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Background: H3B-6545, a novel Selective ERα Covalent Antagonist (SERCA), inactivates both mutant and wild-type ERα by targeting cysteine 530 and enforcing antagonist conformation. It demonstrated a manageable safety profile and single-agent antitumor activity in heavily pretreated ER+, HER2- mBC patients (pts) (Hamilton et al, ASCO, 2021). Methods: The study aims at determining the recommended phase II doses of the combination of H3B-6545 and palbociclib in pts with ER+, HER2- mBC. Other endpoints include safety, pharmacokinetics, and preliminary efficacy. The escalation phase enrolls pts with at least 2 prior therapies in the metastatic setting. Up to one prior chemotherapy and up to one prior CDK4/6 inhibitor are allowed. Each cohort enrolled 6 pts to ensure availability of sufficient PK data. During the first cycle, H3B-6545 was added to palbociclib on day 9. Dose-limiting toxicities (DLTs) were assessed during the first 28 days starting from the 1st day of adding H3B-6545 to palbociclib (cycle 1 day 9 to cycle 2 day 8). Both drugs were started on day 1 of each of the subsequent cycles. Results: As of June 15, 2021, 14 pts were enrolled: 7 in Cohort 1 (H3B-6545 300 mg QD and palbociclib 100 mg QD) and 7 in Cohort 2 (H3B-6545 300 mg QD and palbociclib 125 mg QD). Median age was 61 years (range: 28-75 years), ECOG performance status was 0 in 7 pts (50%) and 1 in 7 pts (50%) and 9 pts (64%) had lung and/or liver metastases. Median number of prior therapies in the metastatic setting was 3 (range: 1-6). Prior therapy in the metastatic setting included fulvestrant (93%), CDK4/6 inhibitors (79%), aromatase inhibitors (64%), and chemotherapy (29%). One pt in each Cohort was not evaluable for dose limiting toxicity (DLT) assessment and no DLTs were observed in the first 2 Cohorts. Seven pts discontinued study treatment because of progression and 1 pt discontinued due to diagnosis of a second primary cancer during the first cycle. Non-hematological grade 2 or higher adverse events (AE), irrespective of causality, reported in ≥2 pts were: nausea, vomiting, abdominal pain, and bone pain, each observed in 2 pts (14%). Gr. 1 and 2 sinus bradycardia were reported in 6 (43%) and 1 pts (7%), respectively. One pt (7%) had grade 1 QT prolongation. No grade 4 AEs or treatment-related deaths were reported. For hematology and chemistry laboratory abnormalities: gr. 3 and 4 neutropenia in 7 pts (50%) and 2 pts (14%), respectively, gr. 3 thrombocytopenia in 1 pt (7%), gr. 3 anemia in 2 pts (14%). Grade 2 decrease in estimated glomerular filtration rate was observed in 7 pts (50%), all reported irrespective of causality. Co-administration of palbociclib had no meaningful impact on H3B-6545 exposure (15% and 21% increase in geometric means of AUC and Cmax, respectively). Co-administration of H3B-6545 modestly increased palbociclib exposure (49% and 36% increase in geometric means of AUC and Cmax, respectively). Among 6 response-evaluable pts in Cohort 1, 2 pts (33%) had confirmed partial responses and 4 pts (67%) had stable disease. Both responding pts received prior therapy with a CDK4/6 inhibitor and fulvestrant. Cohort 2 efficacy data is not yet mature. Recruitment is currently ongoing in Cohort 3 (H3B-6545 450 mg QD and palbociclib 125 mg QD). Conclusions: The combination of H3B-6545 (up to 300 mg dose) and palbociclib (up to 125 mg dose) was well-tolerated and demonstrated preliminary anti-tumor activity in heavily pretreated pts with ER+, HER2- mBC. ClinicalTrials.gov Identifier: NCT04288089. Citation Format: Stephen Johnston, Timothy J Pluard, Judy S Wang, Erika P Hamilton, Dejan Juric, Catherine R Scholz, Elizabeth Hnitecki, Sara Dar, Lei Gao, Lisa Cantagallo, Manav Korpal, Jianjun Alan Xiao, Lihua Yu, Tarek Sahmoud, Antonio Gualberto. H3B-6545 in combination with palbociclib in women with metastatic estrogen receptor-positive (ER+), human epidermal growth factor receptor 2 (HER2)-negative breast cancer, phase 1b study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-17-03.

