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DelMar Pharmaceuticals Announces New Data Supporting the Unique Anti-cancer Mechanism of VAL-083

On April 19, 2016 DelMar Pharmaceuticals, Inc. (OTCQX: DMPI) ("DelMar" and reported that its collaborators from the University of British Columbia’s Vancouver Prostate Center presented results of new research related to the anti-cancer mechanism of its lead anti-cancer product candidate, VAL-083 (dianhydrogalactitol) (Press release, DelMar Pharmaceuticals, APR 19, 2016, View Source [SID:1234511054]).

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Abstract #2985: "Molecular mechanisms of dianhydrogalactitol (VAL-083) in cancer treatment," is being presented during this morning’s "New Mechanisms of Anticancer Drug Action" session at the American Association of Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting in New Orleans.

Specifically,

VAL-083 displayed broad anti-tumor activity against lung and prostate cancer cells;
VAL-083 treatment causes rapid and durable DNA interstrand crosslinks leading to irreparable DNA double-strand breaks, S/G2 phase cell-cycle arrest and apoptosis in cancer cells; and
This new understanding of the molecular mechanisms underlying VAL-083’s anti-cancer activity offers support for effective combination therapies.
"These data indicate that the DNA-damaging cross-links resulting from VAL-083 treatment occur rapidly and, once formed, are not easily repaired by the cell," noted Dr. Dennis Brown, DelMar’s Chief Scientific Officer.

"Typically, a normal cell employs check-point control and DNA repair mechanisms to identify and remove DNA cross-links and double strand breaks such as those resulting from treatment with VAL-083. However, cancer cells, by their very nature tend to have mutations or deficiencies in these mechanisms that may allow VAL-083 mediated cross-links to persist resulting in irreparable and lethal damage to the tumor cell."

Jeffrey Bacha, DelMar’s chairman & CEO continued, "These findings are very exciting and continue to support our belief that VAL-083’s anti-cancer mechanism is unique. Understanding where in the cell cycle VAL-083 elicits its cancer-lethal activity provides guidance in considering combination therapies. This knowledge combined with our own and historical clinical data demonstrating activity against a number of tumors truly establishes a broad stage for the future clinical development of VAL-083."

About the Research:

VAL-083 (dianhydrogalactitol) is a bi-functional alkylating agent causing N7-guanine alkylation and inter-strand DNA crosslinks. VAL-083’s cytotoxic activity is independent of MGMT-expression in various cancer cells and cancer stem cells, suggesting a mechanism that is distinct from that of other alkylating agents. Preclinical and clinical trial data suggest that VAL-083 may have effects in treating various cancers, including lung, brain, cervical, ovarian tumors, and leukemia. However, the detailed molecular mechanisms mediating VAL-083 sensitivity or resistance in cancer have been unclear.

This research was undertaken to investigate the signaling events responsible for VAL-083’s robust activity against cancer.

Crystal violet proliferation assays were performed to assess VAL-083 sensitivity in a variety of cancer cell lines. Propidium iodide (PI) staining and immunofluorescent analyses were used to evaluate cell cycle phases. Western blots were employed to investigate DNA damage response induced by VAL-083 treatment.

Pulse (1 hour) treatment with VAL-083 activated DNA damage signaling pathway as demonstrated by expression of phospho-ATM (S1981), phospho-Chk2 (T68), phospho-RPA32 (S33) and ɣH2A.X which persisted for 24 – 48 hours after removal of VAL-083 from the medium. Specifically, VAL-083 treatment led to long-lasting cell cycle arrest at S/G2 phase of the cell cycle. Additionally, DNA double-strand break signals such as increased levels of ɣH2A.X continued to accumulate at 72 hours following treatment of cancer cells with VAL-083, demonstrating irreparable damage to the tumor cell.

