Peripheral Toxicity Research Articles

Construction and Characterization of Thermosensitive Hydrogel Loaded with Donepezil Nanosuspension and its Application for Transnasal Delivery

AbstractDonepezil (DPZ) is a reversible cholinesterase inhibitor used to treat Alzheimer's disease (AD), while with disadvantages such as gastrointestinal side effects after oral administration and poor adherence in the elderly. The purpose of this study was to develop a thermosensitive hydrogels loaded with donepezil nanosuspension (DPZ‐NS‐gel) for transnasal administration to improve brain targeting and reduce peripheral toxicity. The results of powder X‐ray diffraction and differential scanning calorimeter showed that the crystal type of DPZ changed from form II to form C during the grinding process. DPZ‐NS‐gel was obtained by mixing DPZ‐NS into the blank thermosensitive hydrogel constructed with poloxamer 407 and poloxamer 188. DPZ‐NS‐gel was in sol state at 25 °C and formed gel at 33 °C. Compared with DPZ‐NS, the in vitro release of DPZ‐NS‐gel showed the sustained release profile. In vivo studies indicated that DPZ‐NS‐gel by nasal administration may increase the amount of drug entering into the brain. The in vivo safety evaluation showed no severe inflammatory response and pathological change when DPZ‐NS‐gel was administered by nasal administration. This study provided a promising strategy for clinical application in improving the bioavailability of DPZ in the brain, avoiding oral‐induced gastrointestinal side effects and improving medication adherence in the elderly.

Prevalence and spectrum of manifestations of tamoxifen retinopathy as assessed by multimodal and ultra-widefield retinal imaging

Background/ObjectivesTamoxifen has well-known retinal toxicity, but the epidemiology of this toxicity is poorly defined. This study aims to 1) evaluate the prevalence of tamoxifen retinopathy in a major northeastern metropolitan area based on multimodal retinal imaging and 2) determine whether the additional peripheral retina captured in ultra-widefield (UWF) imaging aids in the diagnosis of tamoxifen retinopathy. MethodsThis retrospective cohort study examined female patients initiated on tamoxifen for at least 12 months prior to their first retinal exam. Two independent graders performed blinded review of spectral-domain optical coherence tomography (OCT) images for evidence of macular toxicity and UWF images for signs of central and peripheral toxicity. A one-tailed two-proportion Z-test determined whether peripheral pigmentary changes were more prevalent in the tamoxifen cohort than age- and gender-matched controls. Results241 eyes from 123 patients were included in the tamoxifen cohort, and 258 eyes from 132 patients were included in the control cohort. Two patients demonstrated definitive tamoxifen retinopathy, for a prevalence of 1.6%. One patient demonstrated crystalline maculopathy on OCT and UWF imaging, while another demonstrated pseudocystic cavitations on OCT imaging. Neither patient had peripheral findings on UWF imaging. Peripheral pigmentary changes were not significantly more prevalent in the tamoxifen cohort. ConclusionsThese findings suggest that UWF imaging does not contribute to diagnosis of tamoxifen retinopathy, and OCT may be the most valuable tool in diagnosing tamoxifen retinopathy. Our prevalence (1.6%) diverges from higher rates in studies screening with similarly advanced retinal imaging. Further large population studies are needed.

MB2033, an anti-PD-L1 × IL-2 variant fusion protein, demonstrates robust anti-tumor efficacy with minimal peripheral toxicity

Interleukin-2 (IL-2), a cytokine with pleiotropic immune effects, was the first approved cancer immunotherapy agent. However, IL-2 is associated with systemic toxicity due to binding with its ligand IL-2Rα, such as vascular leakage syndrome, limiting its clinical applications. Despite efforts to extend the half-life of IL-2 and abolish IL-2Rα interactions, the risk of toxicity remains unresolved. In this study, we developed the bispecific fusion protein MB2033, comprising a novel IL-2 variant (IL-2v) connected to anti-programmed death ligand 1 (PD-L1) via a silenced Fc domain. The IL-2v of MB2033 exhibits attenuated affinity for IL-2Rβγ without binding to IL-2Rα. The binding affinity of MB2033 for PD-L1 is greater than that for IL-2Rβγ, indicating its preferential targeting of PD-L1+ tumor cells to induce tumor-specific immune activation. Accordingly, MB2033 exhibited significantly reduced regulatory T cell activation, while inducing comparable CD8+ T cell activation to recombinant human IL-2 (rhIL-2). MB2033 induced lower immune cell expansion and reduced cytokine levels compared with rhIL-2 in human peripheral blood mononuclear cells, indicating a decreased risk of peripheral toxicity. MB2033 exhibited superior anti-tumor efficacy, including tumor growth inhibition and complete responses, compared with avelumab monotherapy in an MC38 syngeneic mouse model. In normal mice, MB2033 was safer than non-α IL-2v and tolerable up to 30 mg/kg. These preclinical results provide evidence of the dual advantages of MB2033 with an enhanced safety and potent clinical efficacy for cancer treatment.

