The present invention relates to the field of oncogene-targeted therapeutics in the treatment of cancer.
Cancer is among the leading causes of morbidity and mortality worldwide with approximately 14 million new cases and 8.2 million cancer-related deaths in 2012 (WHO, World Cancer Report. Bernard W. Stewart and Christopher P. Wild, eds. 2014). The number of new cases is expected to rise by about 75% over the next 2 decades coincident with an aging population. One defining feature of cancer is the rapid creation of abnormal cells that grow beyond their usual boundaries, and which can then invade adjoining parts of the body and spread to other organs. Oncogenesis is the result of the interaction between genetic factors and external agents such as, but not limited to, ultraviolet radiation, asbestos tobacco smoke, or viral infection. Cancer-causing viral infections such as HBV/HCV and HPV are responsible for up to 20% of cancer deaths in low- and middle-income countries The transformation from normal cells into tumor cells is a multistage process, typically a progression from a pre-cancerous lesion seeded by cancer stem cells, to malignant tumors that metastasize to distant sites. Metastasis is the primary cause of death for human cancers, while certain cancers that rarely metastasize (basal cell carcinoma) are almost never fatal.
Current cancer treatments are dominated by invasive surgery, radiation therapy and chemotherapy protocols, which are frequently ineffective and can have potentially severe side-effects, non-specific toxicity and/or cause traumatizing changes to an individual's body image and/or quality of life. One of the causes for the inadequacy of current cancer treatments is their lack of selectivity for affected tissues and cells. More selective cancer treatments would leave normal cells unharmed thus improving outcome, side-effect profile and quality of life.
While significant advancements have been made, treatment of cancers by chemotherapy frequently results in severe side effects because the therapy used is not specific to the cancer, killing non-cancerous cells including hematopoietic cells critical to immune surveillance. In addition to standard chemotherapy and hormone replacement therapy, new classes of therapies have emerged with directed oncolytic mechanisms. One approach targets either toxins or radioactive isotopes directly into the cancers by coupling the oncolytic agent to monoclonal antibodies (MAb) directed against cancer antigen. Genentech's Kadcyla® is an example of this kind of “smart-bomb” approved for the treatment of breast cancer. Another class are drugs like Gleevec® (Novartis) that antagonize growth pathways specific to cancer cells, such as the bcr-abl oncogene of chronic myelogenous leukemia targeted by Gleevec®. This is the class of agent described in this invention, with the difference that this invention describes a biologic that is a drug delivery tool with a programmable cassette such that it can be theoretically targeted against any oncogene. Other approaches are being designed directed against growth pathways specific to cancer stem cells, which are the seeds for cancer metastasis to distant sites. This stem cell strategy is a preferred realization of this invention because it has been theorized that mutational escape of cancer stem cells is rare compared to cancer tumor cells.
Other realizations of targeted cancer therapies are oncolytic viruses, a technology based on the observation by Coley of spontaneous remissions in certain blood cancers during severe systemic viral infections. Oncolytic viruses are currently approved for the treatment of certain blood dyscrasias and recurrent melanoma Kyprolis® (Amgen, Inc.) or carfilzomib for injection for multiple myeloma, see U.S. Pat. No. 9,315,542 and U.S. Pat. No. 9,309,283. Most recently an oncolytic poliovirus developed at Duke Medical Center gained fast track approval for the treatment of recurrent glioblastoma. The Chicken Anemia Virus (CAV) has been noted to mediate oncolysis through its VP3 (“Apoptin”) protein, an observation that has remained in pre-clinical development owing to bioavailability and delivery issues.
At the present time, patients with recurrent cancer have few options of treatment that offer extended quality of life. The regimented approach to cancer therapy has produced overall improvements in global survival and morbidity rates. However, to the particular individual, these improved statistics do not necessarily correlate with an improvement in their personal situation, or even to prolonged survival. When cancer recurs after these consolidation therapies, it is almost always rapidly fatal even when treated by any of the newer targeted agents.
