Five Prime to Present Preclinical Data at 2016 SITC Annual Meeting Demonstrating Potent Anti-Tumor Activity with Novel Tetravalent Anti-GITR Antibody

On November 11, 2016 Five Prime Therapeutics, Inc. (Nasdaq:FPRX), a clinical-stage biotechnology company focused on discovering and developing innovative immuno-oncology protein therapeutics, reported that a poster featuring preclinical data related to its tetravalent anti-GITR agonist antibody, FPA154, was presented today at the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) Annual Meeting in National Harbor, Maryland (Press release, Five Prime Therapeutics, NOV 11, 2016, View Source [SID1234516495]). Poster #175 titled, "Novel tetravalent anti-GITR antibody is a potent anti-tumor agent in vivo," is available at View Source

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"With our lead anti-GITR candidate, FPA154, now in pre-IND enabling studies, we are pleased to highlight our first preclinical data supporting the development and differentiation of this novel, tetravalent antibody," said Luis Borges, Ph.D., Senior Vice President of Research, at Five Prime. "In vitro data demonstrates that our tetravalent antibody has agonistic activity in the absence of Fc-mediated crosslinking. In vivo, the antibody has potent anti-tumor activity in various murine tumor models and it confers long-term anti-tumor immunity. It alters the ratio of Tregs to effector T cells, creating a favorable environment for an effective anti-tumor immune response. These findings suggest the potential for FPA154 to activate T cell immunity against various tumors and we are working to move this program rapidly toward clinical development."

FPA154 has been designed using single-domain antibodies in a tetravalent format, inducing effector T cell stimulation in vitro that is superior to a conventional bivalent antibody format and conferring agonistic activity even in the absence of Fc-mediated crosslinking. The poster features preclinical data provided by a mouse-reactive surrogate molecule that demonstrate potent inhibition of tumor growth in mouse tumor models:

Potent anti-tumor activity following a single dose: A single dose of tetravalent anti-GITR significantly inhibited tumor growth in multiple models including CT26 and MC38. Treatment was capable of inducing complete tumor rejection, and activity was observed at doses as low as 0.08 mg/kg in both models.

Fc-independent activity: Tetravalent anti-GITR antibody retained partial tumor growth inhibition activity even in the absence of Fc-mediated crosslinking or effector function, whereas a conventional bivalent antibody (DTA-1) required Fc function.
Pharmacodynamic responses: Tetravalent anti-GITR antibody treatment reduced the number of T cells in the peripheral blood 3 days post-treatment. In the tumor, Treg and conventional CD4 T cells decreased, but CD8 T cell numbers were maintained. This resulted in a ratio of CD4 and CD8 effector T cells to Treg that created a favorable environment for an effective anti-tumor immune response.

Induction of long-term immunity: Mice that eliminated CT26 tumors in response to tetravalent anti-GITR were resistant to tumor regrowth upon re-challenge with the same tumor, but not to an antigenically-unrelated tumor.

CytRx Presents Positive Interim Results from On-going Phase 1b/2 Aldoxorubicin Combination Clinical Trial at the 2016 CTOS Annual Meeting

On November 11, 2016 CytRx Corporation (NASDAQ: CYTR), a biopharmaceutical research and development company specializing in oncology, reported a poster with updated interim results from its on-going Phase 1b/2 trial of aldoxorubicin in combination with ifosfamide/mesna in patients with advanced sarcomas at the 2016 Annual Meeting of the Connective Tissue Oncology Society (CTOS) being held in Lisbon, Portugal (Press release, CytRx, NOV 11, 2016, View Source;p=RssLanding&cat=news&id=2221789 [SID1234516494]).

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Forty-two patients have been enrolled to date and 36 were evaluable as of the data cutoff. Of the 36 evaluable patients receiving either 170mg/m2 (n=7) or 250mg/m2 (n=29) of aldoxorubicin plus ifosfamide and mesna, 14 of 36 (39%) achieved a partial response of the target lesion by RECIST 1.1 criteria, 21 of 36 (58%) had stable disease, and one patient had progressive disease. As previously reported in October at the 2016 ESMO (Free ESMO Whitepaper) Congress, median progression-free survival has not yet been reached. Dose-limiting toxicities were not observed in either cohort, and no clinically significant cardiac toxicities were seen. The most common Grade 3 or 4 adverse events were neutropenia (71%), anemia (54%), thrombocytopenia (17%) and febrile neutropenia (14%). There were nine treatment-related serious adverse events, and no treatment-related deaths. The trial has been expanded to allow continued enrollment of additional sarcoma patients at the 250 mg/m2 dose of aldoxorubicin with ifosfamide and mesna.

