Tumor Target Research Articles

Abstract 1806: Modulation of natural killer cell immune response to tumor with novel synthetic tumor -immune cell agonist, NK-TICA(r)

Abstract The tumor specific activation of natural killer (NK) cells with Bicycles is an area of active investigation in immune oncology. NK cells are highly responsive immune cells that can detect and eliminate tumor cells and bridge innate to adaptive immune responses. Bicycles are small (ca.1.5kDa), chemically synthetic, structurally constrained peptides discovered via phage display and optimized using structure-driven design and medicinal chemistry approaches. We have applied the Bicycle platform technology to discover and evaluate a new class of fully synthetic molecules termed NK tumor immune cell agonists (NK-TICA®). The NK-TICA® consists of chemically coupled Bicycles® that bind specifically to the key activating receptor, NKp46, and to tumor antigens, that results in highly potent, antigen-dependent receptor activation and NK cell activation. We demonstrate potent, selective binding of our Bicycles to receptor-expressing cells and the capability of the bifunctional molecule to induce NK cell function in vitro. With Bicycle’s novel NK-TICA® compound, we demonstrate the engagement of NK cells, the specific activation and function of NK cells, and enhanced tumor cytotoxicity in a tumor target- and dose-dependent manner. In conclusion, NK-TICAs drive NK cell-mediated tumor cell killing and cytokine production in vitro and as such have the potential to catalyze the development of durable anti-tumor immunity in tumor types not well served by current therapies. We hypothesize that utilization of Bicycle NK-TICA® as a multifunctional immune cell engager will promote the modulation of NK cells, as well as the infiltration and anti-tumor activity of NK cells in solid tumors. Citation Format: Fay Dufort, Christopher J. Leitheiser, Kathleen Ho, Tucker Ezell, Alexandra Rezvaya, Peter Brown, Liuhong Chen, Philip Brandish, Kevin McDonnell, Michael Skynner, Nicholas Keen. Modulation of natural killer cell immune response to tumor with novel synthetic tumor -immune cell agonist, NK-TICA(r) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1806.

Abstract 5037: DARPins as powerful targeting agents for radioligand therapeutics

Abstract The development of effective radioligand therapeutics (RLTs) is frequently hampered by the lack of high-quality targeting agents that selectively deliver radioactive payloads to the site of disease while sparing healthy tissues. Antibodies can have high affinity and specificity to tumor targets, but their large size results in limited tumor penetration and long systemic half-life is frequently causing haematological toxicities. Alternatively, targeting agents with low molecular weight such as small molecules and peptides often suffer from limited affinity and specificity to the tumor target, resulting in off-target effects and limited tumor retention. DARPins (Designed Ankyrin Repeat Proteins) developed by Molecular Partners combine small size (15 kDa) and ideal binding properties. Due to their rigid-body target binding mode DARPins combine very high affinity and specificity and unless engineered accordingly, DARPins have very short systemic half-lives. Thanks to a simple and robust architecture, DARPins can be efficiently coupled with radioactive payloads, even at elevated temperatures; and they can tolerate sequence-engineering approaches, which are not compatible with other protein scaffolds. To establish the DARPin platform for RLT, we have used DARPin candidates against different tumor targets. We have previously shown that increasing affinity to the tumor target correlates with elevated tumor uptake and long tumor residence in preclinical mouse models. We now also show that DARPins exhibit a homogeneous and deep tumor penetration in vivo that is highly superior to antibody benchmarks. Globular proteins below 60 kDa in size are typically cleared from the bloodstream via the renal pathway. This generally results in a strong kidney accumulation of small sized, protein-based targeting agents and their coupled residualizing radionuclides, leading to dose-limiting kidney toxicities. To overcome this limitation, we have undertaken an extensive engineering approach of the DARPin scaffold. Our results show that sequence engineering strongly reduces kidney uptake of DARPins without affecting their tumor uptake. This effect was confirmed with independent DARPin candidates suggesting a general applicability of the approach. Combined with other orthogonal strategies, we are able obtain favourable tumor to kidney ratios in preclinical mouse models. These results show that our proprietary optimized DARPin platform offers an attractive solution to the limitations of protein-based targeting agents for RLT applications. Together with the fact that high-affinity DARPins can be generated against a large variety of tumor targets, we conclude that our platform provides a powerful basis for the development of next-generation RLTs. Several DARPin-RLT programs in indications with high unmet medical need are currently in development. Citation Format: Andreas Bosshart, Stephan Wullschleger, Martin Behe, Alain Blanc, Stefan Imobersteg, Alexandra Neculcea, Jacqueline Blunschi, Liridon Abduli, Sarah Schütz, Julia Wolter, Christian Reichen, Amelie Croset, Alessandra Villa, Christian Lizak, Anne Goubier, Roger Schibli, Daniel Steiner. DARPins as powerful targeting agents for radioligand therapeutics. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5037.

Abstract 1242: Single cell multiomic map reveals regulatory landscape of human brain metastases

Abstract Capturing comprehensive brain metastasis landscape is critical to the establishment of effective anti-tumor strategies. This study took advantage of single-cell multiomics sequencing to profile the molecular and cellular dynamics in tumor cells and associated microenvironment during brain metastasis. Among different primary cancer types, our data suggest that there are conserved yet distinct tumor cell subpopulations, governed by specific changes in gene expression, chromatin accessibility and tumor-stroma interactions. We characterized the conserved tumor subpopulations of brain metastasis with features of: (1) dormancy, (2) enhanced translation and migration, (3) cell death and (4) high proliferation rate. Dormant tumor cells in brain metastasis appear to limit cell-cell interactions with the surrounding microenvironment. In line with previous observations, dormant cells exhibit distinct stimulation for interferon, oxidative phosphorylation and HIPPO signaling. Despite a pronounced cell plasticity, trajectory analysis uncovered a cell progression pattern and its major sequential states and driving genes. Importantly, the tumor trajectory provides new insights into the regulatory landscape controlling the transition from dormant to proliferating tumor cells. Our findings also point to a valuable use of matched isolated circulating tumor cells and cell-free DNA to map the molecular and cellular dynamics of brain metastases. This work demonstrated that despite a pronounced intratumoral heterogeneity, brain metastases present conserved tumor subpopulations regardless of the patient and primary type. A novel and key finding in this study is the multiomics characterization of the regulatory landscape shaping human brain metatastases. Thus, we believe further understanding of these key regulatory elements could lead to novel tumor targets with broad translational potential. Citation Format: Remi Klotz, Alexis Zukowski, Mohamed Kamal, Frank Attenelo, Srinivas Ramachandran, Min Yu. Single cell multiomic map reveals regulatory landscape of human brain metastases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1242.