About VAL-083

VAL-083 is a "first-in-class," small-molecule chemotherapeutic. In more than 40 Phase I and II clinical studies sponsored by the U.S. National Cancer Institute, VAL-083 demonstrated clinical activity against a range of cancers including lung, brain, cervical, ovarian tumors and leukemia both as a single-agent and in combination with other treatments. VAL-083 is approved in China for the treatment of chronic myelogenous leukemia (CML) and lung cancer, and has received orphan drug designation in Europe and the U.S. for the treatment of malignant gliomas. DelMar recently announced that the FDA’s Office of Orphan Products had also granted an orphan designation to VAL-083 for the treatment of medulloblastoma.

DelMar has demonstrated that VAL-083’s anti-tumor activity is unaffected by the expression of MGMT, a DNA repair enzyme that is implicated in chemotherapy resistance and poor outcomes in GBM patients following standard front-line treatment with Temodar (temozolomide).

DelMar has been conducting a Phase I/II clinical trial in GBM patients whose tumors have progressed following standard treatment with temozolomide, radiotherapy, bevacizumab (Avastin) and a range of salvage therapies at five clinical centers in the United States: Mayo Clinic (Rochester, MN); UCSF (San Francisco, CA) and three centers associated with the Sarah Cannon Cancer Research Institute (Nashville, TN, Sarasota, FL and Denver, CO).

Interim data from the ongoing Phase I/II clinical trial were presented today at the American Association of Cancer Research Annual Meeting (abstract #CT074). Results to date support the potential of a VAL-083 to offer a clinically meaningful survival benefit and a promising new treatment option for GBM patients who have failed or are unlikely to respond to currently available chemotherapeutic regimens. DelMar plans to discuss a proposed Phase III protocol with the FDA in the coming months.

Iomab-B

Iomab-B for Hematopoietic Stem Cells Transplantation:

Iomab-B (BC8-I-131 construct) has already been successfully used as a myeloconditioning/myeloablative agent in over 250 patients with incurable blood cancers (Company Pipeline, Actinium Pharmaceuticals, APR 19, 2016, View Source [SID:1234511053]). In both Phase I and Phase II trials Iomab-B has led to effective cures in patients with no options left. The only potentially curative treatment option for those patients is bone marrow transplantation (BMT), also known as a hematopoietic stem cell transplant (HSCT), but vast majority of patients over the age of 50 are either ineligible for myeloablative conditioning due to concomitant conditions or have a high burden and/or very resistant disease that makes reduced dose conditioning futile.

BC8-I-131 has demonstrated ability to successfully prepare such patients for bone marrow transplants when no other treatment was indicated. ATNM intends to develop Iomab-B through a regulatory approval via a pivotal registration trial in AML refractory/relapsing patients. That would allow for a relatively quick path to the market and provide a potentially curative treatment to patients who currently have little or no chance of achieving even a temporary remission, let alone a cure.

The targeting part of the Iomab-B construct is a monoclonal antibody that targets CD45, an antigen widely expressed on hematopoietic cells but not other tissues. Due to this broad expression, Iomab-B has demonstrated utility in other groups of patients and other indications as well, including Myelodysplastic Syndrome, Acute Lymphoblastic Leukemia, Hodgkin’s Disease and Non-Hodgkin Lymphoma. These are follow-on indications which could be pursued simultaneously or delayed, for cash conservation, and financed from commercial revenues.

The company is already preparing a program for replacing iodine 131 with Actinium 225 to create a second generation drug that would enable a significant expansion of use, described below as Actimab-B, Iomab-B was invented by researchers at the Fred Hutchinson Cancer Research Center (FHCRC), ATNM’s key collaborator on this program from whom ATNM obtained rights for all the commercial uses. FHCRC played a pivotal role in developing the entire field of bone marrow transplantation and the lead Hutchinson researcher, Dr. E. Donnall Thomas received the 1990 Nobel Prize in physiology/medicine for work in this area.

Metabolites of antibody-maytansinoid conjugates: characteristics and in vitro potencies.

