Fasting protects against the side effects of irinotecan but preserves its anti-tumor effect in Apc15lox mutant mice

Mechanisms driving fasting-induced protection from genotoxic injury in the small intestine

Genotoxic agents such as doxorubicin (DXR) can cause damage to the intestines that can be ameliorated by fasting. How fasting is protective and the optimal timing of fasting and refeeding remain unclear. Here, our analysis of fasting/refeeding-induced global intestinal transcriptional changes revealed metabolic shifts and implicated the cellular energetic hub mechanistic target of rapamycin complex 1 (mTORC1) in protecting from DXR-induced DNA damage. Our analysis of specific transcripts and proteins in intestinal tissue and tissue extracts showed that fasting followed by refeeding at the time of DXR administration reduced damage and caused a spike in mTORC1 activity. However, continued fasting after DXR prevented the mTORC1 spike and damage reduction. Surprisingly, the mTORC1 inhibitor, rapamycin, did not block fasting/refeeding-induced reduction in DNA damage, suggesting that increased mTORC1 is dispensable for protection against the initial DNA damage response. In Ddit4-/- mice [DDIT4 (DNA-damage-inducible transcript 4) functions to regulate mTORC1 activity], fasting reduced DNA damage and increased intestinal crypt viability vs. ad libitum-fed Ddit4-/- mice. Fasted/refed Ddit4-/- mice maintained body weight, with increased crypt proliferation by 5 days post-DXR, whereas ad libitum-fed Ddit4-/- mice continued to lose weight and displayed limited crypt proliferation. Genes encoding epithelial stem cell and DNA repair proteins were elevated in DXR-injured, fasted vs. ad libitum Ddit4-/- intestines. Thus, fasting strongly reduced intestinal damage when normal dynamic regulation of mTORC1 was lost. Overall, the results confirm that fasting protects the intestines against DXR and suggests that fasting works by pleiotropic - including both mTORC1-dependent and independent - mechanisms across the temporally dynamic injury response.NEW & NOTEWORTHY New findings are 1) DNA damage reduction following a 24-h fast depends on the timing of postfast refeeding in relation to chemotherapy initiation; 2) fasting/refeeding-induced upregulation of mTORC1 activity is not required for early (6 h) protection against DXR-induced DNA damage; and 3) fasting increases expression of intestinal stem cell and DNA damage repair genes, even when mTORC1 is dysregulated, highlighting fasting's crucial role in regulating mTORC1-dependent and independent mechanisms in the dynamic recovery process.

Dietary approaches for exploiting metabolic vulnerabilities in cancer

Renewed interest in tumor metabolism sparked an enthusiasm for dietary interventions to prevent and treat cancer. Changes in diet impact circulating nutrient levels in the plasma and the tumor microenvironment, and preclinical studies suggest that dietary approaches, including caloric and nutrient restrictions, can modulate tumor initiation, progression, and metastasis. Cancers are heterogeneous in their metabolic dependencies and preferred energy sources and can be addicted to glucose, fructose, amino acids, or lipids for survival and growth. This dependence is influenced by tumor type, anatomical location, tissue of origin, aberrant signaling, and the microenvironment. This review summarizes nutrient dependencies and the related signaling pathway activations that provide targets for nutritional interventions. We examine popular dietary approaches used as adjuvants to anticancer therapies, encompassing caloric restrictions, including time-restricted feeding, intermittent fasting, fasting-mimicking diets (FMDs), and nutrient restrictions, notably the ketogenic diet. Despite promising results, much of the knowledge on dietary restrictions comes from in vitro and animal studies, which may not accurately reflect real-life situations. Further research is needed to determine the optimal duration, timing, safety, and efficacy of dietary restrictions for different cancers and treatments. In addition, well-designed human trials are necessary to establish the link between specific metabolic vulnerabilities and targeted dietary interventions. However, low patient compliance in clinical trials remains a significant challenge.