Abstract 1149: Universal redirection of chimeric antigen receptor T cells against solid tumors via tumor cell membrane-inserting CAR ligands

Abstract Chimeric antigen receptor (CAR) T cell therapy is effective in treating certain hematological malignancies, but its translation to solid tumors has been challenging. Selecting an effective target antigen is hampered by heterogeneous tumor antigen expression and target antigen expression in healthy tissues. We describe a strategy to promote CAR T-mediated destruction of any tumor via intratumoral administration of a membrane-inserting fluorescein isothiocyanate lipid amphiphile molecule (“amph-FITC”) recognizable by a FITC-specific CAR. Firstly, we show labeling of tumor cells with amph-FITC in vitro, mediating cytotoxicity by FITC CAR T cells in coculture. Then, we demonstrate efficient tagging of tumor cells in vivo upon intratumoral injection with minimal labeling of non-tumor tissues, driving FITC CAR T cell proliferation and accumulation in tumors. Subsequently, we determine that this strategy stimulates an anti-tumor response that facilitates tumor regression in several syngeneic and human xenograft mouse models bearing different tissues of origin. In syngeneic models, this strategy induced the infiltration of host T cells and elicited endogenous tumor-specific T cell priming, leading to protection against tumor rechallenge. These results demonstrate the capacity to treat tumors independent of antigen expression or tissue of origin, addressing a major bottleneck in adoptive T cell therapy. Citation Format: Angela Zhang. Universal redirection of chimeric antigen receptor T cells against solid tumors via tumor cell membrane-inserting CAR ligands [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1149.

Abstract 6377: A translatable tumor-killing platform with robust sensitivity towards immune checkpoint inhibitor targeted therapeutics

Abstract The cancer treatment landscape has transformed following the clinical success of early immune checkpoint inhibitors (ICI) which demonstrate the remarkable power of harnessing the immune system to treat a variety of metastatic cancers. Despite the success of Pembrolizumab, Nivolumab and Atezolizumab, the programmed cell death protein-1 (PD1)-programmed death ligand-1/2 (PD-L1/L2) pathway remains a tractable target for many drug discovery programs, particularly for bi-specific or combinational therapies. The PD1 - PD-L1/L2 pathway is important in protecting the host from uncontrolled immune responses, but can be hijacked by tumors, rendering them resistant to immune attack. Antibodies which antagonize this pathway potentiate T-cell mediated tumor destruction yet do not show efficacy in all patients or guarantee long-term protection, in part due to tumor-associated ICI-resistance mechanisms. There is a distinct need to develop novel ICI therapeutics and robust, complex co-culture platforms to better predict clinical efficacy. Here we outline a series of translationally relevant co-culture assays using Pembrolizumab as a benchmark therapeutic alongside other ICI. PD-1 expression levels are known to be low on resting T cells, as indeed are many checkpoint receptors, and so to enhance the therapeutic window, CD3+T cells from healthy human donors were polyclonally stimulated before addition to SK-OV-3 target cell cultures. The SK-OV-3 tumor line was stably transduced with NucLight Red (NLR) to allow co-localization of the caspase 3/7 signal to tumor cells. Autologous, mature monocyte-derived dendritic cells (moDC), expressing high levels of PD-L1/PD-L2 were added into tri-cultures in a 2D tumor killing assay. Tumor killing kinetics were quantified via live cell imaging using an Incucyte S3. Although Pembrolizumab enhanced immune-mediated direct (pre-stimulated) T cell killing, the therapeutic window increased in the presence of autologous moDC. Using a modified 3D (tumor spheroid) format over a longer time course, Pembrolizumab was also shown to enhance PBMC-mediated killing and the ability of moDC to enhance this effect further was determined. In recent years, the development and implementation of combinatorial approaches has resulted in significant improvements in patient responsiveness and disease outcomes for various cancers. Here, we describe a suite of tumor killing assays which can be adapted to multiple tumor or therapeutic targets, with a focus on immune involvement. ICI are shown to work robustly and efficacy tracks expression of the relevant checkpoint receptors, making this a powerful format in which to test combination therapies or novel ICI. Citation Format: Marie Carkill, Kaitlin Mitchell, Lauren Kelsey, Jezrom Self-Fordham, Nunan Robert, Louise Brackenbury. A translatable tumor-killing platform with robust sensitivity towards immune checkpoint inhibitor targeted therapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6377.

Abstract 6715: CLIC1 and CLIC4 ion channels as bioelectric targets for tumor treating fields in pediatric high-grade glioma

