Delta-like Ligand Research Articles

Serum DLK1 During Minipuberty and Pubertal Transition in Healthy Girls and in Girls with Precocious Puberty.

Delta-like non-canonical notch ligand 1 (DLK1) is negatively associated with bodyweight. DLK1 pathogenic variants cause central precocious puberty (CPP) and obesity, suggesting that DLK1 link the well-established association between higher BMI and earlier pubertal onset. However, little is known about the trajectories of circulating DKL1 in healthy girls as well as in girls with precocious puberty. To evaluate longitudinal changes in circulating DLK1 concentrations in 1) full-term, singleton healthy infant girls 2) healthy girls during pubertal transition 3) girls with CPP during treatment with gonadotropin-releasing hormone agonist (GnRHa). Three longitudinal studies of 1) healthy, infant girls (n=85), 2) healthy, peripubertal girls (n=15), 3) girls with CPP before and after GnRHa treatment (n=15).Body fat percentage (BF%) by Slaughter equation. Serum concentrations of DLK1 by ELISA. Serum concentration of DLK1 in healthy infant girls declined significantly through the first year of life (17.6 ng/mL to 9.9 nh/mL, p=0.020). DLK1 was inversely correlated with birth weight and BF%: r=-0.220, p=0.044 and r=-0.503, p<0.001, respectively. DLK1 declined from one year prior to pubertal onset to time of first examination after pubertal onset (10.4 ng/mL to 9.2 n/mL, p=0.004) as well as to time at the last pubertal evaluation (10.4 ng/mL to 9.8 ng/mL, p=0.006). DLK1 levels were not affected by GnRHa treatment. Circulating DLK1 levels declined steeply during infancy and less pronounced through pubertal development. Due to considerable inter-individual variation, DLK1 is not useful as a diagnostic marker of pubertal onset. Importantly, DLK1 was negatively associated with birth weight and body fat percentage.

A proteogenomic surfaceome study identifies DLK1 as an immunotherapeutic target in neuroblastoma

Cancer immunotherapies produce remarkable results in B cell malignancies; however, optimal cell surface targets for many solid cancers remain elusive. Here, we present an integrative proteomic, transcriptomic, and epigenomic analysis of tumor and normal tissues to identify biologically relevant cell surface immunotherapeutic targets for neuroblastoma, an often-fatal childhood cancer. Proteogenomic analyses reveal sixty high-confidence candidate immunotherapeutic targets, and we prioritize delta-like canonical notch ligand 1 (DLK1) for further study. High expression of DLK1 directly correlates with a super-enhancer. Immunofluorescence, flow cytometry, and immunohistochemistry show robust cell surface expression of DLK1. Short hairpin RNA mediated silencing of DLK1 in neuroblastoma cells results in increased cellular differentiation. ADCT-701, a DLK1-targeting antibody-drug conjugate (ADC), shows potent and specific cytotoxicity in DLK1-expressing neuroblastoma xenograft models. Since high DLK1 expression is found in several adult and pediatric cancers, our study demonstrates the utility of a proteogenomic approach and credentials DLK1 as an immunotherapeutic target.

YAP1 Status Defines Two Intrinsic Subtypes of LCNEC with Distinct Molecular Features and Therapeutic Vulnerabilities.

Large cell neuroendocrine carcinoma (LCNEC) is a high-grade neuroendocrine malignancy that, like small cell lung cancer (SCLC), is associated with the absence of druggable oncogenic drivers and dismal prognosis. In contrast to SCLC, however, there is little evidence to guide optimal treatment strategies, which are often adapted from SCLC and non-small cell lung cancer approaches. To better define the biology of LCNEC, we analyzed cell line and patient genomic data and performed IHC and single-cell RNA sequencing of core needle biopsies from patients with LCNEC and preclinical models. In this study, we demonstrate that the presence or absence of YAP1 distinguishes two subsets of LCNEC. The YAP1-high subset is mesenchymal and inflamed and is characterized, alongside TP53 mutations, by co-occurring alterations in CDKN2A/B and SMARCA4. Therapeutically, the YAP1-high subset demonstrates vulnerability to MEK- and AXL-targeting strategies, including a novel preclinical AXL chimeric antigen receptor-expressing T cell. Meanwhile, the YAP1-low subset is epithelial and immune-cold and more commonly features TP53 and RB1 co-mutations, similar to those observed in pure SCLC. Notably, the YAP1-low subset is also characterized by the expression of SCLC subtype-defining transcription factors, especially ASCL1 and NEUROD1, and as expected, given its transcriptional similarities to SCLC, exhibits putative vulnerabilities reminiscent of SCLC, including delta-like ligand 3 and CD56 targeting, as is with novel preclinical delta-like ligand 3 and CD56 chimeric antigen receptor-expressing T cells, and DNA damage repair inhibition. YAP1 defines distinct subsets of LCNEC with unique biology. These findings highlight the potential for YAP1 to guide personalized treatment strategies for LCNEC.

