On April 17, 2023 Merus N.V. (Nasdaq: MRUS) ("Merus", "the Company", "we", or "our"), a clinical-stage oncology company developing innovative, full-length multispecific antibodies (Biclonics and Triclonics), reported interim clinical data as of a February 1, 2023 data cutoff, from the ongoing phase 1/2 trial of the bispecific antibody petosemtamab in previously treated head and neck squamous cell carcinoma (HNSCC) (Press release, Merus, APR 17, 2023, View Source [SID1234630183]). The Plenary Session presentation by Dr. Ezra EW Cohen, Moores Cancer Center, UC San Diego Health, will occur today at the American Association of Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2023, taking place in Orlando, Florida.

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Petosemtamab, or MCLA-158, is a human IgG1 Biclonics designed to bind to cancer cells expressing epidermal growth factor receptor (EGFR) and leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5).

"I am excited by this interim dataset that demonstrates the consistent and clinically meaningful activity of petosemtamab in patients with previously treated head and neck squamous cell carcinoma," said Dr. Andrew Joe, Chief Medical Officer at Merus. "This is clinical validation of a first of its kind EGFR and LGR5 targeting agent."

"There is significant unmet medical need in head and neck squamous cell carcinoma," added Dr. Cohen. "Petosemtamab has the potential to be a meaningful medicine and new standard of care for patients with head and neck cancer."

Updated information and observations from plenary presentation of the ongoing phase 1/2 trial include:

As of the February 1, 2023 data cutoff date, 49 previously treated HNSCC patients (pts) were treated with petosemtamab at the recommended phase 2 dose of 1500 mg intravenous every two weeks
Patient population:
Median age was 63 (range of 31-77); 78% were male
Median prior lines of systemic therapy was 2 (range 1-4); including PD-(L)1 inhibitor in 96% of pts, chemotherapy in 94% and platinum-based chemotherapy in 92% of pts; 2 pts received prior cetuximab
Most frequent primary tumor locations were oropharynx (35%), oral cavity (31%), and larynx (16%)
43 pts were evaluable for efficacy, receiving ≥2 treatment cycles (≥8 weeks) with ≥1 post-baseline tumor assessment or experiencing early progressive disease:
Antitumor activity among 43 pts:
Overall responses rate (ORR) was 37.2% (16/43; 95% CI 23%-53.3%) by RECIST 1.1. per investigator assessment, including 15 confirmed partial responses (PR) and 1 confirmed complete response (CR) (ongoing after 20 months)
Disease control rate (CR + PR + stable disease) was 72.1% (31/43; 95% CI 56.3%-84.7%)
Median time to response was 1.8 months (range 0.8-3.5)
Median duration of response was 6.0 months (95% CI 3.7-NC), with 10 of 16 (62.5%) responders ongoing, and 12 of 43 (27.9%) patients overall ongoing at the time of the data cutoff
Median progression free survival was 5.3 months (95% CI 3.7-6.8); with 29 of 43 pts progressing and 14 of 43 pts censored
Median overall survival was 11.5 months (95% CI 7.2-20.6); with 29 of 49 pts still alive at the data cutoff date
Petosemtamab continued to demonstrate a manageable safety profile:
80 pts were treated with 1500 mg petosemtamab every two weeks across dose escalation and expansion cohorts of the study
Gastrointestinal and skin toxicities were mostly mild to moderate
No treatment-related Grade 5 AEs:
Most frequent related AEs were signs and symptoms of infusion-related reactions (IRRs)
74% Grade 1-4, 21% Grade 3-4 (as grouped term)
Mainly occurred during first infusion
6 of 80 pts discontinued on Day 1 due to a Grade 3-4 IRR
For all patients rechallenged after an IRR, rechallenge was successful
IRRs were manageable with prophylaxis/ prolonged infusion (necessary on Day 1 only)
The presentation is now available on the Merus website.