Cells rapidly adapt to survive harsh environmental conditions through the potent upregulation of molecular chaperones or heat shock proteins (HSPs). The inducible members of the HSP70 family are the fastest and most transcriptionally induced chaperone upon stress. The HSP70 mRNA life cycle regulation in the cytoplasm is unique because it is translated during stress when general translation is repressed and rapidly degraded once conditions are optimal for growth. Contrary to the role of the HSP70 mRNA 5’ untranslated region in maximizing the synthesis of HSP70, we discovered that the coding sequence (CDS) represses its translation through the ribosome quality control (RQC) mechanism. The CDS of the most inducible HSP70 in Saccharomyces cerevisiae, SSA4, is uniquely biased with low-frequency codons that promote ribosome stalling during heat stress. The stalled ribosomes are recognized by RQC components Asc1p and Hel2p and two ribosome proteins, Rps28A and Rps19B, that we identified as new RQC components. Surprisingly, RQC does not signal the degradation of the SSA4 mRNA by no-go-decay (NGD). Instead, Asc1p destabilizes the SSA4 mRNA during recovery from heat stress by a mechanism independent of its ribosome binding and SSA4 CDS codon optimality. Therefore, Asc1p operates two synergistic mechanisms that converge to regulate the life cycle of HSP70 mRNA during stress and recovery. Our research identifies Asc1p as a critical regulator of the stress response and RQC as the system tuning HSP70 synthesis.

RATIONALE: Addition of CDK 4/6 inhibitors to endocrine therapy has become standard for patients (pts) with ER+ and HER2- BC with improvements in overall survival. However, acquired resistance to front-line therapy is inevitable, and response to later-line therapy is poor. H3B-6545 is a selective, orally available, small molecule covalent antagonist of the estrogen receptor (ERα). H3B-6545 binds covalently to a cysteine residue at position 530 of both wild-type and the constitutively active mutant ERα proteins. H3B-6545 demonstrated significant antitumor activity in multiple PDX breast cancer models, including those with mutated ESR1 (the gene encoding ERα). A phase I-II study was conducted to explore the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics, and efficacy of this agent in advanced ER+ and Her2- breast cancer pts (NCT03250676). METHODS: PK samples in phase I were obtained at day 1 and day 15 of cycle 1 (Predose, 0.5, 1, 2, 4, 6, 8, 10, and 24 h post dose) and sparse PK samples were collected in the phase II part of the trial. For pts enrolled in the food effect sub-study of phase II, plasma samples were collected during cycle 1 on day 15 and day 22 (Predose, 0.5, 1, 2, 4, 6, 8, 10, and 24 h post dose). Nonlinear mixed effect model (NONMEM) was applied for development of population PK models to fit H3B-6545 plasma concentration data with NONMEM® version 7.4 software. R was used for data management, visualization and statistical summaries. RESULTS: This phase I-II trial enrolled 47 pts in phase I part and 83 pts in the phase II part at the recommended phase II dose of 450 mg QD as of May 15, 2020. The 1180 plasma concentrations of H3B-6545 from a total of 103 pts at doses of 100-600 mg available as of January 15, 2020 were included in this analysis, with the following characteristics [n or (median, min-max) unit]: race (n=91/5/1/6 for White/Black/Asian/others), age (62.5, 31-81) yrs, body weight (79.5, 49-140) Kg, BMI (26.9, 17.6-45.6) Kg/m2, albumin (40, 29-52) g/dL, ALP (88.5, 39-917) IU/L, ALT (28, 10-193) IU/L, AST (36.5, 13-259) IU/L, bilirubin (8.6, 1.7-25.7) µM and creatinine clearance (112, 49.5-389) mL/min. The median number of prior therapy in the metastatic setting was 3 (range: 1 - 10). Out of 103 patients, 32 pts received treatment with a single high-fat meal to test food effect on PK over a randomized crossover design. H3B-6545 plasma concentrations were best described with a one compartment disposition PK model, plus a combined first- and zero-order parallel absorption and lag time. The estimated apparent clearance (CL/F) and volume of distribution (V/F) were 31 L/h and 422 L, respectively, with a typical terminal half-life of about 10 hours. H3B-6545 was absorbed fast, with a typical tmax of about 4 hours. A moderate to high variability (40-60%) was identified in major PK parameters (CL/F, V/F, bioavailability [F1]). A high-fat meal increased bioavailability by approximately 45% and prolonged tmax, roughly from 4 hours to 6 hours post dose. No significant effect was identified from other covariates: age, body weight, race, albumin, AST, ALP, ALT, bilirubin and creatinine clearance. CONCLUSIONS: H3B-6545 PK profiles in breast cancer patients were well described by a one-compartment disposition model with no significant effect of demographics, liver and renal function. When administered with a high fat meal, H3B-6545 exposure was modestly increased. Citation Format: Oneeb Majid, Jianjun Alan Xiao, Tarek Sahmoud, Sanae Yasuda, Lisa Cantagallo, Erika P Hamilton, Timothy Pluard, Dejan Juric, Antonio Gualberto, Ziad Husseiin. Pharmacokinetics of H3B-6545 in patients with locally advanced or metastatic estrogen receptor-positive HER2 negative breast cancer (ER+ and HER2- BC) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS12-15.