Several antibody-maytansinoid conjugates (AMCs) are in clinical trials for the treatment of various cancers. Each of these conjugates can be metabolized by tumor cells to give cytotoxic maytansinoid metabolites that can kill targeted cells. In preclinical studies in mice, the cytotoxic metabolites initially formed in vivo are further processed in the mouse liver to give several oxidized metabolic species. In this work, the primary AMC metabolites were synthesized and incubated with human liver microsomes (HLMs) to determine if human liver would likely give the same metabolites as those formed in mouse liver. The results of these HLM metabolism studies as well as the subsequent syntheses of the resulting HLM oxidation products are presented. Syntheses of the minor impurities formed during the conjugation of AMCs were also conducted to determine their cytotoxicities and to establish how these impurities would be metabolized by HLM.

Structure of a stapled peptide antagonist bound to nutlin-resistant Mdm2.

As key negative regulator of the p53 tumour suppressor, Mdm2 is an attractive therapeutic target. Small molecules such as Nutlin have been developed to antagonise Mdm2, resulting in p53-dependent death of tumour cells. We have recently described a mutation in Mdm2 (M62A), which precludes binding of Nutlin, but not p53. This Nutlin-resistant variant is not, however, refractory to binding and inhibition by stapled peptide antagonists targeting the same region of Mdm2. A detailed understanding of how stapled peptides are recalcitrant to Mdm2 mutations conferring Nutlin-resistance will aid in the further development of potent Mdm2 antagonists. Here, we report the 2.00 Å crystal structure of a stapled peptide antagonist bound to Nutlin resistant Mdm2. The stapled peptide relies on an extended network of interactions along the hydrophobic binding cleft of Mdm2 for high affinity binding. Additionally, as seen in other stapled peptide structures, the hydrocarbon staple itself contributes to binding through favourable interactions with Mdm2. The structure highlights the intrinsic plasticity present in both Mdm2 and the hydrocarbon staple moiety, and can be used to guide future iterations of both small molecules and stapled peptides for improved antagonists of Mdm2.

BioLineRx Announces Presentation of Detailed Mechanism of Action Data for Lead Oncology Platform at AACR 2016

On April 19, 2016 BioLineRx Ltd. (NASDAQ/TASE: BLRX) reported that detailed results from a study on the underlying mechanism of action of BL-8040, its lead platform for the treatment of multiple cancer and hematological indications, were presented by Prof. Amnon Peled at the American Association of Cancer Research (AACR) (Free AACR Whitepaper) 2016 meeting in New Orleans (Press release, BioLineRx, APR 19, 2016, View Source;p=RssLanding&cat=news&id=2158220 [SID:1234511046]).

The work presented, entitled "CXCR4 Controls BCL-2 Expression and Function by Regulating miR-15a/16-1 Expression in Tumor Cells," illustrates the mechanism by which the CXCR4 pathway controls malignant cell survival and death in preclinical studies. Specifically, the studies point out how BL-8040 increases the expression and activity of a special class of microRNA precursors termed miR-15a/16-1. These microRNA molecules have been previously linked to cancer, and shown to suppress the activity of several tumor-related pro-survival proteins, specifically BCL2, MCL1 and cyclin D1. The studies presented showed that BL-8040 increases the suppression of these three target proteins through miR-15a/16-1, thereby increasing tumor cell death.

The BL-8040 oncology platform is a short cyclic peptide that functions as a high-affinity antagonist for CXCR4, a chemokine receptor that is directly involved in tumor progression, angiogenesis, metastasis and cell survival. CXCR4 is overexpressed in the majority of cancer cells, and its degree of expression often correlates with disease severity.