Company Conference Call and Webcast Information
Merus will hold a conference call and webcast for investors on April 17, 2023 at 6:30 p.m. ET. A replay will be available after the completion of the call in the Investors and Media section of our website for a limited time.

Date & Time: April 17, 2023 at 6:30 p.m. ET
Webcast link: Available on our website
Dial-in: Toll Free: 1 (800) 715-9871 / International: 1 (646) 307-19631
Conference ID: 4032258

About Petosemtamab
Petosemtamab, or MCLA-158, is a bispecific Biclonics low-fucose human full-length IgG1 antibody targeting the epidermal growth factor receptor (EGFR) and the leucine-rich repeat containing G-protein-coupled receptor 5 (LGR5). Petosemtamab is designed to exhibit three independent mechanisms of action including inhibition of EGFR-dependent signaling, LGR5 binding leading to EGFR internalization and degradation in cancer cells, and enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) activity.

On April 17, 2023 ZentalisTM Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical-stage biopharmaceutical company focused on discovering and developing clinically differentiated small molecule therapeutics targeting fundamental biological pathways of cancers, reported preclinical data that supports CCNE1 amplification and / or Cyclin E1 expression as a potential marker for the enrichment of patient populations for treatment with azenosertib, the Company’s potentially first-in-class Wee1 inhibitor product candidate (Press release, Zentalis Pharmaceuticals, APR 17, 2023, View Source [SID1234630182]). These new preclinical data demonstrate that azenosertib drives cancer cell death in Cyclin E1-high tumor cells in vitro and substantially inhibits the growth of Cyclin E1-high, patient-derived, in vivo tumor models.

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The findings are being presented today at the 2023 American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting, in a poster entitled "Cyclin E1 protein overexpression sensitizes ovarian cancer cells to azenosertib (ZN-c3), a novel, selective and orally bioavailable inhibitor of Wee1." The poster can be found on the Company’s website at this link. The poster presentation details are below.

Session Category: Clinical Research Excluding Trials
Session Title: Biomarkers of Therapeutic Benefit 2
Session Date and Time: Monday, April 17, 2023, 9:00 AM ET – 12:30 PM ET
Location: Section 39
Poster Board Number: 27
Abstract Presentation Number: 2153

"We are excited to present new preclinical data demonstrating the utility of Cyclin E1 as a predictive marker to identify patients likely to respond to azenosertib," said Mark Lackner, Ph.D., Chief Translational Officer of Zentalis. "Our findings suggest that Cyclin E1 expression via gene amplification or independent mechanisms sensitizes ovarian cancer cells to azenosertib alone or in combination with chemotherapy. These data confirm and build upon our prior preclinical work, and the published research of others, and provide additional evidence that supports our ongoing clinical trial studying azenosertib as a monotherapy in patients with Cyclin E1-driven ovarian cancer. These data also support the potential development of companion diagnostics for azenosertib."
The study analyzed data from a panel of patient-derived ovarian cancer cell lines in vitro and in vivo models of ovarian cancer. The results show that high Cyclin E1 protein expression is significantly associated with sensitivity to azenosertib, and that artificial overexpression of Cyclin E1 in cell lines with low endogenous Cyclin E1 expression sensitizes those cells to azenosertib. In addition, the study provides foundational details on the mechanistic basis of Cyclin E1 sensitization to Wee1 inhibition, including that Cyclin E1 overexpression results in accumulation of replication stress biomarkers and that azenosertib sensitivity is mediated by CDK2 activity.

The study also provides supportive data for several relevant standard of care chemotherapy combinations based on in vitro synergy assays and suggests that Cyclin E1 expression is a relevant clinical predictive marker. The Company is conducting an analysis of CCNE1 copy number and Cyclin E1 protein expression in its Phase 1b study of azenosertib in combination with chemotherapy in patients with platinum-resistant ovarian cancer. The Company now anticipates sharing these clinical data in the first half of 2023, in advance of original guidance.