e13025 Background: H3B-6545, a highly Selective ERα Covalent Antagonist (SERCA), inactivates both wild-type and mutant ERα by targeting cysteine 530 and enforcing a unique antagonist conformation. At the dose of 450 mg daily, H3B-6545 has a manageable safety profile and demonstrated preliminary single-agent antitumor activity in heavily pretreated ER+, HER2- mBC patients (Hamilton et al, San Antonio Breast Cancer Symposium, 2020). Methods: The study evaluates the safety, pharmacokinetics (PK), and efficacy of H3B-6545 in combination with palbociclib in patients with ER+, HER2- metastatic breast cancer (MBC). The escalation phase enrolls patients with 2 or more prior therapies in the metastatic setting. Up to one prior chemotherapy and up to one prior CDK4/6 inhibitor were allowed. Results: As of January 31, 2021, 10 patients were enrolled; 7 in Cohort 1 (H3B-6545 300 mg QD and palbociclib 100 mg QD) and 3 in Cohort 2 (H3B-6545 300 mg QD and palbociclib 125 mg QD). One patient in Cohort 1 was not evaluable for dose limiting toxicity (DLT) assessment and no DLT was observed in the 6 evaluable patients. One patient discontinued study treatment because of progression and no patients discontinued study treatment due to adverse events (AE). Grade 3 or 4 neutropenia and thrombocytopenia were observed in 4 patients and 1 patient, respectively. One patient had grade 3 hypercalcemia, generalized muscle weakness, hypophosphatemia, fall, and anemia and one patient had grade 3 lipase increase. Four patients had grade 1 bradycardia or sinus bradycardia (asymptomatic) 1 patient had grade 2 sinus bradycardia (symptomatic, no intervention required). Preliminary PK analysis suggested no clinically relevant drug-drug interactions between H3B-6545 and palbociclib, to be confirmed with data from additional cohorts. Recruitment is currently ongoing in Cohort 2. Updated results will be presented. Conclusions: H3B-6545, in combination with palbociclib, was well-tolerated. Clinical trial information: NCT04288089.

e13022 Background: H3B-6545 is a selective, orally available, small molecule antagonist of the estrogen receptor (ER), covalently binding to a cysteine residue at position 530 of both wild-type and the constitutively active mutant ERα proteins. H3B-6545 demonstrated preliminary clinical antitumor activity in breasts cancer patients in phase 1b/2. Methods: This was an open-label phase 1 study to evaluate the relative bioavailability of H3B-6545 from a tablet formulation compared to capsules, and the effect of pantoprazole on the pharmacokinetics of H3B-6545, in healthy post-menopausal women. Subjects were randomized (1:1 ratio) to a combined crossover and fixed sequence 3 periods treatment: A single oral dose (SOD) of 450 mg H3B-6545 fasted on day 1 (capsules or tablets), followed by a 4-day washout; A SOD of 450 mg H3B-6545 fasted on day 5 (crossover formulation from the first period), followed by a 4-day washout; daily oral doses of 40 mg pantoprazole on days 9 to 15 with coadministration of a SOD of 450 mg H3B-6545 (tablets) on day 15. Results: A total of 16 subjects were enrolled and received at least one dose of H3B-6545 and 15 subjects completed all 3 periods. One subject assigned to the tablet/capsule treatment sequence withdrew from the study due to subject decision on day 13 (Period 3), following completion of Period 1 (H3B-6545 tablet) and Period 2 (H3B-6545 capsule). Following a SOD of H3B-6545 capsules alone, tablets alone, or tablets at steady-state QD of pantoprazole, H3B-6545 geometric mean Cmax was about 1070, 1120 and 1330 ng/mL, respectively, AUC was about 16600, 17500 and 18300 ng.h/mL, respectively, half-life was about 11.0, 11.0 and 10.2 hours, respectively, and the median Tmax was about 3.0, 4.0, and 2.0 hours post dose, respectively. The ratio (capsule/tablet) of Cmax and AUC was both about 0.95; steady-state pantoprazole QD increased H3B-6545 Cmax by 20% with no change in AUC. Nine subjects (56.3%) reported at least 1 TEAE during the study with constipation being the most common (43.8%); all TEAEs were mild in severity. There were no SAEs reported. Conclusions: Plasma PK of H3B-6545 is similar between tablets and capsules, and in the absence or presence of pantoprazole. Concurrent use of gastric acid reducers had a minimal effect on H3B-6545 exposure and was not considered clinically meaningful.

