On April 1, 2019 Aptose Biosciences Inc. ("Aptose" or the "Company") (NASDAQ: APTO, TSX: APS), a clinical-stage company developing highly differentiated therapeutics targeting the underlying mechanisms of cancer, reported that new preclinical data for CG-806, its first-in-class, highly potent oral small molecule pan-FLT3/pan-BTK inhibitor, and APTO-253, its MYC inhibitor, are being presented in two separate posters at the 2019 AACR (Free AACR Whitepaper) Annual Meeting in Atlanta, GA (Press release, Aptose Biosciences, APR 1, 2019, View Source [SID1234534822]).

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CG-806 Poster

The poster, CG-806, a pan-FLT3 / pan-BTK inhibitor, demonstrates superior potency against cells from IDH-1 mutant and other non-favorable risk groups of AML patients, explores the activity of CG-806 on primary patient samples with acute myeloid leukemia (AML), in studies that were conducted in collaboration with the Beat AML Initiative. CG-806 demonstrated significant potency across sub-groups of AML cells, including relapsed/refractory AML and those with genetic abnormalities related to poor prognoses in AML patients. CG-806 demonstrated superior potency when compared to other FLT3 inhibitors, including midostaurin, sorafenib, sunitinib, dovitinib, quizartinib, crenolanib and gilteritinib. While patient samples with FLT3-ITD mutations were expected to have greater sensitivity to CG-806, the sensitivity of patient cells with IDH1 R132 mutations was an unexpected finding. In 28-day GLP toxicity and toxicokinetic studies, CG-806 continued to demonstrate a favorable safety profile. The poster also highlights results of combination studies with CG-806 and venetoclax, which demonstrated enhanced killing of primary cancer cells from patients with AML and B-cell cancers.

"With our IND for CG-806 just recently allowed by the FDA, we are eager to begin Phase 1 human clinical trials," said William G. Rice, Ph.D., Chairman, President and Chief Executive Officer. "The Beat AML initiative has allowed us, with our research collaborators at Oregon Health & Science University (OHSU), to test the response of actual patient samples (ex vivo) to CG-806, alone and in combination, and enables us to assess its effectiveness based upon specific genetic profiles of patients. The wealth of CG-806 data continues to grow and strongly supports the clinical development of CG-806. It is our goal to improve the odds of achieving long-term disease remissions for patients."

APTO-253 Poster

The poster, Resistance to APTO-253 caused by internal deletion and alternate promoter usage of the MYC gene in Raji B cells, presents in vitro studies that further define the mechanism of action of APTO-253. A novel small molecule, APTO-253 inhibits expression of the MYC oncogene, leading to apoptosis in human-derived solid tumor and hematologic cancer cells without the myelosuppression seen with other chemotherapies. Researchers found that APTO-253 targets a G-quadruplex motif in the P1/P2 promoter region of the MYC gene and inhibits MYC gene expression to induce apoptosis, resulting in its ability to potently kill hematologic malignant cell lines and primary samples from AML and chronic lymphocytic leukemia (CLL) patients. In this study, researchers performed long-term in vitro studies to determine if and how cells might develop resistance to APTO-253. MYC driven Raji cells required three years in increasing concentrations of APTO-253 in order to adopt multiple modifications and develop high level resistance to APTO-253. These modifications include up-regulation of the ABCG2 transporter, acquisition of a more stable MYC protein lacking the conserved core sequence of MYC Box III generated by deletion of an internal region of the MYC gene exon 2, and utilization of alternate P3 promoter not inhibited by G4 binding and stabilization.

Both of the AACR (Free AACR Whitepaper) posters can be accessed here or at the publications and presentations section of Aptose’s website www.aptose.com.