"These encouraging translational results support the use of CCNE1 copy number and / or Cyclin E1 protein expression as predictive markers that have the potential to significantly improve patient outcomes by enabling us to select the right patients for treatment with azenosertib," said Gordon Mills, M.D., Ph.D., Professor of Cell, Developmental and Cancer Biology, Oregon Health and Science University School of Medicine. The Company is collaborating with Dr. Mills on preclinical and clinical studies related to the effects of Wee1 inhibition on replicative stress, cell cycle modulation and DNA repair.
Another poster being presented at AACR (Free AACR Whitepaper) by the Ivy Brain Tumor Center at Barrow Neurological Institute entitled "Tumor Pharmacokinetics, Pharmacodynamics and Efficacy Analysis of Wee1 inhibitor, Azenosertib in Patient-Derived Xenograft Models of Glioblastoma," demonstrates that azenosertib can achieve pharmacologically-relevant intracerebral free-drug concentrations, and that pharmacodynamic activity is observed in a preclinical glioblastoma model. This research underscores the potential of azenosertib as a therapy for a more extensive range of tumor types than those presently under clinical investigation. Once presented, the poster can be found on the Company’s website using this link. The poster presentation details are below.
Session Category: Experimental and Molecular Therapeutics, Chemistry
Session Title: Pharmacokinetics, Pharmacodynamics, and Molecular Pharmacology
Session Date and Time: Monday, April 17, 2023, 1:30 PM ET – 5:00 PM ET
Location: Section 18
Poster Board Number: 19
Abstract Presentation Number: 2796

About Azenosertib

Zentalis’ azenosertib (ZN-c3) has been designed to be a highly potent and selective Wee1 inhibitor.
Azenosertib is currently being evaluated in the clinic for advanced solid tumors and hematological malignancies in the following three therapeutic settings of high unmet medical need: (1) as a monotherapy, (2) in combination with traditional chemotherapy and DNA damaging agents, and (3) in combination with molecularly targeted agents. As a monotherapy, azenosertib is currently being evaluated in a Phase 2 clinical trial in adult women with uterine serous carcinoma (USC), an aggressive form of endometrial cancer that accounts for approximately 10-15% of all endometrial cancers. We are also evaluating azenosertib as a monotherapy in a Phase 2 clinical trial in patients with Cyclin E1 driven high-grade serous ovarian cancer (HGSOC). The Company is evaluating azenosertib as a monotherapy in a Phase 1 dose optimization clinical trial in patients with advanced solid tumors, and plans to declare the recommended Phase 2 monotherapy dose and provide an update on dose optimization activities in the first half of 2023. In chemotherapy combinations, azenosertib is currently being evaluated in combination with each of paclitaxel, carboplatin, pegylated liposomal doxorubicin (PLD) and gemcitabine in four cohorts in a Phase 1b clinical trial in patients with advanced platinum-resistant ovarian, peritoneal or fallopian tube cancer. The Company plans to disclose results from this study in the first half of 2023, in advance of original guidance. Azenosertib is also currently being evaluated in combination with gemcitabine in a Phase 1/2 clinical trial in adult and pediatric patients with relapsed or refractory osteosarcoma. In combination with molecularly targeted agents, the Company is studying azenosertib in combination with GlaxoSmithKline plc’s (GSK’s) PARP inhibitor, niraparib (ZEJULA), in a Phase 1/2 clinical trial in platinum-resistant ovarian cancer patients who have failed PARP inhibitor maintenance treatment as part of a clinical collaboration with GSK. The Company is also collaborating with Pfizer Inc. to evaluate azenosertib in combination with encorafenib and cetuximab, an FDA-approved standard of care known as the BEACON regimen, in patients with BRAF V600E mutant metastatic colorectal cancer in a Phase 1/2 clinical trial.

