On December 12, 2022 PureTech Health plc (Nasdaq: PRTC, LSE: PRTC) ("PureTech" or the "Company"), a clinical-stage biotherapeutics company dedicated to changing the treatment paradigm for devastating diseases, reported new data supporting the clinical potential of LYT-200, a fully human monoclonal antibody (mAb) designed to inhibit the activity of galectin-9, as a therapeutic agent for the treatment of leukemia (Press release, PureTech Health, DEC 12, 2022, View Source [SID1234625137]). The data were shared in a scientific poster presented at the American Society of Hematology (ASH) (Free ASH Whitepaper) 64th Annual Meeting. LYT-200 is a therapeutic candidate targeting galectin-9, which is expressed by tumors and immune cells and plays a key role in cancer treatment resistance. It is also in development as a treatment for a range of cancer indications with otherwise poor survival rates.

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"The data we are presenting at ASH (Free ASH Whitepaper) add further support to the hypothesis that galectin-9 is an important therapeutic target for not just AML but multiple blood cancers, suggesting LYT-200 may be beneficial across a range of hematologic malignancies and underscores the potential of LYT-200 in an area with significant clinical need for novel treatment regimens," said Aleksandra Filipovic, M.D., Ph.D., Head of Oncology at PureTech. "The National Cancer Institute estimates that about 61,000 new cases of leukemia are diagnosed each year, including about 20,000 in AML. More than 50% of AML patients either don’t respond to initial treatment or experience relapse or death after responding to initial treatment, and have an approximately 12.6% five-year survival rate. The poor overall survival highlights the need for more effective therapies for patients with relapsed and refractory AML."

The ASH (Free ASH Whitepaper) poster evaluates galectin-9 expression and the effects of LYT-200 in multiple types of leukemia. Compared to healthy human peripheral blood mononuclear cells, where galectin-9 surface expression was low or absent, galectin-9 was highly expressed on the surface of all human blood cancer cells tested. Notably, surface expression of galectin-9 often exceeded that of the known inhibitory checkpoint proteins TIM-3 and PD-1.

In all models used, LYT-200 demonstrated significant anti-tumor activity and in addition to its established effects on the immune system in solid tumor models, it also notably induced direct apoptosis or cell death across all leukemia cell types. In a model assessing DNA damage in AML cells, LYT-200 significantly outperformed an anti-TIM3 antibody and had effects that were comparable to Venetoclax, an approved therapeutic for AML. The effects were greatest when both compounds were combined. The in vitro efficacy of LYT-200 against the leukemia subtypes also extended to in vivo survival benefit in both immunocompromised and immunocompetent patient-derived xenograft mouse models. In these models, LYT-200 outperformed chemotherapy and produced the greatest effect in combination.

Collectively, these new data support galectin-9 as a strong potential therapeutic target for a range of cancers. Based on this and other compelling preclinical data generated with LYT-200 in blood cancers, PureTech has initiated a clinical trial to evaluate LYT-200 as a single agent for the treatment of AML with results expected in 2023. PureTech has also completed the bi-monthly and weekly, monotherapy dose escalation portion of the Phase 1 program assessing the safety and tolerability of escalating doses of LYT-200 as a potential treatment of metastatic solid tumors. No dose-limiting toxicities were reported, and the full results will be presented in an upcoming scientific forum. The combination part of the Phase 1 trial in certain metastatic solid tumors with LYT-200 in combination with tislelizumab is expected to begin in the first quarter of 2023.

The scientific poster presented today is available at View Source

About LYT-200

LYT-200 is a fully human IgG4 monoclonal antibody targeting a foundational immunosuppressive protein, galectin-9, for the potential treatment of solid tumors, including pancreatic ductal adenocarcinoma, colorectal cancer and cholangiocarcinoma, with otherwise poor survival rates. A wide variety of preclinical data supports the potential clinical efficacy of LYT-200 and the importance of galectin-9 as a target and suggests a potential opportunity for biomarker development. For example, PureTech has presented data demonstrating high expression of galectin-9 across various solid tumor types and blood cancers and has found in several cancers that galectin-9 levels correlate with shorter time to disease relapse and poor survival. LYT-200 is currently being evaluated in a Phase 1/2 adaptive design trial for the potential treatment of metastatic solid tumors and in a clinical trial for the potential treatment of AML.

