Alessandro Satta

Triple-negative breast cancer (TNBC) is an aggressive disease with poor prognosis and limited therapeutic options. Recent advances in the immunotherapy field have enabled the development of new treatment strategies, among which the use of bispecific antibodies (BsAbs), able to redirect T cells against tumors, has shown promising results. In particular, a BsAb that uses TNF-related apoptosis-inducing ligand receptor 2 (TRAIL-R2) as a target was constructed and demonstrated good results in redirecting CD3⁺ T cells to kill TRAIL-R2-expressing TNBC cells. In the present study, we investigated whether treatment with selinexor, a selective inhibitor of nuclear export (SINE) targeting exportin-1/chromosome maintenance protein 1 (XPO1/CRM1), could potentiate the antitumor activity of this BsAb. In combination experiments, we found that selinexor-exposed TNBC cells exhibited greater growth inhibition when treated with the TRAIL-R2xCD3 BsAb than that expected by simple additivity. Similarly, the apoptosis rate in selinexor/TRAIL-R2xCD3 BsAb-treated TNBC cells was significantly higher than that observed after exposure to either single agent. Together, our results suggest that the combination of selinexor and TRAIL-R2xCD3 BsAb can be a viable anticancer strategy and indicate this treatment as a promising therapeutic option for TNBC patients.

Prostate cancer (PCa) is the second leading cause of cancer-related death in the Western population. The use in oncology of positron emission tomography/computed tomography (PET/CT) with emerging radiopharmaceuticals promises accurate staging of primary disease, restaging of recurrent disease and detection of metastatic lesions. Prostate-specific membrane antigen (PSMA) expression, directly related to androgen-independence, metastasis and progression, renders this tumour associate antigen a good target for the development of new radiopharmaceuticals for PET. Aim of this study was to demonstrate in a preclinical in vivo model (PSMA-positive versus PSMA-negative tumours) the targeting specificity and sensitivity of the anti-PSMA single-chain variable fragment (scFv) labelled with 124I. The 124I-labeling conditions of the antibody fragment scFvD2B were optimized and assessed for purity and immunoreactivity. The specificity of 124I-scFvD2B was tested in mice bearing PSMA-positive and PSMA-negative tumours to assess both ex-vivo biodistribution and immune-PET. The uptake fraction of 124I-scFvD2B was very high on PSMA positive cells (range 75–91%) and highly specific and immuno-PET at the optimal time point, defined between 15 h and 24 h, provides a specific localization of lesions bearing the target antigen of interest (PSMA positive vs PSMA negative tumors %ID/g: p = 0.0198 and p = 0.0176 respectively) yielding a median target/background ratio around 30–40. Preclinical in vivo results of our immuno-PET reagent are highly promising. The target to background ratio is improved notably using PET compared to SPECT previously performed. These data suggest that, upon clinical confirmation of sensitivity and specificity, our anti-PSMA 124I-scFvD2B may be superior to other diagnostic modalities for PCa. The possibility to combine in patients our 124I-scFvD2B in multi-modal systems, such as PET/CT, PET/MR and PET/SPECT/CT, will provide quantitative 3D tomographic images improving the knowledge of cancer biology and treatment.

Recombinant human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or TRAIL-receptor agonistic monoclonal antibodies promote apoptosis in most cancer cells, and the differential expression of TRAIL-R2 between tumor and normal tissues allows its exploitation as a tumor-associated antigen. The use of these antibodies as anticancer agents has been extensively studied, but the results of clinical trials were disappointing. The observed lack of anticancer activity could be attributed to intrinsic or acquired resistance of tumor cells to this type of treatment. A possible strategy to circumvent drug resistance would be to strike tumor cells with a second modality based on a different mechanism of action. We therefore set out to generate and optimize a bispecific antibody targeting TRAIL-R2 and CD3. After the construction of different bispecific antibodies in tandem-scFv or single-chain diabody formats to reduce possible immunogenicity, we selected a humanized bispecific antibody with very low aggregates and long-term high stability and functionality. This antibody triggered TRAIL-R2 in an agonistic manner and its anticancer activity proved dramatically potentiated by the redirection of cytotoxic T cells against both sensitive and resistant melanoma cells. The results of our study show that combining the TRAIL-based antitumor strategy with an immunotherapeutic approach in a single molecule could be an effective addition to the anticancer armamentarium.

Purpose: In the context of prostate cancer (PCa) imaging, the aim of this study was to optimize (in vitro) the specificity and assess preclinically (in vivo) the tumor targeting properties of the 123I-scFvD2B antibody specific for prostate-specific membrane antigen (PSMA).

T cells are the most potent cells of the immune system; however, they fail in the immunosurveillance of tumors. In previous decades, scientists began studying methods to take advantage of T-cell potency in cancer therapy by redirecting them against tumors independently from the T-cell receptor-defined specificity. Among different approaches, the most promising are the use of bispecific antibodies and T-cell engineering to create chimeric antigen receptors. Bispecific antibodies, by simultaneously recognizing target antigen and an activating receptor on the surface of an immune effector cell, offer an opportunity to redirect immune effector cells to kill cancer cells. The other approach is the generation of chimeric antigen receptors by fusing extracellular antibodies to intracellular signaling domains. Chimeric antigen receptor-engineered T cells are able to specifically kill tumor cells in a MHC-independent way. The efficacy of these reagents in different formats has been clinically validated and will be presented here.

The complex physiopathological events occurring after spinal cord injury (SCI) make this devastating trauma still incurable. Self-assembling peptides (SAPs) are nanomaterials displaying some appealing properties for application in regenerative medicine because they mimic the structure of the extra-cellular matrix (ECM), are reabsorbable, allow biofunctionalizations and can be injected directly into the lesion. In this study we evaluated the putative neurorigenerative properties of RADA16-4G-BMHP1 SAP, proved to enhance in vitro neural stem cells survival and differentiation. This SAP (RADA16-I) has been functionalized with a bone marrow homing motif (BMHP1) and optimized via the insertion of a 4-glycine-spacer that ameliorates scaffold stability and exposure of the biomotifs. We injected the scaffold immediately after contusion in the rat spinal cord, then we evaluated the early effects by semi-quantitative RT-PCR and the late effects by histological analysis. Locomotor recovery over 8 weeks was assessed using Basso, Beattie, Bresnahan (BBB) test. Gene expression analysis showed that at 7 days after lesion the functionalized SAP induced a general upregulation of GAP-43, trophic factors and ECM remodelling proteins, whereas 3 days after SCI no remarkable changes were observed. Hystological analysis revealed that 8 weeks after SCI our scaffold increased cellular infiltration, basement membrane deposition and axon regeneration/sprouting within the cyst. Moreover the functionalized SAP showed to be compatible with the surrounding nervous tissue and to at least partially fill the cavities. Finally SAP injection resulted in a statistically significant improvement of both hindlimbs' motor performance and forelimbs-hindlimbs coordination. Altogether, these results indicate that RADA16-4G-BMHP1 induced favourable reparative processes, such as matrix remodelling, and provided a physical and trophic support to nervous tissue ingrowth. Thus this biomaterial, eventually combined with cells and growth factors, may constitute a promising biomimetic scaffold for regenerative applications in the injured central nervous system.