Impact of Caloric Restriction in Breast Cancer Patients Treated with Neoadjuvant Chemotherapy: A Prospective Case Control Study

Background and aims: It is well established that caloric restriction (CR) may influence metabolic and hormonal factors involved in cancer development and progression. Recently, several studies have demonstrated that CR may have a favorable impact on the response to systemic therapy in breast cancer (BC) patients. However, there is a lack of data regarding the influence of CR during neoadjuvant chemotherapy (NACT). Our study's primary aim was to evaluate CR's impact on BC patients undergoing NACT. Secondly, we investigated the nutritional efficacy and safety of this intervention. Methods: We performed a prospective, case-control study in two breast units. A diet group consisting of 39 patients undergoing NACT and CR was enrolled in our study at the same time. CR consisted of a 30% reduction in caloric intake, which increased to 50% on the days before, during, and after the administration of chemotherapy. A control group of 60 patients that underwent the same treatment approach only followed the general dietary recommendations for BC according to WCRF guidelines. The diet group was monitored during the study for both dietary adequacy and weight trends. Results: CR combined with NACT showed a statistically significant therapeutic response in tumor size (OR 2.94, IC 1.07-8.01, p = 0.009) and lymph node status (OR 3.22, IC 1.22-8.56, p = 0.001) compared to NACT alone, even after the adjustment for all biological parameters. Our data also showed the efficacy and safety of this intervention in both anthropometric and biochemical analyses. Conclusions: Patients who adhered to CR showed a better response to NACT, both in the breast and in the axillary lymph nodes, compared to the patients in the control group. Furthermore, the CR diet combined with NACT showed good tolerance and safety.

Verification of fasting-mimicking diet to assist monotherapy of human cancer-bearing models

The efficacy of a single clinical nanodrug for cancer treatment is still unsatisfactory, especially for drug-resistant cancer. Herein, we applied a fasting-mimicking diet (FMD) approach via dietary intervention to assist single clinical nanodrug for breast or ovarian cancer treatments instead of using multi-drug therapies which might cause adverse side effects. Specifically, we adopted Doxil or Abraxane to treat human breast tumor-bearing nude mice and Doxil to treat the human ovarian tumor and drug-resistant ovarian tumor-bearing nude mice under FMD conditions, respectively. According to the results, the FMD condition can promote the cellular uptake and cytotoxicity of a single nanodrug, reduce the ATP level in drug-resistant tumor cells to hinder drug efflux, normalize tumor blood vessels, relieve tumor hypoxia, and increase the accumulation of nanodrugs at tumor sites, thereby enhancing the therapeutic effects on these types of human cancers. Collectively, these results demonstrate that the FMD strategy of significance can become a practical, alternative, and promising assistant for single nanodrug for enhancing cancer therapy and clinical translation.

Fasting: From Physiology to Pathology

Overnutrition is a risk factor for various human diseases, including neurodegenerative diseases, metabolic disorders, and cancers. Therefore, targeting overnutrition represents a simple but attractive strategy for the treatment of these increasing public health threats. Fasting as a dietary intervention for combating overnutrition has been extensively studied. Fasting has been practiced for millennia, but only recently have its roles in the molecular clock, gut microbiome, and tissue homeostasis and function emerged. Fasting can slow aging in most species and protect against various human diseases, including neurodegenerative diseases, metabolic disorders, and cancers. These centuried and unfading adventures and explorations suggest that fasting has the potential to delay aging and help prevent and treat diseases while minimizing side effects caused by chronic dietary interventions. In this review, recent animal and human studies concerning the role and underlying mechanism of fasting in physiology and pathology are summarized, the therapeutic potential of fasting is highlighted, and the combination of pharmacological intervention and fasting is discussed as a new treatment regimen for human diseases.