On December 12, 2022 Monopar Therapeutics Inc. (Nasdaq: MNPR), a clinical-stage biopharmaceutical company focused on developing proprietary therapeutics designed to extend life or improve the quality of life for cancer patients, reported promising data with MNPR-202 from its ongoing collaboration with the Cancer Science Institute of Singapore (CSI Singapore) at the National University of Singapore (NUS) (Press release, Monopar Therapeutics, DEC 12, 2022, View Source [SID1234625136]). The data are displayed in the poster that NUS and Monopar will be presenting this Sunday at the 64th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting & Exposition (ASH 2022). Monopar has made the poster available on its website at the following link: View Source

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MNPR-202 is a promising DNA Damaging Response (DDR) drug candidate, and analog of doxorubicin. It has the same potentially non-cardiotoxic backbone as camsirubicin, Monopar’s clinical stage drug candidate that has shown a favorable heart toxicity profile to-date across three trials, but MNPR-202 is modified at additional sites with the intention of evading certain tumors’ resistance mechanisms to doxorubicin.

Prior exploratory preclinical studies in solid tumors have shown MNPR-202 to have a similar cytotoxic potency to doxorubicin while retaining that potency even in doxorubicin-resistant cancers. The present preclinical work by Dr. Anand Jeyasekharan, MD PhD, of CSI Singapore, which was highlighted by the Gates Cambridge in a recent article: View Source, corroborates MNPR-202’s similar cytotoxic potency to doxorubicin even in blood cancers, while expanding the research in several exciting new directions, including a comparison to doxorubicin on DNA damage response, immune activation, apoptosis, gene expression, and synergy with other cancer compounds for combination usage.

Preclinical Results To-Date

Data from blood cancer preclinical studies to date show that MNPR-202:

– has a similar cytotoxic potency to doxorubicin

– generates increased DNA damage compared to doxorubicin

– has a unique immune activation profile versus doxorubicin

– demonstrates increased apoptosis compared to doxorubicin

– causes a distinct set of genes to be upregulated and downregulated versus doxorubicin; and

-may be superior to doxorubicin in certain combination treatment regimens. A combination drug screen with 183 compounds was performed, revealing distinct differences in the synergy profile between doxorubicin and MNPR-202 with other compounds. As example, MNPR-202 demonstrated a more favorable synergy profile with volasertib compared to doxorubicin.

The results generated to date suggest doxorubicin and MNPR-202 have a similar cytotoxic potency, but likely work through distinct cellular pathways and cause a different ancillary innate immune activation. These intracellular differences also influence drug synergies observed with the two compounds, implying that in the context of certain combinatorial regimens, MNPR-202 may be superior to doxorubicin. MNPR-202 also shows the potential to work in cancers resistant to doxorubicin. Taken together, we believe MNPR-202 has potential to disrupt the current chemotherapy landscape and impact a broad range of cancers.

On December 12, 2022 Merck (NYSE: MRK), known as MSD outside of the United States and Canada, reported, through a subsidiary, a cash tender offer to purchase all outstanding shares of common stock of Imago BioSciences, Inc. (Nasdaq: IMGO) (Press release, Merck & Co, DEC 12, 2022, View Source [SID1234625134]). On Nov. 21, 2022, Merck announced that it had entered into a definitive agreement to acquire Imago.

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Upon the successful closing of the tender offer, stockholders of Imago will receive $36 in cash for each share of Imago common stock validly tendered and not validly withdrawn in the offer, without interest and subject to deduction for any required tax withholding. Following the purchase of shares in the tender offer, Imago will merge with and into a subsidiary of Merck, with Imago surviving the merger. As a result, Imago will become a subsidiary of Merck.

