Reducing Second Gram-Negative Antibiotic Therapy on Pediatric Oncology and Hematopoietic Stem Cell Transplantation Services.

OBJECTIVE To evaluate interventions to reduce avoidable antibiotic use on pediatric oncology and hematopoietic stem cell transplantation (HSCT) services. DESIGN Interrupted time series. SETTING Academic pediatric hospital with separate oncology and HSCT services. PARTICIPANTS Children admitted to the services during baseline (October 2011-August 2013) and 2 intervention periods, September 2013-June 2015 and July 2015-June 2016, including 1,525 oncology hospitalizations and 301 HSCT hospitalizations. INTERVENTION In phase 1, we completed an update of the institutional febrile neutropenia (FN) guideline for the pediatric oncology service, recommending first-line ß-lactam monotherapy rather than routine use of 2 gram-negative agents. Phase 2 included updating the HSCT service FN guideline and engagement with a new pediatric antimicrobial stewardship program. The use of target antibiotics (tobramycin and ciprofloxacin) was measured in days of therapy per 1,000 patient days collected from administrative data. Intervention effects were evaluated using interrupted time series with segmented regression. RESULTS Phase 1 had mixed effects-long-term reduction in tobramycin use (97% below projected at 18 months) but rebound with increasing slope in ciprofloxacin use (+18% per month). Following phase 2, tobramycin and ciprofloxacin use on the oncology service were both 99% below projected levels at 12 months. On the HSCT service, tobramycin use was 99% below the projected level and ciprofloxacin use was 96% below the projected level at 12 months. CONCLUSIONS Locally adapted guidelines can facilitate practice changes in oncology and HSCT settings. More comprehensive and ongoing interventions, including follow-up education, feedback, and engagement of companion services may be needed to sustain changes. Infect Control Hosp Epidemiol 2017;38:1039-1047.

The Hippo effector YAP promotes resistance to RAF- and MEK-targeted cancer therapies.

Resistance to RAF- and MEK-targeted therapy is a major clinical challenge. RAF and MEK inhibitors are initially but only transiently effective in some but not all patients with BRAF gene mutation and are largely ineffective in those with RAS gene mutation because of resistance. Through a genetic screen in BRAF-mutant tumor cells, we show that the Hippo pathway effector YAP (encoded by YAP1) acts as a parallel survival input to promote resistance to RAF and MEK inhibitor therapy. Combined YAP and RAF or MEK inhibition was synthetically lethal not only in several BRAF-mutant tumor types but also in RAS-mutant tumors. Increased YAP in tumors harboring BRAF V600E was a biomarker of worse initial response to RAF and MEK inhibition in patients, establishing the clinical relevance of our findings. Our data identify YAP as a new mechanism of resistance to RAF- and MEK-targeted therapy. The findings unveil the synthetic lethality of combined suppression of YAP and RAF or MEK as a promising strategy to enhance treatment response and patient survival.