Abstract Background: High Grade Glioma is a lethal brain cancer with an average survival of 14 months. Due to the scarcity of effective treatment, and aggressive nature of the tumor, pediatric High Grade Glioma (pHGG) forms a leading cause of CNS cancer-related death in children. Optune™ is a non-invasive therapy that uses alternating electric fields - coined Tumor Treating Fields (TTFields) - to disrupt cancer cell division. Increasing evidence shows that ion channels not only regulate electrical signaling of excitable cells, but also play a crucial role in the development and progression of brain tumors. Ion channels are essential in cell cycle control, invasion and migration of cancer cells and therefore present as valuable therapeutic targets. Methods: CLIC channel expression patterns were identified via multivariate analysis of in-house and publicly available data sets and RNA sequencing of in-house patient tissues. siRNA depletion of CLIC1 and CLIC4 was assessed using cell cycle, clonogenic, migration and proliferation assays, alone and concomitant with TTFields and or CLIC channel inhibitors, IAA94 or metformin. Whole transcriptome gene expression analysis (Human Clariom™ Array) of pHGG cells treated with TTFields was carried out. Whole cell and cell attached patch clamp protocols were used to assess ion channel activity in pHGG and normal astrocytes. Results: Clinical correlation determined that CLIC4 and CLIC1 deficiency was associated with increased overall survival (p=<0.03), with siRNA depletion propagating a reduction in the proliferation, migration and invasion of pHGG cell lines associated with cell cycle arrest. Furthermore, CLIC1 and CLIC4 deficiency exacerbated the killing capacity of TTFields, reducing clonogenic and proliferative capabilities. Concomitant application of either IAA94 or metformin, and TTFields increased the sensitivity of cells to TTFields. Whole transcriptome gene expression analysis of pHGG cell lines treated with TTFields and found that cells treated with TTFields exhibited a down-regulation in CLIC1 and CLIC4 compared to untreated cells. Furthermore, neurophysiological patch clamp experiments revealed increasingly depolarized membrane potential readings in pHGG cell lines compared to normal astrocytes, with unique ion channel activity (including chloride channel function) observed and the potential for further pharmacological exploitation. Conclusions: These data provide rationale that genetic, electrical, and pharmacological manipulation of ion channels can reduce the capacity of childhood brain tumors to proliferate and invade. CLIC channels may be a suitable target to enhance the treatment efficacy of TTFields and help optimize this non-invasive therapy in pediatric HGG patients. Citation Format: Michaela Griffin, Paul Smith, Raheela Khan, Surajit Basu, Stuart James Smith. CLIC1 and CLIC4 ion channels as bioelectric targets for tumor treating fields in pediatric high-grade glioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6715.

Abstract 2960: The novel trifunctional anti-BCMA NK cell engager SAR’514 has potent in-vitro, in-vivo and ex-vivo anti-myeloma effect through dual NK cell engagement

Abstract Multiple Myeloma (MM) is the second most prevalent hematopoietic malignancy, representing 10% of total blood cancers. Despite the emergence of new therapies, it is still an incurable disease. Safe, potent and innovative approaches with long lasting beneficial effects are required. BCMA (B Cell Maturation Antigen) is a cell surface receptor selectively expressed on normal and malignant plasma cells and promote cell proliferation and survival upon binding of its ligands APRIL (A PRoliferation Inducing Ligand) and BAFF (B cell Activating Factor). BCMA expression is highly prevalent on myeloma tumor cells and is maintained after standard of care treatments such as anti-CD38 therapies, or even BCMA-targeting agents (Cohen AD et al. J Clin Invest 2019). The ability of NK cells to intrinsically kill tumor cells, leaving healthy cells unharmed, with minimal pro-inflammatory cytokine release induction as compared to T cell-based therapies makes NK cells ideal immune cells for a safe and efficacious therapeutic approach. We developed SAR’514, a trifunctional NK Cell Engager (NKCE) that activates NK cells through a dual engagement of NKp46 and CD16a, two major NK cell activating receptors highly expressed on NK cells in MM patients, and which redirects the activated NK cells to engage and kill BCMA+ tumor cells. We demonstrated that SAR’514 NK dual engagement was more potent than the single NK engagement with NKp46 or CD16a as well as the combination of NKp46 and CD16a engagement. SAR’514 leads to NK cell activation, degranulation and release of effector cytokines only in the presence of BCMA+ tumor cells. This antitumor activity is associated with very low IL-1β, IL-6, TNFα and IFNγ cytokine release as compared to a T cell engager targeting the same BCMA antigen, in PBMC and in whole blood settings in the presence of BCMA+ tumor target cells. In addition, the in vivo anti-tumor activity of an anti-murine NKp46 surrogate NKCE molecule was investigated in huFcgR transgenic mice engrafted with the EL4-huBCMA murine thymoma model. SAR’514 induced a significant mouse survival at 0.5 to 5 mg/kg with an overall survival of 90% as compared to the control group in which only 20% of mice survived. Importantly, SAR’514 exhibits ex vivo efficacy using bone marrow mononuclear cells (BMMC) from MM patients in an autologous setting showing an active and efficient primary MM cell killing against MM cells from patients that have failed diverse therapies, including standard of care treatments. In summary, these results demonstrate the efficacy of SAR’514 for controlling MM tumors in vivo and ex vivo, and provide consistent support for its clinical development. Citation Format: Alexandre Tang, Laurent Gauthier, Jochen Beninga, Benjamin Rossi, Nicolas Gourdin, Audrey Blanchard-Alvarez, Céline Amara, Jacqueline Courta, Alexandra Basset, Dorothée Bourges, Alexandre Desjonqueres, Emmanuelle Menoret, Catherine Pellat-Deceunynck, Philippe Moreau, Yannis Morel, Marielle Chiron, Eric Vivier, Angela Virone-Oddos. The novel trifunctional anti-BCMA NK cell engager SAR’514 has potent in-vitro, in-vivo and ex-vivo anti-myeloma effect through dual NK cell engagement [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2960.

Abstract 5199: B7-H3 & PD-L1 double-humanized BALB/c mouse: a novel animal model for preclinical studies of human B7-H3 antibodies or bispecific antibodies

Abstract Immune checkpoint molecule B7-H3, also known as CD276, is a member of the B7-CD28 family of immunomodulatory proteins. It is a type I membrane protein with sequence similarities to the extracellular domain of programmed death-ligand 1 (PD-L1). B7-H3 is highly expressed in most human cancers, but has limited distribution in normal tissues, remaining elusive of its receptor. Due to its promising safety as a dominant tumor target, various strategies have been developed to modulate the effect of B7-H3 via monoclonal antibodies, bispecific antibodies, ADC, or CAR-T. To study the effect of these therapies in an immunocompetent mouse model, we established a double humanized B7-H3 and PD-L1 mouse model on BALB/c background (BALB/c-hB7-H3/hPD-L1). In this model, the extracellular domain of murine fragments was replaced by the human counterparts while the trans-membrane and cytoplasmic domain were kept intact. When engrafted with CT26 colon cancer cells, which stably overexpress human B7-H3 and PD-L1 while endogenous murine counterparts were knocked out, the tumor growth was inhibited certain degree by anti-B7-H3 antibody (8H9 Biosimilar, 20mpk, TGI=18.56%) treatment while inhibited significantly after the monotherapy of anti-PD-L1 (Tecentriq, 3 mpk, TGI=55.89%, p<0.001). The same dosage combination of anti-B7-H3 and anti-PD-L1 had a significant inhibition on tumor growth (TGI=76.85%, p<0.001), and had a synergistic effect (CDI<0.7) compared with the monotherapy. Analysis of tumor-infiltrating lymphocytes (TILs) at the end of the efficacy study showed that the proportion of CD45+ immune cells was significantly increased in all of the treated groups. The NK cells were significantly increased and the Treg cells were significantly decreased especially in the combined treatment group. Based on the above, the B7-H3 and PD-L1 double humanized mouse model is suitable for the pre-clinical evaluation of mono or combined immune checkpoint blockade with anti-human B7-H3 and PD-L1 therapy. Citation Format: Shiying Guo, Lingyu Song, Xin Qin, Jianming Xu, Hongyan Sun, Cunxiang Ju, Hongyu Wang, Santi Suryani Chen, Zhiying Li, Mark Wade Moore, Jing Zhao, Xiang Gao. B7-H3 & PD-L1 double-humanized BALB/c mouse: a novel animal model for preclinical studies of human B7-H3 antibodies or bispecific antibodies. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5199.