Gut Microbiota Modulation of Efficacy and Toxicity of Cancer Chemotherapy and Immunotherapy

Accumulating evidence supports not only the functional role of the gut microbiome in cancer development and progression but also its role in defining the efficacy and toxicity of chemotherapeutic agents (5-fluorouracil, cyclophosphamide, irinotecan, oxaliplatin, gemcitabine, methotrexate) and immunotherapeutic compounds (anti-programmed death-ligand 1/anti-programmed cell death protein 1 and anti-cytotoxic T-lymphocyte-associated antigen 4). This evidence is supported in numerous in vitro, animal, and clinical studies that highlight the importance of microbial mechanisms in defining therapeutic responses. The microbiome therefore shapes oncologic outcomes and is now being leveraged for the development of novel personalized therapeutic approaches in cancer treatment. However, if the microbiome is to be successfully translated into next-generation oncologic treatments, a new multimodal model of the oncomicrobiome must be conceptualized that incorporates gut microbial cometabolism of pharmacologic agents into cancer care. The objective of this review is therefore to outline the current knowledge of oncologic pharmacomicrobiomics and to describe how the multiparametric functions of the gut microbiome influence treatment response across cancer types. The secondary objective is to propose innovative approaches for modulating the gut microbiome in clinical environments that improve therapy efficacy and diminish toxic effects derived from antineoplastic agents for patient benefit.

Short-term fasting and fasting mimicking diets combined with chemotherapy: a narrative review

Many patients with cancer search for and use alternative and complementary treatments, aiming to improve the effectiveness of their anticancer treatment and a reduction in treatment-associated side effects. Short-term fasting (STF) and fasting mimicking diets (FMDs) are among the most commonly used dietary interventions. In recent years, different trials have reported the promising results of dietary interventions in combination with chemotherapy, in terms of slowing down tumor growth and reduction in chemotherapy-related side effects. In this narrative review, we identify and describe the current evidence about feasibility and effects of STF and FMDs in cancer patients receiving chemotherapy. The studies that examined the effects of STF when combined with chemotherapy suggest potential benefits regarding reduction in side effects and improved quality of life. We also conclude with a list of well-designed studies that are still recruiting patients, examining the long-term effects of STF.

Fatty acids homeostasis during fasting predicts protection from chemotherapy toxicity

Fasting exerts beneficial effects in mice and humans, including protection from chemotherapy toxicity. To explore the involved mechanisms, we collect blood from humans and mice before and after 36 or 24 hours of fasting, respectively, and measure lipid composition of erythrocyte membranes, circulating micro RNAs (miRNAs), and RNA expression at peripheral blood mononuclear cells (PBMCs). Fasting coordinately affects the proportion of polyunsaturated versus saturated and monounsaturated fatty acids at the erythrocyte membrane; and reduces the expression of insulin signaling-related genes in PBMCs. When fasted for 24 hours before and 24 hours after administration of oxaliplatin or doxorubicin, mice show a strong protection from toxicity in several tissues. Erythrocyte membrane lipids and PBMC gene expression define two separate groups of individuals that accurately predict a differential protection from chemotherapy toxicity, with important clinical implications. Our results reveal a mechanism of fasting associated with lipid homeostasis, and provide biomarkers of fasting to predict fasting-mediated protection from chemotherapy toxicity.

Fasting has been reported to protect from chemotherapy-associated toxicity. Here, the authors show that fatty acid profiles in erythrocyte membranes and gene expression from peripheral blood mononuclear cells are associated to the fasting-mediated benefits during cancer treatment in mice and patients.

Current Evidence and Directions for Intermittent Fasting During Cancer Chemotherapy

Almost 40% of the adult population in the USA will be diagnosed with cancer in their lifetime. Diet is a modifiable factor which is known to affect cancer risk and recurrence. Yet, little is known about how diet influences cancer treatment outcomes. Intermittent fasting, characterized by periods of abstaining from foods and beverages alternated with periods of ad libitum intake, when adopted in the context of chemotherapy, has shown promise in preclinical models resulting in decreased vomiting, diarrhea, visible discomfort, and improved insulin sensitivity and efficacy of chemotherapeutic treatment. Although intermittent fasting during receipt of chemotherapy has been well-established in preclinical models, limited numbers of human studies are now being reported. This review aims to survey the current data examining the effect of intermittent fasting on chemotherapy efficacy, patient treatment outcomes, patient centered outcomes, and circulating biomarkers associated with cancer. Available data show that periodic fasting, a form of intermittent fasting, may hold potential to improve the effectiveness of chemotherapy, decrease treatment-related side effects and cancer-promoting factors such as insulin, while ameliorating treatment-related decreases in quality of life and daily functioning. Larger controlled periodic fasting trials, including exploration of alternate forms of intermittent fasting, are needed to better elucidate the effect of intermittent fasting on treatment and patient outcomes during chemotherapy.

