Time to treatment failure of palbociclib and letrozole as second-line therapy or beyond in hormone receptor-positive advanced breast cancer.

PURPOSE: The management of endocrine therapy resistance is one of the most challenging facets of advanced breast cancer treatment. Palbociclib is an inhibitor of cyclin-dependent kinases 4 and 6 approved for the treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced or metastatic breast cancer in combination with fulvestrant in postmenopausal women with disease progression following endocrine therapy. However, treatment responsiveness of tumors to palbociclib after multiple lines of endocrine therapy is not clearly established. The purpose of this study was to determine the efficacy of palbociclib and letrozole in patients pretreated with one or more lines of endocrine therapy. METHODS: This was a single-center, retrospective cohort study of all postmenopausal hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer patients who received palbociclib and letrozole as a second-line endocrine therapy or beyond (and no prior cyclin-dependent kinases 4 and 6 inhibitor therapy) between February 1, 2015, and July 31, 2016. The primary objective was to evaluate time to treatment failure of palbociclib in combination with letrozole as a second-line of therapy or beyond. RESULTS: Fifty-three patients meeting eligibility criteria were included in the analysis. For the primary outcome, the median time to treatment failure of palbociclib and letrozole was 6.3 months (95% CI 3.1-7.4 months). Progression-free survival of palbociclib and letrozole therapy was 6.4 months (95% CI 4.9-8.3 months). CONCLUSIONS: Palbociclib and letrozole therapy is a viable, effective treatment option for metastatic breast cancer patients who were not exposed to cyclin-dependent kinases 4 and 6 inhibitors as a first-line endocrine therapy. The benefits of palbociclib and letrozole therapy were seen without excessive toxicity, and although neutropenia was common, it may be managed with dose reduction.

Pharmacy-Driven Dexmedetomidine Stewardship and Appropriate Use Guidelines in a Community Hospital Setting.

BACKGROUND: Dexmedetomidine is a widely utilized agent in the intensive care unit (ICU) because it does not suppress respiratory drive and may be associated with less delirium than midazolam or propofol. Cost of dexmedetomidine therapy and debate as to the proper duration of use has brought its use to the forefront of discussion. OBJECTIVE: To validate the efficacy and cost savings associated with pharmacy-driven dexmedetomidine appropriate use guidelines and stewardship in mechanically ventilated patients. METHODS: This was a retrospective cohort study of adult patients who received dexmedetomidine for ICU sedation while on mechanical ventilation at a 433-bed not-for-profit community hospital. Included patients were divided into pre-enactment (PRE) and postenactment (POST) of dexmedetomidine guideline groups. RESULTS: A total of 100 patients (50 PRE and 50 POST) were included in the analysis. A significant difference in duration of mechanical ventilation (11.1 vs 6.2 days, P = 0.006) and incidence of reintubation (36% vs 18% of patients, P = 0.043) was seen in the POST group. Aggregate use of dexmedetomidine 200-µg vials (37.1 vs 18.4 vials, P = 0.010) and infusion days (5.4 vs 2.5 days, P = 0.006) were significantly lower in the POST group. Dexmedetomidine acquisition cost savings were calculated at $374 456.15 in the POST group. There was no difference between the PRE and POST groups with regard to ICU length of stay, expected mortality, and observed mortality. CONCLUSIONS: Pharmacy-driven dexmedetomidine appropriate use guidelines decreased the use of dexmedetomidine and increased cost savings at a community hospital without adversely affecting clinical outcomes.

The crystal structure and mechanism of an unusual oxidoreductase, GilR, involved in gilvocarcin V biosynthesis.

GilR is a recently identified oxidoreductase that catalyzes the terminal step of gilvocarcin V biosynthesis and is a unique enzyme that establishes the lactone core of the polyketide-derived gilvocarcin chromophore. Gilvocarcin-type compounds form a small distinct family of anticancer agents that are involved in both photo-activated DNA-alkylation and histone H3 cross-linking. High resolution crystal structures of apoGilR and GilR in complex with its substrate pregilvocarcin V reveals that GilR belongs to the small group of a relatively new type of the vanillyl-alcohol oxidase flavoprotein family characterized by bicovalently tethered cofactors. GilR was found as a dimer, with the bicovalently attached FAD cofactor mediated through His-65 and Cys-125. Subsequent mutagenesis and functional assays indicate that Tyr-445 may be involved in reaction catalysis and in mediating the covalent attachment of FAD, whereas Tyr-448 serves as an essential residue initiating the catalysis by swinging away from the active site to accommodate binding of the 6R-configured substrate and consequently abstracting the proton of the hydroxyl residue of the substrate hemiacetal 6-OH group. These studies lay the groundwork for future enzyme engineering to broaden the substrate specificity of this bottleneck enzyme of the gilvocarcin biosynthetic pathway for the development of novel anti-cancer therapeutics.