Identification of DLK1, a Notch ligand, as an immunotherapeutic target and regulator of tumor cell plasticity and chemoresistance in adrenocortical carcinoma.

Immunotherapeutic targeting of cell surface proteins is an increasingly effective cancer therapy. However, given the limited number of current targets, the identification of new surface proteins, particularly those with biological importance, is critical. Here, we uncover delta-like non-canonical Notch ligand 1 (DLK1) as a cell surface protein with limited normal tissue expression and high expression in multiple refractory adult metastatic cancers including small cell lung cancer (SCLC) and adrenocortical carcinoma (ACC), a rare cancer with few effective therapies. In ACC, ADCT-701, a DLK1 targeting antibody-drug conjugate (ADC), shows potent in vitro activity among established cell lines and a new cohort of patient-derived organoids as well as robust in vivo anti-tumor responses in cell line-derived and patient-derived xenografts. However, ADCT-701 efficacy is overall limited in ACC due to high expression and activity of the drug efflux protein ABCB1 (MDR1, P-glycoprotein). In contrast, ADCT-701 is extremely potent and induces complete responses in DLK1 + ACC and SCLC in vivo models with low or no ABCB1 expression. Genetic deletion of DLK1 in ACC dramatically downregulates ABCB1 and increases ADC payload and chemotherapy sensitivity through NOTCH1-mediated adrenocortical de-differentiation. Single cell RNA-seq of ACC metastatic tumors reveals significantly decreased adrenocortical differentiation in DLK low or negative cells compared to DLK1 positive cells. This works identifies DLK1 as a novel immunotherapeutic target that regulates tumor cell plasticity and chemoresistance in ACC. Our data support targeting DLK1 with an ADC in ACC and neuroendocrine neoplasms in an active first-in-human phase I clinical trial ( NCT06041516 ).

Relationship between the expressions of DLL3, ASC1, TTF-1 and Ki-67: First steps of precision medicine at SCLC.

This study presents an observational, cross-sectional analysis of 64 patients diagnosed with small cell lung cancer (SCLC) at a reference laboratory for thoracic pathology between 2022 and 2024. The primary objective was to evaluate the expression of Delta-like ligand 3 (DLL3) and other neuroendocrine markers such as Chromogranin, and Synaptophysin, utilizing both traditional immunohistochemistry and digital pathology tools. Patients were primarily older adults, with a median age of over 71, and most biopsies were obtained from lung parenchyma. Immunohistochemistry (IHC) was performed using specific monoclonal antibodies, with DLL3 showing variable expression across the samples. Notably, DLL3 was expressed in 72.3% of the cases, with varied intensities and a semi-quantitative H-score applied for more nuanced analysis. ASCL1 was expressed in 97% of cases, with the majority considered low-expressors. Only 11% had high expression. TTF-1, traditionally not a conventional marker for the diagnosis of SCLC, was positive in half of the cases, suggesting its potential as a biomarker. The study underscores the significant variability in the expression of neuroendocrine markers in SCLC, with implications for both diagnosis and potential therapeutic targeting. DLL3, particularly, shows promise as a therapeutic target due to its high expression rate in the cohort. The use of digital pathology software QuPath enhanced the accuracy and depth of analysis, allowing for detailed morphometric analysis and potentially informing more personalized treatment approaches. The findings emphasize the need for further research into the role of these markers in the management and treatment of SCLC, considering the poor prognosis and high mortality rate observed in the cohort.