Merck will file today with the U.S. Securities and Exchange Commission (the "SEC") a tender offer statement on Schedule TO, which provides the terms of the tender offer. Additionally, Imago will file with the SEC a solicitation/recommendation statement on Schedule 14D-9 that includes the recommendation of the Imago board of directors that their stockholders accept the tender offer and tender their shares.

The tender offer will expire at one minute after 11:59 p.m., Eastern Time, on January 10, 2023, unless extended in accordance with the merger agreement and the applicable rules and regulations of the SEC. The closing of the tender offer is subject to certain conditions, including the tender of shares representing at least a majority of the total number of Imago’s outstanding shares, receipt of applicable regulatory approvals, and other customary conditions. The transaction is expected to close in the first quarter of 2023.

On December 12, 2022 Magenta Therapeutics (Nasdaq: MGTA), a clinical-stage biotechnology company developing novel medicines designed to bring the curative power of stem cell transplant to more patients, highlights updated clinical data from the ongoing MGTA-117 Phase 1/2 dose-escalation clinical trial made in an oral presentation today at the American Society of Hematology (ASH) (Free ASH Whitepaper) 2022 Annual (ASH) (Free ASH Whitepaper) Meeting in New Orleans and provides program updates across the portfolio.

"We have shown that a single dose of MGTA-117 binds target cells, depletes target cells, clears the body quickly as designed, and does so with a favorable tolerability profile in our ongoing Phase 1/2 clinical trial. We believe that these positive clinical data establishes proof-of-mechanism, and that we have reached an active dose. Target cell depletion is a critical measurement of success for MGTA-117, and we are encouraged by the levels of depletion we have observed in both the blood and the bone marrow of relapsed/refractory acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients. We are excited about our planned next steps to take MGTA-117 into transplant-eligible AML and MDS patients as well as into patients who are receiving gene therapy. We are thankful to all of the patients and families who have participated in our trial to date as well as our investigators and the clinical site staff, all of whom have contributed greatly to the advancement of MGTA-117 for patients," said Jason Gardner, President and Chief Executive Officer of Magenta Therapeutics. "Together with the progress we are making on CD45-ADC and MGTA-145, we are pleased with the momentum across our portfolio and the multiple anticipated inflection points for Magenta in the coming year."

MGTA-117 Clinical Data and Continued Development
MGTA-117 is Magenta’s most advanced targeted conditioning product candidate designed to deplete CD117-expressing target cells in the blood and/or bone marrow prior to a patient undergoing stem cell transplant or receiving an ex vivo gene therapy product. MGTA-117 is an anti-CD117 antibody conjugated to an amanitin payload. CD117, also known as c-Kit receptor, is highly expressed on hematopoietic stem cells, progenitor cells and cancer blast cells.

Current Phase 1/2 Patient Population and Potential Significance for Clinical Development
The ongoing Phase 1/2 clinical trial is in relapsed/refractory (R/R) AML and MDS. These patients are deemed ineligible for transplant due to active disease characterized by high numbers of cancer blast cells present in the bone marrow and in the bloodstream. Over 80% of patients with AML and MDS express the CD117 receptor on the surface of their cancer cells. In these patients, CD117+ target cells are a combination of cancer blast cells in the blood and bone marrow and non-malignant stem and progenitor cells in the bone marrow. MGTA-117 is designed to target all of these cells, and clinical evidence of depletion in this patient population provides valuable support that MGTA-117 will robustly deplete target cells in the proposed next phase of development in (i) transplant-eligible AML and MDS patients who have significantly lower numbers of cancer blast cells and (ii) gene therapy patients who have no cancer blast cells. Therefore, Magenta expects MGTA-117 to bind and deplete target cells in the bone marrow in these patient populations, and potentially achieve greater levels of depletion, at the same dose levels studied in R/R AML and MDS patients.

