Implementation, utilization, and evaluation of a pharmacist-driven romiplostim dosing service for patients with immune thrombocytopenia at a multisite cancer centre.

INTRODUCTION: Romiplostim is a thrombopoietin receptor agonist approved for the treatment of patients with chronic immune thrombocytopenia who have had an insufficient response to corticosteroids, immune globulin, or splenectomy. Dose adjustments of romiplostim are based on platelet counts and follow a dosing schema that requires frequent monitoring. As a quality improvement initiative to increase clinical efficiency and promote clinical pharmacy services at our institution, we developed a collaborative practice agreement and implemented a novel pharmacist-driven romiplostim dosing protocol. METHODS: A retrospective chart review was conducted to evaluate the acceptance, utilization, and impact of the pharmacist-driven romiplostim dosing service. The primary outcome of our analysis was the adoption rate by providers of the romiplostim pharmacist dosing service. Secondary endpoints were focused on patients newly initiating romiplostim on the dosing service and included platelet responses and number of dose adjustments by a pharmacist. RESULTS: A total of 54 patients received romiplostim in our analysis: 25 patients who had already been receiving romiplostim and 29 patients who newly initiated romiplostim during the study period. Of the 29 patients newly initiating romiplostim, 27 (93%) had their dosing managed by a pharmacist Twenty-one patients (84%) and 18 patients (75%) achieved an initial and durable response with romiplostim, respectively. Pharmacists made a median of 3 dose adjustments to romiplostim per patient. CONCLUSION: The implementation of a pharmacist-driven romiplostim dosing service led to a significant adoption and utilization by physicians at our health system.

Evaluation of a pharmacist-driven rapid infusion rituximab conversion protocol at a multisite cancer center.

INTRODUCTION: Infusion-related reactions (IRR) are a common adverse event associated with rituximab, an anti-CD20 monoclonal antibody indicated for the treatment of B-cell lymphomas. IRR risk is highest with the first infusion, which is given by a slow titration over an average of 3.5 hours. Subsequent administrations can be given over an accelerated, rapid 90-minute infusion if patients meet specific criteria. To improve rapid infusion rituximab utilization, we developed and implemented a pharmacist-driven protocol which allows pharmacists to change the administration instructions to rapid infusion. METHODS: A retrospective chart review was conducted to evaluate patients age ≥18 years with B-cell lymphomas who were eligible to receive rapid infusion rituximab following protocol implementation. The primary outcome was the prevalence of the use of rapid infusion rituximab for eligible patients. Secondary outcomes included the frequency of pharmacist-initiated conversions to rapid infusion rituximab and incidence of IRR with rapid infusions. RESULTS: A total of 180 patients were included in this study; 89 patients in the pre-protocol group and 91 patients in the post-protocol group. Fifteen patients and 66 patients in the pre-protocol and post-protocol groups, respectively, received rapid infusion rituximab (17% vs. 73%, p < 0.00001). The pharmacist-driven protocol was used to convert 49 patients (54%) to rapid infusion. No IRR occurred in patients receiving rapid infusion rituximab. CONCLUSION: The implementation of a pharmacist-driven protocol led to a significant improvement in the use of rapid infusion rituximab and optimized chair time utilization at our institution.

Evaluation of CYP2C19 Genotype-Guided Voriconazole Prophylaxis After Allogeneic Hematopoietic Cell Transplant.

There is a high risk of voriconazole failure in those with subtherapeutic drug concentrations, which is more common in CYP2C19 (cytochrome P450 2C19) rapid/ultrarapid metabolizers (RMs/UMs). We evaluated CYP2C19 genotype-guided voriconazole dosing on drug concentrations and clinical outcomes in adult allogeneic hematopoietic cell transplant recipients. Poor (PMs), intermediate (IMs), and normal metabolizers (NMs) received voriconazole 200 mg twice daily; RMs/UMs received 300 mg twice daily. Steady-state trough concentrations were obtained after 5 days, targeting 1.0-5.5 mg/L. Of 89 evaluable patients, 29% had subtherapeutic concentrations compared with 50% in historical controls (P < 0.001). Zero, 26%, 50%, and 16% of PMs, IMs, NMs, and RMs/UMs were subtherapeutic. Voriconazole success rate was 78% compared with 54% in historical controls (P < 0.001). No patients experienced an invasive fungal infection (IFI). Genotype-guided dosing resulted in $4,700 estimated per patient savings as compared with simulated controls. CYP2C19 genotype-guided voriconazole dosing reduced subtherapeutic drug concentrations and effectively prevented IFIs.

