Ettore Gilardoni

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Gilardoni

First Name

Ettore

ORCID

0000-0002-2010-2667

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Publications 1 - 10 of 11

Tumor-Targeted Interleukin 2 Boosts the Anticancer Activity of FAP-Directed Radioligand Therapeutics
Galbiati, Andrea; Dorten, Paulina; Gilardoni, Ettore; et al. (2023)
The Journal of Nuclear Medicine
We studied the antitumor efficacy of a combination of ¹⁷⁷Lu-labeled radioligand therapeutics targeting the fibroblast activation protein (FAP) (OncoFAP and BiOncoFAP) with the antibody–cytokine fusion protein L19-interleukin 2 (L19-IL2) providing targeted delivery of interleukin 2 to tumors. Methods: The biodistribution of ¹⁷⁷Lu-OncoFAP and ¹⁷⁷Lu-BiOncoFAP at different molar amounts (3 vs. 250 nmol/kg) of injected ligand was studied via SPECT/CT in mice bearing subcutaneous HT-1080.hFAP tumors, and self-absorbed tumor and organ doses were calculated. The in vivo anticancer effect of 5 MBq of the radiolabeled preparations was evaluated as monotherapy or in combination with L19-IL2 in subcutaneously implanted HT-1080.hFAP and SK-RC-52.hFAP tumors. Tumor samples from animals treated with ¹⁷⁷Lu-BiOncoFAP, L19-IL2, or both were analyzed by mass spectrometry–based proteomics to identify therapeutic signatures on cellular and stromal markers of cancer and on immunomodulatory targets. Results: ¹⁷⁷Lu-BiOncoFAP led to a significantly higher self-absorbed dose in FAP-positive tumors (0.293 ± 0.123 Gy/MBq) than did ¹⁷⁷Lu-OncoFAP (0.157 ± 0.047 Gy/MBq, P = 0.01) and demonstrated favorable tumor-to-organ ratios at high molar amounts of injected ligand. Administration of L19-IL2 or ¹⁷⁷Lu-BiOncoFAP as single agents led to cancer cures in only a limited number of treated animals. In ¹⁷⁷Lu-BiOncoFAP–plus–L19-IL2 combination therapy, complete remissions were observed in all injected mice (7/7 complete remissions for the HT-1080.hFAP model, and 4/4 complete remissions for the SK-RC-52.hFAP model), suggesting therapeutic synergy. Proteomic studies revealed a mechanism of action based on the activation of natural killer cells, with a significant enhancement of the expression of granzymes and perforin 1 in the tumor microenvironment after combination treatment. Conclusion: The combination of OncoFAP-based radioligand therapeutics with concurrent targeting of interleukin 2 shows synergistic anticancer effects in the treatment of FAP-positive tumors. This experimental finding should be corroborated by future clinical studies.
Combinatorial treatment with upadacitinib abrogates systemic toxicity of a tumor-targeted IL-2 fusion protein
Rotta, Giulia; Prodi, Eleonora; Seehusen, Frauke; et al. (2025)
Journal for ImmunoTherapy of Cancer
Background: The administration of recombinant interleukin 2 (IL-2) in oncology is frequently hampered by dose-limiting toxicities, including potentially lethal vascular leak syndrome. Antibody-IL-2 fusion proteins capable of preferential tumor localization have shown encouraging signs of activity in clinical trials; however, they typically cause side effects shortly after intravenous administration, which may limit escalation to curative doses. There is an urgent need to engineer IL-2 products with "activity-on-demand" able to mask on-target off-tumor IL-2 activity without compromising therapeutic efficacy. Methods: To design IL-2 biopharmaceuticals with "activity-on-demand", which would be non-toxic on administration but regain activity at the tumor site, we explored the therapeutic potential of the co-administration of signaling inhibitors with matched pharmacokinetic properties. In this work, we used the tumor-homing F8-IL2 fusion protein, specific to a splice variant of fibronectin, and masked off-tumor toxicity by co-administration of upadacitinib, which rapidly clears from circulation. Vascular leak syndrome was monitored by histopathological analysis, the extent of peripheral edema, and cytokine levels. Immune profiling of the tumors and secondary lymphoid organs was performed by flow cytometry. Results: In immunocompetent tumor-bearing mice, the combinatorial treatment significantly improved tolerability without any detectable loss of therapeutic activity, protecting the mice from body weight loss, uncontrolled systemic cytokine release, and severe vascular leak syndrome manifestations, including peripheral edema. F8-IL2 efficiently controlled tumor growth and retained its immunological activity within the neoplastic mass, as evidenced by the massive natural killer and cytotoxic T-cell infiltrates. Conclusions: This study suggests that combinatorial treatments enable the administration of potentially curative doses of targeted IL-2 products while sparing healthy organs from life-threatening toxicities.