Fasting and fasting-mimicking diets for chemotherapy augmentation

The increasingly older population in most developed countries will likely experience aging-related chronic diseases such as diabetes, metabolic syndrome, heart and lung diseases, osteoporosis, arthritis, dementia, and/or cancer. Genetic and environmental factors, but also lifestyle choices including physical activity and dietary habits, play essential roles in disease onset and progression. Sixty-five percent of Americans diagnosed with cancer now survive more than 5 years, making the need for informed lifestyle choices particularly important to successfully complete their treatment, increase the recovery from the cytotoxic therapy options, and improve cancer-free survival. This review will discuss the findings on the use of prolonged fasting, as well as fasting-mimicking diets to augment cancer treatment. Preclinical studies in rodents strongly support the implementation of these dietary interventions and a small number of clinical trials begin to provide encouraging results for cancer patients and cancer survivors.

How Far Are We from Prescribing Fasting as Anticancer Medicine?

(1) Background: the present review provides a comprehensive and up-to date overview of the potential exploitation of fasting as an anticancer strategy. The rationale for this concept is that fasting elicits a differential stress response in the setting of unfavorable conditions, empowering the survival of normal cells, while killing cancer cells. (2) Methods: the present narrative review presents the basic aspects of the hormonal, molecular, and cellular response to fasting, focusing on the interrelationship of fasting with oxidative stress. It also presents nonclinical and clinical evidence concerning the implementation of fasting as adjuvant to chemotherapy, highlighting current challenges and future perspectives. (3) Results: there is ample nonclinical evidence indicating that fasting can mitigate the toxicity of chemotherapy and/or increase the efficacy of chemotherapy. The relevant clinical research is encouraging, albeit still in its infancy. The path forward for implementing fasting in oncology is a personalized approach, entailing counteraction of current challenges, including: (i) patient selection; (ii) fasting patterns; (iii) timeline of fasting and refeeding; (iv) validation of biomarkers for assessment of fasting; and (v) establishment of protocols for patients’ monitoring. (4) Conclusion: prescribing fasting as anticancer medicine may not be far away if large randomized clinical trials consolidate its safety and efficacy.

Effects of Protein and Calorie Restriction on the Metabolism and Toxicity Profile of Irinotecan in Cancer Patients

Preclinical data suggests that protein and calorie restriction (PCR) might improve treatment tolerability without impairing antitumor efficacy. Therefore, we have studied the influence of PCR on irinotecan pharmacokinetics and toxicity. In this crossover trial, patients with liver metastases of solid tumors were included and randomized to treatment with irinotecan preceded by 5 days of PCR (~ 30% caloric and ~ 70% protein restriction) during the first cycle and a second cycle preceded by a normal diet or vice versa. Pharmacokinetic blood sampling and biopsies of both healthy liver and liver metastases were performed. The primary end point was the relative difference in geometric means for the active metabolite SN-38 concentration in healthy liver analyzed by a linear mixed model. No significant differences were seen in irinotecan (+ 16.8%, P = 0.22) and SN-38 (+ 9.8%, P = 0.48) concentrations between PCR and normal diet in healthy liver, as well as in liver metastases (irinotecan: -38.8%, P = 0.05 and SN-38: -13.8%, P = 0.50). PCR increased irinotecan plasma area under the curve from zero to 24 hours (AUC_0-24h ) with 7.1% (P = 0.04) compared with normal diet, whereas the SN-38 plasma AUC_0-24h increased with 50.3% (P < 0.001). Grade ≥ 3 toxicity was not increased during PCR vs. normal diet (P = 0.69). No difference was seen in neutropenia grade ≥ 3 (47% vs. 32% P = 0.38), diarrhea grade ≥ 3 (5% vs. 21% P = 0.25), and febrile neutropenia (5% vs. 16% P = 0.50) during PCR vs. normal diet. In conclusion, plasma SN-38 exposure increased dramatically after PCR, whereas toxicity did not change. PCR did not alter the irinotecan and SN-38 exposure in healthy liver and liver metastases. PCR might therefore potentially improve the therapeutic window in patients treated with irinotecan.