"The CTOS annual meeting is the preeminent medical conference focused on sarcomas and provides an opportunity to update the international sarcoma community with the latest results for aldoxorubicin, 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. "Our poster highlights that nearly 40% of the sarcoma patients receiving the combination of aldoxorubicin with ifosfamide and mesna achieved a partial response of the target lesion by RECIST criteria, and half of those had greater than 50% shrinkage of their tumors. This is important because it allowed some patients who initially could not have surgery to become eligible for surgery."

The Phase 1b/2 clinical study is a single-center trial that has enrolled 42 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. Up to six cycles of ifosfamide/mesna with aldoxorubicin can be administered, and aldoxorubicin may be continued until tumor progression or unacceptable toxicity occurs. The expansion phase is enrolling 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 doxorubicin in excess of 5,000 mg/m2. Aldoxorubicin is the first-ever single agent to show superiority over doxorubicin in a randomized global Phase 2b clinical trial in first-line STS.

Calithera Biosciences Announces Four Abstracts Selected for Presentation at the Society for Immunotherapy of Cancer (SITC) 2016 Annual Meeting

On November 11, 2016 Calithera Biosciences, Inc. (Nasdaq:CALA), a clinical stage biotechnology company focused on discovering and developing novel small molecule drugs directed against tumor metabolism and tumor immunology targets for the treatment of cancer, reported that data for its drug candidates CB-839, the company’s novel glutaminase inhibitor, and CB-1158, the company’s novel arginase inhibitor, will be presented at the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) 2016 Annual Meeting, which is being held from November 9-13, 2016 in National Harbor, Maryland (Press release, Calithera Biosciences, NOV 11, 2016, View Source;p=RssLanding&cat=news&id=2221726 [SID1234516491]).

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"Both CB-839 and CB-1158 have the distinction of targeting metabolic and immune checkpoints which we believe, through rational combinations, have the potential to be transformational in the treatment of cancer. CB-839 and CB-1158 are each in clinical trials with cohorts planned in combination with approved immunotherapy agents," said Susan Molineaux, Ph.D., President and Chief Executive Officer of Calithera. "We are pleased that CB-1158 shows significant pharmacodynamic effects in patients at the first dose level tested."

Preclinical CB-839 data will be presented in a poster titled, "Targeting tumor glutamine metabolism with CB-839 enhances the efficacy of immune checkpoint inhibitors," by Andy MacKinnon, Ph.D., Calithera Biosciences (Poster #230). Included in the presentation are data that provide further insights into the mechanism by which inhibition of glutaminase by CB-839 enhances T-cell activation and increases the anti-tumor activity of anti-PD-L1 and anti-PD-1 antibodies. Glutamine deprivation during T-cell activation was shown to block Myc expression and Myc-driven metabolic re-programming, and to promote expression of T-cell suppressive markers such as BTLA, CTLA-4, PD-1, and CD73. In two syngeneic animal models, CT26 (colon cancer) and B16 (melanoma) the combination of CB-839 and anti-PD-L1 or anti-PD-1 showed significantly enhanced anti-tumor activity over checkpoint inhibition alone resulting in increased tumor regressions in the CT26 model. Depletion of CD8+ T-cells from these tumor-bearing animals reversed the anti-tumor effects of the combination, confirming an immune-mediated mechanism of action.

CB-1158 data will be presented in a poster titled, "Arginase inhibitor CB-1158 alleviates immunosuppression and enhances anti-tumor responses as a single agent and in combination with other immunotherapies," by Amani Makkouk, Ph.D., Calithera Biosciences (Poster #231). Arginase is expressed in myeloid derived suppressor cells (MDSCs) and exerts an immunosuppressive effect on T-cells and NK cells by depleting arginine and blocking activation. Tumor cell infiltrates in patients with solid tumor cancers contain significant numbers of arginase-expressing MDSCs; as a result, these patients have increased levels of plasma arginase and decreased levels of plasma arginine compared to healthy individuals. CB-1158, a highly selective, orally bioavailable, small molecule inhibitor of human arginase with nanomolar potency, has single agent immune-mediated efficacy in multiple syngeneic animal models. Inhibition of tumor growth was accompanied by an increase in the local concentration of arginine, and the induction of multiple pro-inflammatory changes in the tumor microenvironment. Treatment with CB-1158 also enhanced the anti-tumor activity of adoptive T-cell therapy, checkpoint blockade and chemotherapy in these animal models. CB-1158 is currently being tested in a Phase 1 clinical trial in patients with solid tumors. Three patients in the first cohort were treated with 50 mg of CB-1158 twice daily. This dose was well-tolerated and was pharmacologically active, resulting in sustained elevation of arginine in the plasma of all three patients. The trial is continuing to enroll patients to complete the dose escalation phase of the study, to be followed by combination studies with a PD-1 antibody.

