On September 13, 2016 Siamab Therapeutics, Inc., a biotechnology company developing novel cancer immunotherapies, reported new pre-clinical data that showed its novel ST1 antibody drug conjugates (ADCs) target chemoresistant ovarian cancer cells and demonstrate strong efficacy in ovarian cancer models (Press release, Siamab Therapeutics, SEP 13, 2016, View Source [SID:SID1234515130]). These data were presented at the American Association for Cancer Research (AACR) (Free AACR Whitepaper)’s 11th Biennial Ovarian Cancer Research Symposium 2016 in Seattle, Wash., on Monday, Sept. 12, 2016.

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"The preclinical results are exciting and show the potential of our antibody approach to target chemoresistant tumors in ovarian cancer"

Siamab’s ST1 ADCs target the cancer associated antigen, sialyl-Tn (STn) with high specificity and affinity. STn is present on multiple solid tumors including ovarian, pancreatic, prostate and colon, while showing little normal tissue expression, and has been implicated in immune suppression, metastasis, and a cancer stem cell phenotype.

"The preclinical results are exciting and show the potential of our antibody approach to target chemoresistant tumors in ovarian cancer," said Jeff Behrens, president and chief executive officer of Siamab Therapeutics. "We have developed multiple anti-glycan antibodies and ADCs with unprecedented cancer specificity and efficacy in animal models. These findings hold promise for developing new cancer therapeutics for ovarian cancer patients with disease recurrence who have limited treatment options."

The preclinical data were presented in a poster titled "Targeting a chemoresistant ovarian cancer cell population via the carbohydrate antigen sialyl Tn." The findings showed that Siamab’s ST1 ADCs significantly reduce tumor volume in a sustained fashion in ovarian cancer models. In addition, Siamab’s ST1 target, STn, demarks a population of cells that display a cancer stem cell phenotype as demonstrated by colony- and sphere-forming assays. The findings also showed that following platinum- and taxane-based cytotoxic chemotherapy, STn+ cancer cells are significantly enriched, further supporting their cancer stem cell and chemoresistant phenotype.

Siamab collaborated with Bo Rueda, Ph.D., director of the Vincent Center for Reproductive Biology, in the Department of Obstetrics and Gynecology at Massachusetts General Hospital on this research, funded by a National Cancer Institute SBIR Phase I contract. The collaboration explored the potential of Siamab’s anti-glycan antibodies to target populations of chemoresistant cancer cells. This research also looked at the relationship between tumor associated carbohydrate antigens (TACAs) and chemoresistant cancer cells that demonstrate a cancer stem cell (CSC) phenotype.

"We know chemoresistant cancer cells play a central role in disease recurrence and are particularly challenging to target," said Dr. Rueda. "Siamab’s ADCs targeted STn positive cells, demarking a chemoresistant population, and were effective in shrinking ovarian tumors in animal models. I look forward to continuing to work closely with Siamab as they move this program toward clinical development."

Nabi Biopharmaceuticals has filed a 10-K – Annual report [Section 13 and 15(d), not S-K Item 405] with the U.S. Securities and Exchange Commission (Filing, 10-K, Nabi Biopharmaceuticals, SEP 13, 2016, View Source [SID1234515123]).

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On September 12, 2016 CytRx Corporation (NASDAQ: CYTR), a biopharmaceutical research and development company specializing in oncology, reported that results from its on-going Phase 1b/2 trial of aldoxorubicin in combination with ifosfamide/mesna in patients with advanced sarcomas will be presented at the European Society for Medical Oncology (ESMO) (Free ESMO Whitepaper) 2016 Congress being held in Copenhagen, Denmark, from October 7-11, 2016 (Press release, CytRx, SEP 12, 2016, View Source;p=RssLanding&cat=news&id=2201143 [SID:SID1234515090]).

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"Presenting the results from this trial at the ESMO (Free ESMO Whitepaper) Congress underscores the continued anti-tumor activity of aldoxorubicin across a variety of treatment settings for patients with advanced sarcomas," said Sant Chawla, M.D., F.R.A.C.P., the trial’s principal investigator and Director of the Sarcoma Oncology Center in Santa Monica, California. "The data show that aldoxorubicin can successfully be combined with ifosfamide and mesna, which are regularly given with doxorubicin to patients with first-line soft tissue sarcomas. Based on encouraging results, the trial was expanded to 50 patients and continues to enroll."

The Phase 1b/2 clinical trial has enrolled 38 patients to date with locally advanced, unresectable, and/or metastatic soft tissue sarcoma, intermediate-grade or high-grade chondrosarcoma or osteosarcoma. In the dose escalation phase, patients received either 170mg/m2 or 250mg/m2 of aldoxorubicin in combination with up to a 14-day continuous infusion of ifosfamide (1g/m2/day) plus mesna over a 28-day cycle. The expansion phase will enroll patients at the 250mg/m2 dose of aldoxorubicin and will allow for patients that had received prior chemotherapy to be included. The primary endpoint of the study is safety, and secondary endpoints include overall response rates and progression-free survival.