Effect of a novel anti-PD-1-proIL-2 bifunctional fusion protein on potent anti-tumor activity via PD-1 checkpoint inhibition and conditional IL-2R agonism.

e14697 Background: HD IL-2 was approved by FDA for metastatic melanoma (mM) and renal cell carcinoma (mRCC) but the treatment is associated with severe toxicities. PD-1 blockade has improved the overall survival, but only in 20-30% of cancer patients and many of them experience frequent relapses. Interestingly, HD IL-2 therapy displayed durable anti-tumor activity in mM and mRCC patients who progressed on anti-PD-1. Furthermore, combination therapy of IL-2 and pembrolizumab in mRCC has shown durable 70% response rate, while the ORR of monotherapy is 20% and 33% for IL-2 and pembrolizumab, respectively. Thus, combining IL-2 receptor activation and PD-1 blockade may represent a promising strategy in the post PD-1 era to overcome the resistance and improve the clinical efficacy. PTX-912 is a novel bifunctional PD-1-proIL-2v fusion protein designed to simultaneously harness PD-1 blockade and PD-1-cis directed IL-2R agonism conditionally in TME without the peripheral toxicities associated with IL-2. Methods: The biological functions were demonstrated in human PBMC assays. Anti-tumor efficacy and biomarker studies were evaluated in mouse / human PBMC xenograft models. Tox studies were performed in NHP. Results: PTX-912 shows dose-dependent inhibition of PD-1 pathway measured by GM-CSF and IFNgamma production in an MLR assay. Protease activated PTX-912, but not the intact drug, stimulates the phosphorylation of STAT5 of NK and T cells, the proliferation of CD8 T cells as well as the cytokine production in human whole blood. The potency of pSTAT5 by protease activated product is enhanced by > 10 folds on PD-1+ T cells than T cells without PD-1. When tested in mouse tumor models resistant to PD-1 blockade, PTX-912 demonstrated high potency of tumor inhibition at as low as 0.1 mg/kg dose. In contrast, non-targeted proIL-2v at molar equivalent or higher dose showed minimal antitumor effect in either monotherapy or combination with anti-PD-1. Analysis of PTX-912 treated mice showed increased tumor infiltrating CD4+ and CD8+ T cells, including PD-1+Tcf-1+ and PD-1+ IL-18Ra+TIM3- CD8+ T cells, referred to “stem-like” progenitor effector cells and “better” effector cells, respectively. Activation of the IL-2v in PTX-912 was observed in mouse tumor tissues but not in the plasma. In monkey GLP-compliant 4-week repeat-dose toxicity study, PTX-912 demonstrated excellent safety profiles without overt irAEs that are characteristic of IL-2. Conclusions: Our preclinical data demonstrated that PTX-912 effectively stimulated the expansion and reinvigoration of antigen specific T cells in the tumor tissue resulting in strong anti-tumor efficacy while it did not cause significant peripheral toxicity. Phase 1 clinical trial of PD-1-proIL-2v is planned to start in early 2024 to evaluate the safety, pharmacokinetics and anti-tumor activity in patients with advanced solid tumors.

Update results of anlotinib combined with penpulimab and nab-paclitaxel as first-line treatment for advanced esophageal squamous cell carcinoma (ESCC): A single-arm, open-label phase II clinical trial.

e16017 Background: Recently, PD-1 blockades combined with dual chemotherapy in first-line setting exhibited encouraging efficacy for patients with ESCC. However, the safety profile of conventional dual chemotherapy remained unsatisfactory. Therefore, PD-1 blockades combined with anti-angiogenic tyrosine kinase inhibitors (TKIs) and single chemotherapy regimen might be a promising strategy. Anlotinib, a novel multitarget TKI primarily targeting VEGFR1-3, demonstrated promising therapeutic activity as first-line combination therapy or second-line monotherapy for patients with ESCC in China clinically. Therefore, this study was designed to explore the efficacy and safety of anlotinib combined with penpulimab (PD-1 blockade) and nab-paclitaxel as first-line therapy in advanced ESCC. Preliminary results were presented at the 2024 ASCO-GI Symposium (Abs 340), the consecutively updated results were presented in this report. Methods: Patients with previously untreated metastatic or locally advanced ESCC were recruited and treated with anlotinib (12mg, po, d1~14, q3w) and penpulimab (200mg, iv, d1, q3w) plus nab-paclitaxel (220mg/m2, iv, d1, q3w) until disease progression or unacceptable toxicity. The tumor response was assessed according to RECIST 1.1 using CT scans every two cycles. Adverse events were recorded by severity in accordance with the NCI CTC AE Version 5.0. The predefined sample size was 30. Primary endpoint was PFS and secondary endpoints included safety, ORR, DCR and OS. Results: From Jul 2022 to Dec 2023, a total of 27 patients were enrolled, 25 patients who had received first tumor response were included in this analysis. The best overall response indicated that there were 1 CR (4.0%), 18 PR (72.0%), 3 SD (12.0%) and 3 NE (12.0%). Therefore, the preliminary ORR was 76.0% (95%CI: 54.9%-90.6%), DCR was 88.0% (95%CI: 68.8%-97.5%). Median PFS of the 25 patients was not yet reached. Additionally, safety profile exhibited that the regimen was tolerable. The most common treatment-emergent adverse events among the 27 patients with the incidence > 20% were anemia (40.7%), peripheral nerve toxicity (37.0) and white blood cell decreased (25.9%). Common grade ≥3 treatment-emergent adverse events were white blood cell decreased (7.4%), diarrhea (3.7%), glutamic-pyruvic transaminase was elevated (3.7%), glutamic oxalacetic transaminase increased (3.7%), hypertension (3.7%) and immune enteritis (3.7%). Conclusions: The combination of anlotinib plus penpulimab and nab-paclitaxel as first-line therapy for advanced ESCC demonstrated promising efficacy and manageable safety profile. And the conclusions needed to be confirmed in subsequent trials.

