Noninvasive X-ray stereotactic treatment is considered a promising alternative to catheter ablation in patients affected by severe heart arrhythmia. High-energy heavy ions can deliver high radiation doses in small targets with reduced damage to the normal tissue compared to conventional X-rays. For this reason, charged particle therapy, widely used in oncology, can be a powerful tool for radiosurgery in cardiac diseases. We have recently performed a feasibility study in a swine model using high doses of high-energy C-ions to target specific cardiac structures. Interruption of cardiac conduction was observed in some animals. Here we report the biological effects measured in the pig heart tissue of the same animals six months after the treatment. Immunohistological analysis of the target tissue showed (1.) long-lasting vascular damage, i.e. persistent hemorrhage, loss of microvessels, and occurrence of siderophages, (2.) fibrosis and (3.) loss of polarity of targeted cardiomyocytes and wavy fibers with vacuolization. We conclude that the observed physiological changes in heart function are produced by radiation-induced fibrosis and cardiomyocyte functional inactivation. No effects were observed in the normal tissue traversed by the particle beam, suggesting that charged particles have the potential to produce ablation of specific heart targets with minimal side effects.

Cutaneous T-cell lymphomas (CTCLs), including mycosis fungoides (MF) and Sézary syndrome (SS), are rare hematological malignancies with limited curative treatment options. Despite early-stage responsiveness, these malignancies often relapse in advanced stages, highlighting the need for novel, durable therapies. Similar to other non-Hodgkin lymphomas (NHLs), MF and SS have a greater incidence rate in males than females. The endocrine contribution to this sex difference is unknown. Although several studies could show a potential role of estrogen receptor β (ERβ) on NHL lymphomagenesis, its impact on CTCL development is unknown. In this study, we investigated LY500307, a selective ERβ agonist, as a potential treatment for CTCL. Our results show that LY500307 selectively reduced the viability of CTCL cells, sparing noncancerous skin cells. Liquid chromatography with tandem mass spectrometry analysis revealed that CTCL cells accumulated significantly higher concentrations of LY500307 than normal skin cells, likely contributing to its selective cytotoxicity. Mechanistically, LY500307 induced apoptosis, G2/M cell cycle arrest, and increased sensitivity to chemotherapeutic agents, particularly Monomethyl auristatin E. Furthermore, LY500307 treatment significantly reduced tumor growth in a CTCL xenograft mouse model without notable toxicity. These findings suggest LY500307 as a promising therapeutic agent for CTCL, warranting further clinical investigation, including the potential for topical applications.

Although vaccinia virus (VACV) is the best studied poxvirus, the structure of the mature virus (MV) remains poorly understood. Its asymmetric shape, size and compactness poses a major challenge for electron microscopy (EM) analysis, including cryoEM. Sub-viral particles, in particular membrane-free viral cores, may overcome these limitations. We compare cores obtained by detergent-stripping MVs with cores in the cellular cytoplasm, early in infection. By combining cryo-electron tomography (cryoET), subtomogram averaging (STA) and AlphaFold2 (AF2), abundant core-structures are analyzed, focusing on the prominent palisade layer on the core surface. On detergent-stripped cores, the palisade is composed of densely packed trimers of the major core protein A10. On the core surface they display a random order and their classification indicate structural flexibility. On cytoplasmic cores A10 is organized in a similar manner, indicating that the structures obtained in vitro are physiologically relevant. CryoET and STA also uncover unexpected details of the layers beneath the palisade both on in vitro and in situ cores, that are compared to AF2 structure predictions of known VACV core-associated proteins. Altogether, our data identify for the first time the structure and molecular composition of the palisade units. The results are discussed in the context of the VACV replicative cycle, the assembly and disassembly of the infectious MV.

• The selective GPER agonist G-1 induces growth arrest and apoptosis in malignant T cells while largely sparing normal lymphocytes. • G-1 effectively limits CTCL tumor progression in vivo, highlighting GPER signaling as a promising therapeutic approach.

Background/Objectives: Cutaneous T-cell lymphomas (CTCL), most commonly mycosis fungoides and Sézary syndrome, are rare non-Hodgkin lymphomas. Advanced disease responds poorly to current treatments, highlighting the need for new molecularly tar-geted therapies. WEE1 is a central regulator of the G2/M checkpoint and S-phase progression and has emerged as a therapeutic target in several malignancies, yet it has not been systematically explored in CTCL. Methods: We screened a library of more than 2,200 kinase inhibitors in CTCL cell lines and selected adavosertib for further study. Its effects were tested in four CTCL lines, in primary keratinocytes and fibroblasts, in patient-derived malignant CD4⁺ T cells and healthy donor CD4⁺ T cells, and in a MyLa xenograft model, using viability, apoptosis, cell-cycle, western blot, and phospho-protein array assays. Results: Adavosertib reduced viability at submicromolar IC₅₀ values (0.26–0.56 µM) across all four CTCL lines while largely sparing primary skin cells and was more active in malignant than in healthy donor CD4⁺ T cells. It induced apoptosis and cell-line-specific S-phase and/or G2/M accumulation, lowered WEE1 and phospho-CDK1 (Tyr15), and increased phospho-H2A.X. A phospho-protein array showed activation of checkpoint and stress signalling. In vivo, adavosertib slowed MyLa xenograft growth. Conclusions: These preclinical data identify WEE1 as a therapeutic target in CTCL and support further preclinical and early-phase clinical evaluation of adavosertib in this disease.

Background/Objectives: Cutaneous T-cell lymphomas (CTCL), most commonly mycosis fungoides and Sézary syndrome, are rare non-Hodgkin lymphomas. Advanced disease responds poorly to current treatments, highlighting the need for new molecularly targeted therapies. WEE1 is a central regulator of the G2/M checkpoint and S-phase progression and has emerged as a therapeutic target in several malignancies, yet it has not been systematically explored in CTCL. Methods: We screened a library of more than 2200 kinase inhibitors in CTCL cell lines and selected adavosertib for further study. Its effects were tested in four CTCL lines; primary keratinocytes and fibroblasts; patient-derived malignant CD4⁺ T cells and healthy donor CD4⁺ T cells; and a MyLa xenograft model, using viability, apoptosis, cell-cycle, Western blot, and phospho-protein array assays. Results: Adavosertib reduced viability at submicromolar IC₅₀ values (0.26–0.56 µM) across all four CTCL lines while largely sparing primary skin cells and was more active in malignant than in healthy donor CD4⁺ T cells. It induced apoptosis and cell-line-specific S-phase and/or G2/M accumulation, lowered WEE1 and phospho-CDK1 (Tyr15), and increased phospho-H2A.X. A phospho-protein array showed activation of checkpoint and stress signalling. In a preliminary xenograft experiment, adavosertib slowed MyLa tumour growth. Conclusions: These preclinical data identify WEE1 as a therapeutic target in CTCL and support further preclinical and early-phase clinical evaluation of adavosertib in this disease.