Species of Clostridium bacteria are notable for their ability to lyse tumor cells growing in hypoxic environments. We show that an attenuated strain of Clostridium novyi (C. novyi-NT) induces a microscopically precise, tumor-localized response in a rat orthotopic brain tumor model after intratumoral injection. It is well known, however, that experimental models often do not reliably predict the responses of human patients to therapeutic agents. We therefore used naturally occurring canine tumors as a translational bridge to human trials. Canine tumors are more like those of humans because they occur in animals with heterogeneous genetic backgrounds, are of host origin, and are due to spontaneous rather than engineered mutations. We found that intratumoral injection of C. novyi-NT spores was well tolerated in companion dogs bearing spontaneous solid tumors, with the most common toxicities being the expected symptoms associated with bacterial infections. Objective responses were observed in 6 of 16 dogs (37.5%), with three complete and three partial responses. On the basis of these encouraging results, we treated a human patient who had an advanced leiomyosarcoma with an intratumoral injection of C. novyi-NT spores. This treatment reduced the tumor within and surrounding the bone. Together, these results show that C. novyi-NT can precisely eradicate neoplastic tissues and suggest that further clinical trials of this agent in selected patients are warranted.

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For long-term central lines (CL), the lumen is the major source of central line-associated bloodstream infections (CLABSI). The current standard of care for maintaining catheter patency includes flushing the CL with saline or heparin. Neither agent has any antimicrobial activity. Furthermore, heparin may enhance staphylococcal biofilm formation. We evaluated the safety and efficacy of a novel nonantibiotic catheter lock solution for the prevention of CLABSI. Between November 2015 and February 2016, we enrolled 60 patients with hematologic malignancies who had peripherally inserted central catheters (PICC) to receive the study lock solution. The study lock consisted of 15 or 30 g/ml of nitroglycerin in combination with 4% sodium citrate and 22% ethanol. Each lumen was locked for at least 2 h once daily prior to being flushed. After enrollment of 10 patients at the lower nitroglycerin dose without evidence of toxicity, the dose was escalated to the higher dose (30 g/ml). There were no serious related adverse events or episodes of hypotension with lock administration. Two patients experienced mild transient adverse events (one headache and one rash) possibly related to the lock and that resolved without residual effect. The CLABSI rate was 0 on lock days versus 1.6/1,000 catheter days (CD) off lock prophylaxis, compared with a rate of 1.9/1,000 CD at the institution in the same patient population. In conclusion, the nitroglycerin-based lock prophylaxis is safe and well tolerated. It may prevent CLABSI when given daily to cancer patients. Large, prospective, randomized clinical trials are needed to validate these findings. (This study has been registered at ClinicalTrials.gov under identifier NCT02577718.) KEYWORDS nitroglycerin, catheter, lock solution, central venous catheter, infections, cancer patients C entral venous catheters (CVC) are imperative for the treatment and management of cancer patients, particularly those with hematological malignancies who require a long-term access for the administration of chemotherapy, antibiotics, blood products, and fluids as well as for frequent blood draws. However, these lifelines are the leading source of bloodstream infections, causing at least 400,000 episodes of bloodstream infections yearly in cancer patients (1) and contributing to up to 62% of the bloodstream infections in patients with long-term CVC (2, 3). These catheter-associated infections constitute a major public health challenge, with an estimated mortality rate of 10 to 25% (4) and estimated cost of $45,000 per episode (5).