MGTA-117 Proof-of-Mechanism and Potential Active Dose

Participants Dosed & Available Data. As of December 1, 2022, a total of 15 participants have been dosed with MGTA-117 in Cohorts 1, 2 and 3. All dosed participants contributed data in whole or in part to the preliminary data set depending on an individual’s availability for collecting assessments. Eleven of the 15 dosed participants completed the dose-limiting toxicity safety observation period of 21 days. None of the four participant discontinuations were deemed to be related to MGTA-117.

Target Cell Binding. MGTA-117 bound to CD117-expressing target cells within 15 minutes after dosing in all participants as measured by a receptor occupancy (RO) assay. RO increased with higher dose levels of MGTA-117. The percentage of occupied CD117 receptors was greater, and the receptor occupancy was more durable at the higher dose levels of Cohorts 2 and 3 as compared to Cohort 1 as expected.

Target Cell Depletion.
Depletion in Blood and Bone Marrow. MGTA-117 showed greater depletion of target cancer blast cells in the blood of participants in Cohorts 2 and 3 compared to Cohort 1. In addition, three out of the four participants in Cohort 3 for whom paired bone marrow samples were collected at baseline and post-dosing had depletion of cancer blast cells in both blood and bone marrow. This matched depletion response in the blood and bone marrow provides evidence of an active dose and dose-dependent depletion of CD117-expressing cells.
Two Transplant-Ineligible Participants Became Transplant-Eligible. Participants entering the clinical trial were considered ineligible for stem cell transplant and had active and persistent AML/MDS after receiving one or more anti-leukemic therapies. One relapsed/refractory MDS participant in Cohort 3 had a reduction of bone marrow cancer blast cells to a level that enabled the participant to become eligible for transplant. This is the trial’s second participant who became eligible for transplant after a single dose of MGTA-117. The first participant, from Cohort 1, had relapsed/refractory AML and was previously disclosed.

Clearance. MGTA-117 was shown to be rapidly cleared from the body as expected. No MGTA-117 was detectable in the blood 48 hours after dosing in Cohorts 1 and 2, and over 95% of MGTA-117 was cleared in the blood 48 hours after dosing at the higher dose level of Cohort 3. Rapid clearance of MGTA-117 was engineered into the molecule to ensure avoidance of depleting newly transplanted donor cells in allogeneic transplant or, in the case of gene therapy, of autologous gene-modified cells. In addition, the MGTA-117 ADC was shown to be stable in blood over time in all participants, and no free payload was detectable in the blood of any participants at any time point.

Tolerability. MGTA-117 was well-tolerated in all participants. No serious adverse events were deemed to be related to MGTA-117, and no dose-limiting toxicities were observed. Treatment-related adverse events deemed to be related to MGTA-117 were low-grade liver enzyme elevations, low-grade fever, and grade 3 and grade 4 leukopenia in two participants who had baseline grade 2 and grade 3 leukopenia, respectively. All instances of observed liver enzyme elevations were low-grade, transient and resolved without intervention, as expected.

Continued Trial Progress and Data Expectations. The Phase 1/2 clinical trial is currently enrolling in Cohort 4 (0.13 mg/kg) and Magenta anticipates presenting aggregate clinical data from the clinical trial, including Cohort 4, at a scientific conference in Q1 2023.
MGTA-117 Regulatory Engagement and Clinical Development Next Steps in Transplant-Eligible AML/MDS and Autologous Gene Therapy
As previously disclosed, Magenta has initiated formal engagements with regulatory agencies to transition MGTA-117 into a transplant-eligible AML and MDS patient population. Magenta also plans to engage regulators in H1 2023 for the purposes of initiating a MGTA-117 clinical trial in autologous ex vivo gene therapy.

