A phase 1, open-label, dose-escalation trial of oral TSR-011 in patients with advanced solid tumours and lymphomas.

BACKGROUND: Anaplastic lymphoma kinase (ALK) gene rearrangements are oncogenic drivers in non-small-cell lung cancer (NSCLC). TSR-011 is a dual ALK and tropomyosin-related kinase (TRK) inhibitor, active against ALK inhibitor resistant tumours in preclinical studies. Here, we report the safety, tolerability and recommended phase 2 dose (RP2D) of TSR-011 in patients with relapsed or refractory ALK- and TRK-positive advanced cancers. METHODS: In this sequential, open-label, phase 1 trial (NCT02048488), patients received doses of 30 mg, escalated to 480 mg every 24 hours (Q24h), followed by an expansion cohort of patients with ALK-positive cancers. The primary objective was to evaluate safety and tolerability. Secondary objectives included pharmacokinetics. RESULTS: TSR-011 320- and 480-mg Q24h doses exceeded the maximum tolerated dose. At the RP2D of 40 mg every 8 hours (Q8h), the most common grade 3-4 treatment-emergent adverse events occurred in 3.2-6.5% of patients. Of 14 ALK inhibitor-naive patients with ALK-positive NSCLC, 6 experienced partial responses and 8 had stable disease. CONCLUSIONS: At the RP2D (40 mg Q8h), TSR-011 demonstrated a favourable safety profile with acceptable QTc changes. Limited clinical activity was observed. Based on the competitive ALK inhibitor landscape and benefit/risk considerations, further TSR-011 development was discontinued. CLINICAL TRIAL REGISTRATION NUMBER: NCT02048488.

Pharmacokinetic Interactions of Rolapitant With Cytochrome P450 3A Substrates in Healthy Subjects.

Rolapitant (Varubi) is a neurokinin-1 receptor antagonist approved for the prevention of chemotherapy-induced nausea and vomiting. Rolapitant is primarily metabolized by the cytochrome P450 3A4 (CYP3A4) enzyme. Unlike other neurokinin-1 receptor antagonists, rolapitant is neither an inhibitor nor an inducer of CYP3A4 in vitro. The objective of this analysis was to examine the pharmacokinetics of rolapitant in healthy subjects and assess drug-drug interactions between rolapitant and midazolam (a CYP3A substrate), ketoconazole (a CYP3A inhibitor), or rifampin (a CYP3A4 inducer). Three phase 1, open-label, drug-drug interaction studies were conducted to examine the pharmacokinetic interactions of orally administered rolapitant with midazolam, rolapitant with ketoconazole, and rolapitant with rifampin. The pharmacokinetic profiles of midazolam and 1-hydroxy midazolam metabolites were essentially unchanged when coadministered with rolapitant, indicating the lack of a clinically relevant inhibition or induction of CYP3A by rolapitant. Coadministration of ketoconazole with rolapitant had no effects on rolapitant maximum concentration and resulted in an approximately 20% increase in the area under the concentration-time curve of rolapitant, suggesting that strong CYP3A inhibitors have minimal inhibitory effects on rolapitant exposure. Repeated administrations of rifampin appeared to reduce rolapitant exposure, resulting in a 33% decrease in maximum concentration and 87% decrease in area under the concentration-time curve from time zero to infinity. Coadministration of rolapitant did not affect the exposure of midazolam. Rifampin coadministration resulted in lower concentrations of rolapitant, and ketoconazole coadministration had no or minimal effects on rolapitant exposure. Rolapitant was safe and well tolerated when coadministered with ketoconazole, rifampin, or midazolam. No new safety signals were reported compared with previous studies of rolapitant.

Effects of Rolapitant Administered Intravenously or Orally on the Pharmacokinetics of Digoxin (P-glycoprotein Substrate) and Sulfasalazine (Breast Cancer Resistance Protein Substrate) in Healthy Volunteers.