4090 Background: Evidence suggests that hyperactivated fibroblast growth factor 4 (FGFR4) signaling pathway leads to enhanced tumor growth. Targeting FGFR4 may have therapeutic benefit in tumors with altered FGF19 signaling. A phase I study (NCT02834780) was undertaken to assess H3B-6527, a highly selective covalent FGFR4 inhibitor, in patients with HCC/ICC. Methods: Adults with advanced HCC/ICC, ECOG PS 0-1, well compensated liver function, who progressed after > one prior therapy, received H3B-6527 po daily (QD) or twice-daily (bid) on a 21-day cycle following a 3+3 design. Doses ranged from 300-2000mg QD or 500-700mg BID. Patients in dose escalation were treated regardless of FGF19 status. Patients in expansion had FGF19+ tumors by mRNA testing. Adverse events (AEs), and pharmacokinetics (PK) were assessed. Response was determined by RECIST 1.1/mRECIST imaging every 6 weeks. Results: Study enrollment is complete at 128 patients. Ninety HCC patients were treated (QD = 48, bid = 42). ICC enrollment was suspended after 38 patients due to limited efficacy. No dose-limiting toxicities were seen and no grade 4-5 treatment related AEs have been observed. Recommended Phase II dose for H3B-6527 is 1000mg QD based upon safety, efficacy, and PK data. Grade 3 TEAEs have occurred in 12.5% of patients on QD dosing. Treatment related TEAEs were seen in 62.5% of patients on the QD schedule, with diarrhea (45.8%), fatigue (12.5%), and nausea (12.5%) most frequent. Drug discontinuation due to AEs for QD dosing was 8.3%. Interim data analysis shows that, for HCC patients with >2 prior lines of therapy treated on QD schedule, overall survival was 10.6m, progression-free survival 4.1m, overall response rate 16.7% (all partial responses), and clinical benefit rate 45.8% (responders + durable stable disease >17 weeks). H3B-6527 Cmax and AUC were lower at 300 mg dose but then similar across 500–2000 mg doses. Following oral administration of 1000 mg fasted, H3B-6527 plasma concentration reached peak at a Tmax of ̃2-3 hours and then decayed exponentially, with terminal half-life of ̃4-5 hours. There was no accumulation following QD dose. Dosing with food did not meaningfully change H3B-6527 plasma exposure. Conclusions: H3B-6527 was well tolerated and demonstrated a favorable toxicity and safety profile and encouraging clinical activity in heavily pretreated HCC patients. Final trial results will be presented at conference. Clinical trial information: NCT02834780.

1018 Background: H3B-6545, a selective, small molecule covalent antagonist of ERα demonstrated preclinical and preliminary clinical activity against ER+ breast cancer (Hamilton EP, SABCS, 2020). This study evaluated the activity and tolerability of H3B-6545 in patients (pts) with metastatic ER+, HER2-, breast cancer refractory to endocrine therapy. Methods: Patients received H3B-6545 once daily at the recommended phase II dose of 450 mg. The primary objective of the phase II is to estimate the objective response rate (ORR), progression-free survival (PFS), clinical benefit rate (CBR) and secondary objectives include safety. Results: 83 pts were treated with 450 mg in the phase II part of the trial. Additionally, 11 pts were treated with 450 mg in the phase I part of the trial and are included in this analysis. Median age was 62 years (range: 38 to 87 years), 81% had liver and/or lung metastases, and the median number of prior therapies for metastatic disease was 3 (range: 1 to 8). Prior CDK4/6 inhibitors, aromatase inhibitors, fulvestrant, and chemotherapy were received by 85%, 80%, 72%, and 50% of the pts, respectively. 58 pts (62%) had detectable ESR1 mutations in liquid biopsies, including 10 (11%) and 19 pts (20%) who had clonal Y537S and clonal D538G mutation, respectively. As of January 29, 2021, grade (gr) 2 or higher adverse events (AE) reported in ≥10% were anemia (19%), fatigue (16%), nausea (17%), and diarrhea (12%). Laboratory gr 2 or higher abnormalities reported in ≥10% pts were creatinine clearance decrease (38%), hemoglobin decrease (37%), bilirubin increase (12%), ALT increase (14%), AST increase (13%), and creatinine increase (11%). AE of gr 1 sinus bradycardia (asymptomatic) was reported in 34% and gr 2 (symptomatic, no intervention needed) was reported in 5%. Gr 2 and 3 QTcF prolongation were reported in 2 and 3 pts, respectively. There were no treatment-related deaths. Efficacy estimates are presented in the table below. Responses were observed in heavily pretreated pts, pts with visceral metastases and in pts who received prior fulvestrant, CDK4/6 inhibitor, and/or chemotherapy in the metastatic setting. Conclusions: H3B-6545 has a manageable safety profile and demonstrated single-agent anti-tumor activity in heavily pretreated ER+, HER2- mBC patients. Clinical activity was observed in pts with ESR1 mutations. Clinical trial information: NCT03250676 .[Table: see text]

Ceftolozane/tazobactam, a novel antibacterial with potent activity against Gram-negative pathogens, was developed for treatment of complicated urinary tract infections, including pyelonephritis, and intra-abdominal infections. A phase 1 pharmacokinetic (PK) study of ceftolozane/tazobactam in healthy Japanese, Chinese, and white volunteers was conducted to assess the potential effect of ethnicity on PK. The PK of ceftolozane, tazobactam, and tazobactam metabolite M1 was compared after single 1.5- and 3-g intravenous doses of ceftolozane/tazobactam. Ten Japanese, nine Chinese, and ten white subjects were enrolled, and 27 completed all doses of study medication. Dose-normalized PK parameters for ceftolozane and tazobactam were similar among Japanese, Chinese, and white subjects (at 1.5-g and 3-g doses, ceftolozane area under the plasma concentration-time curve from zero to infinity [AUC0-∞ ] = 166.3, 165.9, and 185.5 h μg/mL, respectively, and 157.7, 158.5, and 181.2 h μg/mL, respectively; tazobactam AUC0-∞ = 48.5, 43.2, and 50.1 h μg/mL, respectively, and 47.3, 43.7, and 50.0 h μg/mL, respectively. The 90% CIs of their ratio estimates were within the range 0.80 to 1.25 with the exception of AUC0-∞ for ceftolozane after the 3-g dose (0.79). The cumulative amount of ceftolozane and tazobactam excreted in urine was similar among ethnic groups. For all groups, treatment-emergent adverse events (AEs) were mild; no deaths or serious AEs were reported. The PK of ceftolozane/tazobactam was approximately dose proportional (i.e. doubling the dose approximately doubles the exposure) and similar among the groups. No dosage adjustment is needed for ceftolozane/tazobactam in Japanese and Chinese patients.