About CG-806

CG-806 is an oral, first-in-class pan-FLT3/pan-BTK multi-cluster kinase inhibitor and is in a Phase 1 clinical trial for hematologic malignancies. This small molecule, in-licensed from CrystalGenomics Inc. in Seoul, South Korea, demonstrates potent inhibition of wild type and all mutant forms of FLT3 (including internal tandem duplication, or ITD, and mutations of the receptor tyrosine kinase domain and gatekeeper region), cures animals of acute myeloid leukemia (AML) tumors in the absence of toxicity in murine xenograft models, and represents a potential best-in-class therapeutic for patients with AML. Likewise, CG-806 demonstrates potent, non-covalent inhibition of the wild type and Cys481Ser (C481S) mutant forms of the BTK enzyme, as well as other oncogenic kinase pathways operative in B cell malignancies, suggesting CG-806 may be developed for various B cell malignancy patients (including CLL/SLL, FL, MCL, DLBCL and others) that are resistant/refractory/intolerant to covalent BTK inhibitors. Because CG-806 targets key kinases/pathways operative in malignancies derived from the bone marrow, it is in development for B-cell cancers and AML.

About APTO-253

APTO-253 is a clinical-stage, small molecule, targeted therapeutic agent that inhibits expression of the MYC oncogene, leading to cell cycle arrest and programmed cell death (apoptosis) in human-derived solid tumor and hematologic cancer cells. Indeed, the first AML patient treated with APTO-253 at the lowest dose level demonstrated significant reductions of MYC expression in peripheral blood mononuclear cells after one 28-day cycle of drug therapy. The MYC oncogene is overexpressed in hematologic cancers, including acute myeloid leukemia (AML). Aptose researchers have reported the ability of APTO-253 to induce cell death, or apoptosis, in multiple blood cancer cell lines including AML, as well as in vitro synergy with various classes of conventional approved and investigational therapies for AML or myelodysplastic syndromes (MDS). New findings reveal that APTO-253 might also serve certain solid tumor patients with BRCA1/2 mutations, but without causing toxicity to the normal bone marrow functions.

On April 1, 2019 Celldex Therapeutics, Inc. (NASDAQ:CLDX) reported promising data from the Company’s growing bispecific and TAM (Tyro3, Axl, MerTK) receptor programs during poster sessions at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2019 (Press release, Celldex Therapeutics, APR 1, 2019, View Source [SID1234534839]).

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"Our research and discovery efforts have yielded multiple promising candidates that address important needs in cancer immunotherapy and complement our pipeline," said Tibor Keler, Ph.D., Executive Vice President and Chief Scientific Officer of Celldex Therapeutics. "CDX-527 joins two powerful pathways in the immune system, PD-1 blockade and CD27 costimulation. The data we presented at AACR (Free AACR Whitepaper) demonstrate that this bispecific antibody candidate has greater activity than the combination of the two individual antibodies and support advancing the program into IND-enabling studies. In addition, we also presented data on our lead candidate antibodies targeting the TAM receptors, which act as checkpoints on myeloid cells. We have uncovered a unique mechanism for antibody-mediated activation of dendritic cells and macrophages and demonstrated that a surrogate MerTK mAb promotes anti-tumor immunity alone and enhances the activity of PD-1 blockade. We look forward to continuing to progress both CDX-527 and our TAM program over the course of the year," concluded Keler.

Presentation Highlights:

Poster #2392: CDX-527: A novel bispecific immune-modulating antibody targeting CD27 and PD-L1 (Vitale, et. al)

