Philochem (Switzerland)

L19IL2 is a clinical-stage antibody-cytokine fusion protein that has been investigated for the treatment of various cancer types. Despite its promising antitumor activity, the precise mechanism of action is still not fully understood. In this work, we employed a myc-driven B-cell lymphoma murine model to demonstrate that systemic administration of L19IL2 induced a robust CD8⁺ T cell-dependent tumor regression across multiple organs without expansion of regulatory T cells. Following L19IL2 administration, intratumoral CD8+ T cells proliferated and acquired effector and memory phenotypes, associated with private clonal expansion and enhanced killing. Moreover, the spatial behavior of peritumoral CD8+ T cells studied by intravital microscopy demonstrated a rapid increase in tumor-directed motility and infiltration following L19IL2 administration. These findings described the detailed mechanism of action of L19IL2 against B cell lymphoma and revealed for the first time the dynamic responses of peritumoral CD8+ T cells to targeted IL2 stimulation, supporting the use of L19IL2 for patients with aggressive B cell lymphoma.

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. 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. 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. 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.

Triple-negative breast cancer (TNBC) lags behind other breast cancer types in targeted therapeutic and diagnostic imaging agent development, largely due to high disease heterogeneity. Noninvasive imaging is essential for diagnosing and staging TNBC and predicting and measuring treatment response. This study targeted a conserved disease-specific extracellular matrix protein domain (the extra domain A of fibronectin [EDA-FN]), with a monoclonal antibody (F8) to overcome tumor cell marker heterogeneity and develop an imaging agent to detect multiple TNBC subtypes and improve diagnostic capacity. Methods: [89Zr]Zr-desferrioxamine [DFO]-F8 was synthesized and evaluated invitro and invivo for EDA-FN binding capacity to detect TNBC by PET/CT in several preclinical xenograft models. Results: [89Zr]Zr-DFO-F8 exhibited specific, blockable EDA-FN binding activity invitro. In vivo experiments demonstrated high tumor uptake in preclinical TNBC xenograft models. [89Zr]Zr-DFO-F8 detected EDA-FN in subcutaneous and orthotopic TNBC xenografts and accumulated in aggressive disease concordantly with EDA-FN expression. Conclusion: EDA-FN imaging with [89Zr]Zr-DFO-F8 exhibits powerful tumor delineation in preclinical tumor delineation across TNBC molecular subtypes invivo.

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.

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.

Pathogenesis of pulmonary hypertension (PH) is a multifactorial process driven by inflammation and pulmonary vascular remodeling. To target these two aspects of PH, we recently tested a novel treatment: Interleukin-9 (IL9) fused to F8, an antibody that binds to the extra-domain A of fibronectin (EDA+ Fn). As EDA+ Fn is not found in healthy adult tissue but is expressed during PH, IL9 is delivered specifically to the tissue affected by PH. We found that F8IL9 reduced pulmonary vascular remodeling and attenuated PH compared with sham-treated mice. To evaluate possible F8IL9 effects on PH-associated inflammatory processes, we analysed the expression of genes involved in pulmonary immune responses. We applied the monocrotaline (MCT) model of PH in mice (n = 44). Animals were divided into five experimental groups: sham-induced animals without PH (control, n = 4), MCT-induced PH without treatment (PH, n = 8), dual endothelin receptor antagonist treatment (dual ERA, n = 8), F8IL9 treatment (n = 12, 2 formats with n = 6 each), or with KSFIL9 treatment (KSFIL9, n = 12, 2 formats with n = 6 each, KSF: control antibody with irrelevant antigen specificity). After 28 days, a RT-PCR gene expression analysis of inflammatory response (84 genes) was performed in the lung. Compared with the controls, 19 genes exhibited relevant (+2.5-fold) upregulation in the PH group without treatment. Gene expression levels in F8IL9-treated lung tissue were reduced compared to the PH group without treatment. This was the case especially for CCL20, CXCL5, C-reactive protein, pentraxin related (CRPPR), and Kininogen-1 (KNG1). In accordance with the hypothesis stated above, F8IL9 treatment diminished the upregulation of some genes associated with inflammation in a PH animal model. Therefore, we hypothesize that IL9-based immunocytokine treatment will likely modulate various inflammatory pathways.

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.

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 invivo 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.