Faculty Bibliography

PURPOSE/OBJECTIVE:Emergency department (ED) visits by patients with cancer frequently end in hospitalization. As concerns about ED and hospital crowding increase, observation unit care may be an important strategy to deliver safe and efficient treatment for eligible patients. In this investigation, we compared the prevalence and clinical characteristics of cancer patients who received observation unit care with those who were admitted to the hospital from the ED. METHODS:We performed a multicenter prospective cohort study of patients with cancer presenting to an ED affiliated with one of 18 hospitals of the Comprehensive Oncologic Emergency Research Network (CONCERN) between March 1, 2016 and January 30, 2017. We compared patient characteristics with the prevalence of observation unit care usage, hospital admission, and length of stay. RESULTS:Of 1,051 enrolled patients, 596 (56.7%) were admitted as inpatients, and 72 (6.9%) were placed in an observation unit. For patients admitted as inpatients, 23.7% had a length of stay ≤2 days. The conversion rate from observation to inpatient was 17.1% (95% CI 14.6-19.4) among those receiving care in an observation unit. The average observation unit length of stay was 14.7 hours. Patient factors associated ED disposition to observation unit care were female gender and low Charlson Comorbidity Index. CONCLUSION/CONCLUSIONS:In this multicenter prospective cohort study, the discrepancy between observation unit care use and short inpatient hospitalization may represent underutilization of this resource and a target for process change.

Lack of absolute selectivity against cancer cells is a major limitation for current cancer therapies. In the previous study, we developed a prodrug strategy for selective cancer therapy using a masked cytotoxic agent puromycin [Boc-Lys(Ac)-Puromycin], which can be sequentially activated by histone deacetylases (HDACs) and cathepsin L (CTSL) to kill cancer cells expressing high levels of both enzymes. Despite the promise as a selective cancer therapy, its requirement of relatively high dosage could be a potential issue in the clinical setting. To address this issue, we aimed to further improve the overall efficacy of our prodrug strategy. Since the proteolytic cleavage by CTSL is the rate-limiting step for the drug activation, we sought to improve the substrate structure for CTSL activity by modifying the α-amino protecting group of lysine. Here we show that protection with Fmoc [Fmoc-Lys(Ac)-Puromycin] exhibits a marked improvement in overall anticancer efficacy compared to the original Boc-Lys(Ac)-Puromycin and this is mainly due to the highly efficient cellular uptake besides its improved substrate structure. Furthermore, to address a concern that the improved drug efficacy might direct high toxicity to the normal cells, we confirmed that Fmoc-Lys(Ac)-Puromycin still retains excellent cancer selectivity in vitro and no obvious systemic off-target toxicity in vivo. Thus our preclinical evaluation data presented here demonstrate that the Fmoc-Lys(Ac)-Puromycin exhibits substantially improved anticancer efficacy, further supporting our approach for the selective cancer therapy.