Intranasal delivery of phenytoin loaded layered double hydroxide nanoparticles improves therapeutic effect on epileptic seizures

Improving the efficiency of antiseizure medication entering the brain is the key to reducing its peripheral toxicity. A combination of intranasal administration and nanomedicine presents a practical approach for treating epileptic seizures via bypassing the blood-brain barrier. In this study, phenytoin (PHT) loaded layered double hydroxide nanoparticles (BSA-LDHs-PHT) were fabricated via a coprecipitation − hydrothermal method for epileptic seizure control. In this study, we expound on the preparation method and characterization of BSA-LDHs-PHT. In-vitro drug release experiment shows both rapid and continuous drug release from BSA-LDHs-PHT, which is crucial for acute seizure control and chronic epilepsy therapy. In-vivo biodistribution assays after intranasal administration indicate excellent brain targeting ability of BSA-LDHs. Compared to BSA-Cyanine5.5, BSA-LDHs-Cyanine5.5 were associated with a higher brain/peripheral ratio across all tested time points. Following intranasal delivery with small doses of BSA-LDHs-PHT, the latency of seizures in the pentylenetetrazole-induced mouse models was effectively improved. Collectively, the present study successfully designed and applied BSA-LDHs-PHT as a promising strategy for treating epileptic seizures with an enhanced therapeutic effect.

Abstract 4070: CIS-demasking cytokine linker technology allows a selective cytokine delivery to activated immune cells while sparing others and peripheral toxicity

Abstract Immunocytokines are promising new therapeutic approaches to enhance T-cell response by delivering interleukins into the tumoral site. Fusion of wild-type or attenuated interleukins to anti-PD-1 antibody has shown some efficacy to preferentially cis-activate PD1-expressing T-cells but on-target/off-tumor activity on PD-1-negative cells is still observed due to the high affinity of the cytokine to its receptor leading a broad systemic effect, toxicity, high clearance and low tumor biodistribution limiting the potential of some immunocytokines (e.g. anti-PD-1/IL-2/IL-15/IL-21). Various strategies have emerged to achieve localized cytokine activation using conditional strategies (e.g. allosteric modulators, MMP-cleavable linkers or pH-dependent binding) that remain challenging due to high dependency to specific TME composition (MMP, acidosis...). We developed the OSE-Cytomask® Platform, a universal and innovative linker technology allowing exclusive cytokine CIS-demasking upon binding of the fused antibody to its target without TRANS-activation associated with undesired effects (e.g. Toxicity). A series of different linkers were screened for optimal cis-activation of cytokine on PD1-expressing vs PD1-negative T-cells using different cytokines fused to a high-affinity anti-PD1. OSE-Cytomask® linker technology decreases IL-2 or IL-15 cytokine activity (pSTAT5 signaling) on PD1-negative cells while maintaining high activation of PD1-transduced T-cells even in co-culture. We confirmed activity of OSE-Cytomask® Immunocytokine on (PD1+) human T-cells while very low activation has been observed in naïve T-cells. Importantly, Cytomask® linker technology does not induce TRANS-activation on PD1-negative T-cells illustrating an innovative and strict CIS-demasking mechanism of action. In vivo, Anti-PD-1/IL-15 and/or anti-PD1/IL-2 OSE-Cytomask® molecules illustrated reduced toxicity after single or multiple injections (2mg/kg). High T-cell proliferation has been observed in tumor-micro-environment where PD1-expressing T cells are located. Low T-cell proliferation in periphery was seen, illustrating the potential of CIS-demasking technology to target the right T-cells at the right place. Altogether, OSE-Cytomask® linker technology illustrates specific intrinsic property to mask cytokine on naïve peripheral immune cells not expressing the target of the antibody while allowing selective CIS-demasking of the cytokine and CIS-activation of activated immune cells expressing (e.g. PD-1). This linker technology could be used with a broad range of cytokine to abrogate OFF-tumor cytokine activity associated with toxicity while selectively CIS-activating activated immune cells in the TME. Citation Format: Aurore Morello, Caroline Mary, Virginie Thepenier, Margaux Seité, Justine Durand, Cécile Batty, Kévin Biteau, Julien Taurelle, Géraldine Teppaz, Amandine Georges, Nicolas Poirier. CIS-demasking cytokine linker technology allows a selective cytokine delivery to activated immune cells while sparing others and peripheral toxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4070.

Abstract 2475: MB5029: A novel anti-PD-1 x IL-2v with improved safety profile and enhanced anti-tumor efficacy by selectively targeting activated T cells

Abstract Interleukin-2 (IL-2) offers therapeutic potential for cancer treatment, however, its clinical application is limited due to systemic adverse effects, such as vascular leakage syndrome (VLS). Notably, the high affinity of IL-2 for the IL-2 receptor α (IL-2Rα) activates immune-suppressive Treg cells and endothelial cells, leading to undesired outcomes. To address this challenge, a number of clinical studies are under development including non-α IL-2 variant (IL-2v) drugs and further the anti-PD-1 x IL-2v for targeted delivery of its IL-2v to PD-1 enriched T cells. Nevertheless, concerns about peripheral toxicity have not yet been solved. Thus, here we present MB5029, a novel anti-PD-1 x IL-2v bispecific fusion protein with modulated IL-2R binding affinity to mitigate the peripheral toxicity maintaining the anti-tumor efficacy. MB5029 has unique characteristics with no binding affinity to IL-2Rα and reduced binding affinity to IL-2Rγ, which is widely and highly expressed in various immune cells. MB5029 exhibited strong STAT5 phosphorylation activity under activated conditions but weak activity in the resting conditions, while the anti-PD-1 x IL-2v (non-α) showed strong STAT5 phosphorylation in both resting and activated conditions. In addition, MB5029 strongly induced the expansion of CD8+ T cells in the activated conditions but less expansion of CD8+ T cells in the resting conditions, in contrast to anti-PD-1 x IL-2v (non-α). The murine surrogate of MB5029 showed remarkable anti-tumor efficacy without body weight loss at the dose range of 1 to 10 mg/kg, whereas anti-muPD-1 x IL-2v (non-α) showed significant body weight loss in several tumor-bearing mice models. Moreover, MB5029 showed 100% complete regression (6/6) at the dose of 5 mg/kg or higher in the MC38 tumor model. The mice with complete response showed no signs of relapse upon tumor re-challenge until day 56, indicating a durable memory response. MB5029 exhibited a comparatively superior safety profile in normal mice. While anti-muPD-1 x IL-2v (non-α) led to significant body weight loss at the dose of 5 mg/kg in normal mice, the murine surrogate of MB5029 was shown to be well-tolerated up to a dose of 30 mg/kg without body weight loss. MB5029 exhibited dose-proportional PK properties and induced expansion of CD8+ T cells in a dose-dependent manner in cynomolgus monkeys. MB5029 is shown to be well-tolerated up to 9 mg/kg without severe clinical signs and no significant increase in eosinophil and cytokines in the blood. Overall, MB5029 represents a promising potential as an immunotherapeutic approach, as it has demonstrated both strong efficacy and good tolerability, along with improved safety margins. Citation Format: Bom Park, Hyojoo Bang, So Woon Kim, Suna Kim, Sunjung Cho, Suyoon Kim, Minwoo Kim, Youngjin Park, Jun-Eui Park. MB5029: A novel anti-PD-1 x IL-2v with improved safety profile and enhanced anti-tumor efficacy by selectively targeting activated T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2475.