In vivo activation of FAP-cleavable small molecule-drug conjugates for the targeted delivery of camptothecins and tubulin poisons to the tumor microenvironment
Bocci, Matilde; Zana, Aureliano; Principi, Lucrezia; et al. (2024)
Journal of Controlled Release
Small molecule-drug conjugates (SMDCs) are increasingly considered as a therapeutic alternative to antibody-drug conjugates (ADCs) for cancer therapy. OncoFAP is an ultra-high affinity ligand of Fibroblast Activation Protein (FAP), a stromal tumor-associated antigen overexpressed in a wide variety of solid human malignancies. We have recently reported the development of non-internalizing OncoFAP-based SMDCs, which are activated by FAP thanks to selective proteolytic cleavage of the -GlyPro- linker with consequent release of monomethyl auristatin E (MMAE) in the tumor microenvironment. In this article, we describe the generation and the in vivo characterization of FAP-cleavable OncoFAP-drug conjugates based on potent topoisomerase I inhibitors (DXd, SN-38, and exatecan) and an anti-tubulin payload (MMAE), which are already exploited in clinical-stage and approved ADCs. The Glycine-Proline FAP-cleavable technology was directly benchmarked against linkers found in Adcetris™, Enhertu™, and Trodelvy™ structures by means of in vivo therapeutic experiments in mice bearing tumors with cellular or stromal FAP expression. OncoFAP-GlyPro-Exatecan and OncoFAP-GlyPro-MMAE emerged as the most efficacious anti-cancer therapeutics against FAP-positive cellular models. OncoFAP-GlyPro-MMAE exhibited a potent antitumor activity also against stromal models, and was therefore selected for clinical development.
Delivery of Monomethyl Auristatin F to the Tumor Microenvironment with Noninternalizing Fibroblast Activation Protein-Cleavable Small Molecule-Drug Conjugates Elicits Potent In Vivo Anticancer Activity
Bocci, Matilde; Principi, Lucrezia; Gilardoni, Ettore; et al. (2025)
Bioconjugate Chemistry
OncoFAP is an ultrahigh affinity ligand of fibroblast activation protein (FAP), a tumor-associated antigen overexpressed in the stroma of the majority of solid tumors. OncoFAP has been previously implemented as a tumor-homing moiety for the development of small molecule drug conjugates (SMDCs). In the same context, the glycine-proline dipeptide was included with the aim to selectively undergo cleavage only in the presence of the target FAP, triggering the consequent release of the cytotoxic payload in the tumor microenvironment. In this work, we evaluate the use of monomethyl auristatin F (MMAF) as a payload, a close derivative of MMAE bearing a charged carboxylic acid that hampers its cellular permeability, typically employed in the development of internalizing antibody-drug conjugates. The novel OncoFAP-GlyPro-MMAF and the previously described OncoFAP-GlyPro-MMAE were compared in a head-to-head therapeutic experiment in mice bearing FAP-positive tumors. Surprisingly, the MMAF conjugate mediated potent antitumor activity, despite its poor cellular permeability.
Ex vivo mass spectrometry-based biodistribution analysis of an antibody-Resiquimod conjugate bearing a protease-cleavable and acid-labile linker
Lopez, Lydia Bisbal; Ravazza, Domenico; Bocci, Matilde; et al. (2023)
Frontiers in Pharmacology
Immune-stimulating antibody conjugates (ISACs) equipped with imidazoquinoline (IMD) payloads can stimulate endogenous immune cells to kill cancer cells, ultimately inducing long-lasting anticancer effects. A novel ISAC was designed, featuring the IMD Resiquimod (R848), a tumor-targeting antibody specific for Carbonic Anhydrase IX (CAIX) and the protease-cleavable Val-Cit-PABC linker. In vitro stability analysis showed not only R848 release in the presence of the protease Cathepsin B but also under acidic conditions. The ex vivo mass spectrometry-based biodistribution data confirmed the low stability of the linker-drug connection while highlighting the selective accumulation of the IgG in tumors and its long circulatory half-life.
Discovery of high-affinity ligands for prostatic acid phosphatase via DNA-encoded library screening enables targeted cancer therapy
Georgiev, Tony; Migliorini, Francesca; Ciamarone, Andrea; et al. (2025)
Nature Biomedical Engineering
