Phase 1 dose-escalation, pharmacokinetic, and cerebrospinal fluid distribution study of TAK-285, an investigational inhibitor of EGFR and HER2.

INTRODUCTION: This phase 1 study assessed safety, maximum tolerated dose (MTD), pharmacokinetics, cerebrospinal fluid (CSF) distribution, and preliminary clinical activity of the receptor tyrosine kinase inhibitor TAK-285. METHODS: Patients with advanced, histologically confirmed solid tumors and Eastern Cooperative Oncology Group performance status ≤2 received daily oral TAK-285; daily dose was escalated within defined cohorts until MTD and recommended phase 2 dose (RP2D) were determined. Eleven patients were enrolled into an RP2D cohort. Blood samples were collected from all cohorts; CSF was collected at pharmacokinetic steady-state from RP2D patients. Tumor responses were assessed every 8 weeks per Response Evaluation Criteria in Solid Tumors. RESULTS: Fifty-four patients were enrolled (median age 60; range, 35-76 years). The most common diagnoses were cancers of the colon (28 %), breast (17 %), and pancreas (9 %). Escalation cohorts evaluated doses from 50 mg daily to 500 mg twice daily; the MTD/RP2D was 400 mg twice daily. Dose-limiting toxicities included diarrhea, hypokalemia, and fatigue. Drug absorption was fast (median time of maximum concentration was 2-3 h), and mean half-life was 9 h. Steady-state average unbound CSF concentration (geometric mean 1.54 [range, 0.51-4.27] ng/mL; n = 5) at the RP2D was below the 50 % inhibitory concentration (9.3 ng/mL) for inhibition of tyrosine kinase activity in cells expressing recombinant HER2. Best response was stable disease (12 weeks of nonprogression) in 13 patients. CONCLUSIONS: TAK-285 was generally well tolerated at the RP2D. Distribution in human CSF was confirmed, but the free concentration of the drug was below that associated with biologically relevant target inhibition.

Venetoclax penetrates in cerebrospinal fluid of an acute myeloid leukemia patient with leptomeningeal involvement.

Relapse at the central nervous system (CNS) in acute myeloid leukemia (AML) carries a dismal prognosis. Treatment options are limited to intrathecal therapy, high-dose cytarabine, high-dose methotrexate, and radiotherapy. Novel strategies are needed. Venetoclax has recently been approved by the FDA, in combination with hypomethylating agents or low-dose cytarabine, for elderly adults or patients ineligible for intensive chemotherapy affected by AML. However, little is known on its efficacy in patients with leptomeningeal involvement. Here, we present a case of a 52-year-old patient affected by AML relapsed at CNS after allogeneic bone marrow transplantation who was treated with venetoclax. We evaluated the concentration of the drug in cerebrospinal fluid (CSF) by HPLC MS/MS method on three different occasions to verify the penetration of the drug through the brain-blood barrier and we observed that the concentration in CSF was similar to the IC50 established in vitro.

Pharmacological properties of MK-3207, a potent and orally active calcitonin gene-related peptide receptor antagonist.

Calcitonin gene-related peptide (CGRP) has long been hypothesized to play a key role in migraine pathophysiology, and the advent of small-molecule antagonists has clearly demonstrated a clinical link between blocking the CGRP receptor and migraine efficacy. 2-[(8R)-8-(3,5-Difluorophenyl)-10-oxo-6,9-diazaspiro[4.5]dec-9-yl]-N-[(2R)-2'-oxo-1,1',2',3-tetrahydrospiro[indene-2,3'-pyrrolo[2,3-b]pyridin]-5-yl]acetamide (MK-3207) represents the third CGRP receptor antagonist to display clinical efficacy in migraine trials. Here, we report the pharmacological characterization of MK-3207, a potent and orally bioavailable CGRP receptor antagonist. In vitro, MK-3207 is a potent antagonist of the human and rhesus monkey CGRP receptors (K(i) = 0.024 nM). In common with other CGRP receptor antagonists, MK-3207 displays lower affinity for CGRP receptors from other species, including canine and rodent. As a consequence of species selectivity, the in vivo potency was assessed in a rhesus monkey pharmacodynamic assay measuring capsaicin-induced changes in forearm dermal blood flow via laser Doppler imaging. MK-3207 produced a concentration-dependent inhibition of dermal vasodilation, with plasma concentrations of 0.8 and 7 nM required to block 50 and 90% of the blood flow increase, respectively. The tritiated analog [3H]MK-3207 was used to study the binding characteristics on the human CGRP receptor. [3H]MK-3207 displayed reversible and saturable binding (K(D) = 0.06 nM), and the off-rate was determined to be 0.012 min(-1), with a t(1/2) value of 59 min. In vitro autoradiography studies on rhesus monkey brain slices identified the highest level of binding in the cerebellum, brainstem, and meninges. Finally, as an index of central nervous system penetrability, the in vivo cerebrospinal fluid/plasma ratio was determined to be 2 to 3% in cisterna magna-ported rhesus monkeys.

Application of the dried spot sampling technique for rat cerebrospinal fluid sample collection and analysis.

Dried blood spotting (DBS) sample collection is gaining favor in the pharmaceutical industry due to benefits that include reduced animal usage and easier sample shipment and storage when compared to traditional plasma collection/analysis. The applicability of the DBS card to alternate, limited-volume, matrices has not been as fully characterized as their use with whole blood. In this paper we explored the application of the DBS sample collection technique to rat cerebrospinal fluid (CSF). A reverse phase HPLC-MS/MS method was developed and characterized for the quantitative bioanalysis of the α7 neutonal nicotinic acetylcholine receptor agonist PHA-00543613 in CSF using the dried spot sampling technique. The characterized assay and dried spot sampling technique was employed to analyze serially collected in vivo rat CSF samples after a single 4mg/kg dose of PHA-00543613 in CSF-cannulated rats. The DBS strategy enabled the collection of more timepoints and produced comparable exposure results to those obtained by the collection and analysis of liquid CSF samples but notably with eight less animals.