Abstract 6582: Preclinical characterization of IPH45, a novel topoisomerase I inhibitor ADC targeting Nectin-4 for the treatment of Nectin-4 expressing tumors

Abstract Background: Nectin-4 is a cell membrane adhesion protein overexpressed in several solid tumors, including urothelial, breast, lung, ovarian, and pancreatic cancers, with limited expression in normal tissues, making it an ideal target for antibody-drug conjugates (ADC). Enfortumab Vedotin (EV, PADCEV®) is an ADC targeting Nectin-4 with a monomethyl auristatin E (MMAE) payload approved for the treatment of patients with urothelial carcinoma (UC), but with limited clinical activity reported beyond UC. In addition, EV causes peripheral neuropathy and skin toxicity, leading to treatment discontinuation. To overcome these limitations and the mechanism of resistance to EV, IPH45, a novel topoisomerase I inhibitor ADC targeting Nectin-4 with an improved therapeutic index, was developed. Methods: In vitro studies were performed to investigate internalization, tumor cell killing and bystander effect, antibody-dependent cellular cytotoxicity (ADCC) and complement activation. In vivo efficacy studies were performed on cell line-derived xenografts (CDX) of triple negative breast cancer, patient-derived xenografts (PDX) of urothelial carcinoma and syngeneic tumor models expressing human Nectin-4. IPH45 efficacy was compared to EV. Toxicology studies to determine the dose range were conducted in rat and non-human primates (NHP). Results: IPH45 consists of a humanized IgG1 targeting a unique epitope in human Nectin-4, non-overlapping with EV, a cleavable linker, and a topoisomerase I inhibitor with a high drug-to-antibody ratio (DAR). In vitro, IPH45 is internalized upon binding to its target and induces direct killing of Nectin-4 expressing tumor cells as well as bystander killing of Nectin-4 non-expressing tumor cells in mixed culture. IPH45 mediates ADCC and complement-mediated killing. IPH45 demonstrates activity in CDX and PDX models with similar effective dose as EV. Moreover, IPH45 shows anti-tumor efficacy in vitro and in vivo in primary and secondary EV resistant models. In dose-range finding toxicology studies in rats and NHP, IPH45, unlike EV, does not elicit skin toxicity. IPH45 remains well tolerated up to the highest dose tested, suggesting a potentially larger therapeutic index than MMAE-based ADCs. Pharmacokinetic analyses in mice, rats, and NHP show minimal release of free toxin in the serum and half-life compatible with Q2W or less frequent dosing schedules in clinic. Conclusion: IPH45 is a topoisomerase I ADC targeting Nectin-4 with the potential for larger therapeutic index than EV, improved safety and dosing regimen, and ability to overcome primary and secondary resistance to EV or other Nectin-4 ADC in development. IPH45 is progressing to the clinic where the translatability of this unique profile into improved patient outcomes will be assessed across indications. Citation Format: Romain Remark, Cécile Bonnafous, Laura Chiossone, Caroline Soulas, Cyril Perrier, Guillaume Habif, Sivan Bokobza, Aurélie Maguer, Rachel Courtois, Julie Lopez, Grégory Fenaux, Olivier Benac, Barbara Carrette, Robin Letay-Drouet, Raja Bonifay, Séverine Augier, Léa Simon, Benjamin Rossi, Ariane Morel, Agnès Represa, Nicola Beltraminelli, Yannis Morel, Carine Paturel, Eric Vivier. Preclinical characterization of IPH45, a novel topoisomerase I inhibitor ADC targeting Nectin-4 for the treatment of Nectin-4 expressing tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6582.