Sustained Clinical Benefit and Intracranial Activity of Tarlatamab in Previously Treated Small Cell Lung Cancer: DeLLphi-300 Trial Update.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Tarlatamab, a bispecific T-cell engager immunotherapy targeting delta-like ligand 3, has shown durable anticancer activity and manageable safety in previously treated small cell lung cancer (SCLC) in DeLLphi-300 phase I and DeLLphi-301 phase II trials. Here, we report extended follow-up of DeLLphi-300 (median follow-up, 12.1 months [range, 0.2-34.3]) in fully enrolled cohorts treated with tarlatamab ≥10 mg dose administered once every two weeks, once every three weeks, or once on day 1 and once on day 8 of a 21-day cycle (N = 152). Overall, the objective response rate (ORR) was 25.0%; the median duration of response (mDOR) was 11.2 months (95% CI, 6.6 to 22.3), and the median overall survival (mOS) was 17.5 months (95% CI, 11.4 to not estimable [NE]). Among 17 patients receiving 10 mg tarlatamab once every two weeks, the ORR was 35.3%, the mDOR was 14.9 months (95% CI, 3.0 to NE), the mOS was 20.3 months (95% CI, 5.1 to NE), and 29.4% had sustained disease control with time on treatment ≥52 weeks. No new safety signals were identified. In modified Response Assessment in Neuro-Oncology Brain Metastases analyses, CNS tumor shrinkage of ≥30% was observed in 62.5% of patients (10 of 16) who had a baseline CNS lesion of ≥10 mm, including in a subset of patients with tumor shrinkage long after previous brain radiotherapy. In DeLLphi-300 extended follow-up, tarlatamab demonstrated unprecedented survival and potential findings of intracranial activity in previously treated SCLC.

Population pharmacokinetic model of ABL001/CTX-009 (anti-VEGF/DLL4) in adult cancer patients with solid tumor.

ABL001/CTX-009 is a bispecific antibody targeting delta-like ligand-4 and vascular endothelial growth factor A. In this study, we developed a population pharmacokinetic (PK) model of ABL001/CTX-009 in patients with solid tumors. A total of 712 plasma concentrations from 30 patients with relapsed or refractory solid tumors were collected from a phase 1 study (NCT03292783). A population PK model was developed using a nonlinear mixed-effect method and was evaluated by graphical and numerical methods. Using the model, the steady-state concentrations were simulated to compare weight-based and fixed-dose regimens and to find optimal dosing intervals. The PK of ABL001/CTX-009 was well described by a two-compartment model with a parallel first-order and Michaelis-Menten elimination kinetics. Body weight was selected as a significant covariate on V1. Model evaluation results suggested that the model was adequate and robust with good precision. Simulations after administrations of fixed or weight-based doses showed similar plasma concentrations. Additionally, 10 mg/kg for every other week and 15 mg/kg for every three-week administration showed comparable plasma concentrations. In conclusion, the model well described the plasma concentrations of ABL001/CTX-009 in patients with solid tumors. The simulation suggested that weight-based dose and fixed dose can provide equivalent systemic exposure.

Prognostic significance of tertiary lymphoid structures in gastric neuroendocrine carcinoma with association to delta-like ligand 3 and neuroendocrine expressions.

Gastric neuroendocrine carcinomas (NECs) are rare cancers with highly aggressive behavior. Although tertiary lymphoid structures (TLSs) are well-known prognostic factors in various cancers, their role in gastric NECs remain unexplored. Unique immunohistochemical subtypes of pulmonary NECs have been discovered, however, their feasibility in gastric NECs is unknown. The presence and maturation of TLSs (lymphoid aggregates, primary and secondary follicles) were assessed in 48 surgically resected gastric NECs and were compared with immunohistochemical subtypes, using a panel of ASCL1, NeuroD1, POU2F3, YAP1, and DLL3 with three neuroendocrine (NE) markers. Patients with secondary follicles had significantly better overall survival (OS) and recurrence-free survival (RFS; both, p = 0.004) than those without them. Based on the hierarchical clustering, gastric NECs were classified into all low/negative (31%), high-YAP1 (19%), high-DLL3/low-NE (29%), and high-NE (21%) expression groups. The high-DLL3/low-NE group was associated with absent TLSs (p = 0.026) and showed the worst OS (p = 0.026). Distant metastasis and a lack of secondary follicles were poor independent prognostic factors of OS and RFS. The assessment of TLSs is a feasible and potent biomarker for gastric NECs, thus enabling better prognosis and moreeffective immunotherapy. Furthermore, gastric NECs can be categorized as four immunohistochemically distinct groups, of which the high-DLL3/low-NE group has the worst OS with lack of TLSs.