A review of fasting effects on the response of cancer to chemotherapy

BACKGROUND & AIMS

Studies suggest that fasting before or during chemotherapy may induce differential stress resistance, reducing the adverse effects of chemotherapy and enhancing the efficacy of drugs. In this article, we review the effects of fasting, including intermittent, periodic, water-only short-term fasting, and caloric restriction on the responsiveness of tumor cells to cytotoxic drugs, their protective effect on normal cells, and possible mechanisms of action.

METHODS

We could not perform a systematic review due to the wide variation in the study population, design, dependent measures, and outcomes (eg, type of cancer, treatment variation, experimental setting, etc.). However, a systematic approach to search and review literature was used. The electronic databases PubMed (MEDLINE), Scopus, and Embase were searched up to July 2020.

RESULTS

Fasting potentially improves the response of tumor cells to chemotherapy by (1) repairing DNA damage in normal tissues (but not tumor cells); (2) upregulating autophagy flux as a protection against damage to organelles and some cancer cells; (3) altering apoptosis and increasing tumor cells' sensitivity to the apoptotic stimuli, and preventing apoptosis-mediated damage to normal cells; (4) depleting regulatory T cells and improving the stimulation of CD8 cells; and (5) accumulating unfolded proteins and protecting cancer cells from immune surveillance. We also discuss how 'fasting-mimicking diet' as a modified form of fasting enables patients to eat a low calorie, low protein, and low sugar diet while achieving similar metabolic outcomes of fasting.

CONCLUSION

This review suggests the potential benefits of fasting in combination with chemotherapy to reduce tumor progression and increase the effectiveness of chemotherapy. However, with limited human trials, it is not possible to generalize the findings from animal and in vitro studies. More human studies with adequate sample size and follow-ups are required to confirm these findings.

Impact of modified short-term fasting and its combination with a fasting supportive diet during chemotherapy on the incidence and severity of chemotherapy-induced toxicities in cancer patients - a controlled cross-over pilot study

BACKGROUND

This pilot trial aimed to investigate whether modified short-term fasting (mSTF) reduces the incidence of chemotherapy-induced toxicities and whether an initial ketogenic diet (KD) as fasting supportive diet reduces fasting-related discomfort and improves the compliance.

METHODS

In this controlled cross-over trial, gynaecologic cancer patients undergoing chemotherapy with a minimum of 4 cycles fasted for 96 h during half of their chemotherapy cycles and consumed a normocaloric diet during the other chemotherapy cycles. The caloric intake during mSTF was restricted to 25% of each patient's daily requirement. In addition, half of the patients should eat a 6-day normocaloric KD prior to each mSTF period to investigate a KD's hunger-suppression effect. Chemotherapy-induced toxicities, fasting-related discomfort, body composition, quality of life, laboratory values, and compliance were assessed at each chemotherapy.

RESULTS

Thirty patients aged 30-74 years (median 54 years) completed the study. During mSTF the frequency and severity score of stomatitis [- 0.16 ± 0.06; 95% CI -0.28 - (- 0.03); P = 0.013], headaches [- 1.80 ± 0.55; 95% CI -2.89 - (- 0.71); P = 0.002], weakness [- 1.99 ± 0.87; 95% CI -3.72 - (- 0.26); P = 0.024] and the total toxicities' score were significantly reduced [- 10.36 ± 4.44; 95% CI -19.22 - (- 1.50); P = 0.023]. We also observed significantly fewer chemotherapy postponements post-mSTF, reflecting improved tolerance of chemotherapy [- 0.80 ± 0.37; 95% CI -1.53 - (- 0.06); P = 0.034]. A significant reduction in mean body weight by - 0.79 ± 1.47 kg during mSTF was not compensated and remained until study's conclusion (P < 0.005). On average, Insulin [- 169.4 ± 44.1; 95% CI -257.1 - (- 81.8); P < 0.001] and Insulin-like growth factor 1 levels [- 33.3 ± 5.4; 95% CI -44.1 - (- 22.5); P < 0.001] dropped significantly during fasting. The KD as a fasting supportive diet neither reduced fasting-related discomfort nor improved compliance of our fasting regimen.