Dr. Kinneret Savitsky, CEO of BioLineRx, stated, "We recently announced the successful top-line results for BL-8040, in combination with Cytarabine, one of the standard-of-care chemotherapies, in a Phase 2 study in relapsed or refractory AML. In that study, BL-8040 showed a triple effect on the leukemic cells. First, BL-8040 monotherapy triggered robust mobilization of AML cells from the bone marrow to the peripheral blood, thereby sensitizing these cells to the chemotherapy and improving its efficacy. Second, BL-8040 monotherapy showed a 3-4 fold increase in the direct apoptotic effect on the leukemia cells in the bone marrow. Last, BL-8040 monotherapy induced leukemia progenitor cells towards differentiation. As a result of these factors, we reported a 38% complete remission rate in the study, compared to historical remission rates in similar patient populations with similar treatment regimens of approximately 20% for Cytarabine on a stand-alone basis. We look forward to providing the full results of this study at an upcoming scientific conference."

"In this regard, we are pleased to announce the current study results presented at the AACR (Free AACR Whitepaper) meeting, which provide significant clarity regarding BL-8040’s mechanism of action relating to apoptosis. The data suggest that BL-8040 is able to indirectly suppress the activity of several tumor-promoting genes, by increasing the activity of the microRNA molecule miR-15a/16-1. Of note, one of these pro-survival proteins, BCL-2, is a validated anti-cancer target that is recently attracting a lot of interest in the drug development space."

"In order to further expand and enhance the potential of our unique oncology platform, BL-8040 is undergoing multiple clinical studies, including our recently announced immuno-oncology collaboration with Merck on a Phase 2 study to investigate BL-8040 in combination with KEYTRUDA for the treatment of pancreatic cancer," concluded Dr. Savitsky.

Link to AACR (Free AACR Whitepaper) On-Line Abstract

About BL-8040
BL-8040 is a clinical-stage drug candidate for the treatment of acute myeloid leukemia, as well as other hematological indications. It is a short cyclic peptide that functions as a high-affinity antagonist for CXCR4, a chemokine receptor that is directly involved in tumor progression, angiogenesis (growth of new blood vessels in the tumor), metastasis (spread of the disease to other organs or organ parts) and cell survival. CXCR4 is over-expressed in more than 70% of human cancers and its expression often correlates with disease severity. In a Phase 1/2, open-label, dose escalation, safety and efficacy clinical trial in 18 multiple myeloma patients, BL-8040, when combined with G-CSF, demonstrated an excellent safety profile at all doses tested and was highly effective in the mobilization of hematopoietic stem cells and white blood cells from the bone marrow to the peripheral blood. Additionally, in a Phase 1 stem-cell mobilization study in healthy volunteers, BL-8040 as a single agent was safe and well tolerated at all doses tested and resulted in efficient stem-cell mobilization and collection in all study participants. Importantly, the results of this study support the use of BL-8040 as one-day, single-dose collection regimen, which is a significant improvement upon the current standard of care.

BL-8040 also mobilizes cancer cells from the bone marrow and may therefore sensitize these cells to chemo- and bio-based anti-cancer therapy. Importantly, BL-8040 has also demonstrated a direct anti-cancer effect by inducing apoptosis. Pre-clinical studies show that BL-8040 inhibits the growth of various tumor types including multiple myeloma, non-Hodgkin’s lymphoma, leukemia, non-small cell lung carcinoma, neuroblastoma and melanoma. BL-8040 also significantly and preferentially stimulated apoptotic cell death of malignant cells (multiple myeloma, non-Hodgkin’s lymphoma and leukemia). Significant synergistic and/or additive tumor cell killing activity has been observed in-vitro and in-vivo when tumor cells were treated with BL-8040 together with Rituximab, Bortezomib, Imatinib, Cytarabine and the FLT-3 inhibitor AC-220 (in NHL, MM, CML, AML, and AML-FLT3-ITD models, respectively). In addition, the recently completed Phase 2 clinical trial in AML patients has demonstrated robust mobilization and apoptosis of cancer cells, along with a clinically meaningful response rate. BL-8040 was licensed by BioLineRx from Biokine Therapeutics and was previously developed under the name BKT-140.