Effect of CYP3A4, CYP3A5, and ABCB1 Polymorphisms on Intravenous Tacrolimus Exposure and Adverse Events in Adult Allogeneic Stem Cell Transplant Patients.

Pharmacogenetics influences oral tacrolimus exposure; however, little data exist regarding i.v. tacrolimus. We investigated the impact of genetic polymorphisms in CYP3A4, CYP3A5, and ABCB1 on i.v. tacrolimus exposure and toxicity in adult patients receiving an allogeneic hematopoietic stem cell transplant for hematologic malignancies. Germline DNA was extracted from buccal swabs and genotyped for CYP3A4, CYP3A5, and ABCB1 polymorphisms. Continuous i.v. infusion of tacrolimus .03 mg/kg/day was initiated on day +5 post-transplant, and steady-state blood concentrations were measured 4days later. We evaluated the association between phenotypes and prevalence of nontherapeutic target concentrations (below or above 5 to 15 ng/mL) as well as tacrolimus-related toxicities. Of 63 patients, 28.6% achieved the target concentration; 71.4% were >15ng/mL, which was more common in CYP3A4 intermediate/normal metabolizers (compared with rapid) and those with at least 1 ABCB1 C2677T loss-of-function allele (P < .05). ABCB1 C2677T was significantly associated with concentrations >15ng/mL (odds ratio, 6.2; 95% confidence interval, 1.8 to 23.6; P = .004) and tacrolimus-related toxicities (odds ratio, 7.5; 95% confidence interval, 1.6 to 55.2; P = .02). ABCB1 C2677T and CYP3A4 are important determinants of i.v. tacrolimus exposure, whereas ABCB1 C2677T also impacts tacrolimus-related toxicities in stem cell transplants.

American Society for Blood and Marrow Transplantation Pharmacy Special Interest Group Survey on Chimeric Antigen Receptor T Cell Therapy Administrative, Logistic, and Toxicity Management Practices in the United States.

Administration of immune effector cell (IEC) therapy is a complex endeavor requiring extensive coordination and communication of various healthcare and administrative teams. Chimeric antigen receptor (CAR) T cells are the most established IEC therapy available. As of July 2018 two commercial gene therapy products, tisagenlecleucel and axicabtagene ciloleucel, have been approved by the US Food and Drug Administration. To gain insight into the infrastructure and practices across the country, the American Society for Blood and Marrow Transplantation Pharmacy Special Interest Group conducted an electronic survey on the current administrative, logistic, and toxicity management practices of CAR T cell therapy across the United States. This survey consists of 52 responses from institutions of varying sizes, most of which (∼80%) had previous investigational experience with CAR T cell therapy. Absorbing the energy of this exciting new treatment has challenged hematopoietic cell transplant programs across the country to strengthen department infrastructure, develop new committees and policies, and implement significant education to ensure safe administration. With the variety of experience with CAR T cell therapy, we hope this survey can contribute to the existing published literature and provide support and consensus to established and developing IEC programs and practice guidelines.

Hematopoietic cell transplantation in chronic myeloid leukemia in the age of tyrosine kinase inhibitors.

The development and widespread use of tyrosine kinase inhibitors (TKIs) has relegated the use of hematopoietic cell transplant (HCT), in most countries, to chronic myeloid leukemia (CML) patients who fail or are intolerant to TKIs. Its long-term cost effectiveness compared to TKIs, however, has maintained its use as front-line treatment in some areas. Advances in HCT, including the development of intravenous busulfan and plasma assays permitting dose adjustment, have improved results of HCT in CML. Improved supportive care has lowered the incidence of non-relapse mortality and improved survival. The availability of reduced-intensity preparative regimens, molecular typing of unrelated donors, and the use of cord blood and haploidentical donors has expanded the application of HCT to nearly any patient with an appropriate indication. From 2006 to 2010, approximately one thousand HCTs were performed annually in patients with CML. Better understanding of recent advances will improve the appropriate use and results of HCT in patients with CML.

Defective chromatin recruitment and retention of NHEJ core components in human tumor cells expressing a Cyclin E fragment.

