Human induced pluripotent stem cell-derived liver-on-a-chip for studying drug metabolism: the challenge of the cytochrome P450 family

The liver is the primary organ responsible for the detoxification and metabolism of drugs. To date, a lack of preclinical models that accurately emulate drug metabolism by the human liver presents a significant challenge in the drug development pipeline, particularly for predicting drug efficacy and toxicity. In recent years, emerging microfluidic-based organ-on-a-chip (OoC) technologies, combined with human induced pluripotent stem cell (hiPSC) technology, present a promising avenue for the complete recapitulation of human organ biology in a patient-specific manner. However, hiPSC-derived organoids and liver-on-a-chip models have so far failed to sufficiently express cytochrome P450 monooxygenase (CYP450) enzymes, the key enzymes involved in first-pass metabolism, which limits the effectiveness and translatability of these models in drug metabolism studies. This review explores the potential of innovative organoid and OoC technologies for studying drug metabolism and discusses their existing drawbacks, such as low expression of CYP450 genes. Finally, we postulate potential approaches for enhancing CYP450 expression in the hope of paving the way toward developing novel, fully representative liver drug-metabolism models.

Sialic acid, the secret gift for the brain

The human brain grows rapidly in early life which requires adequate nutrition. Human milk provides optimal nutrition for the developing brain, and breastfeeding significantly improves the cognition development of infants. These benefits have been largely attributed to human milk oligosaccharides (HMOS), associated with sialic acid (Sia). Subsequently, sialylated HMOS present a vital source of exogenous Sia to infants. Sialic acid is a key molecule essential for proper development of gangliosides, and therefore critical in brain development and function. Recent pre-clinical studies suggest dietary supplementation with Sia or sialylated oligosaccharides enhances intelligence and cognition performance in early and later life. Furthermore, emerging evidence suggests the involvement of Sia in brain homeostasis and disbalance correlates with common pathologies such as Alzheimer's disease (AD). Therefore, this review will discuss early brain health and development and the role of Sia in this process. Additionally, studies associating breastfeeding and specific HMOS to benefits in cognitive development are critically assessed. Furthermore, the review will assess studies implying the potential role of HMOS and microbiota in brain development via the gut-brain axis. Finally, the review will summarize recent advances regarding the role of Sia in neurodegenerative disease in later life and potential roles of dietary Sia sources.

A randomized phase II study comparing capecitabine alone with capecitabine and oral cyclophosphamide in patients with advanced breast cancer-cyclox II

BACKGROUND

Capecitabine and cyclophosphamide are active in patients with advanced breast cancer, have non-overlapping toxic effects and synergy pre-clinically. We explored the efficacy and toxic effect of an all-oral combination of capecitabine with cyclophosphamide versus capecitabine alone in a multicentre, randomized, phase II study.

PATIENTS AND METHODS

Patients with locally advanced or metastatic breast cancer were randomized to treatment with capecitabine given continuously (666 mg/m(2) b.i.d. days 1-28) alone (C) or with oral cyclophosphamide (100 mg/m(2) days 1-14 of a 28-day cycle) (CCy) for up to six cycles.

RESULTS

Eighty-two patients were randomized. There was no complete response. The proportions with partial response were 36% on C and 44% on CCy, a difference of 7.9% [95% confidence interval (CI) -13.4 to 29.1]. Significant toxic effect was uncommon: grade ≥3 diarrhoea in 4 (10%) versus 1 (3%) patients; grade ≥3 fatigue in 2 (5%) versus 5 patients (13%) and grade ≥2 hand-foot syndrome in 7 (17%) versus 11 (28%) patients receiving C versus CCy, respectively. Median progression-free survival was 3.1 months on C and 6.9 months on CCy, not significantly different statistically. There was no difference in overall survival.

CONCLUSION

The difference in tumour response suggests a reasonable chance that CCy is superior to C alone.

Topotecan in combination with carboplatin: phase I trial evaluation of two treatment schedules

BACKGROUND

Topotecan and cisplatin combinations have shown schedule-dependent toxicity, which may in part be due to cisplatin nephrotoxicity. As carboplatin is less nephrotoxic and increasingly replacing cisplatin in clinical practice, the aim of this study was to define the optimal sequence and dose for topotecan in combination with carboplatin.

PATIENTS AND METHODS

Two parallel phase I trials, with pharmacokinetic studies, were conducted administering carboplatin on day 1 with topotecan on days 1-5 (schedule A) or days 8-12 (schedule B). repeated every 3 weeks.

RESULTS

Twenty-one patients were treated over two dose levels, carboplatin AUC 4 [glomerular filtration rate (GFR) calculated from 51Cr-EDTA clearance] with topotecan 0.5 or 0.75 mg/m2. At the first dose level, six patients were evaluable for each schedule. With schedule A, from 34 cycles, there were two dose reductions and 10 treatment delays due to myelosuppression. With schedule B from 25 cycles, there was one reduction and 10 delays. At dose level 2, both patients in schedule A had dose-limiting neutropenia. In contrast, there was no dose-limiting toxicity with schedule B in six patients, although the majority of cycles were delayed.

CONCLUSION

The combination of topotecan and carboplatin using these 3-weekly schedules lead to significant myelotoxicity with attendant dose reductions and delays; the optimal scheduling of these agents remains to be defined.

Fatal bleomycin pulmonary toxicity in the west of Scotland 1991-95: a review of patients with germ cell tumours

We conducted a retrospective review of fatal bleomycin pulmonary toxicity in patients treated for germ cell tumours during 1991-95 at the Beatson Oncology Centre, Glasgow. Case notes of patients treated with bleomycin were reviewed with respect to cumulative bleomycin dose, renal impairment, exposure to supplemental oxygen, thoracic radiotherapy and age. A total of 194 patients underwent chemotherapy, of whom 180 received bleomycin-containing regimens. Five fatal cases of pulmonary toxicity were identified, an incidence of 2.8%. These cases were older than the remaining patients (P < 0.001), with a median age at diagnosis of 55 vs 33 years. The incidence of fatal pulmonary toxicity increased with each decade of life above age 30. Renal function also differed between the two groups, with the worst glomerular filtration rate recorded at the time of bleomycin administration for each patient, lower in the fatal group, median 69 vs 107 ml min(-1) (P < 0.001). There was no difference with respect to cumulative bleomycin dose or exposure to supplemental oxygen. For patients aged over 40 years, especially those with renal function in the lower range of normal, the risk of developing fatal toxicity may exceed 10%. The benefits of bleomycin could be questioned for this age group.