In addition, two posters describing trial design will be presented during the "Clinical Trials in Progress" session:

CX-1158-101: A first-in-human phase I study of a small molecule inhibitor of arginase (CB-1158) as monotherapy and in combination with an anti-PD-1 checkpoint inhibitor in patients with solid tumors

Presenter: Siqing Fu, M.D., Ph.D., University of Texas, MD Anderson Cancer Center, Poster #155

CX-839-004: A phase I/II study of the safety, pharmacokinetics, and pharmacodynamics of the glutaminase inhibitor CB-839 combined with nivolumab in patients with renal cell carcinoma, melanoma, and non-small cell lung cancer

Presenter: Elaine Lam, M.D., University of Colorado, Denver, Poster #166

Advaxis to Present Phase 1 Combination Data and New Preclinical Data Using AXAL at Upcoming Society for Immunotherapy of Cancer (SITC) 2016 Annual Meeting

On November 11, 2016 Advaxis, Inc. (NASDAQ:ADXS), a clinical stage biotechnology company developing cancer immunotherapies, reported new data highlighting the potential therapeutic benefit of Advaxis’ lead immunotherapy candidate, axalimogene filolisbac (AXAL), both as a monotherapy and in combination with antibody-based immunotherapies in multiple patient populations with HPV+ cancers (Press release, Advaxis, NOV 11, 2016, View Source [SID1234516490]). These data will be presented at the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) Annual Meeting & Associated Programs this week in National Harbor, MD.

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A Phase 1/2 study of durvalumab alone or in combination with AXAL in recurrent/persistent or metastatic cervical or human papillomavirus (HPV)+ squamous cell cancer of the head and neck (HNSCC): Preliminary Phase 1 results (SITC 2016 abstract no. 215354)
This Phase 1 (Part A; 3+3) dose-escalation study was designed to assess the overall safety and select the recommended phase 2 dose (RP2D) of AXAL in combination with durvalumab in patients with recurrent/metastatic cervical or HPV+ HNSCC cancer. Patients received AXAL (1×109 colony-forming units [CFU]) every four weeks and durvalumab (3 mg/kg or 10 mg/kg) every two weeks.

Preliminary results from Part A dose escalation showed that there were no dose limiting toxicities observed, and the safety profile was consistent with previous findings for both AXAL and durvalumab. The recommended phase 2 dose was established as 1×109 CFU for AXAL and 10 mg/kg for durvalumab. One patient with cervical cancer achieved a complete response, which remains ongoing after 12 months of follow-up, and one patient, also with cervical cancer, achieved a partial response with subsequent disease progression. In addition, two patients with HNSCC achieved stable disease. Treatment related adverse events (TRAE) were reported in 91 percent of patients; the majority were either grade 1 or grade 2 events such as chills, fever, nausea and hypotension. Grade 3 TRAEs occurred in three patients, and one patient experienced a grade 4 event.

"When treating or evaluating investigational therapies for these kinds of metastatic, recurrent tumors, it is rare for an immunotherapy to result in a complete response," said Brian Slomovitz, MD, principal investigator and Director of the Division of Gynecologic Oncology in the Department of Obstetrics and Gynecology at the University of Miami Miller School of Medicine. "These early data show encouraging anti-tumor activity of the combination of AXAL and durvalumab and the regimen was generally well tolerated, which supports continued study of this combination regimen."

Combination of Listeria-based human papillomavirus (HPV)-E7 cancer vaccine (AXAL) with CD137 agonistic antibody provides an effective immunotherapy for HPV+ tumors in a mouse model (SITC 2016 abstract no. 215321)
A preclinical study evaluated the ability of AXAL to control tumor growth, prolong survival and reprogram the tumor microenvironment in combination with agonistic antibodies of T cell co-stimulatory receptors or with antagonistic antibodies of immune checkpoint inhibitors in an HPV+ tumor model. Of the monoclonal antibodies (mAbs) tested, anti-CD137 mAb and anti-CTLA-4 mAb were the most effective at synergizing with AXAL to eradicate established HPV+ tumors and to provide long-term survival (>8 weeks). Complete tumor regression was observed in 28 percent of the AXAL + anti-CD137 mAb treatment group and in 33 percent of the AXAL + anti-CTLA-4 mAb treatment group.