FZ-AD005, a Novel DLL3-Targeted Antibody-Drug Conjugate with Topoisomerase I Inhibitor, Shows Potent Antitumor Activity in Preclinical Models.

Delta-like ligand 3 (DLL3) is overexpressed in small cell lung cancer (SCLC) and has been considered an attractive target for SCLC therapy. Rovalpituzumab tesirine was the first DLL3-targeted antibody-drug conjugate (ADC) to enter clinical studies. However, serious adverse events limited progress in the treatment of SCLC with rovalpituzumab tesirine. In this study, we developed a novel DLL3-targeted ADC, FZ-AD005, by using DXd with potent cytotoxicity and a relatively better safety profile to maximize the therapeutic index. FZ-AD005 was generated by a novel anti-DLL3 antibody, FZ-A038, and a valine-alanine (Val-Ala) dipeptide linker to conjugate DXd. Moreover, Fc-silencing technology was introduced in FZ-AD005 to avoid off-target toxicity mediated by FcγRs and showed negligible Fc-mediated effector functions in vitro. In preclinical evaluation, FZ-AD005 exhibited DLL3-specific binding and demonstrated efficient internalization, bystander killing, and excellent in vivo antitumor activities in cell line-derived xenograft and patient-derived xenograft models. FZ-AD005 was stable in circulation with acceptable pharmacokinetic profiles in cynomolgus monkeys. FZ-AD005 was well tolerated in rats and monkeys. The safety profile of FZ-AD005 was favorable, and the highest nonseverely toxic dose was 30 mg/kg in cynomolgus monkeys. In conclusion, FZ-AD005 has the potential to be a superior DLL3-targeted ADC with a wide therapeutic window and is expected to provide clinical benefits for the treatment of patients with SCLC.

Inhibition of DLL4/Notch Signaling Pathway Promotes M2 Polarization and Cell Proliferation in Pulmonary Arterial Hypertension.

In this study, we conducted a comprehensive analysis to identify key genes and pathways associated with pulmonary arterial hypertension (PAH) and investigated the role of delta-like ligand 4 (DLL4) in PAH pathogenesis. Through integrated analysis of multiple data sets, we identified 6 candidate differentially expressed genes (DEGs), notably DLL4, which showed the highest distinguishing efficiency between PAH and control samples. Functional and pathway enrichment analyses revealed the involvement of DLL4 in critical biological processes and pathways related to PAH, including notch signaling, immune cell function, and inflammatory responses. Further investigation demonstrated that decreased DLL4 expression correlated with increased M2 macrophage polarization, suggesting a potential role for DLL4 in preventing M2 differentiation. Additionally, the DLL4/Notch1 axis was found to influence the Notch profile and regulate signaling mediators during M2 differentiation. These findings highlight DLL4 as a promising biomarker and therapeutic target for PAH, shedding light on the underlying molecular mechanisms and providing insights for the development of novel treatment strategies.

Modulating endothelial cell dynamics in fat grafting: the impact of DLL4 siRNA via adipose stem cell extracellular vesicles.

In the context of improving the efficacy of autologous fat grafts (AFGs) in reconstructive surgery, this study delineates the novel use of adipose-derived mesenchymal stem cells (ADSCs) and their extracellular vesicles (EVs) as vehicles for delivering delta-like ligand 4 (DLL4) siRNA. The aim was to inhibit DLL4, a gene identified through transcriptome analysis as a critical player in the vascular endothelial cells of AFG tissues, thereby negatively affecting endothelial cell functions and graft survival through the Notch signaling pathway. By engineering ADSC EVs to carry DLL4 siRNA (ADSC EVs-siDLL4), the research demonstrated a marked improvement in endothelial cell proliferation, migration, and lumen formation, and enhanced angiogenesis in vivo, leading to a significant increase in the survival rate of AFGs. This approach presents a significant advancement in the field of tissue engineering and regenerative medicine, offering a potential method to overcome the limitations of current fat grafting techniques.NEW & NOTEWORTHY This study introduces a groundbreaking method for enhancing autologous fat graft survival using adipose-derived stem cell extracellular vesicles (ADSC EVs) to deliver DLL4 siRNA. By targeting the delta-like ligand 4 (DLL4) gene, crucial in endothelial cell dynamics, this innovative approach significantly improves endothelial cell functions and angiogenesis, marking a substantial advancement in tissue engineering and regenerative medicine.