About Aldoxorubicin

Aldoxorubicin is a rationally-engineered cytotoxic which combines doxorubicin, a widely used chemotherapeutic agent, with a novel linker molecule that binds directly and specifically to circulating albumin, the most abundant protein in the bloodstream. Protein-hungry tumors concentrate albumin, which facilitates the delivery of the linker molecule with the attached doxorubicin to tumor sites. In the acidic environment of the tumor, but not the neutral environment of healthy tissues, doxorubicin is released. Typically, doxorubicin is delivered systemically and is highly toxic, which limits its dose to a level below its maximum therapeutic benefit. Doxorubicin also is associated with many side effects, especially the potential for damage to heart muscle at cumulative doses greater than 450 mg/m2. Using this acid-sensitive linker technology, aldoxorubicin delivers greater doses of doxorubicin (3 ½ to 4 times). To date, there has been no evidence of clinically significant effects of aldoxorubicin on heart muscle, even at cumulative doses of drug well in excess of 2,000 mg/m2. Aldoxorubicin is the first-ever single agent to show superiority over doxorubicin in a randomized clinical trial in first-line STS.

On September 12, 2016 Aptose Biosciences Inc. (NASDAQ:APTO) (TSX:APS), a clinical-stage company developing new therapeutics and molecular diagnostics that target the underlying mechanisms of cancer, reported that it has submitted a formal response to the U.S. Food and Drug Administration (FDA) regarding the previously announced clinical hold of Aptose’s Phase 1b clinical trial of APTO-253 in patients with hematologic cancers (Press release, Aptose Biosciences, SEP 12, 2016, View Source;p=RssLanding&cat=news&id=2201082 [SID:SID1234515091]). Aptose provided responses to all of the questions cited in the clinical hold letter issued by the FDA.

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"This submission represents months of disciplined labor to resolve a manufacturing matter related to APTO-253 that arose during our Phase 1b Trial in patients with AML and high-risk MDS," commented Dr. William G. Rice, Chairman, President and Chief Executive Officer. "Although the FDA will make the ultimate decision whether our clinical trial may resume, all of their questions have been addressed."

During a Phase 1b clinical trial with APTO-253, a clinical site experienced stoppage of the infusion pump during an IV infusion caused by back pressure as a result of clogging of the in-line filter. The Company determined the root cause was a chemistry-based issue with the molecule, and the Company is now working with a drug product that does not cause filter clogging or pump stoppage during mock infusion studies performed to confirm the acceptability of the updated product through the clinical infusion procedures. Such improvements to the APTO-253 manufacturing process required to address the filter clogging event will be incorporated into a Chemistry, Manufacturing and Control (CMC) amendment to our Investigational New Drug application.

On September 12, 2016 Circle Pharma, Inc., reported that it will apply its computational design and synthetic chemistry platform to design and create a physical screening library of novel macrocyclicpeptides (Press release, Circle Pharma, SEP 12, 2016, View Source [SID1234635670]). Once completed, the library is initially expected to comprise several hundred macrocycles that will be designed to potentially disrupt bioactive conformations commonly found in protein-protein interactions known to drive disease processes, and will deploy backbone scaffolds screened in silica for intrinsic cell permeability characteristics. In addition, the design of the library will permit the simple creation of derivative libraries tailored to specific features of a therapeutic target class.

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PfizerInc.(NYSE:PFE) has entered into an agreement with Circle under which Pfizer will provide support for the library build, and Circle has granted Pfizer non-exclusive rights to screen the library against certaintargets. The rights granted to Pfizer exclude specified targets for which Circle has reserved exclusive rights to screen the library.

"This physical library will complement Circle’s target-specific computational design toolkit," said David J. Earp, J.D., Ph.D., Circle’s President and CEO. "We expect to use the library for our internal pipeline discovery work, and we will make it available to all of our collaboration partners in drug discovery."

About Macrocyclic Peptides

Macrocyclic peptides have the potential to provide access to the large proportion of therapeutic targets (estimated at up to 80%) that are considered undruggable with conventional small molecule or biologic modalities. Inparticular, there is great interest in developing macrocycles to modulate protein-protein interactions, which play a role in almost all disease conditions, including cancer, fibrosis, inflammation and infection. However, the development of macrocyclic therapeutics has been limited to this point by the need for a greater understanding of how to design macrocycles with appropriate pharm acokinetics, cell permeability and oral bioavailability. As a result, most clinical-stage macro cyclic peptide drugs address extracellular protein targets because of the challenge of identifying cell permeable macrocycles. The ability to design potent macrocycles with intrinsic permeability is expected to give access to a large number of important therapeutic targets that have been out of reach to this point.