MYC targeting by OMO-103 in solid tumors: a phase 1 trial.

Among the 'most wanted' targets in cancer therapy is the oncogene MYC, which coordinates key transcriptional programs in tumor development and maintenance. It has, however, long been considered undruggable. OMO-103 is a MYC inhibitor consisting of a 91-amino acid miniprotein. Here we present results from a phase 1 study of OMO-103 in advanced solid tumors, established to examine safety and tolerability as primary outcomes and pharmacokinetics, recommended phase 2 dose and preliminary signs of activity as secondary ones. A classical 3 + 3 design was used for dose escalation of weekly intravenous, single-agent OMO-103 administration in 21-day cycles, encompassing six dose levels (DLs). A total of 22 patients were enrolled, with treatment maintained until disease progression. The most common adverse events were grade 1 infusion-related reactions, occurring in ten patients. One dose-limiting toxicity occurred at DL5. Pharmacokinetics showed nonlinearity, with tissue saturation signs at DL5 and a terminal half-life in serum of 40 h. Of the 19 patients evaluable for response, 12 reached the predefined 9-week time point for assessment of drug antitumor activity, eight of those showing stable disease by computed tomography. One patient defined as stable disease by response evaluation criteria in solid tumors showed a 49% reduction in total tumor volume at best response. Transcriptomic analysis supported target engagement in tumor biopsies. In addition, we identified soluble factors that are potential pharmacodynamic and predictive response markers. Based on all these data, the recommended phase 2 dose was determined as DL5 (6.48 mg kg-1).ClinicalTrials.gov identifier: NCT04808362 .

Reducing MYC's transcriptional footprint unveils a good prognostic gene signature in melanoma.

MYC's key role in oncogenesis and tumor progression has long been established for most human cancers. In melanoma, its deregulated activity by amplification of 8q24 chromosome or by upstream signaling coming from activating mutations in the RAS/RAF/MAPK pathway-the most predominantly mutated pathway in this disease-turns MYC into not only a driver but also a facilitator of melanoma progression, with documented effects leading to an aggressive clinical course and resistance to targeted therapy. Here, by making use of Omomyc, the most characterized MYC inhibitor to date that has just successfully completed a phase I clinical trial, we show for the first time that MYC inhibition in melanoma induces remarkable transcriptional modulation, resulting in severely compromised tumor growth and a clear abrogation of metastatic capacity independently of the driver mutation. By reducing MYC's transcriptional footprint in melanoma, Omomyc elicits gene expression profiles remarkably similar to those of patients with good prognosis, underlining the therapeutic potential that such an approach could eventually have in the clinic in this dismal disease.

In Vivo Antitumor and Antimetastatic Efficacy of a Polyacetal-Based Paclitaxel Conjugate for Prostate Cancer Therapy.

Prostate cancer (PCa), one of the leading causes of cancer-related deaths, currently lacks effective treatment for advanced-stage disease. Paclitaxel (PTX) is a highly active chemotherapeutic drug and the first-line treatment for PCa; however, conventional PTX formulation causes severe hypersensitivity reactions and limits PTX use at high concentrations. In the pursuit of high molecular weight, biodegradable, and pH-responsive polymeric carriers, one conjugates PTX to a polyacetal-based nanocarrier to yield a tert-Ser-PTX polyacetal conjugate. tert-Ser-PTX conjugate provides sustained release of PTX over 2 weeks in a pH-responsive manner while also obtaining a degree of epimerization of PTX to 7-epi-PTX. Serum proteins stabilize tert-Ser-PTX, with enhanced stability in human serum versus PBS (pH 7.4). In vitro efficacy assessments in PCa cells demonstrate IC50 values above those for the free form of PTX due to the differential cell trafficking modes; however, in vivo tolerability assays demonstrate that tert-Ser-PTX significantly reduces the systemic toxicities associated with free PTX treatment. tert-Ser-PTX also effectively inhibits primary tumor growth and hematologic, lymphatic, and coelomic dissemination, as confirmed by in vivo and ex vivo bioluminescence imaging and histopathological evaluations in mice carrying orthotopic LNCaP tumors. Overall, the results suggest the application of tert-Ser-PTX as a robust antitumor/antimetastatic treatment for PCa.

