Purpose The need to improve chemotherapeutic efficacy against head and neck squamous cell carcinomas (HNSCC) is well recognized. In this study, we investigated the potential of targeting the established tumor vasculature in combination with chemotherapy in head and neck cancer. Methods Experimental studies were carried out in multiple human HNSCC xenograft models to examine the activity of the vascular disrupting agent (VDA) 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in combination with chemotherapy. Multimodality imaging (magnetic resonance imaging, bioluminescence) in conjunction with drug delivery assessment (fluorescence microscopy), histopathology and microarray analysis was performed to characterize tumor response to therapy. Long-term treatment outcome was assessed using clinically-relevant end points of efficacy. Results Pretreatment of tumors with VDA prior to administration of chemotherapy increased intratumoral drug delivery and treatment efficacy. Enhancement of therapeutic efficacy was dependent on the dose and duration of VDA treatment but was independent of the chemotherapeutic agent evaluated. Combination treatment resulted in increased tumor cell kill and improvement in progression-free survival and overall survival in both ectopic and orthotopic HNSCC models. Conclusion Our results show that preconditioning of the tumor microenvironment with an antivascular agent primes the tumor vasculature and results in enhancement of chemotherapeutic delivery and efficacy in vivo. Further investigation into the activity of antivascular agents in combination with chemotherapy against HNSCC is warranted.

The high mortality rate associated with castration-resistant prostate cancer (CRPC) underscores the need for improving therapeutic options for this patient population. The purpose of this study was to examine the potential of vascular targeting in prostate cancer. Experimental studies were carried out in subcutaneous and orthotopic Myc-CaP prostate tumors implanted into male FVB mice to examine the efficacy of a novel microtubule targeted vascular disrupting agent (VDA), EPC2407 (Crolibulin™). A non-invasive multimodality imaging approach based on magnetic resonance imaging (MRI), bioluminescence imaging (BLI), and ultrasound (US) was utilized to guide preclinical trial design and monitor tumor response to therapy. Imaging results were correlated with histopathologic assessment, tumor growth and survival analysis. Contrast-enhanced MRI revealed potent antivascular activity of EPC2407 against subcutaneous and orthotopic Myc-CaP tumors. Longitudinal BLI of Myc-CaP tumors expressing luciferase under the androgen response element (Myc-CaP/ARE-luc) revealed changes in AR signaling and reduction in intratumoral delivery of luciferin substrate following castration suggestive of reduced blood flow. This reduction in blood flow was validated by US and MRI. Combination treatment resulted in sustained vascular suppression, inhibition of tumor regrowth and conferred a survival benefit in both models. These results demonstrate the therapeutic potential of vascular targeting in combination with androgen deprivation against prostate cancer.

Background: As the number of indicated malignancies for which immune checkpoint inhibitor therapy such as pembrolizumab grows the descriptions of associated immune-related adverse events (irAEs) increases as well. On rare occasions immunotherapy can lead to development of Hemophagocytic Lymphohistiocytosis (HLH) which is a potentially lethal inflammatory disorder characterized by histiocyte activation and cytokine storm. At this time no cases of HLH developing in head and neck squamous cell carcinoma (HNSCC) patients receiving pembrolizumab have been reported. Case presentation: Here we describe the first documented case of pembrolizumab-induced HLH in a 61 year-old male with metastatic HNSCC after having received multiple prior cycles of pembrolizumab without event. Following cycle 14 the patient developed fever associated with new pancytopenia and transaminitis prompting hospital admission. Infectious workup was negative, his metastatic lesions were found to be stable, and there was no evidence of new malignancy. Further workup demonstrated hyperferritinemia and bone marrow biopsy demonstrated hemophagocytosis concerning for pembrolizumab-induced HLH. Etoposide and dexamethasone therapy was initiated leading to clinical improvement and safe discharge. Conclusions: Immunotherapy is a groundbreaking therapeutic intervention for patients with malignancy, however by nature of their mechanism carry a risk of inflammatory side effects. In rare circumstances these inflammatory reactions include potentially deadly syndromes such as HLH. As immunotherapeutics such as pembrolizumab become more widely utilized increased awareness of complications such as HLH is clinically relevant.

HLH is a catastrophic and likely underdiagnosed pathology with multiple triggers including infection. PVB19 can cause persistent marrow infection leading to HLH despite negative acute serologic markers making timely diagnosis difficult. Increased awareness of PVB19‐HLH is warranted given its potentially lethal nature and the careful interpretation required with serologic markers.

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