Transplant-Eligible AML and MDS. Magenta anticipates that MGTA-117’s pharmacokinetics (PK), pharmacodynamics (PD) and tolerability in Cohorts 1-3 will support alignment with regulatory authorities to study MGTA-117 in AML and MDS transplant-eligible patients. Importantly, the proposed study design in the transplant setting will allow for the measurement of depletion of CD117-expressing cells in the bone marrow after a single dose of MGTA-117 prior to reduced-intensity conditioning (RIC) and the ensuing allogeneic transplant. By depleting residual cancer blast cells prior to a standard RIC regimen, MGTA-117 has the potential to boost disease control prior to transplant and improve disease outcomes post-transplant. These potential positive outcomes could address the current significant unmet need associated with RIC-conditioning where AML and MDS patients relapse at a rate of 40%-50% within six months post-transplant1. Pending regulatory alignment, Magenta plans to share additional details of the proposed transplant-eligible MGTA-117 study design in Q1 2023.

Gene Therapy. Magenta expects to use the clinical data package from the ongoing Phase 1/2 trial, together with supporting insights from PK/PD modeling, to engage with regulators on a potential MGTA-117 clinical trial in autologous ex vivo gene therapy. In a gene therapy clinical trial, Magenta anticipates dosing patients with MGTA-117 to deplete stem and progenitor cells before the patient receives an infusion of gene-modified stem cells, with a goal of replacing the current standard-of-care conditioning that relies on high doses of chemotherapeutic agents such as busulfan, which is known to be carcinogenic. Magenta anticipates sharing more details in 2023 as development plans progress in collaboration with gene therapy partners. Magenta has existing clinical collaborations with gene therapy companies and anticipates entering into additional collaborations as MGTA-117 development advances.
CD45-ADC IND-Enabling Plans
Magenta’s CD45-ADC is a second targeted conditioning ADC, designed to selectively target and deplete both stem cells and immune cells, and is intended to replace the use of chemotherapy-based conditioning prior to stem cell transplant in patients with blood cancers and autoimmune diseases.

As previously disclosed, Good Manufacturing Practice (GMP) manufacturing and other investigative new drug application (IND)-enabling activities are ongoing for the CD45-ADC program. A Good Laboratory Practice (GLP) toxicology study is expected to be completed in H2 2023.

Magenta anticipates regulatory interactions prior to filing an IND and anticipates providing further details on the CD45-ADC program in 2023, including molecule design, key preclinical data, and timelines to IND.
MGTA-145 Phase 2 Progress
Magenta is developing MGTA-145, in combination with plerixafor, to improve the process by which stem cells are released out of the bone marrow and into the bloodstream, known as stem cell mobilization. The mobilized cells are then collected and available for transplant. This is the first step for patients and is required for the majority of transplants and stem cell gene therapies.

Magenta, in partnership with bluebird bio, is enrolling patients in a Phase 2 clinical trial evaluating the ability of MGTA-145 in combination with plerixafor to mobilize stem cells for collection in patients with sickle cell disease.

Due to enrollment delays at the clinical sites that are unrelated to MGTA-145, Magenta anticipates disclosing clinical data in H1 2023.
Conference Call Information:
Magenta will host a conference call and webcast at 8:30 a.m. Eastern Time / 7:30 a.m. Central Time tomorrow, Tuesday, December 13, 2022 to review the MGTA-117 data presented at the 2022 ASH (Free ASH Whitepaper) Annual Meeting.

To access the conference call, please register online at https://register.vevent.com/register/BI872661cff05d4191a7bb100830aae147. Upon registering, each participant will be provided with call details and a conference ID. The live webcast of the call and slide deck may be accessed at View Source, or by visiting the Investors & Media section of the company’s website at View Source A replay of the webcast will be available shortly after the conclusion of the call and will be archived on the Events & Presentations page.