Abstract 4072: Unleashing natural IL-18 activity using an anti-IL-18BP blocker antibody induces potent immune stimulation and anti-tumor effects

Abstract IL-18 is an inflammasome induced proinflammatory cytokine that augments T and NK cell activity and stimulates IFNγ production. The activity of IL-18 is naturally blocked by a high affinity endogenous binding protein (IL-18BP). IL-18BP is induced in the tumor microenvironment (TME) in response to IFNγ upregulation in a negative feedback mechanism. By evaluating 88 human tumor specimens and serum samples we were able to show that IL-18 is upregulated in the TME (median 11.2ng/gr) compared to serum samples (median 0.3ng/ml). Moreover, we showed that most of the IL-18 is bound by IL-18BP. IL-18BP-bound IL-18 levels were largely above the amount required for T cell activation in vitro (1.2ng/gr), implying that blocking IL-18BP has the potential to release IL-18 in tumors above the minimum range required for immune system stimulation. Next, to assess whether tumor endogenous IL-18 levels released by IL-18BP blockade are sufficient to provoke anti-tumor responses, COM503, a high affinity (<1pM) anti-IL-18BP Ab, was generated and examined in T and NK cell-based assays. In a co-culture assay of tumor cells with ex-vivo stimulated human tumor infiltrating CD8+ lymphocytes, COM503 was able to displace IL-18 from a pre-formed complex and enhance IFNγ (197%, p<0.01) and TNFα (84% p<0.01) secretion. Additionally, COM503 induced human NK cell activation as reflected by increased IFNγ secretion (26-fold, p<0.001). Finally, in human ex vivo dissociated tumor cells assay, COM503 mediated an increase in Granzyme B (25%), IFNγ (38%), TNFα (58%) and IL-12 (50%) production. In vivo, administration of an anti-mouse IL-18BP Ab resulted in potent anti-tumor responses and increased survival across multiple mouse tumor models. In orthotopic E0771 tumor model, anti-IL-18BP Ab induced significant tumor growth inhibition (91% TGI, p<0.0001), as well as pronounced TME-localized immune modulation. This modulation included an increase in CD8+ T cells expansion (108.5%, p=0.015) and activation, specifically in polyfunctional effector IFNγ+GrB+CD8+ T cells (259%, p=0.02) and IFNγ+TNFα+NK cells (77%, p=0.001). Similarly, anti-tumor effects were shown in MC38OVAdim model (58% TGI, p<0.001), accompanied by a robust TME-localized immune modulation including increased CD8+ T cells expansion (85%, p=0.009) and IFNγ secretion (76%, p=0.052). In contrast to immune modulation in the TME, no increase in inflammatory cytokines and lymphocyte numbers or activation state was observed in serum and spleen. Taken together, our data suggest that IL-18 is upregulated in the TME, mostly bound by IL-18BP, and could be exploited to induce pronounced TME-localized immune modulation. Anti-IL-18BP Ab approach has a leading edge in inhibiting tumor growth while avoiding peripheral toxicity associated with administration of a cytokine. COM503 is currently undergoing IND-enabling studies. Citation Format: Assaf Menachem, Zoya Alteber, Gady Cojocaru, Tal Fridman Kfir, Dan Blat, Olga Leiderman, Moran Galperin, Lital Sever, Nadav Cohen, Keren Cohen, Roy Zvi Granit, Sandra Vols, Masha Frenkel, Lior Faigenbloom, Liron Soffer, Karin Meyer, Keren Menachem, Hadas Galon Tilleman, Dina Morein, Itamar Borukhov, Amir Toporik, Michal Perpinial Shahor, Evgeny Tatirovsky, Pierre Ferre, Eran Ophir. Unleashing natural IL-18 activity using an anti-IL-18BP blocker antibody induces potent immune stimulation and anti-tumor effects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4072.

Abstract 2473: A novel anti-PD-1 and proIL-2 bifunctional fusion protein delivers potent anti-tumor activity via PD-1 checkpoint inhibition and tumor selective IL-2R agonism preferentially on antigen specific T cells

Abstract High-dose IL-2 (HD IL-2) induces complete and durable responses in RCC and melanoma but the treatment is associated with severe toxicities. PD-(L)1 blockade represents a recent breakthrough in immunotherapy with solid tumors, but only 20-30% of patients can benefit from the therapy and most responders eventually develop resistance. In more recent clinical studies with small number of subjects, HD IL-2 has shown promising responses in patients who progressed on anti-PD-1 therapy and combination therapy of HD-IL-2 and PD-1 blockade has resulted in high rate of objective response. In an attempt to maximize the clinical benefit of these immunotherapies to a broader patient population with deeper response and in the meantime to minimize the severe toxicity of HD IL-2, we have generated a novel bifunctional PD-1-proIL-2v fusion protein harnessing the mechanisms of PD-1 blockade and PD-1-cis directed tumor conditional IL-2R activation. PD-1-proIL-2v shows dose dependent inhibition of PD-1 immune checkpoint pathway measured by GM-CSF and IFNγ production in an MLR assay. Protease activated PD-1-proIL-2v, but not the intact drug, stimulates the phosphorylation of STAT5 of NK and T cells, the proliferation of CD8 T cells as well as the cytokine production in human whole blood. The potency of pSTAT5 by protease activated product is enhanced by 10-20 folds on PD-1+ T cells than T cells without PD-1. When tested in mouse tumor models resistant to PD-1 blockade, PD1-proIL-2v demonstrated high potency of tumor inhibition at as low as 0.1 mg/kg dose. In contrast, non-targeted proIL-2v at molar equivalent or higher dose showed minimal antitumor effect in either monotherapy or combination with anti-PD-1. Analysis of PD-1-proIL-2v treated mice showed dramatically increased tumor infiltrating CD4+ and CD8+ T cells, including PD-1+Tcf-1+ and PD-1+ IL-18Ra+TIM3− CD8+ T cells, referred to “stem-like” progenitor effector cells and “fresh” effector cells, respectively. Activation of the IL-2 procytokine in PD-1-proIL-2v was observed in mouse tumor tissues but not in the plasma. In monkey GLP-compliant 4-week repeat-dose toxicity study, PD-1-proIL-2v demonstrated excellent safety profiles without overt irAEs that are characteristic of IL-2. In conclusion, our preclinical data demonstrated that PD-1-proIL-2v effectively stimulated the expansion and reinvigoration of antigen specific T cells in the tumor tissue resulting in strong anti-tumor efficacy while it did not cause significant peripheral toxicity. Phase 1 clinical trial of PD-1-proIL-2v is planned to start in early 2024 to evaluate the safety, pharmacokinetics and anti-tumor activity in advanced solid tumors. Citation Format: Zijuan Li, Feifei Zhang, Ze Zhang, Harry Zhou. A novel anti-PD-1 and proIL-2 bifunctional fusion protein delivers potent anti-tumor activity via PD-1 checkpoint inhibition and tumor selective IL-2R agonism preferentially on antigen specific T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2473.