Rolapitant is a selective and long-acting neurokinin-1 receptor antagonist approved in an oral formulation in combination with other antiemetic agents for the prevention of delayed chemotherapy-induced nausea and vomiting in adults. Four open-label phase 1 studies evaluated the safety and drug-drug interactions of a single dose of rolapitant given intravenously (166.5 mg) or orally (180 mg) with oral digoxin (0.5 mg) or sulfasalazine (500 mg), probe substrates for the P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), respectively. Administration of intravenous rolapitant with the substrates did not result in clinically significant effects on digoxin and sulfasalazine pharmacokinetics. In contrast, peak concentration and area under the curve for last quantifiable plasma concentrations increased by 71% (geometric mean ratio [GMR], 1.71; 90% confidence interval [CI], 1.49-1.95) and 30% (GMR, 1.30; 90%CI, 1.19-1.42), respectively, when rolapitant was coadministered orally with digoxin compared with digoxin alone; they increased by 140% (GMR, 2.40; 90%CI, 2.02-2.86) and 127% (GMR, 2.27; 90%CI, 1.94-2.65), respectively, when rolapitant was given orally with sulfasalazine compared with sulfasalazine alone. Adverse events were mild to moderate in severity in the absence or presence of rolapitant. There were no abnormal clinical laboratory or electrocardiogram findings. Thus, whether administered orally or intravenously, rolapitant was safe and well tolerated. Patients taking oral rolapitant with P-gp and BCRP substrates with a narrow therapeutic index should be monitored for potential adverse events; although increased plasma concentrations of these substrates may raise the risk of toxicity, they are not contraindicated.

Electrically Elicited Quadriceps Muscle Torque: A Comparison of 3 Waveforms.

Study Design A controlled laboratory study, with a single-blind, block-randomization crossover design. Objectives To compare the electrically elicited knee extensor torque produced by 3 clinically available waveforms: 2500-Hz burst-modulated alternating current (BMAC), 1000-Hz BMAC, and 1000-Hz burst-modulated biphasic square-wave pulsed current (BMBPC). Background Neuromuscular electrical stimulation (NMES) is the therapeutic use of electrical current to strengthen muscle. Muscle torque produced by NMES is limited by discomfort. Methods The knee extensor maximal volitional isometric torque (KEMVIT) of 33 able-bodied participants (18 female) was measured and used to normalize the electrically elicited knee extensor torque to produce a percent of KEMVIT (%KEMVIT). Electrically elicited isometric knee extensor torque was measured in response to each of the waveforms at the participants' maximum tolerance. Results The average maximum tolerated stimulation produced 32.0 ± 16.7 %KEMVIT with 2500-Hz BMAC, 38.2 ± 18.4 %KEMVIT with 1000-Hz BMAC, and 42.2 ± 17.1 %KEMVIT with 1000-Hz BMBPC. Tukey honest significant difference (HSD) post hoc testing revealed a statistically significant difference between 2500-Hz BMAC and 1000-Hz BMAC (P = .046), and between 2500-Hz BMAC and 1000-Hz BMBPC (P<.001). No statistically significant difference was found between 1000-Hz BMAC and 1000-Hz BMBPC (P = .267). Conclusion For eliciting maximum knee extensor muscle torque, 1000-Hz BMBPC and 1000-Hz BMAC were similarly effective, and 2500-Hz BMAC was less effective. J Orthop Sports Phys Ther 2018;48(3):217-224. Epub 19 Dec 2017. doi:10.2519/jospt.2018.7601.

Bioequivalence of Intravenous and Oral Rolapitant: Results From a Randomized, Open-Label Pivotal Study.