Abstract 5668: Using clinical utility index (CUI) to determine the optimal biological dose of a nonfucosylated anti-TIGIT antibody: A proposed alternative to maximum tolerated dose (MTD)

Abstract SEA-TGT is a human nonfucosylated monoclonal antibody (mAb) targeting the T cell immunoreceptor with immunoglobulin (Ig) and ITIM domains (TIGIT) protein. TIGIT is an immunoregulatory receptor expressed on activated and memory T cells, Tregs, and NK cells. TIGIT binding to CD155 and CD112 on tumor cells drives an inhibitory signal resulting in decreased T cell functionality. TIGIT targeting has been reported to release these inhibitory signals, drive Treg depletion, augment CD8+ T cell generation, and promote anti-tumor responses. SGNTGT-001 (NCT04254107) is a phase 1 clinical trial that evaluated the safety and tolerability of SEA-TGT as monotherapy in solid tumors and lymphomas at doses ranging from 0.01 to 6 mg/kg. Because an MTD was not identified in dose escalation, pharmacokinetic (PK) and pharmacodynamic (PD) endpoints were measured to assess biological activity and inform dose selection. The biological activity of SEA-TGT as monotherapy was compared across different dose levels using a clinical utility index (CUI), which mathematically integrated multiple clinically-meaningful PK and PD endpoints into a single readout. PD endpoints included NK and CD8+ T cell proliferation, maintenance of overall peripheral CD8+ T cell numbers, depletion of peripheral regulatory T cells, and peripheral target engagement. The PK endpoint was pharmacokinetic linearity. Surrogates of predicted tumor efficacy metrics included tumor target engagement and formation of the TIGIT:SEA-TGT:Fc receptor gamma (FcγRIIIa) trimer complexes in the tumor. An increase in the CUI score, representing an increase in biological activity, was observed during dose escalation, with an apparent plateau between the 0.3 and 6.0 mg/kg levels. Based on safety signals at 6 mg/kg and PK variability at lower doses, 1 and 3 mg/kg were of most interest for further evaluation. Both 1 and 3 mg/kg represented biologically active dose levels as they showed PK and PD activity that were within desirable ranges and had similarly high overall CUI scores relative to all doses evaluated. Dose selection for SEA-TGT was based on biological activity as assessed via PK/PD endpoints and integrated into a CUI model. Based on the totality of clinical data and the CUI results from monotherapy dose escalation from SGNTGT-001, the SEA-TGT dose of 1 mg/kg was determined to be the lowest biologically active dose with acceptable safety and tolerability. Citation Format: Gabriela Patilea-Vrana, John Harrold, Joseph A. Ware, Shaparak Lonning, Hun Lee, Lisa Brooks, Haley Neff-LaFord, William D. Hanley, Andres Forero-Torres. Using clinical utility index (CUI) to determine the optimal biological dose of a nonfucosylated anti-TIGIT antibody: A proposed alternative to maximum tolerated dose (MTD). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5668.

Abstract 6174: ATX-101, a peptide drug targeting PCNA, enhances the effect of gemcitabine in liposarcoma and leiomyosarcoma

Abstract Soft tissue sarcomas are heterogeneous mesenchymal neoplasms and account for 1% of all cancers in adults. Over 50 sarcomas subtypes have been classified and many have very limited treatment options which include surgery, chemotherapy and radiation. Two of the most common sarcomas are liposarcoma and leiomyosarcoma which are often treated with chemotherapies such as doxorubicin, dacarbazine and gemcitabine with low response rates. There is now more than ever an urgent need for new therapies for sarcoma. PCNA (Proliferating Cell Nuclear Antigen) is considered to be a key regulator of DNA and cell cycle control. In addition, it has been implicated to have roles in metabolism, cellular signaling and some immunological functions. PCNA forms complexes with proteins bearing a novel PCNA-interacting Peptide Motif called APIM (AlkB homolog 2 PCNA Interacting Motif). This binding usually occurs during stress responses such as those achieved during cancer therapy or cancer development. By preventing stress proteins from repairing or defending themselves, cancer therapies can be made more effective. We examined the in vitro effects of ATX-101, a PCNA-APIM protein interaction blocking peptide, on liposarcoma cell lines LS141, DDLS, SW872, 93T449 and 94T778 and leiomyosarcoma cell lines SK-LMS, SK-UT1 and SK-UT-1B. Cell survival, as measured by cell proliferation assays, indicated IC50s of 7.5-15µM with ATX-101. Enhanced combination effects with ATX-101 and chemotherapies such as doxorubicin, irinotecan and gemcitabine were also observed by proliferation assay. Synergism, with ATX-101 and gemcitabine, was indicated with SynergyFinder analysis. Cell cycle changes exhibited increases of S and G2 phases when treated with ATX-101 and gemcitabine. This correlated with increase of cell cycle proteins, cyclin B1 and cyclin A2. Western blot observations included increase of apoptotic marker, cleaved caspase 3, and DNA damage marker, pH2A.X. In addition, immunofluorescence assay showed increasing pH2A.X with ATX-101 and gemcitabine. In vivo studies revealed ATX-101 enhanced gemcitabine decrease of tumor volume in leiomyosarcoma cell line xenograft, SK-UT1. Tumor target inhibition by western blot showed increased pH2A.X and cleaved PARP along with decreased RAD51 API protein with combination treatment. Taken these observations and results, there is strong evidence of combining gemcitabine with ATX-101 in liposarcoma and leiomyosarcoma. Citation Format: Elgilda Musi, Tahir Sheikh, Matthew Ingham, Sminu Bose, Gary K. Schwartz. ATX-101, a peptide drug targeting PCNA, enhances the effect of gemcitabine in liposarcoma and leiomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6174.

