Physiologically Based Pharmacokinetic Modeling in Regulatory Science: An Update From the U.S. Food and Drug Administration’s Office of Clinical Pharmacology

This commentary provides an update on the status of physiologically based pharmacokinetic modeling and simulation at the U.S. Food and Drug Administration's Office of Clinical Pharmacology. Limitations and knowledge gaps in integration of physiologically based pharmacokinetic approach to inform regulatory decision making, as well as the importance of scientific engagement with drug developers who intend to use this approach, are highlighted.     

Impaired hemorheology in patients with postmastectomy lymphedema

Lymphedema of the arm is one of the most disabling and serious complications of breast cancer. Apart from tumor infiltration or fibrosis of lymphatic pathways, little is known about factors favoring the development of lymphedema. In the present study, we investigated the impact of rheologic parameters, e.g. red cell aggregation (EA) and plasma viscosity (PV), and of capillary morphology and capillary flow in patients with breast cancer with (n = 18) and without (n = 18) lymphedema. Patients with lymphedema showed a significant increase of red cell aggregation (p < 0.001) that indicates a systemic component of lymphedema and might offer a possibility of prevention and therapy of this condition. A hitherto unclassified protein factor favoring red cell aggregation and lymphedema might be postulated.     

Isolated limb infusion chemotherapy with or without hemofiltration for recurrent limb melanoma

AIM: To better define the efficacy and the safety of intra-arterial infusion performed with or without hemofiltration for recurrent limb melanoma.METHODS: Patients with the following characteristics were included in the study: recurrent limb melanoma not indicated for surgical resection, measurable disease in the extremity, > 18 years, performances status (Eastern Cooperative Oncology Group ) was 0-1 and life expectancy of at least 6 mo. Twenty nine consecutive patients were enrolled in the study. Patients underwent fluoroscopic placement of angiographic arterial and venous catheters to infuse the drug in the artery [isolated limb infusion (ILI)], and to stop the out flow (venous). Melphalan was rapidly infused into the isolated limb via the arterial catheter after the inflation of venous balloon catheter. Then the circulation of the limb was completely blocked with a pneumatic cuff at the root of the limb. Haemofiltration (HF) was available only in the main center, and was performed with an extracorporeal perfusion system, in order to reduce high systemic toxic peaks of drug.RESULTS: Thirty seven ILI were done in 29 cases (31 ILI-HF and 6 ILI) between 2001 and 2014 at Ancona and Pesaro Hospitals, Italy. Clinical outcomes were monitored 30 d after treatment. Eleven patients (38%) received infusion of melphalan alone, 7 (24%) melphalan associated to mitomicin C and 7 (24%) melphalan associated to cisplatin, the remaining 4 were treated with cisplatin, melphalan and epirubicin or cisplatin and mitomicin C. The overall response rate was 66%, in particular, 3 patients (10%) were complete responders and 16 (56%) were partial responders; whereas 7 patients (24%) had stable disease, and 3 (10%) showed progressive disease. Limb toxicity was assessed adopting Wieberdink scale, with evidence of 90% of low grade (I and II) toxicity.CONCLUSION: ILI-HF and ILI are effective and safe treatments for recurrent non-resectable limb melanoma. They present evidence of favorable clinical benefit and is effective in delaying progression.     

DNA methylation changes measured in pre‐diagnostic peripheral blood samples are associated with smoking and lung cancer risk

DNA methylation changes are associated with cigarette smoking. We used the Illumina Infinium HumanMethylation450 array to determine whether methylation in DNA from pre‐diagnostic, peripheral blood samples is associated with lung cancer risk. We used a case‐control study nested within the EPIC‐Italy cohort and a study within the MCCS cohort as discovery sets (a total of 552 case‐control pairs). We validated the top signals in 429 case‐control pairs from another 3 studies. We identified six CpGs for which hypomethylation was associated with lung cancer risk: cg05575921 in the AHRR gene (p‐value_pooled = 4 × 10^?17), cg03636183 in the F2RL3 gene (p‐value_pooled = 2 × 10 ^{? 13}), cg21566642 and cg05951221 in 2q37.1 (p‐value_pooled = 7 × 10^?16 and 1 × 10^?11 respectively), cg06126421 in 6p21.33 (p‐value_pooled = 2 × 10^?15) and cg23387569 in 12q14.1 (p‐value_pooled = 5 × 10^?7). For cg05951221 and cg23387569 the strength of association was virtually identical in never and current smokers. For all these CpGs except for cg23387569, the methylation levels were different across smoking categories in controls (p‐values_{heterogeneity} ≤ 1.8 x10 ^{? 7}), were lowest for current smokers and increased with time since quitting for former smokers. We observed a gain in discrimination between cases and controls measured by the area under the ROC curve of at least 8% (p‐values ≥ 0.003) in former smokers by adding methylation at the 6 CpGs into risk prediction models including smoking status and number of pack‐years. Our findings provide convincing evidence that smoking and possibly other factors lead to DNA methylation changes measurable in peripheral blood that may improve prediction of lung cancer risk.     

Angiotensin-converting enzyme (CD143) marks hematopoietic stem cells in human embryonic, fetal, and adult hematopoietic tissues

Previous studies revealed that mAb BB9 reacts with a subset of CD34(+) human BM cells with hematopoietic stem cell (HSC) characteristics. Here we map BB9 expression throughout hematopoietic development and show that the earliest definitive HSCs that arise at the ventral wall of the aorta and surrounding endothelial cells are BB9(+). Thereafter, BB9 is expressed by primitive hematopoietic cells in fetal liver and in umbilical cord blood (UCB). BB9(+)CD34(+) UCB cells transplanted into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice contribute 10-fold higher numbers of multilineage blood cells than their CD34(+)BB9(-) counterparts and contain a significantly higher incidence of SCID-repopulating cells than the unfractionated CD34(+) population. Protein microsequencing of the 160-kDa band corresponding to the BB9 protein established its identity as that of somatic angiotensin-converting enzyme (ACE). Although the role of ACE on human HSCs remains to be determined, these studies designate ACE as a hitherto unrecognized marker of human HSCs throughout hematopoietic ontogeny and adulthood.     

Laser-induced osteoblast proliferation is mediated by ROS production

Low-level laser therapy (LLLT) is widely used in regenerative medicine and in dental therapy by virtue of its beneficial effects in a plethora of pathological conditions. In this study, the effect of a 980 nm diode laser on pre-osteoblasts proliferation has been evaluated, along with reactive oxygen species (ROS) production. We hypothesized that ROS were a key factor in LLLT-induced pre-osteoblasts proliferation, as it is known that ROS can induce the activation of many biological pathways, leading to cell proliferation, differentiation or apoptosis. Murine pre-osteoblasts MC3T3 cells were irradiated with different energy outputs (1–50 J) in the absence or presence of the antioxidant N-Acetyl-L-cysteine (NAC). Laser treatment, in the absence of NAC, was able to induce a fluence-dependent statistically significant increase in ROS generation, while the presence of NAC strongly inhibited it. Cell proliferation, measured after laser stimulation, was significantly increased both at low and higher energy, with a peak at 10 J in the absence of the antioxidant. On the contrary, in the presence of NAC, laser irradiation was not able to induce any cell proliferation, suggesting a crucial role of ROS in this laser-induced cell effect. These results suggest that LLLT may be a useful tool for bone regeneration therapy and an effective range of fluences to be used is indicated.