Delta-like noncanonical notch ligand 2 regulates the proliferation and differentiation of sheep myoblasts through the Wnt/β-catenin signaling pathway.

This study delved into the role ofdelta-like noncanonical notch ligand 2(DLK2) in the cell cycle, proliferation, apoptosis, and differentiation of myoblasts, as well as its interaction with the classical Wnt/β-catenin signaling pathway in regulating myoblast function. The research revealed that upregulation of DLK2 in myoblasts during the proliferation phase enhanced myoblast proliferation, facilitated cell cycle progression, and reduced apoptosis. Conversely, downregulation of DLK2 expression using siRNA during the differentiation phase promoted myoblast hypertrophy and fusion, suppressed the expression of muscle fiber degradation factors, and expedited the differentiation process. DLK2 regulates myoblasts function by influencing the expression of various factors associated with the Wnt/β-catenin signaling pathway, including CTNNB1, FZD1, FZD6, RSPO1, RSPO4, WNT4, WNT5A, andadenomatous polyposis coli. In essence, DLK2, with the involvement of the Wnt/β-catenin signaling pathway, plays a crucial regulatory role in the cell cycle, proliferation, apoptosis, and differentiation of myoblasts.

Tarlatamab: First Approval.

Tarlatamab (tarlatamab-dlle: IMDELLTRA™) is a first-in-class, half-life extended bispecific delta-like ligand 3 (DLL3)-directed CD3 T-cell engager being developed by Amgen for the treatment of small cell lung cancer (SCLC) and neuroendocrine prostate cancer. Tarlatamab binds to DLL3 on the surface of tumour cells and CD3 on the surface of cytotoxic T lymphocytes (CTLs), resulting in T-cell activation, release of inflammatory cytokines and CTL-mediated cell death of DLL3-expressing tumour cells. In May 2024, tarlatamab received its first approval in the USA for the treatment of adults with extensive stage SCLC (ES-SCLC) with disease progression on or after platinum-based chemotherapy. Tarlatamab received accelerated approval for this indication based on overall response rate and duration of response in the pivotal phase 2 DeLLphi-301 study, and continued approval may be contingent on the demonstration of clinical benefit in a confirmatory trial(s). Tarlatamab is under regulatory review in Brazil, Canada, Israel and the UK, and clinical studies are underway in multiple countries. This article summarizes the milestones in the development of tarlatamab leading to this first approval for ES-SCLC with disease progression on or after platinum-based chemotherapy.

Circulating tumor cells: advancing personalized therapy in small cell lung cancer patients.

Small cell lung cancer (SCLC) is a highly aggressive cancer with a dismal 5-year survival of < 7%, despite the addition of immunotherapy to first-line chemotherapy. Specific tumor biomarkers, such as delta-like ligand 3 (DLL3) and schlafen11 (SLFN11), may enable the selection of more efficacious, novel immunomodulating targeted treatments like bispecific T-cell engaging monoclonal antibodies (tarlatamab) and chemotherapy with PARP inhibitors. However, obtaining a tissue biopsy sample can be challenging in SCLC. Circulating tumor cells (CTCs) have the potential to provide molecular insights into a patient's cancer through a "simple" blood test. CTCs have been studied for their prognostic ability in SCLC; however, their value in guiding treatment decisions is yet to be elucidated. This review explores novel and promising targeted therapies in SCLC, summarizes current knowledge of CTCs in SCLC, and discusses how CTCs can be utilized for precision medicine.

Imaging with [89Zr]Zr-DFO-SC16.56 anti-DLL3 antibody in patients with high-grade neuroendocrine tumours of the lung and prostate: a phase 1/2, first-in-human trial