Exposure to genotoxic agents, such as ionizing radiation (IR), produces double-strand breaks, repaired predominantly in mammalian cells by non-homologous end-joining (NHEJ). Ku70 was identified as an interacting partner of a proteolytic Cyclin E (CycE) fragment, p18CycE. p18CycE endogenous generation during IR-induced apoptosis in leukemic cells and its stable expression in epithelial tumor cells sensitized to IR. γH2AX IR-induced foci (IRIFs) and comet assays indicated ineffective NHEJ DNA repair in p18CycE-expressing cells. DNA pull-down and chromatin recruitment assays revealed that retention of NHEJ factors to double-strand breaks, but not recruitment, was diminished. Similarly, IRIFs of phosphorylated T2609 and S2056-DNA-PKcs and its target S1778-53BP1 were greatly decreased in p18CycE-expressing cells. As a result, DNA-PKcs chromatin association was also increased. 53BP1 IRIFs were suppressed when p18CycE was generated in leukemic cells and in epithelial cells stably expressing p18CycE. Ataxia telangiectasia mutated was activated but not its 53BP1 and MDC1 targets. These data indicate a profound influence of p18CycE on NHEJ through its interference with DNA-PKcs conformation and/or dimerization, which is required for effective DNA repair, making the p18CycE-expressing cells more IR sensitive. These studies provide unique mechanistic insights into NHEJ misregulation in human tumor cells, in which defects in NHEJ core components are rare.

A C-terminal fragment of Cyclin E, generated by caspase-mediated cleavage, is degraded in the absence of a recognizable phosphodegron.

We have previously shown that caspase-mediated cleavage of Cyclin E generates p18-Cyclin E in hematopoietic tumor cells. Its expression can induce apoptosis or sensitize to apoptotic stimuli in many cell types. However, p18-cyclin E has a much shorter half-life than Cyclin E, being more effectively ubiquitinated and degraded by the 26 S proteasome. A two-step process has emerged that regulates accelerated degradation of Cyclin E, with a caspase-mediated cleavage followed by enhanced proteasome-mediated degradation. We show that recognition of p18-Cyclin E by the Skp1-Cul1-Fbw7 (SCF) complex and its interaction with the Fbw7 protein isoforms can take place independently of phosphorylation of p18-Cyclin E at a C-terminal phosphodegron. In addition to the SCF(Fbw7) pathway, Ku70 binding that facilitates Hdm2 recruitment may also be implicated in p18-Cyclin E ubiquitination. Blocking p18-Cyclin E degradation with proteasome inhibitors increases levels of p18-Cyclin E and enhances its association with Ku70, thus leading to Bax release, its activation, and apoptosis. Moreover, cells expressing p18-Cyclin E are more sensitive to treatment with proteasome inhibitors, such as Bortezomib. By preventing its proteasomal degradation, p18-Cyclin E, but not Cyclin E, may become an effective therapeutic target for Bortezomib and apoptotic effectors in hematopoietic malignancies.

DNA damage response and apoptosis.

A number of methods have been developed to examine the morphologic, biochemical, and molecular changes that happen during the DNA damage response that may ultimately lead to death of cells through various mechanisms that include apoptosis. When cells are exposed to ionizing radiation or chemical DNA-damaging agents, double-stranded DNA breaks (DSB) are generated that rapidly result in the phosphorylation of histone variant H2AX. Because phosphorylation of H2AX at Ser 139 correlates well with each DSB, phospho-H2AX is a sensitive marker to used to examine the DNA damage and its repair. Apoptotic cells are characterized on the basis of their reduced DNA content and morphologic changes, including nuclear condensation, which can be detected by flow cytometry (sub-G1 DNA content), trypan blue, or Hoechst staining. The appearance of phosphatidylserine on the plasma membrane with annexin V-fluorochrome conjugates indicates the changes in plasma membrane composition and function. By combining it with propidium iodide staining, this method can also be used to distinguish early versus late apoptotic or necrotic events. The activation of caspases is another well-known biochemical marker of apoptosis. Finally, the Bcl-2 family of proteins and the mitochondria that play a critical role in DNA damage-induced apoptosis can be examined by translocation of Bax and cytochrome c in and out of mitochondria. In this chapter, we discuss the most commonly used techniques used in our laboratory for determining the DNA damage response leading to apoptosis.

Caspase-3 activation is a critical determinant of genotoxic stress-induced apoptosis.