Abstract 6334: VBI-002, a CD47xICAM-1 bispecific antibody for the treatment of hepatocellular carcinoma, melanoma and non-small cell lung cancers

Abstract Intercellular Cell Adhesion Molecule 1 (ICAM-1, CD54) is a type I transmembrane protein and a member of the immunoglobulin superfamily. ICAM-1 is involved in many key processes such as cell-cell interactions, signal transduction and leukocytes trans-endothelial migration. ICAM-1 is constitutively present at low levels on healthy tissues but highly expressed in some hematological cancers and solid tumors, making it an attractive tumor target. VBI-002 is a novel human IgG1 based CD47xICAM-1 bispecific antibody with excellent safety profile and potent single agent activities in xenograft models of lymphoma, multiple myeloma and some solid tumors (Cancer Res 2022;82(12_Suppl):Abstract nr 3430). The bispecific design allows VBI-002 to selectively block CD47/SIRPα binding in tumor cells with high ICAM-1 expression. In contrast to the benchmark CD47 monoclonal antibody, VBI-002 exhibits minimal red blood cell binding and does not cause hemagglutination. In non-human primate (NHP) safety study, four weekly doses of 60 mg/kg VBI-002 were well-tolerated with only mild and reversible reduction in hemoglobin and platelets. Here we further investigate the anti-tumor activities of VBI-002 in solid tumors. Gene expression analysis suggested that ICAM-1 is highly expressed in non-small cell lung cancers (NSCLC), melanoma and a subset of hepatocellular carcinoma. Flow cytometry studies confirmed the frequent co-expression of ICAM-1 and CD47 in these tumors. VBI-002 has potent ICAM-1 dependent SIRPα blocking, antibody-dependent cellular phagocytosis and antibody-dependent cellular cytotoxicity activities against cell lines of NSCLC, hepatocellular carcinoma, and melanoma. Furthermore, in vivo efficacy studies demonstrated that VBI-002 has potent single agent activities in cell line derived xenograft (CDX) models of NSCLC, hepatocellular carcinoma, and melanoma. Weekly dose of 20 mg/kg VBI-002 is sufficient to stop tumor growth or drive tumor regression in most models. Notably, VBI-002 is highly effective against NSCLC CDX models carrying Kras mutation and it synergizes with paclitaxel to provide additional anti-tumor activity. In conclusion, VBI-002 is a versatile novel CD47xICAM-1 bispecific antibody with potent single agent activity in various solid tumors and combined well with standard of care chemotherapies for added activity. Thus, VBI-002 warrants clinical evaluations as a single agent and in combination with standard of care chemotherapies. Citation Format: Oi Kwan Wong, Xinhua Wang, Leonard Post, Xiaocheng Chen. VBI-002, a CD47xICAM-1 bispecific antibody for the treatment of hepatocellular carcinoma, melanoma and non-small cell lung cancers. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6334.

Abstract 2941: ROR1 targeted 4-1BB costimulatory bispecific antibody, ABL102, exhibits potent in vitro and vivo antitumor activity and superior safety profile

Abstract ROR1, a member of the ROR (Receptor Tyrosine Kinase-Like Orphan Receptor)-family, is overexpressed in the process of embryo and fetal development, and controls cell polarity, cell migration and neurite growth. The expression is gradually reduced as development progresses, and it is hardly expressed in adults, but the overexpression of ROR1 is observed in various blood and solid cancer cells, so it is classified as an oncofetal gene. ABL102, a First-in-Class bispecific antibody targeting ROR1 and 4-1BB, elicits superior T cell activation by tumor specific T cell engagement through ROR1 dependent 4-1BB clustering. Our data showed that tumor target dependents binding of ROR1 and costimulatory 4-1BB by ABL102 induced 4-1BB activation in cell-based 4-1BB bioassay. ABL102 lead to IFN-γ secretion and tumor cell killing with a ROR1 dependent manner in co-culture assay with tumor cells and human PBMC. In h4-1BB knock-in mouse model bearing hROR1-expressing tumors, ABL102 potently inhibited tumor progression with a high rate of complete remission (CR). Mice with CR were further protected from the rechallenge of previously exposed tumors after 3 months of cessation of ABL102 treatment, implicating that immunological memory might be generated. In 4-week pilot toxicity study using cynomolgus monkeys, no ABL102-related toxicity was observed up to 100mg/kg, including mortality, body weight, hematology, liver toxicity, clinical chemistry and pathology, indicating a favorable safety profile. In conclusion, ABL102 exhibited potent in vitro and vivo anti-tumor activity and it was well tolerated and safe in the NHP toxicity study. These results strongly suggest that ABL102 is promising therapeutics for ROR1 positive cancer patients. Citation Format: Yangsoon Lee, Kyeong-Su Park, Wonjun Son, Sora Kim, Hyunseong Youn, Jiseon Yoo, Hanbyul Lee, Jonghwa Won. ROR1 targeted 4-1BB costimulatory bispecific antibody, ABL102, exhibits potent in vitro and vivo antitumor activity and superior safety profile [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2941.