An improved approach to treatment would be to design agents targeted to inhibiting oncogenes using Directed Antagonists to cancer Growth Signals (DAGRS™), with low toxicity and good bioavailability. This invention captures the cancer-killing activity of certain oncolytic viruses in a simple peptide, sparing the toxicities associated with a multitude of other viral proteins that are superfluous to oncolysis but a source of toxicity. In the example of oncolyitc poliovirus for glioblastoma, the investigators had the profound head start to safety of an attenuated poliovirus that has been used safely for 60 years as a vaccine. While its approval for use in adult glioblastoma is a major advance, glioblastoma is also a disease of children. The coupling of the historically higher incidence of paralytic polio in children with the global immune suppression associated with cancers raises the concern that the safety profile of the oncolytic poliovirus may not be nearly as good in children as it is in adults.
The treatment of diverse cancers with the power and adaptability of DAGRS™ is a major beneficial outcome that can derive from this invention. As one example, individual profiling of cancers is becoming commonplace as a strategy to better tailor therapeutics to the unique genetics of the patient. Because in principle DAGRS™ can be targeted against any oncogene, a pair or even a trio of synergistic DAGRS™ could be administered to the cancer patient that precisely antagonize that individual's oncogene profile. As a second example, mutations have been discovered that render some fraction of cancers particularly susceptible to specific directed oncolytics. Invariably the cancers under treatment undergo mutational escape so that, while there is a short term benefit in tumor regression, the long term benefit in survival is most frequently marginal. Because the downstream escape pathways are limited and reproducible, a DAGRS™ that targets and blocks the most common downstream escape mechanism(s) could be administered along with another directed oncolytic, thereby potentiating the efficacy of both.
The present invention describes an improved composition and methods for the treatment of cancer that incorporate the administration of a synthetic, genetically engineered Directed Antagonists to cancer Growth Signals (DAGRS™) targeted at inhibiting an oncogene. Because DAGRS™ are constructed from diverse small stretches of genetic material that are tiled together in a unique arrangement, DAGRS™ compositions of matter have less than 50% homology to any naturally occurring biologic. DAGRs have the ability to deliver a biologic from outside the cell through the cytoplasm to the nucleus, and are engineered to bind to specific targets through introduction of specific peptide fragments into a cassette that locks the peptide into a high affinity configuration. DAGRS™ can in principle be targeted against any oncogene. Preferred oncogene targets illustrated in this invention are E2F and AKT, which are effective against many cancers in vitro. AKT is a particularly attractive target because it is found to be mutated in approximately 80% of human cancers, its inhibition mediates a p53 independent apoptosis, and its specific activity in G2 phase dividing (cancer) cells supports a good safety profile for normal cells. The CAV VP3 protein (“Apoptin”) mediates oncolysis at least in part through AKT, and Apoptin has been shown to kill a wide variety of cancer cells but not normal cells in vitro. Apoptin has been coupled to Tat monomer as an in vitro delivery tool with positive results. However, the toxicities inherent in native HIV Tat monomer, as well as the general instability of peptides linked together side by side as investigated, render this design unsuitable for in vivo use and clinical application owing to safety problems. DAGRS™ use two inherent properties of Tat, one that locks a signal-transducing peptide into an active conformation within the first 20 amino acids of the protein, making for the cloning cassette, and the well-described TAR and RK-rich membrane translocation sequence (aa 38-60 of SF2 Tat). An SH3 binding domain described here naturally encoded at the amino terminus of HIV-1 Tat is removed from the cassette, and inhibitory peptides for eg AKT or E2F are swapped into the cassette. As we have discovered that this SH3-binding domain is a major source of toxicity, in this process DAGRS™ are rendered much safer than Tat. A CRD that sits just carboxyl to the cassette, and is a major source of Tat reactivity, is “humanized” to remove toxicity by replacement alternatively with a human C-rich spacer, or the CRD from non-pathogenic SIV Tat. Because the present invention appreciates that DAGRS™ affinity for signal-transducing target is a property of its conformation, and that DAGRS™ bioavailability depends upon membrane translocation, the DAGRS™ described in the present invention preserves both of these functionalities. These DAGRS™ constructs provide improved safety and better bioavailability for therapeutics in the treatment of cancer and other in vivo applications.
PRALINE program was used to generate the alignments.