A number of methods have been developed to identify the cells that undergo apoptosis by analyzing the morphological, biochemical, and molecular changes that take place during this universal biological process. The best recognized biochemical hallmark of both early and late stages of apoptosis is the activation of cysteine proteases (caspases). Detection of active caspase-3 in cells and tissues is an important method for apoptosis induced by a wide variety of apoptotic signals. Most common assays for examining caspase-3 activation include immunostaining, immunoblotting for active caspase-3, colorimetric assays using fluorochrome substrates, as well as employing the fluorescein-labeled CaspaTag pan-caspase in situ detection kit.

A jekyll and hyde role of cyclin E in the genotoxic stress response: switching from cell cycle control to apoptosis regulation.

Cyclin E protein levels and associated kinase activity rise in late G(1) phase, reach a peak at the G(1)/S transition, and quickly decline during S phase. The cyclin E/Cdk2 complex has a well-established function in regulating two fundamental biological processes: cell cycle progression and DNA replication. However, cyclin E expression is deregulated in a wide range of tumors. Our recent reports have uncovered a critical role for cyclin E, independent of Cdk2, in the cell death of hematopoietic tumor cells exposed to genotoxic stress. An 18-kD C-terminal fragment of cyclin E, p18-cyclin E, which is generated by caspase-mediated cleavage in hematopoietic cells during genotoxic stress-induced apoptosis has a critical role in the amplification of the intrinsic apoptotic pathway. By interacting with Ku70, p18-cyclin E liberates Bax, which participates in the amplification of apoptosis by sustaining a positive feedback loop targeting mitochondria. This process is independent of p53 function and new RNA or protein synthesis. Therefore, cyclin E emerges as an arbiter of the genotoxic stress response by regulating a finite physiological balance between cell proliferation and death in hematopoietic cells.

E2F4 function in G2: maintaining G2-arrest to prevent mitotic entry with damaged DNA.

Mammalian cells undergo cell cycle arrest in response to DNA damage through multiple checkpoint mechanisms. One such checkpoint pathway maintains genomic integrity by delaying mitotic progression in response to genotoxic stress. Transition though the G2 phase and entry into mitosis is considered to be regulated primarily by cyclin B1 and its associated catalytically active partner Cdk1. While not necessary for its initiation, the p130 and Rb-dependent target genes have emerged as being important for stable maintenance of a G2 arrest. It was recently demonstrated that by interacting with p130, E2F4 is present in the nuclei and plays a key role in the maintenance of this stable G2 arrest. Increased E2F4 levels and its translocation to the nucleus following genotoxic stress result in downregulation of many mitotic genes and as a result promote a G0-like state. Irradiation of E2F4-depleted cells leads to enhanced cellular DNA double-strand breaks that may be measured by comet assays. It also results in cell death that is characterized by caspase activation, sub-G1 and sub-G2 DNA content, and decreased clonogenic cell survival. Here we review these recent findings and discuss the mechanisms of G2 phase checkpoint activation and maintenance with a particular focus on E2F4.

Interaction of a cyclin E fragment with Ku70 regulates Bax-mediated apoptosis.

The cyclin E/Cdk2 complex plays an essential role in the G(1)/S cell cycle transition and DNA replication. Earlier we showed that in hematopoietic tumor cells, caspase-mediated cleavage of cyclin E generates p18-cyclin E, which is unable to interact with Cdk2 and therefore plays a role independent of the cell cycle. The expression of a cleavage-resistant cyclin E mutant greatly diminishes apoptosis, indicating the critical role of cyclin E cleavage. p18-cyclin E expression can induce apoptosis or sensitization to apoptotic stimuli in many cell types. Here we identify Ku70 as a specific p18-cyclin E-interacting partner. In hematopoietic tumor cell lines, the association of p18-cyclin E with Ku70 induces the dissociation of Bax from Ku70, followed by Bax activation. This mechanism of Bax activation leads to the amplification of the apoptosis signal in all tumor cell lines examined. N-terminal Ku70 deletion mutants are unable to bind to p18-cyclin E to regulate its apoptotic effect. p18-cyclin E-mediated amplification of apoptosis is dependent on Bax and Ku70 being greatly diminished in Ku70(-/-) and Bax(-/-) mouse embryo fibroblasts and in hematopoietic cells where Bax knockdown was achieved by short interfering RNA. The p18-cyclin E/Ku70 and Bax/Ku70 interactions provide a balance between apoptosis and the survival of cells exposed to genotoxic stress.