Abstract 2962: ASP2138, a novel 2+1 format, claudin 18.2 x CD3 bispecific antibody, demonstrates selectivity and activity in preclinical cancer models

Abstract Claudin 18.2 (CLDN18.2) is a member of the claudin family of proteins that are involved in the formation of tight junctions in epithelia and endothelia. In normal tissue, CLDN18.2 is expressed exclusively on gastric epithelial cells. CLDN18.2 expression is maintained during malignant transformation of gastric epithelia. In addition, it is aberrantly expressed in other tumor types, including esophageal, pancreatic, and lung adenocarcinomas. Thus, CLDN18.2 is considered to be an attractive tumor target antigen for antibody-based cancer immunotherapy. ASP2138 is an immunoglobulin G (IgG)-based, asymmetric 2+1 format, T-cell bispecific antibody comprising bivalent humanized anti-CLDN18.2 antigen-binding fragments and a monovalent anti-CD3 single-chain variable fragment. CD3 is a surface protein complex expressed on all T-cell populations and its clustering causes T-cell activation. Therefore, CD3 bispecific antibodies allow for simultaneous engagement with both CD3 and a tumor-associated antigen (TAA), resulting in retargeting of cytotoxic T cells specifically against TAA-positive tumor cells in a human leukocyte antigen-independent manner. ASP2138 is in development for the treatment of patients with CLDN18.2-positive gastric or gastroesophageal junction adenocarcinoma or pancreatic adenocarcinoma, and is being evaluated in an ongoing phase 1/1b clinical trial (NCT05365581). In this study, ASP2138 demonstrated selective binding to CLDN18.2 and CD3 without binding to other homologs and isoforms of CLDN18.2. Cytotoxicity and T-cell activation of ASP2138 were assessed using CLDN18.2-expressing tumor cells in combination with human peripheral blood mononuclear cells (PBMCs) as effector cells in a redirected T-cell cytotoxicity assay in vitro. ASP2138 showed cytotoxicity against CLDN18.2-expressing gastric or pancreatic cancer cells and increased interferon-gamma production and expression of T-cell activation markers. The cytotoxic activities were dependent on the effector cell to target cell ratio and CLDN18.2 expression on tumor cells. ASP2138 exhibited an antitumor effect on human CLDN18.2-expressing gastric cancer in a human PBMC-engrafted NOG mouse model in vivo. In summary, ASP2138 is expected to show a clinical effect through cytotoxicity against CLDN18.2-expressing tumor cells by T-cell activation that results from selective binding to CLDN18.2 and CD3. Citation Format: Taisuke Nakazawa, Hiroaki Tanaka, Aya Kikuchi, Rumana Rashid, Kendra N. Avery, Jing Qi, Alex Nisthal, Masashi Shimazaki, Kenna Shirasuna. ASP2138, a novel 2+1 format, claudin 18.2 x CD3 bispecific antibody, demonstrates selectivity and activity in preclinical cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2962.

Abstract 6318: Preclinical characterization of ARX305, a next-generation anti-CD70 antibody drug conjugate for the treatment of CD70-expressing cancers

Abstract CD70 has emerged as an attractive tumor target with its over-expression in multiple solid and hematological cancers, yet tightly controlled and limited expression in normal cells. In the last decade, multiple anti-CD70 antibody drug conjugates (ADCs) have been developed, but most, if not all, of these ADC programs have been discontinued. Using an expanded genetic code to create Engineered Precision Biologics (EPBs), Ambrx has developed ARX305, a CD70-targeted next-generation antibody drug conjugate (ADC) to potentially overcome the challenges associated with earlier ADCs and treat patients with cancers over-expressing CD70. ARX305 is comprised of a proprietary, high-affinity, humanized anti-CD70 antibody stably and site-specifically conjugated to AS269, a potent microtubule inhibitor. After binding to CD70 expressed on target tumor cells, ARX305 internalizes and releases the cytotoxic payload pAF-AS269 which inhibits cellular proliferation. In vitro testing across a panel of solid and liquid tumor cell lines showed ARX305 elicited highly potent and specific cell killing across multiple tumor types with medium to high CD70 expression levels. In multiple in vivo CD70-expressing xenograft or disseminated models, ARX305 induced significant tumor growth inhibition or regression whereas unconjugated antibody exhibited poor activity. ARX305 utilizes stable oxime conjugation chemistry, a non-cleavable PEG linker, and a membrane-impermeable payload to minimize premature payload release in circulation and associated off-target toxicity. These properties of ARX305 result in high serum stability, with rodent pharmacokinetic studies confirming a similar exposure profile of ARX305 compared to unconjugated antibody and a long serum half-life. Repeat dose toxicokinetic studies in cynomolgus monkeys demonstrated ARX305 was tolerated at exposures well above therapeutic exposures in mouse pharmacology studies, indicating a wide therapeutic index. In summary, the highly potent anti-tumor activity in multiple tumor types and wide therapeutic index of ARX305 support clinical evaluation of this next generation anti-CD70 ADC. ARX305 is currently in a Phase 1 dose escalation study in China, and the IND in the United States is open. Citation Format: Lillian Skidmore, Jingjing Zhu, David Mills, Ting Jin, Suqin Li, Keith Tatsukawa, Nick A. Knudsen, Liying Gong, Jay Nelson, Kari Cox, Amha G. Hewet, Jianing Wang, Tim Buss, Feng Tian, Gang Xia, Shawn Zhang. Preclinical characterization of ARX305, a next-generation anti-CD70 antibody drug conjugate for the treatment of CD70-expressing cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6318.

Abstract 3775: Multi-omic spatial analysis with simultaneous detection of small RNAs, mRNAs and proteins using the novel RNAscope™ Plus technology