Improving the specificity of prostate cancer treatment requires ligands that bind selectively and with ultra-high affinity to tumour-associated targets absent from healthy tissues. Prostatic acid phosphatase has emerged as an alternative target to prostate-specific membrane antigen, as it is expressed in a broader subset of prostate cancers and is not detected in healthy organs such as the salivary glands and kidneys. Here, to discover selective binders to prostatic acid phosphatase, we constructed two DNA-encoded chemical libraries comprising over 6.7 million small molecules based on proline and phenylalanine scaffolds. Screening against the purified human prostatic acid phosphatase yielded OncoACP3, a small organic ligand with picomolar binding affinity. When radiolabelled with lutetium-177, OncoACP3 selectively accumulated in enzyme-expressing tumours with a long residence time (biological half-life greater than 72 h) and a high tumour-to-blood ratio (>148 at 2 h after administration). Lutetium-177-labelled OncoACP3 cured tumours in mice at low, well-tolerated doses. Its conjugation to the cytotoxic agent monomethyl auristatin E facilitated tumour-selective payload deposition, resulting in potent anti-tumour activity. The modular structure of OncoACP3 supports flexible payload delivery for the targeted treatment of metastatic prostate cancer.
A novel strategy to generate immunocytokines with activity-on-demand using small molecule inhibitors
Rotta, Giulia; Gilardoni, Ettore; Ravazza, Domenico; et al. (2024)
EMBO Molecular Medicine
Cytokine-based therapeutics have been shown to mediate objective responses in certain tumor entities but suffer from insufficient selectivity, causing limiting toxicity which prevents dose escalation to therapeutically active regimens. The antibody-based delivery of cytokines significantly increases the therapeutic index of the corresponding payload but still suffers from side effects associated with peak concentrations of the product in blood upon intravenous administration. Here we devise a general strategy (named “Intra-Cork”) to mask systemic cytokine activity without impacting anti-cancer efficacy. Our technology features the use of antibody-cytokine fusions, capable of selective localization at the neoplastic site, in combination with pathway-selective inhibitors of the cytokine signaling, which rapidly clear from the body. This strategy, exemplified with a tumor-targeted IL12 in combination with a JAK2 inhibitor, allowed to abrogate cytokine-driven toxicity without affecting therapeutic activity in a preclinical model of cancer. This approach is readily applicable in clinical practice.
Permutational Encoding Strategy Accelerates HIT Validation from Single-Stranded DNA-Encoded Libraries
Puglioli, Sara; Fabbri, Mosè; Comacchio, Claudia; et al. (2024)
Bioconjugate Chemistry
DNA-Encoded Libraries (DELs) allow the parallel screening of millions of compounds for various applications, including de novo discovery or affinity maturation campaigns. However, library construction and HIT resynthesis can be cumbersome, especially when library members present an unknown stereochemistry. We introduce a permutational encoding strategy suitable for the construction of highly pure single-stranded single-pharmacophore DELs, designed to distinguish isomers at the sequencing level (e.g., stereoisomers, regio-isomers, and peptide sequences). This approach was validated by synthesizing a mock 921,600-member 4-amino-proline single-stranded DEL ("DEL1"). While screening DEL1 against different targets, high-throughput sequencing results showed selective enrichment of the most potent stereoisomers, with enrichment factors that outperform conventional encoding strategies. The versatility of our methodology was additionally validated by encoding 24 scaffolds derived from different permutations of the amino acid sequence of a previously described cyclic peptide targeting Fibroblast Activation Protein (FAP-2286). The resulting library ("DEL2") was interrogated against human FAP, showing selective enrichment of five cyclic peptides. We observed a direct correlation between enrichment factors and on-DNA binding affinities. The presented encoding methodology accelerates drug discovery by facilitating library synthesis and streamlining HIT resynthesis while enhancing enrichment factors at the DEL sequencing level. This facilitates the identification of HIT candidates prior to medicinal chemistry and affinity maturation campaigns.
Targeted interleukin-2 enhances the in vivo anti-cancer activity of Pluvicto™
Georgiev, Tony; Principi, Lucrezia; Galbiati, Andrea; et al. (2024)