Ceftolozane/tazobactam is an antibacterial approved at 1.5 g (1g/0.5 g) every 8 hours (q8h); higher doses may provide additional benefits in difficult-to-treat infections. We conducted a phase I trial in healthy adults evaluating safety, tolerability, and pharmacokinetics of 3 g (2 g/1 g) ceftolozane/tazobactam administered q8h for 10 days. Sixteen participants were randomized (2:1:1) to 3 g ceftolozane/tazobactam, 1.5 g ceftolozane/tazobactam, or placebo. Participants underwent regular safety and plasma drug level assessments, with a follow-up safety visit 7 days after completion. No adverse events (AEs) were reported with placebo; 75% of participants in the 1.5-g and 50% in the 3-g arm experienced AEs. AE types were similar between the ceftolozane/tazobactam groups; all AEs were mild. No participants experienced clinically meaningful laboratory assessment or electrocardiogram abnormalities. Both ceftolozane and tazobactam exhibited dose-proportional pharmacokinetics without accumulation and without substantial differences in clearance and volume of distribution between groups. In the 3-g group, mean ceftolozane parameters were: peak concentration 104 μg/mL (day 1), 112 μg/mL (day 10); half-life 3 hours (day 10); area under the concentration-time curve (AUC(0-t) ) 272 μg·h/mL (day 1), 300μg·h/mL (day 10). Mean tazobactam parameters were: peak concentration 28 μg/mL (day 1), 26 μg/mL (day 10); half-life 1 hour (day 10); AUC(0-t) 47μg·h/mL (day 1), 41μg·h/mL (day 10). Administration of 3 g ceftolozane/tazobactam q8h for 10 days was safe and well tolerated in healthy volunteers.

Ceftolozane/tazobactam is a novel antipseudomonal cephalosporin and β-lactamase inhibitor in clinical development for treatment of complicated urinary tract (cUTI) and intra-abdominal (cIAI) infections and nosocomial pneumonia. The population pharmacokinetics of ceftolozane/tazobactam were characterized in healthy volunteers, subjects with varying degrees of renal function, and patients with cIAI or cUTI. Serum concentration data from 376 adults who received ceftolozane/tazobactam in doses ranging from 500 to 3000 mg were analyzed to identify factors contributing to the pharmacokinetic variability. Ceftolozane/tazobactam pharmacokinetics were well described by a linear two-compartment model with first-order elimination and moderate between-subject variability in both clearance and volume of distribution (Vc). For both ceftolozane and tazobactam, clearance was highly correlated with renal function with creatinine clearance influencing exposure, and infection influencing Vc. Body weight was an additional covariate affecting the Vc of ceftolozane. Other covariates tested, such as age, body weight, sex, ethnicity, and presence of infection, had no clinically relevant effects on exposure. The final pharmacokinetic models adequately described the plasma concentrations of ceftolozane and tazobactam and form the basis for further modeling and simulation including evaluation of probability of target attainment in a diverse population with varying demographics, degrees of renal function, and infection status.

MK-0457, an Aurora kinase and BCR-ABL inhibitor, was studied on a Phase I/II study in 77 patients with refractory hematologic malignancies. The average number of cycles per patient was 3 (range 1-21). Maximum tolerated doses for a 5-day short infusion and continuous infusion regimens were 40 mg/m(2)/h and 144 mg/m(2)/h, respectively. Drug-related adverse events (AEs) included transient mucositis and alopecia. Eight of 18 patients with BCR-ABL T315I-mutated chronic myelogenous leukemia (44%) had hematologic responses and one of three patients (33%) with Philadelphia chromosome-positive acute lymphoblastic leukemia obtained complete remission. MK-0457 has important activity in patients with leukemias expressing the highly resistant T315I BCR-ABL mutation.

The serotonin 5-HT1B receptor is a potential target for the pharmacologic treatment of depression. Positron emission tomography (PET) determination of 5-HT1B receptor occupancy with drug candidates targeting this receptor in non-human primate and human subjects may facilitate translation of research from animal models and guide dose selection for clinical studies. AZD3783 is a recently developed, orally bioavailable 5-HT1B receptor antagonist with potential antidepressant properties. To determine the relationship between plasma concentration of AZD3783 and occupancy at primate brain 5-HT1B receptors using PET and the radioligand [11C]AZ10419369. PET studies with [11C]AZ10419369 were performed in three non-human primates at baseline and after intravenous injection of AZD3783. Subsequently, PET measurements were undertaken in six human subjects at baseline and after administration of different single oral doses of AZD3783 (1–40 mg). After administration in non-human primates and human subjects, AZD3783 reduced regional [11C]AZ10419369 binding in a dose-dependent and saturable manner. The AZD3783 plasma concentration required for 50% receptor occupancy (K i,plasma) for monkeys was 25 and 27 nmol/L in occipital cortex and striatum, respectively. Corresponding estimates for human occipital cortex and ventral striatum were 24 and 18 nmol/L, respectively. The potential antidepressant AZD3783 binds in a saturable manner to brain 5-HT1B receptors with a similar in vivo affinity for human and monkey receptors. [11C]AZ10419369 can be successfully used to determine occupancy at brain 5-HT1B receptors in vivo and constitutes a useful tool for dose selection in clinical studies with 5-HT1B receptor compounds.

