Preclinical Development of a Romidepsin Nanoparticle Demonstrates Superior Tolerability and Efficacy in Models of Human T-Cell Lymphoma and Large Granular Lymphocyte Leukemia.

Histone deacetylase (HDAC) inhibitors are a widely recognized and valued treatment option for patients with relapsed or refractory peripheral T cell lymphomas (PTCL). Romidepsin is a relatively selective Class I HDAC inhibitor originally approved for patients with relapsed or refractory (R/R) cutaneous T cell lymphoma (CTCL) and subsequently R/R PTCL. Unfortunately, the FDA approval of romidepsin for R/R PTCL was withdrawn due to a negative Phase 4 post-marketing requirement (PMR), diminishing further the treatment options for patients with PTCL. Herein we describe the development of a first-in-class polymer nanoparticle of romidepsin (Nanoromidepsin) using an innovative amphiphilic di-block copolymer-based nanochemistry platform. Nanoromidepsin exhibited superior pharmacologic disposition, with improved tolerability and safety in murine models of T-cell lymphoma. Nanoromidepsin also exhibited superior anti-tumor efficacy in multiple models including in vitro T cell lymphoma (TCL) cell lines, ex vivo LGL leukemia primary patient samples, and murine TCL xenografts. Nanoromidepsin demonstrated greater accumulation in tumors and a statistically significant improvement in overall survival (OS) compared to romidepsin in murine xenograft models. These findings collectively justify the clinical development of Nanoromidepsin in patients with T-cell malignancies.

Inhibition of neurotensin receptor 1 selectively sensitizes prostate cancer to ionizing radiation.

Radiotherapy combined with androgen depletion is generally successful for treating locally advanced prostate cancer. However, radioresistance that contributes to recurrence remains a major therapeutic problem in many patients. In this study, we define the high-affinity neurotensin receptor 1 (NTR1) as a tractable new molecular target to radiosensitize prostate cancers. The selective NTR1 antagonist SR48692 sensitized prostate cancer cells in a dose- and time-dependent manner, increasing apoptotic cell death and decreasing clonogenic survival. The observed cancer selectivity for combinations of SR48692 and radiation reflected differential expression of NTR1, which is highly expressed in prostate cancer cells but not in normal prostate epithelial cells. Radiosensitization was not affected by androgen dependence or androgen receptor expression status. NTR1 inhibition in cancer cell-attenuated epidermal growth factor receptor activation and downstream signaling, whether induced by neurotensin or ionizing radiation, establish a molecular mechanism for sensitization. Most notably, SR48692 efficiently radiosensitized PC-3M orthotopic human tumor xenografts in mice, and significantly reduced tumor burden. Taken together, our findings offer preclinical proof of concept for targeting the NTR1 receptor as a strategy to improve efficacy and outcomes of prostate cancer treatments using radiotherapy.

Radiosensitization and modulation of p44/42 mitogen-activated protein kinase by 2-Methoxyestradiol in prostate cancer models.

2-Methoxyestradiol (2ME2) is an endogenous estradiol metabolite that inhibits microtubule polymerization, tumor growth, and angiogenesis. Because prostate cancer is often treated with radiotherapy, and 2ME2 has shown efficacy as a single agent against human prostate carcinoma, we evaluated 2ME2 as a potential radiosensitizer in prostate cancer models. A dose-dependent decrease in mitogen-activated protein kinase phosphorylation was observed in human PC3 prostate cancer cells treated with 2ME2 for 18 h. This decrease correlated with in vitro radiosensitization measured by clonogenic assays, and these effects were blocked by the expression of constitutively active MEK. Male nude mice with subcutaneous PC3 xenografts in the hind leg were treated with 2ME2 (75 mg/kg) p.o. for 5 days, and 2 Gy radiation fractions were delivered each day at 4 h after drug treatment. A statistically significant super-additive effect between radiation and 2ME2 was observed in this subcutaneous model, using analysis of within-animal slopes. A PC-3M orthotopic model was also used, with bioluminescence imaging as an end point. PC-3M cells stably expressing the luciferase gene were surgically implanted into the prostates of male nude mice. Mice were given oral doses of 2ME2 (75 mg/kg), with radiation fractions (3 Gy) delivered 4 h later. Mice were then imaged weekly for 4 to 5 weeks with a Xenogen system. A significant super-additive effect was also observed in the orthotopic model. These data show that 2ME2 is an effective radiosensitizing agent against human prostate cancer xenografts, and that the mechanism may involve a decrease in mitogen-activated protein kinase phosphorylation by 2ME2.