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Simple SummaryROR1, a tumor-associated antigen (TAA), is widely expressed in various cancers. However, its expression in HNSCC remains poorly characterized. Given the demonstrated tolerability of ROR1-targeting therapies in clinical trials, ROR1 may represent a promising TAA for T cell-based peptide vaccine development. Here, we demonstrate that ROR1 is widely expressed in HNSCC tissue specimens and cell lines, with significantly higher expression in HNSCC than in healthy tissues. To develop an ROR1-targeted peptide vaccine, we identified a novel ROR1-derived epitope capable of eliciting antitumor T cell responses against HNSCC. ROR1-reactive helper T cell (HTL) lines secreted effector cytokines and exhibited direct cytotoxic activity against ROR1+ HNSCC cell lines in a human leukocyte antigen (HLA)-DR-restricted manner. Furthermore, the tumoricidal activity of T cells was enhanced by ICIs targeting the PD-L1/PD-1 and PD-L2/PD-1 axes. These findings suggest that ROR1 could serve as a promising immunotherapeutic target in patients with HNSCC. AbstractBackground/Objectives: Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer, with limited responsiveness to immune checkpoint inhibitors (ICIs). Cancer vaccine therapy is a promising novel immunotherapeutic approach that stimulates tumor-specific T cells. Receptor tyrosine kinase-like orphan receptor 1 (ROR1), which is overexpressed in malignant tumors but minimally expressed in normal tissues, presents a promising target for immunotherapy. This study aimed to evaluate ROR1 as a target for helper T lymphocyte (HTL)-based peptide vaccine immunotherapy in HNSCC. Methods: ROR1 expression in HNSCC tissues was assessed by immunohistochemistry. A novel ROR1-derived epitope (ROR1403¨C417) was identified and used to generate ROR1-reactive HTLs. Functional assays measuring IFN-¦Ã and granzyme B secretion, as well as direct cytotoxicity, were performed. The effects of ICIs on HTL activity were also examined. The presence of ROR1-reactive T cells in the peripheral blood of patients with HNSCC was evaluated. Results: ROR1 positivity rates in HNSCC tissues were significantly higher (80.0%) than those in healthy controls (16.7%), and high ROR1 expression correlated with advanced clinical stages. HTL lines recognized the ROR1403¨C417 peptide in a human leukocyte antigen (HLA)-DR-restricted manner, secreted effector cytokines, and exhibited direct cytotoxicity against ROR1+ tumor cells. Dual PD-L1/PD-L2 blockade further enhanced HTL responses. ROR1-reactive T cells were detected in the peripheral blood of patients with HNSCC. Conclusions: ROR1 represents a promising target for immunotherapy in HNSCC. The ROR1403¨C417 peptide can elicit ROR1-reactive HTLs that exhibit antitumor responses against HNSCC cell lines, which can be enhanced by ICIs. These findings support the potential of ROR1-targeted peptide vaccine therapy for HNSCC.

Chronic myeloid leukemia (CML) is a leading example of a malignancy where a molecular targeted therapy revolutionized treatment but has rarely led to cures. Overcoming tyrosine kinase inhibitor (TKI) drug resistance remains a challenge in the treatment of CML. We have recently identified miR-185 as a predictive biomarker where reduced expression in CD34 + treatment-na?ve CML cells was associated with TKI resistance. We have also identified PAK6 as a target gene of miR-185 that was upregulated in CD34 + TKI-nonresponder cells. However, its role in regulating TKI resistance remains largely unknown. In this study, we specifically targeted PAK6 in imatinib (IM)-resistant cells and CD34 + stem/progenitor cells from IM-nonresponders using a lentiviral-mediated PAK6 knockdown strategy. Interestingly, the genetic and pharmacological suppression of PAK6 significantly reduced proliferation and increased apoptosis in TKI-resistant cells. Cell survivability was further diminished when IM was combined with PAK6 knockdown. Importantly, PAK6 inhibition in TKI-resistant cells induced cell cycle arrest in the G2-M phase and cellular senescence, accompanied by increased levels of DNA damage-associated senescence markers. Mechanically, we identified a PAK6-mediated MDM2-p21 axis that regulates cell cycle arrest and senescence. Thus, PAK6 plays a critical role in determining alternative cell fates in leukemic cells, and targeting PAK6 may offer a therapeutic strategy to selectively eradicate TKI-resistant cells.

The human bone marrow (BM) microenvironment involves hematopoietic and non-hematopoietic cell subsets organized in a complex architecture. Tremendous efforts have been made to model it in order to analyze normal or pathological hematopoiesis and its stromal counterpart. Herein, we report an original, fully-human in vitro 3D model of the BM microenvironment dedicated to study interactions taking place between mesenchymal stromal cells (MSC) and hematopoietic stem and progenitor cells (HSPC) during the hematopoietic differentiation. This fully-human Artificial Marrow Organoid (AMO) model is highly efficient to recapitulate MSC support to myeloid differentiation and NK cell development from the immature CD34?+?HSPCs to the most terminally differentiated CD15?+?polymorphonuclear neutrophils, CD64?+?monocytes or NKG2A-KIR2D?+?CD57?+?NK subset. Lastly, our model is suitable for evaluating anti-leukemic NK cell function in presence of therapeutic agents. Overall, the AMO is a versatile, low cost and simple model able to recapitulate normal hematopoiesis and allowing more physiological drug testing by taking into account both immune and non-immune BM microenvironment interactions.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-07717-9.