Phosphino-polycarboxylic acid (PPCA), a phosphorus-labeled linear polymer, has been widely used for controlling scale formation in the oil/gas field and water treatment processes because of its strong scale-inhibiting capability, high thermal stability, and environmental acceptability. PPCA is similar to poly(acrylic acid) with about 1% (w/w) phosphorus added to facilitate analytical measurement. In this study, the thermodynamic properties of PPCA and Ca−PPCA complexes in aqueous solution have been studied by combining electrostatic theory with potentiometric titrations. The acid−base and calcium complex solution chemistry of PPCA has been determined from 0.01 to 5 m ionic strength and from 25 to 90 °C. For simplicity, PPCA is reduced to a hypothetical, averaged monoacid, HA, with the same concentration of the PPCA monomer. Both proton and calcium dissociation reactions are defined as 1:1 type hypothetical reactions. That is, HA ↔ H+ + A- with pKH = pH − log(θu/θH) and Ca(A···A) ↔ Ca2+ + (A···A)2- with pK...

The induction periods of BaSO4 nucleation from supersaturated solutions have been measured over a wide range of conditions in the presence and absence of phosphino-polycarboxylic acid (PPCA). The inhibition of Barite nucleation in the presence of PPCA was correlated to the solution chemistry over a wide range of conditions. Only the dissociated fraction and the metal-complexed fraction of PPCA are effective to inhibit BaSO4 nucleation, while the protonated fraction has a poor inhibitory effect toward Barite nucleation. Ca2+ enhances the overall efficiency of PPCA through forming Ca−PPCA complexes and decreasing the fraction of protonated PPCA. Temperature does not strongly affect the Barite nucleation inhibition by PPCA. A set of equations has been proposed to model Barite nucleation time in the presence and absence of PPCA.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Calcitonin gene-related peptide (CGRP) was first described as a potent vasodilator. • CGRP is also increasingly recognized as a key player in the pathophysiology of migraine, and CGRP receptor antagonists potentially offer a new approach for treating migraine. • A novel pharmacodynamic assay to measure CGRP receptor antagonist activity non-invasively in humans has been developed, which involves measuring the increase in dermal blood flow induced by topical application of capsaicin on the forearm. WHAT THIS STUDY ADDS • This study shows that the novel oral CGRP receptor antagonist, telcagepant, inhibits the increases in dermal blood flow induced by the topical application of capsaicin on the human forearm. • This experimental medicine model may have utility to assist in dose selection for the development of CGRP receptor antagonists. AIMS To evaluate inhibition of capsaicin-induced increase in dermal blood flow (DBF) following telcagepant (MK-0974), a potent and selective orally bioavailable calcitonin gene-related peptide (CGRP) receptor antagonist being developed for the acute treatment of migraine. METHODS A three-period crossover study in 12 healthy adult men. Each subject received a single oral dose of telcagepant 300 mg, telcagepant 800 mg or placebo at 0 h, followed 0.5 and 3.5 h later by two topical doses of 300 and 1000 µg capsaicin per 20 µl water–ethanol mixture. Capsaicin was applied at two sites on the volar surface of the subjects' left and right forearms. DBF was assessed by laser Doppler perfusion imaging immediately before (‘baseline’), and 0.5 h after each capsaicin application at 1 and 4 h. Plasma samples to determine telcagepant concentrations were collected immediately after laser Doppler perfusion imaging. A pharmacodynamic model was developed to explore the relationship between plasma concentration and inhibition of capsaicin-induced increase in DBF. RESULTS Geometric mean plasma concentrations after dosing with 300 mg and 800 mg telcagepant were 720 and 1146 nm, respectively, at 1 h, vs. 582 and 2548 nm, respectively, at 4 h. The pharmacodynamic model suggested that the EC90 for telcagepant inhibition of capsaicin-induced increases in DBF was 909 nm. CONCLUSIONS Telcagepant inhibits the increases in DBF induced by the topical application of capsaicin on the human forearm. This experimental medicine model may have utility to assist in dose selection for the development of CGRP receptor antagonists.