The use of bispecific antibodies provides opportunities to engage two independent pathways involved in controlling immune responses to tumors. Preclinical and clinical studies support the safety and benefit of combining PD-1 blockade with a CD27 agonist.
The bispecific CDX-527 combines a novel and potent PD-L1 antibody for blocking the PD-1 checkpoint pathway with the binding domains of a CD27 agonist antibody for CD27-mediated costimulation of T cells.
CDX-527 demonstrated potent inhibition of PD-1 signaling and T cell activation using in vitro models with reporter cell lines and human primary cell cultures.
Anti-tumor activity was tested with a surrogate bispecific molecule that binds mouse PD-L1 and human CD27 in human CD27-expressing transgenic mice. The bispecific demonstrated potent anti-tumor activity in a BCL1 lymphoma model and was significantly more effective than the combination of the CD27 and PD-L1 monoclonal antibodies (mAbs).
A pilot study in non-human primates suggests that CDX-527 demonstrates good pharmacokinetic properties and no toxicities were observed.
Based on the promising data observed to date and the PK/PD profiles, Celldex has initiated manufacturing activities and investigational new drug (IND) enabling studies to support clinical studies of CDX-527.
Poster #1555: Monoclonal antibodies targeting the TAM family of receptor tyrosine kinases (Alvarado, et al)

TAM receptors (Tyro3, Axl, MerTK) are receptor tyrosine kinases (RTKs) expressed in innate immune cells. These receptors have been gaining importance in the immunotherapy field due to their role as checkpoint molecules on macrophages, dendritic cells, and other immune cells, where they can negatively regulate anti-tumor immunity.
Celldex presented data showing that lead candidate mAbs targeting MerTK, Axl or Tyro-3 activate myeloid cells, including monocytes, macrophages and dendritic cells, enhancing pro-inflammatory cytokine release, increasing expression of costimulatory molecules and enhancing T cell activation in mixed lymphocyte reaction (MLR) assays.
Celldex demonstrated that the potent activity of the TAM-specific antibodies are dependent on a unique coupling of the TAM receptors with Fc receptors.
Celldex’s most advanced program targets MerTK, where the Company has demonstrated that antibody targeting of MerTK in mice elicits an inflammatory cytokine response similar to that observed in the human cells and in MerTK deficient mice and has anti-tumor activity when dosed alone or in combination with a PD-1 inhibitor in a colon cancer model.
These data support development of anti-TAM mAbs as therapies to activate innate immune responses with a potential for systemic dosing. The Company intends to advance potential candidates into development activities this year.

On April 1, 2019 AVEO Oncology (NASDAQ:AVEO) and Biodesix, Inc. reported results from an investigator-sponsored Phase Ib expansion cohort of ficlatuzumab, AVEO’s potent hepatocyte growth factor (HGF) inhibitory antibody product candidate, in combination with cytarabine in patients with relapsed and refractory acute myeloid leukemia (AML) (Press release, AVEO, APR 1, 2019, View Source [SID1234534855]). The results were presented in a poster session at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) 2019 Annual Meeting. The presentation, titled, "CyFi: Results from a phase Ib expansion cohort of ficlatuzumab (Fi) combined with high-dose cytarabine (Cy) in patients with high risk relapsed or refractory acute myeloid leukemia (AML)" (abstract CT078/2) is available in the Publications & Presentations section of AVEO’s website.

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Elevated serum HGF level is an adverse prognostic factor associated with worse survival in AML and other cancers. Pre-clinical models have shown that myeloid blasts produce HGF and that blocking the HGF/c-Met pathway sensitizes blasts to cell death. The Phase Ib trial, which was funded by Gateway for Cancer Research and is being conducted at the UCSF Medical Center under the direction of Charalambos Andreadis, M.D., Associate Professor of Clinical Medicine, Director, Clinical Research Support Office, UCSF Helen Diller Family Comprehensive Cancer Center, was designed to assess the safety, tolerability and preliminary efficacy of ficlatuzumab with cytarabine in AML patients who are refractory to first line therapy (7+3) or have relapsed within one year of induction, a population known to have poor outcomes.

The maximally tolerated dose was 20 mg/kg of ficlatuzumab on day 1 followed by 2 g/m2 cytarabine daily on days 2-7. Of 12 patients who received ficlatuzumab and cytarabine at the maximally tolerated dose, one of whom was non-evaluable, 6 achieved a complete response (CR). Of 18 patients enrolled in the study, 17 were evaluable and 9 achieved a CR. The most frequent grade 3/4 treatment emergent adverse events observed were febrile neutropenia, LFT abnormalities, and electrolyte disturbance. There was one death from sepsis and multi-organ failure that was determined to be disease related, and one patient withdrew from the study due to grade 4 gastrointestinal bleed, determined to be likely ficlatuzumab related. scRNA sequencing identified a TNF alpha and IFN gamma inflammatory signature that correlated with response to ficlatuzumab at count recovery.