Delta-like ligand 3 (DLL3) is aberrantly expressed on the surface of small-cell lung cancer (SCLC) and neuroendocrine prostate cancer cells. We assessed the safety and feasibility of the DLL3-targeted imaging tracer [89Zr]Zr-DFO-SC16.56 (composed of the anti-DLL3 antibody SC16.56 conjugated to p-SCN-Bn-deferoxamine [DFO] serving as a chelator for zirconium-89) in patients with neuroendocrine-derived cancer. We conducted an open-label, first-in-human study of immunoPET-CT imaging with [89Zr]Zr-DFO-SC16.56. The study was done at Memorial Sloan Kettering Cancer Center, New York, NY, USA. Patients aged 18 years or older with a histologically verified neuroendocrine-derived malignancy and an Eastern Cooperative Oncology Group performance status of 0-2 were eligible. An initial cohort of patients with SCLC (cohort 1) received 37-74 MBq [89Zr]Zr-DFO-SC16.56 as a single intravenous infusion at a total mass dose of 2·5 mg and had serial PET-CT scans at 1 h, day 1, day 3, and day 7 post-injection. The primary outcomes of phase 1 of the study (cohort 1) were to estimate terminal clearance half-time, determine whole organ time-integrated activity coefficients, and assess the safety of [89Zr]Zr-DFO-SC16.56. An expansion cohort of additional patients (with SCLC, neuroendocrine prostate cancer, atypical carcinoid tumours, and non-small-cell lung cancer; cohort 2) received a single infusion of [89Zr]Zr-DFO-SC16.56 at the same activity and mass dose as in the initial cohort followed by a single PET-CT scan 3-6 days later. Retrospectively collected tumour biopsy samples were assessed for DLL3 by immunohistochemistry. The primary outcome of phase 2 of the study in cohort 2 was to determine the potential association between tumour uptake of the tracer and intratumoural DLL3 protein expression, as determined by immunohistochemistry. This study is ongoing and is registered with ClinicalTrials.gov, NCT04199741. Between Feb 11, 2020, and Jan 30, 2023, 12 (67%) men and six (33%) women were enrolled, with a median age of 64 years (range 23-81). Cohort 1 included three patients and cohort 2 included 15 additional patients. Imaging of the three patients with SCLC in cohort 1 showed strong tumour-specific uptake of [89Zr]Zr-DFO-SC16.56 at day 3 and day 7 post-injection. Serum clearance was biphasic with an estimated terminal clearance half-time of 119 h (SD 31). The highest mean absorbed dose was observed in the liver (1·83 mGy/MBq [SD 0·36]), and the mean effective dose was 0·49 mSv/MBq (SD 0·10). In cohort 2, a single immunoPET-CT scan on day 3-6 post-administration could delineate DLL3-avid tumours in 12 (80%) of 15 patients. Tumoural uptake varied between and within patients, and across anatomical sites, with a wide range in maximum standardised uptake value (from 3·3 to 66·7). Tumour uptake by [89Zr]Zr-DFO-SC16.56 was congruent with DLL3 immunohistochemistry in 15 (94%) of 16 patients with evaluable tissue. Two patients with non-avid DLL3 SCLC and neuroendocrine prostate cancer by PET scan showed the lowest DLL3 expression by tumour immunohistochemistry. One (6%) of 18 patients had a grade 1 allergic reaction; no grade 2 or worse adverse events were noted in either cohort. DLL3 PET-CT imaging of patients with neuroendocrine cancers is safe and feasible. These results show the potential utility of [89Zr]Zr-DFO-SC16.56 for non-invasive in-vivo detection of DLL3-expressing malignancies. National Institutes of Health, Prostate Cancer Foundation, and Scannell Foundation.

DAREON-8: A phase I, open-label, dose escalation/expansion trial of the DLL3-targeting T-cell engager, BI 764532, combined with first-line (1L) standard of care (platinum, etoposide, and anti-PD-L1 antibody) in patients (pts) with extensive-stage small cell lung carcinoma (ES-SCLC).