Background. MK-0457 (VX-680) is a small-molecule inhibitor of Aurora kinases A, B, and C, FLT3, and JAK-2 with nanomolar level broad spectrum pre-clinical anti-tumor activity. The T315I BCR-ABL mutation mediates high level resistance to imatinib, dasatinib and nilotinib. A Phase I study of MK-0457 is being conducted in patients with refractory hematologic malignancies. The study regime is a 5 day continuous IV regimen given every 2 to 3 weeks. Methods. Fifteen CML patients received MK-0457 dosed at 8, 12, 16, 20, 24, 28, and 32 mg/m2/hr (11/15 had detectable BCR-ABL T315I). Peripheral blood for biomarker studies was available from patients at the 12 mg/m2/hr dose and above. Specimens were drawn prior to initiation of the infusion and at the end of the infusion (Day 5) during Cycle 1. Patient specimens have been analyzed using flow cytometry assays to measure BCR-ABL inhibition (phospho-CRKL), FLT3 and JAK-2 inhibition (phospho-STAT5) and Aurora kinase inhibition (phospho-histone H3). Results. MK-0457 has in vitro activity against cells expressing wild-type or mutated BCR-ABL, including the T315I BCR-ABL mutation. In CML and ALL patients with the T315I BCR-ABL mutation, MK-0457 is capable of inhibiting BCR-ABL as measured by the phospho-CRKL assay. The observed decrease in BCR-ABL activity trends with plasma exposure to MK-0457. At dose levels less than 20 mg/m2/hr, plasma exposure of MK-0457 typically does not exceed 1 micromolar and inhibition of BCR-ABL has not been observed. At exposures that exceed 1 micromolar, MK-0457 inhibits BCR-ABL, with pCRKL abundance falling below the lower limit of detection in one patient dosed at 24 mg/m2/hr and decreasing compared to baseline in several other patients. There is also a trend correlating degree of BCR-ABL inhibition as measured by the pCRKL biomarker and clinical response to MK-0457. Conclusions. MK-0457 inhibits BCR-ABL activity in CML and ALL patients with the BCR-ABL T315I mutation. Objective responses have been observed in patients without demonstrable BCR-ABL inhibition, suggesting that inhibition of Aurora kinase may also contribute to the clinical efficacy of MK-0457 in CML and ALL patients with the BCR-ABL T315I mutation.

Background. MK-0457 (VX-680) is a small-molecule inhibitor of aurora kinases A, B, and C, FLT3, BCR-ABL, and JAK2. MK-0457 exhibits nanomolar level broad-spectrum preclinical anti-tumor activity. Specifically, MK-0457 inhibits proliferation of patient-derived AML cells in vitro, and improves survival of a Ba/F3 FLT3 ITD murine model of systemic AML. A Phase I study of MK-0457 is being conducted in patients with a broad range of hematological malignancies, including acute myeloid and lymphoid leukemias. Methods. After IRB approval, 15 consenting patients with relapsed/refractory AML and ALL, ECOG performance status ≤ 2, and adequate organ function were enrolled using a standard dose escalation scheme with 3 patients/dose level until dose-limiting toxicity (DLT), followed by 6 patients/level. MK-0457 was administered by continuous 5-day intravenous infusion every 2 to 3 weeks. DLT was defined as grade 3 or higher non-hematologic toxicity during cycle 1. Pharmacokinetics (PKs) were collected pre-dose through 168 h and analyzed for MK-0457 by HPLC/mass spec. Results. Thirteen patients with AML and 2 patients with ALL were enrolled at 8, 12, 20, 24, and 28 mg/m2/hr. Among AML patients, two had a diploid karyotype and the remainder had complex unfavorable cytogenetic abnormalities. Two AML patients had a prior JAK2-positive MPD, transformed to AML, and then received MK-0457 as their 1st AML treatment. One AML patient received MK-0457 as first salvage, three as second salvage, and the remainder as salvage attempt three or higher. Both ALL patients failed prior multiagent chemotherapy; one of these patients had Philadelphia (Ph)-positive ALL and progressed after prior BCR-ABL inhibitor therapy, including dasatinib. The latter patient carried the BCR-ABL inhibitor resistance mutation, T315I. Four of 5 AML patients without baseline grade 3/4 myelosuppression in one cell line developed grade 4 neutropenia, including both JAK2-positive AML patients. Normalization of the platelet count during cycle one occurred in one MPD patient with thrombocytosis at baseline (~800 x 103/mL); Grade 3 thrombocytopenia occurred during cycle one in the other MPD patient with a normal baseline. The Ph+-ALL patient had eradication of peripheral blood blasts at the end of 2 cycles of therapy. No MK-0457 attributable extramedullary grade 2 or above adverse events were seen. Mild hair thinning was seen in some patients at dose levels 20 mg/m2/hr and above. Preliminary PK analysis showed dose-dependent linearity at steady state, with a biexponential decay at the end of infusion characterized by a rapid a decay followed by a slower b decay (t1/2 10–20 hrs). Conclusions. MK-0457 at well tolerated doses achieves myelosuppression in refractory AML and ALL patients. Its activity in JAK2+ transformed AML patients may be partially attributable to JAK2 inhibitory activity. The role of aurora kinase inhibition in the above responses is not yet established. As neither maximum tolerated dose nor dose limiting toxicity has been defined to date, dose finding on this Phase I study of MK-0457 is on-going in the acute leukemia population with 36 mg/m2/hr as the current dose level under investigation.