Stereotactic Body Radiation Therapy for Sacral Metastases: Deviation From Recommended Target Volume Delineation Increases the Risk of Local Failure

PurposeAlthough spine stereotactic body radiotherapy (SBRT) is considered a standard of care in the mobile spine, mature evidence reporting outcomes specific to sacral metastases is lacking. Furthermore, there is a need to validate the existing sacral SBRT international consensus contouring guidelines to define the optimal contouring approach. We report mature rates of local failure (LF), adverse events, and the impact of contouring deviations in the largest experience to date specific to sacrum SBRT. Methods/MaterialsConsecutive patients who underwent sacral SBRT from 2010-2021 were retrospectively reviewed. Primary endpoint was magnetic resonance imaging-based LF with a specific focus on adherence to target volume contouring recommendations. Secondary endpoints included vertebral compression fracture (VCF) and neural toxicity. ResultsOf the 215 sacrum segments treated in 112 patients, most received 30 Gy/4 fractions (51%), 24 Gy/2 fractions (31%), or 30 Gy/5 fractions (10%). Sixteen percent of segments were non-adherent to the consensus guideline with a more restricted target volume (under-contoured). The median follow-up was 21.4 months (range, 1.5-116.9). The cumulative incidence of LF at 1 and 2 years was 18.4% and 23.1%, respectively. In those with guideline adherent vs. non-adherent contours, the LF rate at 1 year was 15.1% vs. 31.4% and at 2 years 18.8% vs. 40.0% (HR=2.5, 95% CI 1.4-4.6, p=0.003), respectively. On multivariable analysis, guideline non-adherence (HR=2.4, 95% CI 1.3-4.7, p=0.008), radioresistant histology (HR=2.4, 95% CI 1.4-4.1, p<0.001), and extraosseous extension (HR=2.5, 95% CI 1.3-4.7, p=0.005) predicted for an increased risk of LF. The cumulative incidence of VCF was 7.1% at 1 year and 12.3% at 2 years. Seven patients (6.3%) developed peripheral nerve toxicity, of which 4/7 had been previously radiated. ConclusionsSacral SBRT is associated with high efficacy rates and an acceptable toxicity profile. Adhering to consensus guidelines for target volume delineation is recommended to reduce the risk of LF.

Absence of functional deficits in rats following systemic administration of an AAV9 vector despite moderate peripheral nerve and dorsal root ganglia findings: A clinically silent peripheral neuropathy

Adeno-associated virus (AAV)-based vectors are commonly used for delivering transgenes in gene therapy studies, but they are also known to cause dorsal root ganglia (DRG) and peripheral nerve toxicities in animals. However, the functional implications of these pathologic findings and their time course remain unclear. At 2, 4, 6, and 8 weeks following a single dose of an AAV9 vector carrying human frataxin transgene in rats, non-standard functional assessments, including von Frey filament, electrophysiology, and Rotarod tests, were conducted longitudinally to measure allodynia, nerve conduction velocity, and coordination, respectively. Additionally, DRGs, peripheral nerves, brain and spinal cord were evaluated histologically and circulating neurofilament light chain (NfL) was quantified at 1, 2, 4, and 8 weeks, respectively. At 2 and 4 weeks after dosing, minimal-to-moderate nerve fiber degeneration and neuronal degeneration were observed in the DRGs in some of the AAV9 vector-dosed animals. At 8 weeks, nerve fiber degeneration was observed in DRGs, with or without neuronal degeneration, and in sciatic nerves of all AAV9 vector-dosed animals. NfL values were higher in AAV9 vector-treated animals at weeks 4 and 8 compared with controls. However, there were no significant differences in the three functional endpoints evaluated between the AAV9 vector- and vehicle-dosed animals, or in a longitudinal comparison between baseline (predose), 4, and 8 week values in the AAV9 vector-dose animals. These findings demonstrate that there is no detectable functional consequence to the minimal-to-moderate neurodegeneration observed with our AAV9 vector treatment in rats, suggesting a functional tolerance or reserve for loss of DRG neurons after systemic administration of AAV9 vector.

Safety and efficacy of enfortumab vedotin in patients with metastatic/locally advanced urothelial cancer: Real-world evidence from a European database.