Abstract Regulatory RNA molecules such as microRNAs (miRNA) and long non-coding RNAs play critical roles in regulating translation of mRNA to protein. Several miRNAs have been implicated in disease initiation and progression, especially in cancer. The regulatory mechanisms of miRNAs and other small RNAs such as antisense oligos (ASOs) and silencing RNAs (siRNA) have been exploited to develop oligonucleotide therapies for 1. undruggable targets, 2. achieving longer-term effects 3. rapid production of therapeutics and 4. lower drug development costs. These therapeutics have the promise to treat debilitating neurodegenerative diseases, rare and inherited disorders. RNA therapies are typically delivered as a part of nanoparticles or a viral vector. Regardless of the delivery mechanism, methods to understand the biodistribution of the vector, transgene expression and cell type identification in a spatial context is crucial to study the safety and efficacy of these therapies. Built on the flagship RNAscope technology, the RNAscope Plus assay can detect 1 small RNA and 3 mRNA targets using TSA-based fluorescent readouts and is compatible with the new fluorescent Vivid™ dyes. Fixed, fresh frozen samples and formalin fixed paraffin embedded (FFPE) tissues are supported by manual and automated workflows using the Leica Bond Rx system. We have leveraged this technology to investigate spatial expression profile of miRNA and associated RNA targets across different tissue types and applications. We can also combine protein detection using a target antibody to visualize cell-type specific markers. This assay was used to demonstrate expression of miRNAs and target genes implicated in tumor initiation, progression, and angiogenesis. Expression of miR-205, associated tumor target genes such as PanCK, PTEN and tumor suppressor TP53 was visualized in head and neck cancer tumors. Downregulation of tumor-suppressor, TP53 resulted in upregulation of miR-205 which downregulates PTEN expression. Pan-CK stained the tumor region in the tissue. Similarly, miR-155 expression was observed in niche areas within breast cancer, head and neck cancer and cervical cancer tumors. Expression of miR-155 demonstrated correlation with high VEGF expression suggesting its role in angiogenesis. This novel platform will enable researchers to visualize regulatory RNA simultaneously with target RNAs, cell-type and morphology markers in intact cells/tissues with single cell resolution. This technology can provide meaningful insights into disease pathology driven by miRNAs as well as assess biodistribution and efficacy of oligonucleotide therapeutics. Citation Format: Anushka Dikshit, Sayantani Basak, Sonali Deshpande, Manvir Sambhi, Li-Chong Wang, Maithreyan Srinivasan. Multi-omic spatial analysis with simultaneous detection of small RNAs, mRNAs and proteins using the novel RNAscope™ Plus technology. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3775.

Accurate and Fast Deep Learning Dose Prediction for a Preclinical Microbeam Radiation Therapy Study Using Low-Statistics Monte Carlo Simulations.

Microbeam radiation therapy (MRT) utilizes coplanar synchrotron radiation beamlets and is a proposed treatment approach for several tumor diagnoses that currently have poor clinical treatment outcomes, such as gliosarcomas. Monte Carlo (MC) simulations are one of the most used methods at the Imaging and Medical Beamline, Australian Synchrotron to calculate the dose in MRT preclinical studies. The steep dose gradients associated with the 50μm-wide coplanar beamlets present a significant challenge for precise MC simulation of the dose deposition of an MRT irradiation treatment field in a short time frame. The long computation times inhibit the ability to perform dose optimization in treatment planning or apply online image-adaptive radiotherapy techniques to MRT. Much research has been conducted on fast dose estimation methods for clinically available treatments. However, such methods, including GPU Monte Carlo implementations and machine learning (ML) models, are unavailable for novel and emerging cancer radiotherapy options such as MRT. In this work, the successful application of a fast and accurate ML dose prediction model for a preclinical MRT rodent study is presented for the first time. The ML model predicts the peak doses in the path of the microbeams and the valley doses between them, delivered to the tumor target in rat patients. A CT imaging dataset is used to generate digital phantoms for each patient. Augmented variations of the digital phantoms are used to simulate with Geant4 the energy depositions of an MRT beam inside the phantoms with 15% (high-noise) and 2% (low-noise) statistical uncertainty. The high-noise MC simulation data are used to train the ML model to predict the energy depositions in the digital phantoms. The low-noise MC simulations data are used to test the predictive power of the ML model. The predictions of the ML model show an agreement within 3% with low-noise MC simulations for at least 77.6% of all predicted voxels (at least 95.9% of voxels containing tumor) in the case of the valley dose prediction and for at least 93.9% of all predicted voxels (100.0% of voxels containing tumor) in the case of the peak dose prediction. The successful use of high-noise MC simulations for the training, which are much faster to produce, accelerates the production of the training data of the ML model and encourages transfer of the ML model to different treatment modalities for other future applications in novel radiation cancer therapies.

Abstract 2734: Modulation of resting T cell status to enhance transduction and CAR T expansion following exposure to CD8-targeted fusosomes

Abstract Introduction: Fusosomes are novel viral vectors pseudotyped with a modified paramyxovirus envelope targeting specific cell types. We have generated a CD8-targeted fusosome to deliver a CD19-directed chimeric antigen receptor (CAR) transgene to CD8+ T cells in vivo following intravenous (i.v.) injection. Although fusosomes are capable of genetically modifying resting T cells, modulation with chemical or biological agents may increase transduction and facilitate CAR T expansion. Here, we demonstrate that rapamycin and IL-7 enhance resting T cell transduction, and IL-7 supports the expansion of in vivo generated CAR T cells to increase anti-tumor efficacy. Methods: CD8a-targeted fusosome encoding GFP or CD19CAR transgene were generated. To measure the effect on transduction, T cells were pre-treated with IL-7 (15 ng/ml) or rapamycin (30 μM) prior to fusosome exposure. Transduction was assessed by flow cytometry and vector copy number after 7-10 days in culture. CAR T cell function and expansion were assessed in coculture assays with CD19+ Nalm6 tumor cells using live cell imaging. To measure anti-tumor efficacy with a combined fusosome and IL-7 approach, immunodeficient NSG mice were challenged i.v. with Nalm6 tumors expressing firefly luciferase (5E5 cells/mouse) on day -4, PBMC (1E7 cells/mouse) on day -1 followed by CD8/CD19CAR fusosome (1E7 IU/mouse) on day 0. IL-7 (1-5 μg/mouse) was administered subcutaneously twice weekly. Tumor growth was monitored by bioluminescence imaging. Results: CD8/CD19CAR fusosome were effective at transducing resting T cells. Pre-treatment with IL-7 alone resulted in a moderate increase in transduction efficiency (1.5x). In contrast, pre-treatment with both IL-7 and rapamycin further increased transduction efficiency (>5x). As IL-7 could also be used to support CAR T expansion, we tested whether IL-7 post-fusosome exposure could increase CAR T cell numbers and anti-tumor efficacy. In the absence of tumor targets, IL-7 promoted the expansion of CD8+ CAR T cells as well as non-transduced T cells. However, in the presence of tumor antigen, IL-7 treatment resulted in selective expansion of CAR T cells over bystander T cells (40x vs 10x, respectively) in vitro. Importantly, systemic IL-7 treatment following CD8/CD19CAR fusosome administration increased efficacy in Nalm6 tumor bearing NSG mice compared to those treated with fusosome only. Conclusion: T cell-targeted fusosomes encoding a CAR transgene potentially represent a novel, off-the-shelf therapeutic approach for cancer. This study demonstrates that modulation of the resting T cell state can increase susceptibility to fusosome-mediated transduction. The potency of CD8/CD19CAR fusosomes can be increased by pre-treatment of resting T cells with IL-7 and rapamycin to increase transduction or post-treatment with IL-7 to expand CAR T cells to increase anti-tumor efficacy Citation Format: Brian Dolinski, Vandana Chaturvedi, Daryl Humes, Christina Proano, Mariliis Ott, Jesus Moreno, Garrett Zipp, Aaron Lampano, Hadega Aamer, Ouwen Liang, Neal van Hoeven, Kutlu G. Elpek, Aaron E. Foster, Terry J. Fry. Modulation of resting T cell status to enhance transduction and CAR T expansion following exposure to CD8-targeted fusosomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2734.