On April 17, 2023 Xencor, Inc. (NASDAQ:XNCR), a clinical-stage biopharmaceutical company developing engineered antibodies and cytokines for the treatment of cancer and autoimmune diseases, reported new preclinical data generated from engineered CD28 bispecific antibodies targeting the solid tumor antigens CEACAM5, ENPP3, mesothelin, STEAP1 and Trop-2 (Press release, Xencor, APR 17, 2023, View Source [SID1234630181]). For each molecule, in vitro T cell activation was enhanced in combination with a CD3 T cell engager. The data were presented in a poster titled "Tumor-specific CD28 costimulatory bispecific antibodies enhance T cell activation in multiple solid tumors" (Abstract 2983) at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting in Orlando, Florida.

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T cells in the tumor microenvironment require engagement of both their T cell receptor (TCR) and their co-stimulatory receptors, like CD28, to achieve full activation. The CD28 signal is diminished in cancer because tumor cells do not typically express CD28 ligands (i.e., CD80 and CD86), which leads to potentially compromised activity of CD3 T cell engagers or anti-PD1 checkpoint inhibitors.

Xencor has developed a modular XmAb bispecific antibody platform that allows for the rapid generation of drug candidates that co-stimulate CD28 only in the presence of tumor cells and TCR engagement. Xencor’s XmAb bispecific Fc domain serves as a scaffold for a non-superagonist anti-CD28 binding domain and any tumor-associated antigen of interest. Xencor’s Xtend Fc technology further enhances circulating half-life of the antibody.

"Xencor has rapidly generated multiple CD28 co-stimulatory bispecific antibodies with potential broad applicability across a range of solid tumors, and each of these programs has demonstrated compelling activity," said John Desjarlais, Ph.D., executive vice president and chief scientific officer at Xencor. "We are leveraging the plug-and-play nature of our XmAb bispecific antibody platforms to generate and explore additional CD28 drug candidates against a broader universe of solid tumor targets."

The poster will be archived under "Events & Presentations" in the Investors section of the Company’s website located at www.xencor.com.

About XmAb808 (B7-H3 x CD28)

Xencor is conducting a Phase 1 study of XmAb808 in patients with advanced solid tumors. XmAb808 is a tumor-selective, co-stimulatory XmAb 2+1 bispecific antibody designed to bind to the broadly expressed tumor antigen B7-H3 and selectively to the CD28 T-cell co-receptor only when bound to tumor cells, which was demonstrated in in vitro studies. Strong potentiation of checkpoint and CD3 cytotoxic activity was also observed in vivo. XmAb808 is a wholly owned Xencor program.

On April 17, 2023 Vincerx Pharma, Inc. (Nasdaq: VINC), a biopharmaceutical company aspiring to address the unmet medical needs of patients with cancer through paradigm-shifting therapeutics, reported a poster of preclinical data of VIP236 monotherapy treatment in PDX and metastatic PDX mouse models across several tumor types at the 2023 American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting (Press release, Vincerx Pharma, APR 17, 2023, View Source [SID1234630180]).

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VIP236 is a first-in-class SMDC with a tailored design to efficiently treat patients with aggressive and metastatic cancer. VIP236 binds to activated αVβ3 integrin, allowing specific homing to the tumor, and is efficiently cleaved by neutrophil elastase (NE). Both proteins are present in the tumor microenvironment (TME), are highly expressed in advanced metastatic tumors, and are associated with poor prognosis. Anticancer activity occurs after a specific and targeted release of an optimized CPT payload by NE in the TME. Once the optimized CPT payload penetrates and accumulates in the cell, it inhibits topoisomerase 1 (TOP1), causing DNA damage and leading to cell death. The novel optimized CPT payload of VIP236 was designed for high permeability with low active efflux potential to overcome transporter-mediated resistance observed with SN38, the active metabolite of irinotecan, which is also a CPT.