553 Background: Enfortumab vedotin (EV) is an antibody drug conjugate targeting Nectin-4. It was approved by EMA/FDA in patients (pts) with metastatic/ locally advanced urothelial cancer post platinum and immune check point inhibitors following the results of the EV-301 trial. We report updated efficacy and safety data of EV in a large European cohort of real-world pts (GUARDIANS consortium) treated in hospitals and private practices. Methods: Retrospective data were collected from 25 German and Swiss hospitals and private practices for pts who received EV. Adverse events (AEs) were reported according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 criteria. Objective responses were evaluated by local investigators according to Response Evaluation Criteria in Solid Tumors version 1.1. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Results: Weidentified 188 pts (32.4% female) with a median age of 66 yrs (range 31-89; 22.3% &gt;/= 75 yrs). Eastern Cooperative Oncology Group performance status (ECOG PS) was 0/1/2/3-4/unknown in 36/39/11/3/11%. EV was administered in the fourth or later line in 43% of pts. Overall response rate (ORR) was 46.3% (partial remission: 42.0%, complete response 4.3%), disease control rate was 58.0%. Median OS (mOS) was 12.0 months (mo) (95% confidence interval 9.65-14.35) and median PFS (mPFS) was 7.0 mo (95% confidence interval 5.43-8.57). Any-grade AEs were observed in 71% and CTCAE grade ≥3 AEs in 32% of pts. Most common AEs were peripheral sensory neuropathy (33.5% any grade), skin toxicity (24.5%) and fatigue (22.9%). In pts &gt;/= 75 yrs, females, and pts treated in &gt;/=4th line mOS, mPFS, ORR, and toxicities were comparable to younger and male counterparts and pts treated in &lt;4th line, respectively. Limitations are retrospective design and short follow-up. Conclusions: Anti-tumor activity of EV in real-world pts including difficult-to-treat subgroups is comparable to the results of the pivotal EV-301 trial. No new safety signals were observed.

Abstract IA011: Engineered IL-12 delivery to the tumor matrix to achieve enhanced efficacy and safety in multiple advanced tumors

Abstract Background. Our goal is to create an effective and novel immunotherapy against multiple solid tumors with minimal toxicity. IL-12 is an “ideal” immune-activator, capable of activating both innate and acquired immune response. We tested more than 20 reported pro-inflammatory cytokines, and found IL-12 shows the most potent anti-tumor activity. Peripheral toxicity limits the use of systemic IL-12 therapy in the clinic. We have hypothesized that the tumor-specific drug delivery system would improve IL-12 immunotherapies. We took original approaches of protein engineering. Methods. We developed technologies to turn the tumor collagen into a drug reservoir after intravenous injections. The recombinant fusion of IL-12 to a collagen binding domain (CBD) derived from the VWF A3 domain allows for targeted IL-12 delivery into the tumor stroma. Here, we evaluated the pharmacology, safety, efficacy and the effects of CBD-IL-12 to the tumor microenvironment. Results. Intravenously-injected CBD proteins preferentially localized to the tumor, but not in other organs in mice. Single intravenous injection of CBD-IL-12 (recombinant fusion protein) eradicated most EMT6 breast cold tumors. CBD-IL-12-treated mice that were tumor-free developed systemic immunological memory, as 12 mice out of 13 rejected rechallenge with the breast tumor cells in their contralateral mammary fat pad. Single intravenous injection of CBD-IL-12 induced 67% complete remission of established B16F10 tumors. CBD fusion to IL-12 reduced the systemic toxicity, such as 50% reduction of hepatotoxicity markers and cytokine storm. CBD-IL-12 treatment increased intratumoral cytokine and immune cell numbers. In short, this tumor collagen-targeting approach improves both safety and efficacy of IL-12. We showed that the CBD can target multiple solid tumor types, because the CBD exploits the abnormality of tumor vasculature-specific pathological structure (e.g. leakiness and exposure of collagen to the bloodstream). So far, we have shown that CBD-IL-12 has significant anti-tumor efficacy in breast, lung, ovarian, liver, colon, prostate, melanoma, head and neck, pancreatic cancers and melanoma, sarcoma, and glioblastoma in syngeneic mouse models. CBD-IL-12 is effective in cold, advanced, spontaneous tumors, low-mutation burden tumors, and prevents metastasis and recurrence. CBD-IL-12 stimulated antigen-presenting cells and T cells. Also, humanized mice treated with humanized CBD-IL-12 show great anti-tumor effects in patient-derived lung and ovarian tumors. Humanized CBD-IL-12 was tested in dogs, and showed great tolerability at the therapeutic dose. Human CBD-IL-12 molecule was successfully manufactured in a clinical-grade. Conclusions. Intravenously injected CBD–IL-12 is effective to multiple difficult, immunologically cold tumors with low mutation burdens. Collagen is an attractive target because abnormally high expression of collagen is a shared nature of tumors, regardless of tumor types and patients. VWF A3 domain naturally exists in our body, minimizing the risk of immunogenicity. Citation Format: Jun Ishihara. Engineered IL-12 delivery to the tumor matrix to achieve enhanced efficacy and safety in multiple advanced tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr IA011.

A CD276-Targeted Antibody-Drug Conjugate to Treat Non-Small Lung Cancer (NSCLC).

Non-small cell lung cancer (NSCLC) patients, accounting for approximately 85% of lung cancer cases, are usually diagnosed in advanced stages. Traditional surgical resection and radiotherapy have very limited clinical benefits. The objective of this study was to develop and evaluate a targeted therapy, antibody-drug conjugate (ADC), for NSCLC treatment. Specifically, the CD276 receptor was evaluated and confirmed as an ideal surface target of NSCLC in the immunohistochemistry (IHC) staining of seventy-three patient tumor microarrays and western blotting analysis of eight cell lines. Our anti-CD276 monoclonal antibody (mAb) with cross-activity to both human and mouse receptors showed high surface binding, effective drug delivery and tumor-specific targeting in flow cytometry, confocal microscopy, and in vivo imaging system analysis. The ADC constructed with our CD276 mAb and payload monomethyl auristatin F (MMAF) showed high anti-NSCLC cytotoxicity to multiple lines and effective anti-tumor efficacy in both immunocompromised and immunocompetent NSCLC xenograft mouse models. The brief mechanism study revealed the integration of cell proliferation inhibition and immune cell reactivation in tumor microenvironments. The toxicity study did not detect off-target immune toxicity or peripheral toxicity. Altogether, this study suggested that anti-CD276 ADC could be a promising candidate for NSCLC treatment.