European Journal of Nuclear Medicine and Molecular Imaging
Purpose: Pluvicto™ ([¹⁷⁷Lu]Lu-PSMA-617), a radioligand therapeutic targeting prostate-specific membrane antigen (PSMA), has been recently approved for the treatment of metastatic castration-resistant prostate cancer (mCRPR). The drug suffers from salivary gland and kidney uptake that prevents its dose escalation to potentially curative doses. In this work, we sought to potentiate the in vivo anti-cancer activity of Pluvicto™ by combining it with L19-IL2, a clinical-stage investigational medicinal product based on tumor-targeted interleukin-2. Methods: We established a new PSMA-expressing model (HT-1080.hPSMA) and validated it using a fluoresceine analogue of PSMA-617 (compound 1). The HT-1080.hPSMA model was used to study the saturation and tumor retention of Pluvicto™ (compound 2) and to run combination therapy studies with L19-IL2. To complement our understanding of the mechanism of action of this novel combination, we conducted proteomics experiments on tumor samples after therapy with Pluvicto™ alone or in combination with the immunocytokine. Results: High, selective, and long-lived tumor uptake was observed for Pluvicto™ (2) in the novel HT-1080.hPSMA model. Therapy studies in HT-1080.hPSMA tumor-bearing mice revealed that the combination of Pluvicto™ (2) plus L19-IL2 mediated curative and durable responses in all animals. Potent in vivo anti-cancer activity was observed solely for the combination modality, at doses that were well tolerated by treated animals. Proteomics studies indicated that L19-IL2 boosts the activation of the immune system in animals pre-treated with Pluvicto™. Conclusion: The therapeutic efficacy of Pluvicto™ at low radioactive doses can be effectively enhanced by the combination with L19-IL2. Our findings warrant further clinical exploration of this novel combination modality.
Preclinical Evaluation of ¹⁷⁷Lu-OncoFAP-23, a Multivalent FAP-Targeted Radiopharmaceutical Therapeutic for Solid Tumors
Galbiati, Andrea; Bocci, Matilde; Ravazza, Domenico; et al. (2024)
The Journal of Nuclear Medicine
Fibroblast activation protein (FAP) is abundantly expressed in the stroma of most human solid tumors. Clinical-stage radiolabeled FAP ligands are increasingly used as tools for the detection of various cancer lesions. To unleash the full therapeutic potential of FAP-targeting agents, ligands need to remain at the tumor site for several days after administration. We recently described the discovery of OncoFAP, a high-affinity small organic ligand of FAP with a rapid accumulation in tumors and low uptake in healthy tissues in cancer patients. Trimerization of OncoFAP provided a derivative (named TriOncoFAP, or OncoFAP-23) with improved FAP affinity. In this work, we evaluated the tissue biodistribution profile and the therapeutic performance of OncoFAP-23 in tumor-bearing mice. Methods: OncoFAP-23 was radiolabeled with the theranostic radionuclide 177Lu. Preclinical experiments were conducted on mice bearing SK-RC-52.hFAP (BALB/c nude mice) or CT-26.hFAP (BALB/c mice) tumors. 177Lu-OncoFAP and 177Lu-FAP-2286 were included in the biodistribution study as controls. Toxicologic evaluation was performed on Wistar rats and CD1 mice by injecting high doses of OncoFAP-23 or its cold-labeled counterpart, respectively. Results:177Lu-OncoFAP-23 emerged for its best-in-class biodistribution profile, high and prolonged tumor uptake (i.e., ∼16 percentage injected dose/g at 96 h), and low accumulation in healthy organs, which correlates well with its potent single-agent anticancer activity at low levels of administered radioactivity. Combination treatment with the tumor-targeted interleukin 2 (L19-IL2, a clinical-stage immunocytokine) further expands the therapeutic window of 177Lu-OncoFAP-23 by potentiating its in vivo antitumor activity. Proteomics studies revealed a potent tumor-directed immune response on treatment with the combination. OncoFAP-23 and natLu-OncoFAP-23 exhibited a favorable toxicologic profile, without showing any side effects or signs of toxicity. Conclusion: OncoFAP-23 presents enhanced tumor uptake and tumor retention and low accumulation in healthy organs, findings that correspond to a strongly improved in vivo antitumor efficacy. The data presented in this work support the clinical development of 177Lu-OncoFAP-23 for the treatment of FAP-positive solid tumors.

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Ettore Gilardoni

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