"The preclinical data presented at AACR (Free AACR Whitepaper) demonstrate that VIP236 had potent and durable antitumor activity in multiple mouse models implanted with tumor cells from cancer patients," said Ahmed Hamdy M.D., Chief Executive Officer of Vincerx. "VIP236 treatment was efficacious in a PDX non-small cell lung cancer model, including durable complete responses (CRs). Additionally, we observed significant tumor growth inhibition in a PDX colorectal cancer (CRC) liver metastasis model and significantly reduced lung and brain metastasis in a PDX orthotopic triple negative breast cancer (TNBC) model. Most notably, in gastric PDX and cell line-derived cancer models, VIP236 showed significant tumor growth inhibition compared with ENHERTU, an approved antibody-drug conjugate (ADC), independent of HER2 status. We know ENHERTU works in HER2 low breast cancer, so we’re encouraged to see our SMDC showing improved in vivo efficacy not just in HER2 high but also in HER2 low and HER2 negative gastric models. It’s important to note that showing this type of activity in PDX models is impressive, since these models are representative of the heterogeneity of human cancer and more meaningful than results seen in cell lines."

Dr. Hamdy continued, "The results presented at AACR (Free AACR Whitepaper), together with our previous findings showing that the anticancer potency of VIP236 can deliver up to 40 times more drug to the cancer while sparing surrounding tissues and normal organs, suggest that VIP236 has the potential to provide new treatment options for patients across various aggressive tumor types. We are excited with the continued progress of our bioconjugation platform and have started dosing the first cohort in our Phase 1 VIP236 dose-escalation study in patients with advanced solid tumors."

Key Presentation Highlights:
Poster presentation, titled, VIP236: A small molecule drug conjugate with an optimized camptothecin payload has significant activity in patient-derived and metastatic cancer models, presented by Beatrix Stelte-Ludwig, Ph.D., Vincerx Pharma GmbH, Monheim, Germany, include:

In an orthotopic metastatic breast cancer PDX model, immunohistochemistry analysis revealed an increase of αvβ3 and elastase staining after VIP236 treatment, while TOP1 expression remained stable. These results suggest VIP236 has potential antineoplastic activity across various advanced and metastatic cancers.
The mechanism of action of VIP236’s optimized CPT is characterized by TOP1 inhibition, which leads to DNA damage and, ultimately, cell death. DNA damage can be measured by phosphorylation of ɣH2Ax.
Time- and treatment-dependent phosphorylation of ɣH2Ax cells from the SNU16 cell line derived mouse model confirmed on-target TOP1 inhibition from the liberated optimized CPT payload derived from VIP236 and subsequent DNA damage.

VIP236 was efficacious in a PDX non-small cell lung cancer (NSCLC) model, with durable CRs. Partial responses and stable diseases were observed in PDX colon, renal, and TNBC models. Additionally, VIP236 treatment induced significant tumor growth inhibition in a PDX CRC liver metastatic model and significant reduction in lung and brain metastasis in a PDX orthotopic TNBC model. The reduction of brain metastases suggests successful VIP236 penetration of the blood-brain barrier.

In gastric PDX cancer models, VIP236 treatment showed significant tumor growth inhibition compared with the approved anti-HER2 ADC, ENHERTU (trastuzumab deruxtecan), independent of HER2 expression levels. Similar results were observed in a cell line-derived mouse model (HER2neg SNU16).
VIP236 is currently being evaluated in a first-in-human Phase 1 dose-escalation study in patients with advanced solid tumors (NCT05712889).

The poster can be accessed on the presentations section of the Vincerx website.

On April 17, 2023 Vincerx Pharma, Inc. (Nasdaq: VINC), a biopharmaceutical company aspiring to address the unmet medical needs of patients with cancer through paradigm-shifting therapeutics, reported a poster of preclinical data on novel integrin αvβ3-targeted small molecule drug conjugates (SMDCs) at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting (Press release, Vincerx Pharma, APR 17, 2023, View Source [SID1234630179]).