Rolapitant, a selective and long-acting neurokinin-1 receptor antagonist, is approved in an oral formulation for the prevention of delayed chemotherapy-induced nausea and vomiting in adults. The objective of this pivotal study was to assess the bioequivalence of a single intravenous infusion of rolapitant versus a single oral dose of rolapitant. In this randomized, open-label phase 1 study, healthy volunteers were administered rolapitant as a 180-mg oral dose or a 30-minute 166.5-mg intravenous infusion. Blood samples for pharmacokinetic analysis were collected predose and at points up to 912 hours postdose. Criteria for bioequivalence of the intravenous dose versus the oral dose were met if the 90% confidence intervals (CIs) for the ratios of the geometric least-squares means (GLSMs) for the area under the plasma concentration-time curve (AUC) from time 0 to the time of the last quantifiable concentration (AUC0-t ) and AUC from time 0 extrapolated to infinity (AUC0-∞ ) for rolapitant were within 0.80-1.25. Mean rolapitant systemic exposure and half-lives were similar in the oral (n = 62) and intravenous (n = 61) rolapitant groups. The 90%CIs of the ratio of GLSMs were within the 0.80-1.25 range for AUC0-t (0.94-1.09) and AUC0-∞ (0.93-1.10). The incidence of treatment-emergent adverse events, all mild or moderate in severity, was similar in the intravenous and oral groups. A 166.5-mg intravenous infusion of rolapitant met the bioequivalence criteria based on AUC to a 180-mg oral dose and was well tolerated.

E unum pluribus: multiple proteins from a self-processing polyprotein.

Many applications of genetic engineering require transformation with multiple (trans)genes, although to achieve these using conventional techniques can be challenging. The 2A oligopeptide is emerging as a highly effective new tool for the facile co-expression of multiple proteins in a single transformation step, whereby a gene encoding multiple proteins, linked by 2A sequences, is transcribed from a single promoter. The polyprotein self-processes co-translationally such that each constituent protein is generated as a discrete translation product. 2A functions in all the eukaryotic systems tested to date and has already been applied, with great success, to a broad range of biotechnological applications: from plant metabolome engineering to the expression of T-cell receptor complexes, monoclonal antibodies or heterodimeric cytokines in animals.

A needs assessment: Fellowship Directors Forum of the American Academy of Hospice and Palliative Medicine.

The Fellowship Directors Forum, a special interest group of the American Academy of Hospice and Palliative Medicine (AAHPM) initiated an assessment of the needs of directors of fellowship programs in the emerging specialty of hospice and palliative care. One major finding, which may contribute to understanding the needs of other new disciplines, is that directors come into this role with clinical and teaching experience, but lacking administrative, educational, and management skills perceived as necessary to success. A study team collected data from current and former fellowship directors across the United States using an online survey and telephone interviews. The survey was sent to 60 current and former directors, with a 60% response rate, and 16 randomly selected directors were interviewed. Results showed that directors believe development of an outcome-based standardized curriculum is vitally important to advancement of the field, and that this should be developed collaboratively through the Forum. Although directors were confident of their own clinical and teaching skills, directors identified a lack of adequate training and experience in several management and educational skill areas critical to running a successful fellowship program. The study team made several recommendations: develop models from parts of existing programs that can be incorporated into a standardized curriculum to meet Accreditation Council of Graduate Medical Education (ACGME) requirements; provide workshops and toolkits for new directors to address the lack of management and educational skills; and establish new communication methods through more or longer forum meetings, a dedicated website, and an online discussion group.

Co-translational, intraribosomal cleavage of polypeptides by the foot-and-mouth disease virus 2A peptide.

During co-translational protein import into the endoplasmic reticulum ribosomes are docked onto the translocon. This prevents inappropriate exposure of nascent chains to the cytosol and, conversely, cytosolic factors from gaining access to the nascent chain. We exploited this property of co-translational translocation to examine the mechanism of polypeptide cleavage by the 2A peptide of the foot-and-mouth disease virus. We find that the scission reaction is unaffected by placing 2A into a co-translationally targeted protein. Moreover, the portion of the polypeptide C-terminal to the cleavage site remains in the cytosol unless it contains its own signal sequence. The pattern of cleavage is consistent with the proposal that the 2A-mediated cleavage reaction occurs within the ribosome itself. In addition, our data indicate that the ribosome-translocon complex detects the break in the nascent chain and prevents any downstream protein lacking a signal sequence from gaining access to the endoplasmic reticulum.