"Patients with AML who are refractory to induction therapy or relapse within one year have poor outcomes," said Dr. Andreadis. "Elevated serum HGF level is an adverse prognostic factor, and these results demonstrate that the anti-HGF antibody ficlatuzumab combined with cytarabine holds potential to affect outcomes in patients with relapsed or refractory AML. We look forward to potentially evaluating ficlatuzumab in larger outcome studies in AML."

"In addition to an attractive tolerability profile observed to date, we also see the potential to identify biomarkers of response using RNA sequencing. In light of these data, we believe that further evaluation in this patient population is warranted, and we look forward to considering additional studies with our partners at Biodesix as a potential next step for the program," said Michael Bailey, president and chief executive officer of AVEO.

"We look forward to supporting ficlatuzumab’s biomarker development initiatives with a broad set of diagnostic technologies," said Paul Beresford, chief business officer of Biodesix.

About Ficlatuzumab

Ficlatuzumab (formerly known as AV-299) is a potent hepatocyte growth factor (HGF) inhibitory antibody that binds to the HGF ligand with high affinity and specificity to inhibit HGF/c-Met biological activities. AVEO and Biodesix, Inc. have a worldwide agreement to develop and commercialize ficlatuzumab. Ficlatuzumab is currently being evaluated in investigator-sponsored trials in squamous cell carcinoma of the head and neck (HNSCC), metastatic pancreatic ductal cancer (PDAC), and acute myeloid leukemia (AML).

On April 1, 2019 Atara Biotherapeutics, Inc. (Nasdaq: ATRA), a leading off-the-shelf, allogeneic T-cell immunotherapy company developing novel treatments for patients with cancer, autoimmune and viral diseases, reported off-the-shelf, allogeneic CAR T platform preclinical proof-of-concept results at the American Association of Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2019 in Atlanta, Georgia (Press release, Atara Biotherapeutics, APR 1, 2019, View Source [SID1234534875]).

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"Atara is building a leading next-generation CAR T pipeline," said Christopher Haqq, M.D., Ph.D., Executive Vice President and Chief Scientific Officer of Atara Biotherapeutics. "Preclinical results presented today demonstrate that our EBV-specific T cell platform has the potential to be efficiently engineered to generate off-the-shelf, allogeneic CAR T immunotherapies with favorable characteristics. We look forward to advancing this technology using novel co-stimulatory domains and intrinsic checkpoint inhibition, leveraging Atara’s research expertise and world-class T cell manufacturing capabilities."

Atara engineered EBV-specific T cells to express second-generation CD19 CARs (EBV.CD19.CAR T), utilizing CD28 or 4-1BB co-stimulatory domains, resulting in high expression of both the CD19 CAR and EBV T cell receptor (TCR). EBV.CD19.CAR T cells exerted potent and specific cytotoxicity against CD19 or EBV-positive cells and had limited activity against CD19-negative cells, while also depleting alloreactive activity. EBV.CD19.CAR T cells also demonstrated a central memory phenotype that balances expansion with effector function and is associated with persistence.

"EBV.CD19.CAR T cells exhibited optimal CAR T characteristics and in vivo function," said Blake T. Aftab, Ph.D., Vice President, Head of Preclinical and Translational Science for Atara Biotherapeutics. "These data also demonstrate that Atara’s off-the-shelf, allogeneic CAR T process effectively eliminated in vitro alloreactivity. Our findings establish feasibility for combining EBV-specific T cells with novel CAR technologies and support our further development of next-generation off-the-shelf, allogeneic CAR T clinical candidates."