MK-0457 (VX-680) is a small molecule inhibitor of aurora kinases A, B, and C, FLT3, and JAK-2 with nanomolar level broad spectrum pre-clinical anti-tumor activity. The T315I BCR-ABL mutation mediates high level resistance to imatinib, dasatinib and nilotinib. MK-0457 has in vitro activity against cells expressing wild-type or mutated BCR-ABL, including the T315I BCR-ABL mutation. A Phase I study of MK-0457 is being conducted in patients with refractory hematologic malignancies. The study regime is a 5-day continuous IV regimen given every 2 to 3 weeks. To date, dose levels of 8 (N=4), 12 (N=5), 16 (N=3), 20 (N=4), 24 (N=15), 28 (N=6), and 32 (N=3) mg/m2/hr have been investigated. No MK-0457-attributable extramedullary Grade 3 adverse events (AEs) have been observed to date, and thus, the maximum-tolerated dose (MTD) has not yet been reached. Grade 1 nausea was observed in 1 patient each at the 12 and 24 mg/m2/hr levels, and there have been 4 patients with Grade 1 alopecia. Dose-proportional PK has been observed across dose levels. Myelosuppression is consistently seen with MK-0457 at all dose levels studied to date and appears dose-related. Of 40 patients on study to date, 15 had CML, 2 had ALL, 13 had acute myeloid leukemia (AML), and 10 had rapidly progressive or transforming MPD. A nested PCR strategy followed by direct DNA sequencing using the dideoxy chain termination method was used to detect and monitor mutations in codons 221 to 500 of the BCR-ABL kinase domain in CML and ALL patients. Of 15 patients with CML, 11 had a T315I BCR-ABL mutation as had 1 of 2 ALL patients. Of 14 currently evaluable patients with CML, 11 had an objective (hematologic, cytogenetic, and/or molecular) response, including all 11 patients with the T315I mutation. The patient with T315I-mutant ALL also had an objective response. Six of 8 currently evaluable patients with JAK-2 positive refractory MPD have achieved an objective response. Downregulation of BCR-ABL and CrkL phosphorylation in leukemia cells from CML and ALL patients treated on study has been documented – the possible role of aurora kinase inhibition in these clinical responses requires further investigation. Accrual to the study is ongoing at the 36 mg/m2/hr dose level. The currently reported cases are the first observed clinical activity of a kinase inhibitor against the T315I positive CML/ALL and JAK-2 positive MPD. The observation of responses in these patients to doses of MK-0457 associated with no significant toxicity warrants further study.

3009 Background: The AKs are essential for mitotic progression, spindle formation, centrosome maturation, chromosomal segregation, and cytokinesis. Elevated expression occurs frequently in tumors. MK-0457 (VX-680) is a potent AK inhibitor, with Ki values of 0.66, 18 and 4.6 nM for AKs A, B and C, respectively. MK-0457 inhibits proliferation of transformed cells in vitro (IC50’s 15–113 nM), and induces colon and pancreatic cancer xenograft regressions. Methods: After IRB approval, consenting patients (pts) with refractory solid tumors (median 3 prior regimens, range 2–6) and adequate hematologic and organ function were enrolled using an accelerated dose escalation scheme with 1–2 pts/dose level until ≥ grade 2 toxicity, followed by 3–6 pts/level. MK-0457 was administered by continuous 5-day intravenous infusion every 28 days. Dose-limiting toxicity (DLT) was grade 3 non-hematologic or grade 4 hematologic toxicity ≥ 5 days, or grade 4 febrile neutropenia (FN) during cycle 1. PKs were collected pre-dose through 168 h and analyzed for MK-0457 and metabolites by HPLC/mass spec. Steady state volume of distribution (Vdss), clearance (CL), maximal concentration (Cmax) and terminal half-life (t1/2) were determined by WinNonLin. Results: 16 pts received MK-0457 dosed at 0.5, 1, 2, 4, 8, and 12 mg/m2/h. Median number of cycles was 2 (range 1–6). DLT was asymptomatic neutropenia ≥ 5 days at 12 mg/m2/h. At 8 mg/m2/h, 1 pt experienced FN in cycle 2; a second developed a grade 2 allergic reaction. Three pts achieved stable disease as best response, and two of them completed 6 cycles. Plasma concentrations reached steady state rapidly (i.e., within 24 h) and declined biexponentially after the end of infusion; after a rapid initial decay, a slower decaying terminal phase demonstrated a t1/2 ∼15 h. PK parameters include Vdss = 237 ± 107 (SD) L/m2 and CL = 517 ± 141 ml/min/m2. At 8 mg/m2/h, Cmax was ∼650 nM. Conclusion: MK-0457 is generally well tolerated and achieves plasma levels similar to those causing regressions in xenografts. CL is high and exposures achieved are roughly dose proportional. Because 8 mg/m2/h was well tolerated in heavily pre-treated pts, escalation to 10 mg/m2/h is underway. Baseline tumor samples will be assessed for predictive biomarkers at the recommended phase II dose. [Table: see text]