TPS8127 Background: Platinum/etoposide chemotherapy in combination with anti-PD-L1 antibodies is the 1L standard of care (SoC) for pts with ES-SCLC. However, most pts relapse and subsequent treatment (Tx) options are limited. Hence, outcomes are poor with a 5-year survival rate of &lt; 7%. Delta-like ligand 3 (DLL3) is a Notch receptor ligand expressed on tumor cells but not on normal cells. BI 764532 is an IgG-like T-cell engager (TcE) that binds simultaneously to CD3 on T-cells and DLL3 on tumor cells, resulting in selective, T-cell mediated tumor cell lysis. An ongoing Phase I trial of BI 764532 (NCT04429087) in pts with pretreated DLL3-positive tumors demonstrated an overall response rate of 28%, a disease control rate of 54%, and a manageable safety profile. Here, we describe DAREON-8 (NCT06077500), a Phase I open-label dose escalation/expansion trial of BI 764532 plus SoC as a 1L Tx for pts with ES-SCLC. Methods: Pts will be recruited from ~20 sites into this two-part trial. In Part A (dose escalation), ~30 pts will receive escalating doses of intravenous BI 764532 (target dose after step-in dosing) plus carboplatin/etoposide + atezolizumab. Dose escalation will be guided by a Bayesian logistic regression model with overdose control. Tx with BI 764532 will continue for 36 months, withdrawal or progressive disease (PD). The primary objective is to determine the maximum tolerated dose (MTD) of BI 764532 and/or the recommended dose for expansion (RDE)/recommended Phase II dose (RP2D) for BI 764532 plus SoC. Safety, efficacy and/or PK assessments will guide the RDE/RP2D. The primary endpoint focuses on the occurrence of dose-limiting toxicities (DLTs) in the MTD evaluation period. In Part B (dose expansion), ~30 pts will receive BI 764532 at the RDE/RP2D determined in Part A for 36 months, withdrawal or PD and platinum/etoposide + either atezolizumab or durvalumab. The primary objective of Part B is to confirm the safety and tolerability of BI 764532 at the RDE/RP2D plus SoC Tx as measured by the occurrence of DLTs during the on-Tx period. Key inclusion criteria include confirmed ES-SCLC; no prior systemic treatment for ES-SCLC; and eligibility to receive platinum/etoposide chemotherapy + anti-PD-L1 antibodies. Key exclusion criteria include previous Tx with DLL3-targeting TcEs; persistent, unresolved toxicity from previous Txs; immunodeficiency, or systemic steroid or other immunosuppressive therapy ≤7 days prior to first dose of BI 764532; and significant cardio/cerebrovascular disease. Clinical trial information: NCT06077500 .

Updated results from a phase 1/2 study of HPN328, a tri-specific, half-life (T1/2) extended DLL3-targeting T-cell engager in patients (pts) with small cell lung cancer (SCLC) and other neuroendocrine cancers (NEC).

8090 Background: Delta-like canonical Notch ligand 3 (DLL3) is highly expressed on the cell surface of neuroendocrine carcinomas, which have few approved treatment options in the refractory, metastatic setting. HPN328 is DLL3-targeting T-cell engager. HPN328 has 3 binding domains including anti-DLL3 for target engagement, anti-albumin for half-life extension, and anti-CD3 for T cell engagement and activation. Methods: Pts with relapsed/refractory, metastatic SCLC, neuroendocrine prostate cancer (NEPC) and other NEC associated with DLL3 expression are eligible. Primary objectives are safety, maximum tolerated dose (MTD) and pharmacokinetics (PK). Secondary objectives are immunogenicity and efficacy. Overall response rate (ORR) is determined using modified RECIST v1.1 to include extracranial response assessment for pts treated with radiotherapy for brain metastases while on treatment. HPN328 is administered IV QW or Q2W with priming dose preceding target dose in higher dose cohorts. Results: As of January 5, 2024, 86 pts received HPN328 doses of 0.015-24 mg across 14 cohorts (SCLC [n = 54;63%]; other NEC [n = 32;37%]). The median (range) number of prior regimens was 3 (1-7); 83% previously received a PD-1/PD-L1 blocker. Treatment is ongoing in 24 of 46 (52%) pts in the dose optimization cohorts (1 mg priming dose with 12 or 24 mg target doses QW or Q2W). Treatment-related AEs in ≥ 10% of pts included CRS (59% [30% G1, 26% G2, 3% G3+]), dysgeusia (36%), fatigue (34%), diarrhea (19%), nausea (17%), vomiting (14%), decreased appetite and decreased neutrophil count (13% each), and weight decreased (11%). No G3-4 CRS was seen at target doses. Immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 9% of pts, all G1-2. The maximum tolerated priming dose was 1 mg; dose escalation of target dose continued up to 24 mg QW without reaching a maximum tolerated target dose. Among efficacy evaluable pts treated in dose optimization cohorts, the confirmed ORR in SCLC was 50% (12/24), with one complete response (CR). In NEC (other than NEPC) the confirmed ORR was 44% (4/9), with one CR. Four of eleven pts with NEPC had unconfirmed PRs in 1 mg priming dose cohorts, with 5 NEPC pts remaining on treatment &gt; 20 weeks. HPN328 exhibited linear PK with dose-proportional increases in exposure and a median T1/2 of 71 hrs. Transient increases in cytokines up to 24 hrs post-dose and T-cell activation were observed. Conclusions: HPN328 is well tolerated and clinically active in SCLC, NEC, and NEPC. Current dose optimization cohorts have completed enrollment and data continue to mature; selection of a recommended phase 2 dose will be made based upon complete mature data. Updated safety and efficacy results will be presented. Clinical trial information: NCT04471727 .