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Vincerx’s next-generation modular bioconjugation platform is designed to effectively target tumors with different modalities, including SMDCs and antibody-drug conjugates (ADCs). Our next-generation bioconjugation technology overcomes many of the known challenges of first-generation conjugation platforms and has shown increased safety and efficacy in relevant whole animal models. The platform consists of novel linker chemistries for tumor specific payload release; a toolbox of potent payload classes with novel modes of action to address a broad range of cancer targets; and tunable features that allow for optimization of the payload’s physiochemical profile to match target tumor biology.

"The preclinical data presented at AACR (Free AACR Whitepaper) demonstrate our ability to synthesize and characterize novel SMDCs," said Ahmed Hamdy M.D., Chief Executive Officer of Vincerx. "The data showed high elastase-dependent potency and cytotoxicity across several cancer cell lines. Furthermore, the data demonstrate excellent plasma stability in rats with low plasma clearance from several αvβ3 conjugates."

Dr. Hamdy continued, "Based on these results, the large scope of potential payloads and tolerated conjugation chemistries gives rise to a versatile strategy for selective delivery of payloads to the tumor microenvironment that does not require the tumor target to internalize. Furthermore, these encouraging results demonstrate the extensive scientific expertise of the Vincerx team and our commitment to discovering and developing paradigm-shifting conjugates for patients with cancer. We are excited about the potential expansion of our bioconjugation platform and continue to evaluate linker variations with in vivo studies across different payload classes."

Key Presentation Highlights:
Poster presentation, titled, Synthesis and characterization of novel small molecule drug conjugates with different payloads designed to be released in tumor microenvironment by neutrophil elastase, presented by Hans-Georg Lerchen, Ph.D., Vincerx Pharma GmbH, Monheim, Germany, include:

Imaging studies with fluorescent conjugates indicate efficient tumor homing in the tumor microenvironment of the αvβ3 binder and tumor-associated cleavage by neutrophil elastase (NE).
An optimized camptothecin (CPT; topoisomerase inhibitor), P-TEFbi (CDK9/CycT inhibitor) and kinesin spindle protein inhibitor (KSPi) were successfully converted into αvβ3-targeted SMDCs (VIP550, VIP280, and VIP1339, respectively) using different chemical handles (alcohol, sulfoximine and primary amine).
NE-cleavable linkers show high elastase-dependent potency with IC50 values of αvβ3 conjugates VIP550, VIP280 and VIP1339 in the nanomolar range across several cancer cell lines (786-0, HT29, NCI-H292, and SUM149) reaching similar potency as compared with the respective payloads alone.

αvβ3 conjugates VIP280, VIP550 and VIP1339 demonstrated excellent plasma stability and elastase-mediated release of CPT, P-TEFbi and KSPi payloads in rat plasma as well as in buffer at pH7.4.

Plasma clearance of all 3 small molecule drug αvβ3 conjugates was low with clearance being in the following rank ordering: VIP1339 > VIP550 > VIP280. Half-life was longer for SMDCs with the lowest clearance estimates. The ratio between AUC of the payload and parent SMDC was decreasing in the order of VIP280 > VIP550 > VIP1339. A 15-fold reduction in this ratio between VIP280 and VIP550 suggest a large increase in in vivo stability of the payload linker for VIP550 compared with VIP280.

Strong in vivo efficacy was shown with the SMDC VIP550 with a CPT payload in the MX1 TNBC mouse model. VIP550 monotherapy exhibits tumor regression in the 20 mg/kg intravenous 2 days on/5 days off treatment schedule (PR: 12/12). Once weekly application of VIP550 achieved stable disease (T/C: 0.34) and was slightly less efficacious compared with VIP236 (T/C: 0.24). No significant impact on mean body weight of mice was observed, indicating good tolerability of VIP550 and VIP236.

The poster can be accessed on the presentations section of the Vincerx website.