Spatiotemporal local and abscopal cell death and immune responses to histotripsy focused ultrasound tumor ablation.

Introduction: Histotripsy is a novel focused ultrasound tumor ablation modality with potent immunostimulatory effects. Methods: To measure the spatiotemporal kinetics of local andabscopal responses to histotripsy, C57BL/6 mice bearing bilateral flank B16 melanoma or Hepa1-6 hepatocellular carcinoma tumors were treated with unilateral sham or partial histotripsy. Treated and contralateral untreated (abscopal) tumors were analyzed using multicolor immunofluorescence, digital spatial profiling, RNA sequencing (RNASeq), and flow cytometry. Results: Unilateral histotripsy triggered abscopal tumor growth inhibition. Within the ablation zone, early high mobility group box protein 1 (HMGB1) release and necroptosis were accompanied by immunogenic cell death transcriptional responses in tumor cells and innate immune activation transcriptional responses in infiltrating myeloid and natural killer (NK) cells. Delayed CD8+ T cell intratumoral infiltration was spatiotemporally aligned with cancer cell features of ferroptosis; this effect was enhanced by CTLA-4 blockade and recapitulated in vitro when tumor-draining lymph node CD8+ T cells were co-cultured with tumor cells. Inoculation with cell-free tumor fractions generated by histotripsy but not radiation or freeze/thaw conferred partial protection from tumor challenge. Discussion: We propose that histotripsy may evoke local necroptotic immunogenic cell death, priming systemic adaptive immune responses and abscopal ferroptotic cancer cell death.

Non-thermal histotripsy tumor ablation promotes abscopal immune responses that enhance cancer immunotherapy.

BACKGROUND: Developing the ability to use tumor-directed therapies to trigger potentially therapeutic immune responses against cancer antigens remains a high priority for cancer immunotherapy. We hypothesized that histotripsy, a novel non-invasive, non-thermal ablation modality that uses ultrasound-generated acoustic cavitation to disrupt tissues, could engender adaptive immune responses to tumor antigens. METHODS: Immunocompetent C57BL/6 mice inoculated with flank melanoma or hepatocellular carcinoma tumors were treated with histotripsy, thermal ablation, radiation therapy, or cytotoxic T lymphocyte-associated protein-4 (CTLA-4) blockade checkpoint inhibition. Lymphocyte responses were measured using flow cytometric and immunohistochemical analyses. The impact of histotripsy on abscopal immune responses was assessed in mice bearing bilateral tumors, or unilateral tumors with pulmonary tumors established via tail vein injection. RESULTS: Histotripsy ablation of subcutaneous murine melanoma tumors stimulated potent local intratumoral infiltration of innate and adaptive immune cell populations. The magnitude of this immunostimulation was stronger than that seen with tumor irradiation or thermal ablation. Histotripsy also promoted abscopal immune responses at untreated tumor sites and inhibited growth of pulmonary metastases. Histotripsy was capable of releasing tumor antigens with retained immunogenicity, and this immunostimulatory effect was associated with calreticulin translocation to the cellular membrane and local and systemic release of high mobility group box protein 1. Histotripsy ablation potentiated the efficacy of checkpoint inhibition immunotherapy in murine models of melanoma and hepatocellular carcinoma. CONCLUSIONS: These preclinical observations suggest that non-invasive histotripsy ablation can be used to stimulate tumor-specific immune responses capable of magnifying the impact of checkpoint inhibition immunotherapy.

Prehospital use of continuous positive airway pressure for acute severe congestive heart failure.

BACKGROUND: The utility of continuous positive airway pressure (CPAP) in the in-hospital treatment of congestive heart failure (CHF) is well established. Its exact role is less clear in the prehospital arena. OBJECTIVE: To describe the prehospital use of CPAP for patients presenting with acute severe heart failure in a large Emergency Medical Services system in New Jersey. METHODS: Retrospective review of prehospital charts from January 1, 2005 to December 31, 2006 of patients treated for acute CHF. Inclusion criteria for eligibility for CPAP mask use were: respiratory rate > 25 breaths/min, labored and shallow breathing, bilateral rales, history of CHF, intact mental status, and prehospital clinical diagnosis of CHF. Data collected included demographics, vital signs, oxygen saturation (SaO(2)), need for endotracheal intubation (ETI), and complications. RESULTS: There were 1306 charts reviewed; 387 patients met inclusion criteria. Of the 387, 149 patients had placement of CPAP (38.5%). The prehospital treatment times were (CPAP = 30 min; non-CPAP = 31 min; p < 0.01). The increase in SaO(2) for the CPAP group (9%) vs. the non-CPAP group (5%) was statistically significant (p < 0.01). Systolic blood pressure (BP) reduction (CPAP [27.1 mm Hg], non-CPAP [19.9 mm Hg], p < 0.01), diastolic BP reduction (CPAP [14.1 mm Hg], non-CPAP [7.4 mm Hg], p < 0.01), heart rate reduction (CPAP [17.2 beats/min], non-CPAP [9.6 beats/min], p < 0.01), respiratory rate reduction (CPAP [5.63], non-CPAP [4.09], p < 0.01), and ETI reduction (CPAP [2.6%], non-CPAP [5.46%], p < 0.01), all were statistically significant. Adjunctive CHF treatments were similar between the groups. CONCLUSION: The use of CPAP for eligible patients with acute severe CHF seems to be feasible and beneficial. Large-scale randomized prospective prehospital studies are needed to validate these results.

Analysis and applicability of the Dutch EMS system into countries developing EMS systems.

Development of an Emergency Medical Services (EMS) system is a challenging task for administrators, government agencies, and politicians. Factors such as the political climate, governmental support, and monetary resources heavily influence and shape the development of an EMS system. There are various systems in place to meet the functional needs and abilities of different regions while maintaining the basic principle of providing fast attention to those in need, and transportation to a definitive care facility. In this report, we describe the current Dutch EMS system in Amsterdam and the methods of daily pre-hospital health care delivery used, while exploring its potential applicability in developing nations. The Dutch EMS system is a nurse-driven triage system, both at the dispatch level and at the treatment level. Of the approximate yearly 165,000 calls received at the dispatch center, 40% of the requests were triaged based on national protocols such that no emergency ambulance dispatching was necessary. Furthermore, 30% of patients were treated at the scene, and did not subsequently require emergency transport to a definitive care facility.