CONCLUSION

MSTF is safe and feasible in gynaecologic cancer patients. Our results indicate that mSTF during chemotherapy can reduce chemotherapy-induced toxicities and enhance the tolerance of chemotherapy. Larger clinical trials are required to recommend mSTF for cancer patients.

TRIAL REGISTRATION

germanctr.de: DRKS00011610, registered 30 January, 2017.

The effects of fasting on drug metabolism

Introduction: There is considerable variability in the rates and extent of drug metabolism between patients due to physiological, genetic, pharmacologic, environmental and nutritional factors such as fasting. This variability in drug metabolism may result in treatment failure or, conversely, in increased side effects or toxicity. Preclinical studies have shown that fasting alters drug metabolism by modulating the activity of drug metabolizing enzymes involved. However, until recently little was known about the effects of fasting on drug metabolism in humans.Areas covered: This review describes the effects of fasting on drug metabolism based on both preclinical studies and studies performed in humans.Expert opinion: A better understanding of the effects of fasting may improve the efficacy and safety of pharmacotherapy for individual patients. Fasting contributes to variability in human drug metabolism by differentially affecting drug metabolizing enzymes. Although the effects of fasting on drug metabolism appear to be small (between 10-20%), fasting may be relevant for drugs with a small therapeutic range and/or in combination with other factors that contribute to variability in drug metabolism such as physiological, genetic or pharmacological factors. Therefore, additional research on this topic is warranted.

Caloric restriction is associated with preservation of muscle strength in experimental cancer cachexia

Caloric restriction increases lifespan and healthspan, and limits age-associated muscle wasting. In this study, we investigate the impact of 30% caloric restriction (CR) in a murine cancer cachexia model. Forty CD2F1 mice were allocated as C26 tumor-bearing (TB) + ad libitum food intake (dietary reference intake [DRI]), TB CR, non-TB (NTB) CR, or NTB matched intake (MI). TB groups were inoculated subcutaneously with 0.5x10⁶ C26 cells 14 days after initiating CR. Bodyweight, food intake, and grip-strength were recorded periodically. Gastrocnemius (GCM) and tibialis anterior (TA) muscles were resected and weighed 3 weeks after tumor inoculation. mRNA expression of MuRF1, Atrogin-1, myogenin, and MyoD was determined. At tumor inoculation, the mean body weight of TB CR was 88.6% of initial body weight and remained stable until sacrifice. TB DRI showed wasting before sacrifice. TB groups experienced muscle wasting compared with NTB MI. Grip-strength change was less severe in TB CR. Expression of MuRF1, Atrogin-1, and MyoD was similar between TB DRI and both CR groups. Expression of myogenin was increased in CR groups. In conclusion, caloric restriction limits loss of muscle strength but has no impact on muscle mass despite significant loss of body weight in an experimental cancer-associated cachexia model.

Individualization of Irinotecan Treatment: A Review of Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics

Since its clinical introduction in 1998, the topoisomerase I inhibitor irinotecan has been widely used in the treatment of solid tumors, including colorectal, pancreatic, and lung cancer. Irinotecan therapy is characterized by several dose-limiting toxicities and large interindividual pharmacokinetic variability. Irinotecan has a highly complex metabolism, including hydrolyzation by carboxylesterases to its active metabolite SN-38, which is 100- to 1000-fold more active compared with irinotecan itself. Several phase I and II enzymes, including cytochrome P450 (CYP) 3A4 and uridine diphosphate glucuronosyltransferase (UGT) 1A, are involved in the formation of inactive metabolites, making its metabolism prone to environmental and genetic influences. Genetic variants in the DNA of these enzymes and transporters could predict a part of the drug-related toxicity and efficacy of treatment, which has been shown in retrospective and prospective trials and meta-analyses. Patient characteristics, lifestyle and comedication also influence irinotecan pharmacokinetics. Other factors, including dietary restriction, are currently being studied. Meanwhile, a more tailored approach to prevent excessive toxicity and optimize efficacy is warranted. This review provides an updated overview on today’s literature on irinotecan pharmacokinetics, pharmacodynamics, and pharmacogenetics.