DeLLphi-301: Tarlatamab phase 2 trial in small cell lung cancer (SCLC)—Efficacy and safety analyzed by presence of brain metastasis.

8015 Background: Brain metastases affect 40%–70% of patients with SCLC. Tarlatamab, a BiTE (bispecific T-cell engager) immunotherapy targeting delta-like ligand 3, demonstrated durable responses and promising survival outcomes in patients with previously treated SCLC (10 mg Q2W) (DeLLphi-301; NCT05060016; Ahn M-J, N Engl J Med 2023). Here, tarlatamab efficacy and safety in patients with baseline brain metastases from DeLLphi-301 are reported. Methods: The DeLLphi-301 study design has been published. Patients with treated, stable, asymptomatic brain metastases were included. Subgroup analyses for efficacy (blinded independent central review [BICR] assessments) and safety by presence or absence of baseline brain metastases were performed. Intracranial activity was assessed. Post enrollment, brain imaging was performed if clinically indicated. Results: As of 27 June 2023, 186 patients had received tarlatamab (ECOG PS: 0–1; median prior lines of therapy: 2; median follow-up: 13.6 months). 29% of patients (54/186) had treated and stable brain metastases at baseline. Most patients (91%) with brain metastases had received prior local radiotherapy; 6% each had received surgery only or both radiotherapy and surgery. Overall systemic objective response rate (ORR; RECIST 1.1) was 45.3% in patients with brain metastases and 32.6% in patients without brain metastases (Table). Any grade immune effector cell associated neurotoxicity syndrome and associated neurological events occurred in 24.1% of patients with brain metastases and in 13.6% of patients without brain metastases; grade ≥ 3 events occurred in the 100 mg group only: 9.4% and 1.8%, respectively, and did not lead to tarlatamab discontinuation in any patient with brain metastases. Analysis of intracranial activity will be presented. Conclusions: Tarlatamab showed promising efficacy and a favorable benefit-risk profile in patients with previously treated SCLC and stable brain metastases. Clinical trial information: NCT05060016 . [Table: see text]

Delta-like ligand 3: A promising target against small cell lung cancer.

This commentary highlighted the current knowledge about novel DLL3-targeting agents for refractory small cell lung cancer.

HPN328, a Trispecific T Cell-Activating Protein Construct Targeting DLL3-Expressing Solid Tumors.

Delta-like ligand 3 (DLL3) is expressed in more than 70% of small cell lung cancers (SCLCs) and other neuroendocrine-derived tumor types. SCLC is highly aggressive, and limited therapeutic options lead to poor prognosis for patients. HPN328 is a trispecific T cell-activating construct (TriTAC) consisting of three binding domains: a CD3 binder for T-cell engagement, an albumin binder for half-life extension, and a DLL3 binder for tumor cell engagement. In vitro assays, rodent models, and non-human primates were used to assess the activity of HPN328. HPN328 induces potent dose-dependent killing of DLL3-expressing SCLC cell lines in vitro, concomitant with T-cell activation and cytokine release. In an NCI-H82 xenograft model with established tumors, HPN328 treatment led to T-cell recruitment and anti-tumor activity. In an immunocompetent mouse model expressing a human CD3ε epitope, mice previously treated with HPN328 withstood tumor rechallenge, demonstrating long-term anti-tumor immunity. When repeat doses were administered to cynomolgus monkeys, HPN328 was well tolerated up to 10 mg/kg. Pharmacodynamic changes, such as transient cytokine elevation, were observed, consistent with the expected mechanism of action of T-cell engagers. HPN328 exhibited linear pharmacokinetics in the given dose range with a serum half-life of 78 to 187 hours, supporting weekly or less frequent administration of HPN328 in humans. Preclinical and nonclinical characterization suggests that HPN328 is a highly efficacious, safe, and novel therapeutic candidate. A phase 1/2 clinical trial is currently underway testing safety and efficacy in patients with DLL3-expressing malignancies.