Surface-Engineered Monocyte Immunotherapy Combined Graphene Quantum Dots Effective Against Solid Tumor Targets.

The immunosuppressive tumor microenvironment (TME) of solid tumors inhibits most drug delivery system-based nanomaterials from achieving deep penetration in tumor tissue and interferes with T cell activity in terms of differentiation and exhaustion, which is becoming a critical therapy hurdle for solid tumors. Therefore, developing a therapeutic strategy with abilities of rapid establishment of tumor-targeted cells, elimination of immune obstacles, and enhanced active immunization is very important, while is still a big challenge. A new strategy was explored to enhance immune therapy via the conjugation of microRNA155 (miR) to the surface of therapeutic monocyte with graphene quantum dots (GQDs). TME was reversed using surface-engineered monocyte immunotherapy via reprogramming pro-tumoral M2 TAMs into antitumor M1, and thus tumor elimination was dramatically enhanced. Such a surface-engineered monocyte immunotherapy has been demonstrated to be well tolerated to intravenous administration and bio-compatible, showing the potential to be extended for the solid tumor treatment.

Particle Reirradiation of Malignant Epithelial and Neuroectodermal Sinonasal Tumors: A Case Series from CNAO

Sinonasal cancers (SNCs) are rare and heterogeneous in histology and biological behavior. The prognosis is generally unfavorable, especially in inoperable cases. In recent years, for some histologies, such as undifferentiated sinonasal carcinoma (SNUC), multimodal treatment with a combination of induction chemotherapy, surgery, and chemo/radiotherapy (RT) has improved the prognosis. Nevertheless, still about half of the patients treated incur a recurrence, in most of the cases at the local site. Surgery with and without RT is usually the treatment choice in cases of recurrence after previous RT in combination with systemic therapy or RT in a histology-driven fashion. In the case of inoperable disease or contraindications to surgery, RT is still a valid treatment option. In this context, hadron therapy with protons (PT) or carbon ions (CIRT) is often preferred due to the physical and biological characteristics of charged particles, allowing the administration of high doses to the tumor target while sparing the surrounding healthy tissues and potentially limiting the side effects due to the high cumulative dose. In the absence of a standard of care for the recurrent setting, we aimed to investigate the role of re-RT with PT or CIRT. We retrospectively analysed 15 patients with recurrent, previously irradiated, SNCs treated at our institution between 2013 and 2020. Local control (LC) and overall survival (OS) were estimated by the Kaplan-Meier method. Acute and late toxicities were scored according to the National Cancer Institute's Common Terminology Criteria for Adverse Events CTCAE version 5.0. A total of 13 patients received CIRT and 2 patients received PT. The median re-RT dose was 54 GyRBE (range 45-64 GyRBE) delivered in 3 or 4 GyRBE/fr (fraction) for the CIRT, and 2 Gy RBE/fr for the PT schedule. LC was 44% at the 1-year follow-up and 35.2% at the 3-year follow-up. OS at 1 and 3 years were 92.9% and 38.2%, respectively. Fourteen patients developed G1-G2 acute toxicity (dermatitis and mucositis), and no patients developed G3-G5. Regarding late toxicity, 10 patients encountered at maximum G1-2 events, and 4 did not experience any toxicity. Only for one patient G3 late toxicity was reported (dysphagia requiring a percutaneous endoscopic gastrostomy).

Bronchoscopic Evaluation of a Steerable Needle for Simulated Tumor Targets in the Lung Periphery: A Feasibility Study (Bullseye)

Background: Peripheral bronchoscopy is often performed to biopsy peripheral pulmonary lesions. Despite technological advancements to improve reach and access to the lung periphery, the diagnostic yield of peripheral bronchoscopy has been inconsistent, and challenging, particularly for lesions that are adjacent to peripheral bronchi. Current biopsy instruments are reliant on the catheter or scope to align properly with targeted lesions. Objectives: This study evaluates the feasibility of using a steerable biopsy needle to gain access to peripheral tumor targets in a cadaveric model. Methods: Simulated tumor targets 10–30 mm in axial diameter were placed into human cadavers. Bronchoscopy was performed using a 4.2 mm OD flexible bronchoscope, CT-anatomic correlation, and multi-planar fluoroscopy for lesion localization. Once at the targeted location, a steerable needle was deployed and the needle position was determined to be in the central zone, peripheral zone, or outside of the lesion by cone beam CT imaging. If the needle position was within the lesion, a fiducial marker was deployed to mark the needle position, and the needle was articulated and/or rotated in an attempt to place another fiducial marker into a different location within the same lesion. If the needle was outside of the lesion, the bronchoscopist was provided with two additional attempts to gain access to the lesion. Results: Fifteen tumor targets were placed with a mean lesion size of 20.4 mm. The majority of lesions were located in the upper lobes. One fiducial marker was placed in 93.3% of lesions and a second fiducial marker was successfully placed in 80% of lesions. A fiducial marker was placed within the central zone in 60% of lesions. Conclusion: The steerable needle was successfully placed within 93% of targeted lesions 10–30 mm in diameter in a cadaveric model, with the ability steer the instrument into another portion of the lesion in 80% of cases. The ability to steer and control needle positioning toward and within peripheral lesions may complement existing catheter and scope technology during peripheral diagnostic procedures.