DAGRS™ peptide derived from chicken anemia virus VP3
DAGRS™ peptide derived from the SH3-binding region of human AKT
DAGRS™ peptide derived from AKT modified to be “right-handed” as VP3 and to contain a canonical PPxPP Src SH3-binding site. (Kay, Williamson, and Sudol, FASEB J 14, 231, 2000).
DAGRS™ encoding the E2F promoter binding peptide as described by Bertino.
DAGRS™ are targeted drugs aimed to control tumor growth, and prevent or resolve metastases, while avoiding many of the side effects associated with standard chemotherapy.
The present invention provides for improved oncogene-directed biologics which in its simplest realization locks a signal transducing peptide into an NH2 terminal cassette in a biologically active configuration protected from degradation, and links this sequence to a carboxyl KR-rich membrane translocation sequence (MTS, SEQ ID2). The construct is designed to facilitate bioavailability and stability of the oncogene-inhibitory peptide. The Tat-encoded membrane translocation sequence (SEQ ID2, “penetrin”) has been screened for safety in clinical trial (Voskens et al. Head Neck 34, 1734, 2012). Additionally, Tat contains sequences critical for its entering the nuclear transcriptome (TAR) and to its binding cyclin (SEQ ID1, underlined) that are a preferred realization of this invention (SEQ ID 1), because they are proposed to maintain all functionalities while conserving correct domain spacing within Tat. It is not known whether TAR (aa 38-47 within Tat) contributes to Tat toxicity, so another realization of this invention preferred for safety replaces Tat TAR/MTS with a fully human sequence studied to have similar functionalities as Tat. As an example, human Atx-3 mediates the translocation of human VCP to the nucleus: the peptide sequence responsible for these functionalities is illustrated (Atx-3 amino acids 277-291, SEQ ID 3). Noteworthy that like Tat SEQ ID3 encodes a short stretch of amino acids preceding its KR-rich MTS. A schematic of the DAGRS™ construct is illustrated in
DAGRS™ use a molecular design evolved by the SIV/HIV Tat protein, but are humanized for safety. Overall, DAGRS™ composition of matter range between 0-33% identity to Tat. This is critical because HIV Tat is a toxic substance which precludes its use in clinical applications. Following the molecular design of SIV Tat (
The present invention further improves bioavailability by combining the membrane translocation sequences of Tat with the targeted killing effect of Apoptin, or any STP. The invention is not interfered with by patent filings proposing to link Apoptin to Tat for improved bioavailability (US 20020176860, US 2008/0234466) because those inventors on the Tat-Apoptin patents acknowledge that native Tat is too toxic to be administered to humans (see Los et al., Apoptin, a tumor-selective killer, Biochem Biophys Acta. 1793, (2009) 1335-1342), and because the DAGRS™ sequences bear <33% identity to Tat. Translocation of Tat-GFP-monomer is shown in
Another embodiment of the present invention is a DAGRS™ with a transcription factor/protein activator region such as a peptide capable of binding to E2F promoter ((SEQ ID 9). This design bears analogy to SIV Tat in encoding an acidic region, while the AKT design bears analogy to HIV Tat in encoding an SH3-binding domain As for SEQ ID 6-8, it could be beneficial to distance E2F peptide (SEQ ID 9) by 4 or 5 amino acids from the COOH P staple.
This is the first time that a functional viral domain has been matched up (“humanized”) to a human protein fragment, and in so doing describes a key humanization invention. The example of
Although the present invention has been described with reference to specific embodiments, workers skilled in the art will recognize that many variations may be made therefrom and it is to be understood and appreciated that the disclosures in accordance with the invention show only some preferred embodiments and advantages of the invention without departing from the broader scope and spirit of the invention. It is to be understood and appreciated that these discoveries in accordance with this invention are only those which are illustrated of the many additional potential applications that may be envisioned by one of ordinary skill in the art, and thus are not in any way intended to be limiting of the invention. Accordingly, other objects and advantages of the invention will be apparent to those skilled in the art from the detailed description together with the claims.
This application claims the benefit of U.S. Provisional Application No. 62/362,254, filed Jul. 14, 2016 and incorporated by reference in its entirety.
Number | Date | Country | |
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62362254 | Jul 2016 | US |