1 Scott, Journal of Clinical Oncology 2017. View Source

On December 12, 2022 Electra Therapeutics, Inc., a clinical stage biotechnology company developing novel antibody therapies that target signal regulatory proteins (SIRP), reported presentations and clinical progress for ELA026, the company’s first-in-class antibody in development for the treatment of secondary hemophagocytic lymphohistiocytosis (sHLH), a life-threatening inflammatory disease. Three poster presentations supporting the company’s clinical development of ELA026 in sHLH are highlighted at the 64th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting being held in New Orleans from December 10-13, 2022 (Press release, Electra Therapeutics, DEC 12, 2022, View Source [SID1234625105]).

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Electra also announced today that a Phase 1b global study of ELA026 in sHLH patients has been initiated and is ongoing (ClinicalTrials.gov identifier: NCT05416307). The Phase 1b study is highlighted as a clinical trial in progress poster at ASH (Free ASH Whitepaper), titled "A Phase 1b study of ELA026 in patients with secondary hemophagocytic lymphohistiocytosis." The Phase 1b study is an open-label, single-arm, multicenter study which will evaluate the safety and efficacy of ELA026, assess biomarkers and identify a dose for Phase 2/3 testing.

"We are excited to advance ELA026 in the clinic as a novel approach targeting SIRP to address the aberrant myeloid and T cell activity that drives the sHLH disease process," said Gary Patou, MD, Chief Medical Officer of Electra. "We have created a robust design for this Phase 1b study with the aim of progressing rapidly toward a Phase 2/3 study so we can accelerate ELA026 as a potential treatment option for sHLH patients in need."

Study Results Presented at ASH (Free ASH Whitepaper) Annual Meeting
Preclinical studies demonstrated ELA026’s proof-of-mechanism of SIRP targeting and depletion of pathological immune cells that drive sHLH. The poster presentation at ASH (Free ASH Whitepaper), titled "Characterization of ELA026, a clinical-stage monoclonal antibody that rapidly and potently depletes myeloid cells and T lymphocytes," describes the pharmacology of ELA026 which binds to and depletes SIRP-expressing cells, and its pharmacokinetic (PK) profile and pharmacodynamic (PD) effects in non-human primates. The preclinical data includes the following highlights:

In in vitro studies, ELA026 was shown to bind to SIRP proteins on the surface of primary human and cynomolgus monkey monocytes and T cells, inducing potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP).
In vivo administration of ELA026 in cynomolgus monkeys showed a rapid and potent depletion of SIRP-expressing monocytes and lymphocytes, with a well-defined PK/PD relationship. Reversibility of the PD effect was achieved following washout suggesting that ELA026 treatment is not associated with long-term immunosuppression.

Electra also presented results of a sHLH natural history study at the ASH (Free ASH Whitepaper) Annual Meeting in a poster, titled "Identification and characterization of a retrospective cohort of secondary hemophagocytic lymphohistiocytosis (sHLH) patients in the US," showing that sHLH is a complex disease to diagnose and treat. The study has thus far reviewed approximately 1,500 unique patient medical records from a large medical system in the US and supports the need to improve our ability to identify sHLH patients and better understand the potential underestimation of the incidence of sHLH.

"We appreciate the dedication of the Electra team in supporting patients and families impacted by histiocytosis. sHLH is a life-threatening inflammatory disease with no approved treatments and, as a result, many patients suffer the debilitating effects of this condition," said Deanna Fournier, Executive Director, Histiocytosis Association. "We welcome the promising new approach that ELA026 offers, and we join the patient community in supporting the advancement of new treatments for sHLH. Opportunities like these are what continue to give us hope!"

The three posters are available on Electra’s website.

About Secondary Hemophagocytic Lymphohistiocytosis (sHLH)
Secondary hemophagocytic lymphohistiocytosis (sHLH) is a life-threatening hyperinflammatory condition for which there is no approved treatment. sHLH can be triggered by cancer, immunotherapy, infection, or an autoimmune disease. Once triggered, sHLH requires immediate intervention. Without treatment, it can rapidly progress from symptoms such as persistent fever, hepatomegaly and/or splenomegaly, and cytopenias, to multi-organ failure and death.