The study demonstrated a reprogramming of the tumor microenvironment in favor of antitumor immunity in both of the combination treatment groups. Importantly, there were increased percentages of tumor antigen-specific T cells and mature dendritic cells as well as decreased percentages of regulatory T cells and immunosuppressive macrophages compared to the single-agent treatments. Together, these data show that AXAL in combination with a CD137 agonistic antibody or with a CTLA-4 antagonistic antibody synergize to enhance antitumor immunity.

AIM2CERV: a randomized phase 3 study of adjuvant AXAL immunotherapy following chemoradiation in patients who have high-risk locally advanced cervical cancer (HRLACC) (SITC 2016 abstract no. 214095)
Advaxis’ Phase 3 AIM2CERV trial is a double-blind, placebo-controlled, multinational, multicenter, randomized study (NCT02853604). AIM2CERV is designed to demonstrate the efficacy and safety of AXAL as an adjuvant treatment in patients with stage I-IVA high risk, locally-advanced cervical cancer who have received cisplatin-based concurrent chemoradiation therapy (CCRT). Following CCRT, patients will receive AXAL for up to one year. A disease-free survival analysis will be conducted following at least 184 events. The study will enroll approximately 450 patients at 150 sites. Several trial sites are currently open and actively screening patients. In July, Advaxis received a Special Protocol Assessment for the AIM2CERV trial, as well as Fast Track designation for AXAL as an adjuvant therapy for HRLACC patients. For more information on Advaxis clinical trials, visit www.clinicaltrials.gov.

The presentation slides and audio are now available at www.advaxis.com.

Atreca Presents Promising Findings from Lead Antibody Program at Society for Immunotherapy of Cancer (SITC) Annual Meeting

On November 11, 2016 Atreca, Inc., a biotechnology company focused on developing novel therapeutics based on a deep understanding of the human immune response, reported positive preclinical findings generated using the Company’s Immune Repertoire Capture (IRC) technology, presented at the SITC (Free SITC Whitepaper) 2016 Annual Meeting, which is taking place in National Harbor, Maryland, November 9-13, 2016 (Press release, Atreca, NOV 11, 2016, View Source [SID1234522962]). In a poster titled, "Immune Profiling of an Elite Responder Following Checkpoint Inhibitor Therapy Reveals Functional Anti Tumor Antibodies Within Expanded IgG Lineages," a research team including scientists at Atreca and collaborators at a leading institution reported key research findings, including:

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Atreca’s IRC technology generated diverse antibodies from the active immune response of an individual with Stage 4 melanoma who had experienced long-term non-progression of disease following cancer regimens including anti-CTLA4 immunotherapy. These antibodies were sequenced from the patient’s blood plasmablasts, activated B cells that play a critical role in immune responses.
In in vitro assays, antibodies were shown to selectively bind tumor tissue but not normal tissue and to bind tumor types beyond the cancer type of the original patient.
Select antibodies demonstrated in vitro tumor killing through antibody-dependent cellular cytotoxicity (ADCC).
"Atreca is pioneering next-generation approaches to cancer immunotherapy based on our ability to elucidate the repertoire of cancer patient antibodies and T cell receptors (TCRs) contributing to positive outcomes," stated Daniel Emerling, Ph.D., Atreca’s Senior Vice President, Research. "In our presentation at SITC (Free SITC Whitepaper), we reported sequencing of over 2500 plasmablasts and identification of clonal antibody families from one exceptional cancer responder. By generating natively paired antibody heavy and light chain sequences, we were able to confirm the ability of a patient’s antibodies to target tumor cells and destroy them, including tumor types unrelated to that of the patient."

"Atreca is advancing a pipeline of therapeutic candidates that can drive and focus the activity of immune responses in cancer immunotherapy, particularly those unleashed by checkpoint inhibitors and immune activators," said Tito A. Serafini, Ph.D., Atreca’s President, Chief Executive Officer, and Co-Founder. "We are thrilled to present data highlighting the power and productivity of our platform at one of the leading cancer immunotherapy conferences. Our lead program is rapidly advancing in preclinical in vivo studies, and we look forward to further progress of our additional programs across multiple indications."

For more information on Atreca’s product portfolio, please visit View Source