and the PARP inhibitor rucaparib in soft-tissue sarcomas.

BACKGROUND: Trabectedin has recently been approved in the USA and in Europe for advanced soft-tissue sarcoma patients who have been treated with anthracycline-based chemotherapy without success. The mechanism of action of trabectedin depends on the status of both the nucleotide excision repair (NER) and homologous recombination (HR) DNA repair pathways. Trabectedin results in DNA double-strand breaks. We hypothesized that PARP-1 inhibition is able to perpetuate trabectedin-induced DNA damage. METHODS: We explored the effects of combining a PARP inhibitor (rucaparib) and trabectedin in a large panel of soft-tissue sarcoma (STS) cell lines and in a mouse model of dedifferentiated liposarcoma. RESULTS: The combination of rucaparib and trabectedin in vitro was synergistic, inhibited cell proliferation, induced apoptosis, and accumulated in the G2/M phase of the cell cycle with higher efficacy than either single agent alone. The combination also resulted in enhanced γH2AX intranuclear accumulation as a result of DNA damage induction. In vivo, the combination of trabectedin and rucaparib significantly enhanced progression-free survival with an increased percentage of tumor necrosis. CONCLUSION: The combination of PARP inhibitor and trabectedin is beneficial in pre-clinical models of soft-tissue sarcoma and deserves further exploration in the clinical setting.

Heterogeneous Mechanisms of Secondary Resistance and Clonal Selection in Sarcoma during Treatment with Nutlin.

Nutlin inhibits TP53-MDM2 interaction and is under investigation in soft-tissue sarcomas (STS) and other malignancies. Molecular mechanisms of secondary resistance to nutlin in STS are unknown. We performed whole-transcriptome sequencing (RNA-seq) on three pretreatment and secondary resistant STS cell lines selected based on their high primary sensitivity to nutlin. Our data identified a subset of cancer gene mutations and ploidy variations that were positively selected following treatment, including TP53 mutations in 2 out of 3 resistant cell lines. Further, secondary resistance to nutlin was associated with deregulation of apoptosis-related genes and marked productive autophagy, the inhibition of which resulted in significant restoration of nutlin-induced cell death. Collectively, our findings argue that secondary resistance to nutlin in STS involved heterogeneous mechanisms resulting from clonal evolution and several biological pathways. Alternative dosing regimens and combination with other targeted agents are needed to achieve successful development of nutlin in the clinical setting.

Anticonvulsant and analgesic activities of crude extract and its fractions of the defensive secretion from the Mediterranean sponge, Spongia officinalis.

This study progresses in the direction of identifying component(s) from the Mediterranean sponge, Spongia officinalis with anticonvulsant and analgesic activities. We investigated the efficacy of crude extract and its semi-purified fractions (F1-F3) of the defensive secretion from Spongia officinalis for their in vivo anticonvulsant activity using the pentylenetetrazole (PTZ) seizure model and analgesic activity using the writhing test in mice. Among the series the crude extract exhibited interesting analgesic activity in a dose dependent manner. Similarly the fraction F2 showed a partial protection of mice from PTZ-induced seizure and interesting analgesic activity in a dose dependent manner. The purification and the determination of chemical structure(s) of compound(s) of this active fraction are under investigation.

Encapsulation of docetaxel into PEGylated gold nanoparticles for vectorization to cancer cells.

Encapsulation of docetaxel and its solubilization in water was carried out in PEGylated gold nanoparticles (AuNPs) as shown by 1H NMR (600 MHz) and UV/Vis spectroscopy and dynamic light scattering. Vectorization of PEGylated AuNP-encapsulated docetaxel was probed in vitro toward human colon carcinoma (HCT15) and human breast cancer (MCF7) cells. AuNPs alone presented no cytotoxicity toward either MCF7 or HCT15 adenocarcinoma cells. AuNP-docetaxel was found to be 2.5-fold more efficient than docetaxel alone against MCF7 cells, and the IC50 value of AuNP-docetaxel against HCT15 cells was lower than that of free docetaxel; the increased efficiency brought about by AuNP drug encapsulation was ∼1.5-fold.

ERCC5/XPG, ERCC1, and BRCA1 gene status and clinical benefit of trabectedin in patients with soft tissue sarcoma.

BACKGROUND: The objective of this study was to determine whether specific single nucleotide polymorphisms (SNPs) from nucleotide excision repair (NER) and homologous recombination (HR) DNA repair pathways are associated with sensitivity to trabectedin in patients with soft tissue sarcoma (STS). METHODS: The authors analyzed excision repair cross-complementation group 5/xeroderma pigmentosum group G (ERCC5/XPG) (NER), excision repair cross-complementation group 1 (ERCC1) (NER), and breast cancer 1 (BRCA1) (HR) SNPs and messenger RNA expression levels in tumor specimens from 113 patients with advanced STS who were enrolled in previously published phase 2 trials or in a compassionate-use program. The 6-month progression-free rate (PFR), progression-free survival (PFS), and overall survival (OS) were analyzed according to ERCC5, ERCC1, and BRCA1 status using log-rank tests. RESULTS: High expression of the common allele (aspartic acid at codon 1104) of ERCC5, high expression of ERCC1, and BRCA1 haplotype were associated significantly with improved PFR, PFS, and OS. The ERCC1 thymine-to-cytosine (T→C) SNP at codon 19007 and BRCA1 expression were not associated with outcome. On univariate analysis, tumor histology, favorable NER status (high expression of common ERCC5 and/or high ERCC1 expression status), and favorable BRCA1 haplotype (at least 1 triple-adenine plus guanine [AAAG] allele) were the sole variables associated significantly with PFS and OS. CONCLUSIONS: In the current study, ERCC5, ERCC1, and BRCA1 status represented a potential DNA repair signature that could be used for the prediction of clinical response to trabectedin in patients with STS.