Analysis of the aphthovirus 2A/2B polyprotein 'cleavage' mechanism indicates not a proteolytic reaction, but a novel translational effect: a putative ribosomal 'skip'.

The 2A region of the aphthovirus foot-and-mouth disease virus (FMDV) polyprotein is only 18 aa long. A 'primary' intramolecular polyprotein processing event mediated by 2A occurs at its own C terminus. FMDV 2A activity was studied in artificial polyproteins in which sequences encoding reporter proteins flanked the 2A sequence such that a single, long, open reading frame was created. The self-processing properties of these artificial polyproteins were investigated and the co-translational 'cleavage' products quantified. The processing products from our artificial polyprotein systems showed a molar excess of 'cleavage' product N-terminal of 2A over the product C-terminal of 2A. A series of experiments was performed to characterize our in vitro translation systems. These experiments eliminated the translational or transcriptional properties of the in vitro systems as an explanation for this imbalance. In addition, the processing products derived from a control construct encoding the P1P2 region of the human rhinovirus polyprotein, known to be proteolytically processed, were quantified and found to be equimolar. Translation of a construct encoding green fluorescent protein (GFP), FMDV 2A and beta-glucuronidase, also in a single open reading frame, in the presence of puromycin, showed this antibiotic to be preferentially incorporated into the [GFP2A] translation product. We conclude that the discrete translation products from our artificial polyproteins are not produced by proteolysis. We propose that the FMDV 2A sequence, rather than representing a proteolytic element, modifies the activity of the ribosome to promote hydrolysis of the peptidyl(2A)-tRNA(Gly) ester linkage, thereby releasing the polypeptide from the translational complex, in a manner that allows the synthesis of a discrete downstream translation product to proceed. This process produces a ribosomal 'skip' from one codon to the next without the formation of a peptide bond.

The 'cleavage' activities of foot-and-mouth disease virus 2A site-directed mutants and naturally occurring '2A-like' sequences.

The 2A/2B cleavage of aphtho- and cardiovirus 2A polyproteins is mediated by their 2A proteins 'cleaving' at their own C termini. We have analysed this activity using artificial reporter polyprotein systems comprising green fluorescent protein (GFP) linked via foot-and-mouth disease virus (FMDV) 2A to beta-glucuronidase (GUS) -- forming a single, long, open reading frame. Analysis of the distribution of radiolabel showed a high proportion of the in vitro translation products (approximately 90%) were in the form of the 'cleavage' products GUS and [GFP2A]. Alternative models have been proposed to account for the 'cleavage' activity: proteolysis by a host-cell proteinase, autoproteolysis or a translational effect. To investigate the mechanism of this cleavage event constructs encoding site-directed mutant and naturally occurring '2A-like' sequences were used to program in vitro translation systems and the gel profiles analysed. Analysis of site-directed mutant 2A sequences showed that 'cleavage' occurred in constructs in which all the candidate nucleophilic residues were substituted -- with the exception of aspartate-12. This residue is not, however, conserved amongst all functional '2A-like' sequences. '2A-like' sequences were identified within insect virus polyproteins, the NS34 protein of type C rotaviruses, repeated sequences in Trypanosoma spp. and a eubacterial alpha-glucosiduronasesequence(Thermatoga maritima aguA). All of the 2A-like sequences analysed were active (to various extents), other than the eubacterial alpha-glucosiduronase 2A-like sequence. This method of control of protein biogenesis may well not, therefore, be confined to members of the PICORNAVIRIDAE: Taken together, these data provide additional evidence that neither FMDV 2A nor '2A-like' sequences are autoproteolytic elements.