Engineering pH-Sensitive Stable Nanovesicles for Delivery of MicroRNA Therapeutics.

MicroRNAs (miRNAs) are small non-coding endogenous RNAs, which are attracting a growing interest as therapeutic molecules due to their central role in major diseases. However, the transformation of these biomolecules into drugs is limited due to their unstability in the bloodstream, caused by nucleases abundantly present in the blood, and poor capacity to enter cells. The conjugation of miRNAs to nanoparticles (NPs) could be an effective strategy for their clinical delivery. Herein, the engineering of non-liposomal lipid nanovesicles, named quatsomes (QS), for the delivery of miRNAs and other small RNAs into the cytosol of tumor cells, triggering a tumor-suppressive response is reported. The engineered pH-sensitive nanovesicles have controlled structure (unilamellar), size (<150 nm) and composition. These nanovesicles are colloidal stable (>24 weeks), and are prepared by a green, GMP compliant, and scalable one-step procedure, which are all unavoidable requirements for the arrival to the clinical practice of NP based miRNA therapeutics. Furthermore, QS protect miRNAs from RNAses and when injected intravenously, deliver them into liver, lung, and neuroblastoma xenografts tumors. These stable nanovesicles with tunable pH sensitiveness constitute an attractive platform for the efficient delivery of miRNAs and other small RNAs with therapeutic activity and their exploitation in the clinics.

MYC Inhibition Halts Metastatic Breast Cancer Progression by Blocking Growth, Invasion, and Seeding.

MYC's role in promoting tumorigenesis is beyond doubt, but its function in the metastatic process is still controversial. Omomyc is a MYC dominant negative that has shown potent antitumor activity in multiple cancer cell lines and mouse models, regardless of their tissue of origin or driver mutations, by impacting on several of the hallmarks of cancer. However, its therapeutic efficacy against metastasis has not been elucidated yet. Here we demonstrate for the first time that MYC inhibition by transgenic Omomyc is efficacious against all breast cancer molecular subtypes, including triple-negative breast cancer, where it displays potent antimetastatic properties both in vitro and in vivo. Importantly, pharmacologic treatment with the recombinantly produced Omomyc miniprotein, recently entering a clinical trial in solid tumors, recapitulates several key features of expression of the Omomyc transgene, confirming its clinical applicability to metastatic breast cancer, including advanced triple-negative breast cancer, a disease in urgent need of better therapeutic options. Significance: While MYC role in metastasis has been long controversial, this manuscript demonstrates that MYC inhibition by either transgenic expression or pharmacologic use of the recombinantly produced Omomyc miniprotein exerts antitumor and antimetastatic activity in breast cancer models in vitro and in vivo, suggesting its clinical applicability.

Intrinsic cell-penetrating activity propels Omomyc from proof of concept to viable anti-MYC therapy.

Inhibiting MYC has long been considered unfeasible, although its key role in human cancers makes it a desirable target for therapeutic intervention. One reason for its perceived undruggability was the fear of catastrophic side effects in normal tissues. However, we previously designed a dominant-negative form of MYC called Omomyc and used its conditional transgenic expression to inhibit MYC function both in vitro and in vivo. MYC inhibition by Omomyc exerted a potent therapeutic impact in various mouse models of cancer, causing only mild, well-tolerated, and reversible side effects. Nevertheless, Omomyc has been so far considered only a proof of principle. In contrast with that preconceived notion, here, we show that the purified Omomyc mini-protein itself spontaneously penetrates into cancer cells and effectively interferes with MYC transcriptional activity therein. Efficacy of the Omomyc mini-protein in various experimental models of non-small cell lung cancer harboring different oncogenic mutation profiles establishes its therapeutic potential after both direct tissue delivery and systemic administration, providing evidence that the Omomyc mini-protein is an effective MYC inhibitor worthy of clinical development.

