Absolute Bioavailability of Vemurafenib in Patients With BRAF V600 Mutation–Positive Malignancies

Advances in Understanding and Management of Erdheim-Chester Disease

Erdheim Chester Disease (ECD) is a rare histiocytic disorder marked by infiltration of organs with CD68+ histiocytes. ECD stems from mutations of BRAF and MAP2K1 in hematopoietic stem and progenitor cells (HSPCs), which further differentiate into monocytes and histiocytes. Histopathology reveals lipid-containing histiocytes, which test positive for CD68 and CD133 in immunohistochemistry. Signs and symptoms vary and depend on the organ/s of manifestation. Definitive radiological results associated with ECD include hairy kidney, coated aorta, and cardiac pseudotumor. Treatment options primarily include anti-cytokine therapy and inhibitors of BRAF and MEK signaling.

The application of Phase 0 and microtracer approaches in early clinical development: past, present, and future

Phase 0 microdosing studies were introduced to the drug development community approximately 20 years ago. A microdose is defined as less than 1/100th of the dose calculated based on animal data to yield a pharmacological effect in humans, with a maximum of 100 μg, or 30 nmoles for protein products. In our experience, Phase 0 microdose studies have not been fully embraced by the pharmaceutical industry. This notion is based on the number of Phase 0 studies that we have been involved in. Thus, we conducted at least 17 Phase 0 microdose studies in the Zero's (on average, two per year), but in the years beyond this, it was only 15 studies (1.4 per year); in these latter years, we did conduct a total of 23 studies which employed an intravenous (i.v.) microdose for absolute bioavailability (ABA) assessments (two per year on average), which are the most used and potentially informative type of clinical study using a microdose, albeit they are formally not microdose studies. In the current review, we summarize the past use of and experience with Phase 0 microdose designs in early clinical development, including intravenous 14C microdose ABA studies, and assess what is needed to increase the adoption of useful applications of Phase 0/microdose studies in the near future.

Current Trends in API Co-Processing: Spherical Crystallization and Co-Precipitation Techniques

Active Pharmaceutical Ingredients (APIs) do not always exhibit processable physical properties, which makes their processing in an industrial setup very demanding. These issues often lead to poor robustness and higher cost of the drug product. The issue can be mitigated by co-processing the APIs using suitable solvent media-based techniques to streamline pharmaceutical manufacturing operations. Some of the co-processing methods are the amalgamation of API purification and granulation steps. These techniques also exhibit adequate robustness for successful adoption by the pharmaceutical industry to manufacture high quality drug products. Spherical crystallization and co-precipitation are solvent media-based co-processing approaches that enhances the micromeritic and dissolution characteristics of problematic APIs. These methods not only improve API characteristics but also enable direct compression into tablets. These methods are economical and time-saving as they have the potential for effectively circumventing the granulation step, which can be a major source of variability in the product. This review highlights the recent advancements pertaining to these techniques to aid researchers in adopting the right co-processing method. Similarly, the possibility of scaling up the production of co-processed APIs by these techniques is discussed. The continuous manufacturability by co-processing is outlined with a short note on Process Analytical Technology (PAT) applicability in monitoring and improving the process.

Considering the Oral Bioavailability of Protein Kinase Inhibitors: Essential in Assessing the Extent of Drug-Drug Interaction and Improving Clinical Practice

Protein kinase inhibitors share pharmacokinetic (PK) pathways among themselves. They are all metabolized by several cytochromes P450 (CYP). For most of them, CYP3A4 is the predominant metabolic pathway. However, their oral bioavailability differs. For example, the oral bioavailability of imatinib has been estimated at nearly 100%, but that of ibrutinib averages 3% due to its high hepatic first-pass effect. Overall, the smaller the oral bioavailability, the larger its interindividual PK variability. Indeed, for drugs with low oral bioavailability, the extent of their absorption is an additional cause (along with elimination variability) of differences in drug exposure among patients. The impact of drug-drug interaction (DDI) also differs between drugs with low or high oral bioavailability. We describe and explain why the impact of CYP3A4 inhibitors and inducers is much greater for protein kinase inhibitors with low oral bioavailability. The effect of food on protein kinase inhibitors and DDIs corresponding to plasma protein binding will also be considered. Finally, the benefits of these concepts in clinical practice (including therapeutic drug monitoring) will be discussed. Overall, our main objective was to apply fundamental PK concepts to understanding the main clinical issues of these oral anticancer drugs.

Erdheim-Chester disease: a comprehensive review from the ophthalmologic perspective

Erdheim-Chester disease (ECD) is a rare clonal histiocytic neoplasm with less than 1200 documented cases to date. The disease is life-threatening and difficult to recognize, although increasing awareness as well as the integration of clinical, imaging, pathology information , and genetic studies have led to a recent exponential increase in new reported cases. ECD affects multiple organs and systems, including skeletal, neurologic, and cardiovascular. Pulmonary, retroperitoneal, and cutaneous lesions have also been reported in various combinations. Until the discovery that more than half of ECD patients harbor the BRAF-V600E mutation or other mutations in the mitogen-activated protein kinase (MAPK) and RAS pathways, Interferon-a was the first-line treatment. Nowadays BRAF and MEK-inhibitors targeted therapies are the mainstay of treatment. Ophthalmologic involvement occurs in 25% -30% of ECD cases, usually in the form of orbital involvement presenting with exophthalmos and ophthalmoplegia. Other ophthalmologic manifestations include palpebral xanthelasmas, anterior uveitis and vitritis, optic disk edema, choroidal infiltration, recurrent serous retinal detachment, retinal drusen-like deposits and retinal pigment epithelial changes. ECD patients can also present with ocular symptoms as a result of adverse effects of the treatment regimens. In some cases with smoldering or protean symptoms, the emergence of eye manifestations triggered the diagnosis. Ophthalmologists have to be aware of the disease, recognize the constellation of ECD symptoms, and contribute to the diagnosis, treatment, and follow-up of ECD patients.