High-dose methotrexate-based regimens with or without vincristine for the treatment of primary central nervous system lymphoma.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) is a rare malignancy with few treatment options. One regimen used for induction is rituximab, high-dose methotrexate (HD-MTX), procarbazine, and vincristine (R-MPV). A common institutional practice is removing vincristine (VCR) from this regimen due to its poor CNS penetration and associated toxicities. The aim of this study was to evaluate how the omission of VCR from HD-MTX-based induction impacted clinical outcomes. METHODS: In a retrospective review, patients with PCNSL who received HD-MTX-based induction therapy between January 1, 2010 and May 31, 2018 were evaluated. Patients were stratified according to treatment into 2 groups, VCR-containing therapy versus no VCR. The primary endpoint was complete response (CR) rate following the completion of induction chemotherapy. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and adverse event rate. RESULTS: Twenty-nine patients were included: 16 patients in the VCR group and 13 in the non-VCR group. A CR was achieved in 7 (44%) and 5 (38%) (odds ratio [OR] = 1.24; 95% confidence interval [CI]: 0.28-5.53) patients, respectively. Median OS was 85.3 (95% CI: 20.2-85.3) versus 67.1 months (95% CI: 10.5-NR) and median PFS was 60.7 (95% CI: 9.4-NR) versus 23.7 months (95% CI: 4.7-NR) in the VCR group versus non-VCR group, respectively. The incidence of any grade peripheral neuropathy was higher in the VCR group. CONCLUSIONS: CR rate, OS, and PFS were similar between groups regardless of VCR inclusion. Adverse events were higher in the VCR group. Larger studies are required to further evaluate the efficacy of VCR in PCNSL induction regimens.

Progression-Free Survival for Real-World Use of Palbociclib in Hormone Receptor-Positive Metastatic Breast Cancer.

BACKGROUND: Additional use of cyclin-dependent kinase 4/6 inhibitors with endocrine therapy improves progression-free survival (PFS) in advanced hormone receptor (HR)-positive HER2-negative breast cancer. However, neutropenia is a common reason for dose reductions, leading to concerns about palbociclib efficacy at lower doses. A safety analysis confirmed no PFS differences between palbociclib doses in the second-line setting, but to our knowledge, this has not been evaluated for first-line treatment. PATIENTS AND METHODS: In this retrospective, single-center cohort study we evaluated real-world use of first-line palbociclib with aromatase inhibitor (AI) treatment in HR-positive, HER2-negative metastatic breast cancer patients who received treatment between February 2015 and July 2017. The primary objective was to determine PFS of treatment with palbociclib and an AI in a real-world first-line setting. Secondary objectives included determining the PFS for patients treated with palbociclib on the basis of final doses, time to first dose reduction, time to treatment failure (TTF), and safety. RESULTS: Seventy patients were included in the final analysis. Median PFS was 26.4 months. No significant differences in PFS were observed on the basis of final doses of palbociclib (P = .77). Time to first dose reduction was 2.3 months. Median TTF was 26.1 months. Dose delays, reductions, and Grade 3/4 neutropenia were common (63%, n = 44; 57%, n = 40; and 62%, n = 43, respectively). CONCLUSION: Real-world first-line palbociclib treatment produced outcomes similar to those in PALOMA-2 (Palbociclib and Letrozole in Advanced Breast Cancer) (median PFS 26.4 months vs. 24.8 months) despite more dose reductions (57%, n = 40 vs. 36%, n = 160) and shorter time to first dose reduction (2.3 vs. 3.0 months). No significant differences in PFS were observed for the varying palbociclib doses. Palbociclib dose reductions might not significantly affect PFS in the first-line setting.