BET inhibition is an effective approach against KRAS-driven PDAC and NSCLC.

Effectively treating KRAS-driven tumors remains an unsolved challenge. The inhibition of downstream signaling effectors is a way of overcoming the issue of direct targeting of mutant KRAS, which has shown limited efficacy so far. Bromodomain and Extra-Terminal (BET) protein inhibition has displayed anti-tumor activity in a wide range of cancers, including KRAS-driven malignancies. Here, we preclinically evaluate the effect of BET inhibition making use of a new BET inhibitor, BAY 1238097, against Pancreatic Ductal Adenocarcinoma (PDAC) and Non-Small Cell Lung Cancer (NSCLC) models harboring RAS mutations both in vivo and in vitro. Our results demonstrate that BET inhibition displays significant therapeutic impact in genetic mouse models of KRAS-driven PDAC and NSCLC, reducing both tumor area and tumor grade. The same approach also causes a significant reduction in cell number of a panel of RAS-mutated human cancer cell lines (8 PDAC and 6 NSCLC). In this context, we demonstrate that while BET inhibition by BAY 1238097 decreases MYC expression in some cell lines, at least in PDAC cells its anti-tumorigenic effect is independent of MYC regulation. Together, these studies reinforce the use of BET inhibition and prompt the optimization of more efficient and less toxic BET inhibitors for the treatment of KRAS-driven malignancies, which are in urgent therapeutic need.

Improved pharmacokinetic profile of lipophilic anti-cancer drugs using ανß3-targeted polyurethane-polyurea nanoparticles.

Glutathione degradable polyurethane-polyurea nanoparticles (PUUa NP) with a disulfide-rich multiwalled structure and a cyclic RGD peptide as a targeting moiety were synthesized, incorporating a very lipophilic chemotherapeutic drug named Plitidepsin. In vitro studies indicated that encapsulated drug maintained and even improved its cytotoxic activity while in vivo toxicity studies revealed that the maximum tolerated dose (MTD) of Plitidepsin could be increased three-fold after encapsulation. We also found that pharmacokinetic parameters such as maximum concentration (Cmax), area under the curve (AUC) and plasma half-life were significantly improved for Plitidepsin loaded in PUUa NP. Moreover, biodistribution assays in mice showed that RGD-decorated PUUa NP accumulate less in spleen and liver than non-targeted conjugates, suggesting that RGD-decorated nanoparticles avoid sequestration by macrophages from the reticuloendothelial system. Overall, our results indicate that polyurethane-polyurea nanoparticles represent a very valuable nanoplatform for the delivery of lipophilic drugs by improving their toxicological, pharmacokinetic and whole-body biodistribution profiles.

Conformational and functional variants of CD44-targeted protein nanoparticles bio-produced in bacteria.

Biofabrication is attracting interest as a means to produce nanostructured functional materials because of its operational versatility and full scalability. Materials based on proteins are especially appealing, as the structure and functionality of proteins can be adapted by genetic engineering. Furthermore, strategies and tools for protein production have been developed and refined steadily for more than 30 years. However, protein conformation and therefore activity might be sensitive to production conditions. Here, we have explored whether the downstream strategy influences the structure and biological activities, in vitro and in vivo, of a self-assembling, CD44-targeted protein-only nanoparticle produced in Escherichia coli. This has been performed through the comparative analysis of particles built from soluble protein species or protein versions obtained by in vitro protein extraction from inclusion bodies, through mild, non-denaturing procedures. These methods have been developed recently as a convenient alternative to the use of toxic chaotropic agents for protein resolubilization from protein aggregates. The results indicate that the resulting material shows substantial differences in its physicochemical properties and its biological performance at the systems level, and that its building blocks are sensitive to the particular protein source.