EBV.CD19.CAR T anti-tumor activity was evaluated in vivo in a mouse model of aggressive lymphoma. Following a period of tumor establishment, a single injection of EBV.CD19.CAR T cells significantly inhibited tumor growth.

Additionally, yesterday at the AACR (Free AACR Whitepaper) Annual Meeting 2019, Atara’s collaborators at Memorial Sloan Kettering Cancer Center (MSK), Prasad S. Adusumilli, M.D., and Michel Sadelain, M.D., Ph.D., presented Phase 1 clinical results for a mesothelin-target CAR T immunotherapy that included safety data, anti-tumor responses, and combination data with a PD-1 checkpoint inhibitor. The results further support Atara’s planned development of a next-generation, mesothelin-targeted CAR T immunotherapy using MSK’s novel 1XX CAR signaling domain and PD-1 dominant negative receptor (DNR) checkpoint inhibition technologies for patients with mesothelin-associated solid tumors.

Abstract 2310: Functional demonstration of CD19 chimeric antigen receptor (CAR) engineered Epstein-Barr virus (EBV) specific T cells: An off-the-shelf, allogeneic CAR T-cell immunotherapy platform
Session Category: Immunology
Session Title: Adoptive Cell Therapy 2
Poster Presentation Date and Time: Monday, April 1, 2019, from 1:00 p.m. – 5:00 p.m. EDT
Location: Georgia World Congress Center, Exhibit Hall B
Authors: Blake T. Aftab, Rhine R. Shen, Christina D. Pham, Michelle Wu, Daniel J. Munson
Affiliations: Atara Biotherapeutics

On April 1, 2019 Candel Therapeutics (a.k.a. Advantagene, Inc.) reported the closing of a $22.5 million Series C Preferred Stock financing led by Northpond Ventures. Participating syndicate members included Sands Capital Ventures, H7 Holdings and Level One Partners. Michael P. Rubin, M.D., Ph.D., founder and CEO of Northpond Ventures, will join the company as a member of its board of directors (Press release, Candel Therapeutics, APR 1, 2019, View Source [SID1234537125]).

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"We are thrilled to join forces with the Candel team and embark on this great journey together. We have the potential to be a force for good in the world, which is what drives us," said Dr. Rubin.

"We are grateful for the financial flexibility resulting from this financing," stated Dr. Estuardo Aguilar-Cordova, Chairman and CEO of Candel Therapeutics. "The addition of Michael to our board of directors is a big win for the company and brings significant relevant expertise."

The completion of the Series C brings the total capital raised by Candel in the last year to $51.2 million. The company plans to use the proceeds to expand its operational capabilities and further accelerate its ongoing clinical development initiatives. Candel’s lead programs are based on the company’s Gene Mediated Cytotoxic Immunotherapy (GMCI) technology and include two randomized studies in prostate cancer, including a Phase 3 under an FDA approved Special Protocol Assessment. The Company also has ongoing clinical programs in glioma, lung and pancreatic cancer.

"We have the most comprehensive and promising clinical data set in the field of developing viral immunotherapies in multiple tumor indications," explained Dr. Aguilar-Cordova. "We are particularly excited about expanding our efforts for brain tumor patients as they are in desperate need of new treatment options."

Candel’s efforts in pursuit of an effective treatment for brain cancer are significant. The company has completed a Phase 2 clinical study in high grade glioma that showed promising results, including an indication of survival benefit. The launch of a combination GMCI-checkpoint inhibitor clinical study, in collaboration with Bristol-Myers Squibb and the Adult Brain Tumor Consortium, was recently announced. The Company also has an ongoing study for recurrent GBM patients with rQNestin34.5, the company’s oncolytic herpes-based platform. Additionally, the Company plans to use proceeds from this financing to launch a GMCI pivotal trial for brain cancer patients.

For more information about its clinical programs, please visit www.clinicaltrials.gov or click the following link: View Source;term=advantagene&cntry=&state=&city=&dist=