PEG2000-PLA-based nanoscale polymeric micelles reduce paclitaxel-related toxicity in beagle dogs

Nanoplatform-based drug delivery plays an important role in clinical practice. Polymeric micellar (Pm) nanocarriers have been demonstrated to reduce the toxicity of paclitaxel in rats and non-small cell lung cancer (NSCLC) patients. However, the underlying toxicological profile needs to be further illustrated. Here, we used beagles as study subjects and sought to further observe the toxicological profile of polymeric micellar paclitaxel (Pm-Pac) via acute toxicity tests and short-term and long-term toxicity tests. The results from the acute toxicity test indicated that the lethal dose of Pm-Pac in beagles was 20–30 mg/kg, and the acute toxicity-targeted organs were the digestive system and immuno-haematopoietic system. The short-term toxicity test suggested that paclitaxel-induced toxicity (peripheral neuropathy toxicity, haemopoietic toxicity, heart system toxicity, and so on) in beagles can be reduced when paclitaxel is delivered via the Pm delivery system. The long-term toxicity test suggested that Pm-Pac can reduce haemopoietic toxicity in beagles. Collectively, this study provides novel insight into the toxicological profile of Pm-Pac in healthy beagles and provides a potential basis for promising clinical combination strategies in the future.

Long-term effects of pancreatic islet transplantation on polyneuropathy in patients with brittle diabetes: A single-center experience.

Pancreatic islet transplantation (ITx) is increasingly used in patients with brittle type 1 diabetes (T1D). If successful, ITx results in insulin-free euglycemia, but its application is limited by a need for lifelong immunosuppression. The aim of this study was to assess the long-term effects of ITx on the occurrence and course of polyneuropathy in a cohort of patients with brittle T1D. In this prospective, single-center study, 13 patients (4 males and 9 females) with brittle T1D had a baseline neurological exam with the calculation of Utah Neuropathy Scale (UNS) and a limited nerve conduction study before ITx, and about yearly after in the patients who achieved insulin independence. Patients were followed for a period of 17 to 133 months. There was no significant difference between UNS and nerve conduction study parameters at baseline and at the end of follow-up, except for significant decreases in peroneal (50.34 ± 6.12 vs. 52.42 ± 6.47 ms, P = 0.005) and ulnar (27.5 ± 2.15 vs. 29.45 ± 2.10 ms, P = 0.009) F-wave latencies and an increase in ulnar sensory nerve conduction velocity (49.98 ± 6.27 vs. 47.19 ± 5.36 m/s, P = 0.04). If successful, ITx has a good long-term safety profile for peripheral nerve toxicity, and a favorable effect on diabetic neuropathy.

Pharmacokinetics, biodistribution and toxicology of novel cell-penetrating peptides

Cell-penetrating peptides (CPPs) have been used in basic and preclinical research in the past 30 years to facilitate drug delivery into target cells. However, translation toward the clinic has not been successful so far. Here, we studied the pharmacokinetic (PK) and biodistribution profiles of Shuttle cell-penetrating peptides (S-CPP) in rodents, combined or not with an immunoglobulin G (IgG) cargo. We compared two enantiomers of S-CPP that contain both a protein transduction domain and an endosomal escape domain, with previously shown capacity for cytoplasmic delivery. The plasma concentration versus time curve of both radiolabelled S-CPPs required a two-compartment PK analytical model, which showed a fast distribution phase (t1/2α ranging from 1.25 to 3 min) followed by a slower elimination phase (t1/2β ranging from 5 to 15 h) after intravenous injection. Cargo IgG combined to S-CPPs displayed longer elimination half-life, of up to 25 h. The fast decrease in plasma concentration of S-CPPs was associated with an accumulation in target organs assessed at 1 and 5 h post-injection, particularly in the liver. In addition, in situ cerebral perfusion (ISCP) of L-S-CPP yielded a brain uptake coefficient of 7.2 ± 1.1 µl g−1 s−1, consistent with penetration across the blood–brain barrier (BBB), without damaging its integrity in vivo. No sign of peripheral toxicity was detected either by examining hematologic and biochemical blood parameters, or by measuring cytokine levels in plasma. In conclusion, S-CPPs are promising non-toxic transport vectors for improved tissue distribution of drug cargos in vivo.

A mouse model of sensory neuropathy induced by a long course of monomethyl-auristatin E treatment

Antibody-drug conjugates (ADCs) are anticancer drugs consisting of a monoclonal antibody, targeting selective tumor antigens, to which has been frequently associated a highly potent cytotoxic agent, the monomethyl auristatin E (MMAE) using a chemical linker. MMAE is a tubulin polymerization inhibitor derived from dolastin-10. These MMAE-ADCs are responsible for peripheral nerve toxicities. Our objective was to develop and characterize a mouse model of MMAE-induced peripheral neuropathy induced by free MMAE injections.MMAE was injected in Swiss mice at 50 μg/kg i.p. every other day for 7 weeks. Assessments of motor and sensory nerve functions were performed once a week on MMAE and Vehicle-treated mice. Sciatic nerve and paw skin were removed at the end of experiment for subsequent immunofluorescence and morphological analysis.MMAE did not affect motor coordination, muscular strength and heat nociception, but significantly induced tactile allodynia in MMAE-treated mice compared with Vehicle-treated mice from day 35 to day 49. MMAE significantly reduced myelinated and unmyelinated axon densities in sciatic nerves and led to a loss of intraepidermal nerve fiber in paw skin.In summary, long course of low dose of MMAE induced a peripheral sensory neuropathy associated with nerve degeneration, without general state alteration. This model may represent a ready accessible tool to screen neuroprotective strategies in the context of peripheral neuropathies induced by MMAE-ADCs.