Imaging diagnosis-magnetic resonance imaging findings of an intracranial epidural tuberculoma in a dog.

Magnetic resonance (MR) imaging is highly sensitive for detecting tuberculomas in human patients but the specificity of the MR imaging features is low. Misdiagnosis with intracranial neoplasia is common, especially with dural-based lesions or lesions located in the epidural space. We describe the MR imaging characteristics of an intracranial epidural tuberculoma caused by Mycobacterium tuberculosis infection in a dog. The intracranial mass and skull flat bone lysis and erosion are similar to those described in human caseating tuberculomas and can mimic intracranial neoplastic disease.

Clinical, pathologic, and magnetic resonance imaging characteristics of canine disc extrusion accompanied by epidural hemorrhage or inflammation.

Our aim was to characterize the magnetic resonance (MR) imaging features of canine disc extrusion accompanied by epidural hemorrhage or inflammation. We correlated the imaging characteristics of this type of disc extrusion in 46 dogs and compared these features with clinical signs and pathologic findings. Data from 50 control dogs with MR imaging features of a disc extrusion with no associated hemorrhage or inflammation, characterized by a T2-hypointense extradural mass, were used for comparison of the relative location of the two types of lesions and prognosis. Disc extrusion causing epidural hemorrhage or inflammation is more common in the caudal aspect of the lumbar spine than disc extrusions that do not cause signs of hemorrhage or inflammation (P < 0.05) in MR images. In dogs with disc extrusion and associated epidural hemorrhage or inflammation, there was no association between MR imaging features and signalment, the presence or absence of hemorrhage, or pathologic findings. The appearance of the lesion created by disc extrusion with epidural hemorrhage and inflammation encompasses a wide variety of imaging features, likely related to the duration of the hemorrhage and associated inflammatory changes. In 10 of 46 dogs these secondary changes masked identification of the disc extrusion itself in the MR images. An awareness of the variety of MR imaging features of disc extrusion accompanied by extradural hemorrhage or inflammation is important to avoid making an incorrect diagnosis and to facilitate a proper surgical approach. The prognosis of dogs with disc extrusion accompanied by hemorrhage or inflammation does not appear to be different than for dogs with disc extrusion and without imaging signs of epidural hemorrhage or inflammation.

Diabetic neuropathy: electrophysiological and morphological study of peripheral nerve degeneration and regeneration in transgenic mice that express IFNbeta in beta cells.

Diabetic neuropathy is one of the most frequent complications in diabetes but there are no treatments beyond glucose control, due in part to the lack of an appropriate animal model to assess an effective therapy. This study was undertaken to characterize the degenerative and regenerative responses of peripheral nerves after induced sciatic nerve damage in transgenic rat insulin I promoter / human interferon beta (RIP/IFNbeta) mice made diabetic with a low dose of streptozotocin (STZ) as an animal model of diabetic complications. In vivo, histological and immunohistological studies of cutaneous and sciatic nerves were performed after left sciatic crush. Functional tests, cutaneous innervation, and sciatic nerve evaluation showed pronounced neurological reduction in all groups 2 weeks after crush. All animals showed a gradual recovery but this was markedly slower in diabetic animals in comparison with normoglycemic animals. The delay in regeneration in diabetic RIP/IFNbeta mice resulted in an increase in active Schwann cells and regenerating neurites 8 weeks after surgery. These findings indicate that diabetic-RIP/IFNbeta animals mimic human diabetic neuropathy. Moreover, when these animals are submitted to nerve crush they have substantial deficits in nerve regrowth, similar to that observed in diabetic patients. When wildtype animals were treated with the same dose of STZ, no differences were observed with respect to nontreated animals, indicating that low doses of STZ and the transgene are not implicated in development of the degenerative and regenerative events observed in our study. All these findings indicate that RIP/IFNbeta transgenic mice are a good model for diabetic neuropathy.