Effects of short-term fasting on cancer treatment

Growing preclinical evidence shows that short-term fasting (STF) protects from toxicity while enhancing the efficacy of a variety of chemotherapeutic agents in the treatment of various tumour types. STF reinforces stress resistance of healthy cells, while tumor cells become even more sensitive to toxins, perhaps through shortage of nutrients to satisfy their needs in the context of high proliferation rates and/or loss of flexibility to respond to extreme circumstances. In humans, STF may be a feasible approach to enhance the efficacy and tolerability of chemotherapy. Clinical research evaluating the potential of STF is in its infancy. This review focuses on the molecular background, current knowledge and clinical trials evaluating the effects of STF in cancer treatment. Preliminary data show that STF is safe, but challenging in cancer patients receiving chemotherapy. Ongoing clinical trials need to unravel if STF can also diminish toxicity and increase efficacy of chemotherapeutic regimes in daily practice.

The transcriptomic response to irinotecan in colon carcinoma bearing mice preconditioned by fasting

Background

Irinotecan use is limited due to severe toxicity. Preconditioning by fasting (PBF) protects against side effects of irinotecan while preserving its antitumor activity. The mechanisms underlying the effects of PBF still need to be elucidated. Here, we investigated the transcriptional responses of PBF on irinotecan in both tumor and healthy liver tissue.

Experimental approach

Male BALB/c mice were subcutaneously injected with C26 colon carcinoma cells. Twelve days after tumor inoculation, two groups were fasted for three days and two groups were allowed food ad libitum (AL). Subsequently, both groups received one dose of irinotecan. Twelve hours after administration mice were sacrificed and blood, tumor and liver tissue were harvested. Blood samples were analyzed to determine liver, kidney and bone marrow function, tissues were used for transcriptome analyses.

Key results

The AL irinotecan group showed worsened organ function and decreased leukocyte numbers. These effects were abated in PBF animals. PBF led to an altered transcriptional response in the liver of irinotecan-treated mice, including decreased cellular injury and increased stress resistance. Hepatic metabolism of irinotecan was also significantly changed due to PBF. The transcriptional response of tumor tissue observed after PBF was hardly affected compared to AL fed animals.

Conclusions

Transcriptional changes after PBF to irinotecan treatment showed an improved protective stress response in healthy liver but not in tumor tissue, including changes in irinotecan metabolism. These data help to unravel the mechanisms underlying the effects of fasting on irinotecan and help to improve outcome of chemotherapeutic treatment in cancer patients.

Effect of Short-Term Fasting on Systemic Cytochrome P450-Mediated Drug Metabolism in Healthy Subjects: A Randomized, Controlled, Crossover Study Using a Cocktail Approach

Background and Objective

Short-term fasting can alter drug exposure but it is unknown whether this is an effect of altered oral bioavailability and/or systemic clearance. Therefore, the aim of our study was to assess the effect of short-term fasting on oral bioavailability and systemic clearance of different drugs.

Methods

In a randomized, controlled, crossover trial, 12 healthy subjects received a single administration of a cytochrome P450 (CYP) probe cocktail, consisting of caffeine (CYP1A2), metoprolol (CYP2D6), midazolam (CYP3A4), omeprazole (CYP2C19) and warfarin (CYP2C9), on four occasions: an oral (1) and intravenous (2) administration after an overnight fast (control) and an oral (3) and intravenous (4) administration after 36 h of fasting. Pharmacokinetic parameters of the probe drugs were analyzed using the nonlinear mixed-effects modeling software NONMEM.

Results

Short-term fasting increased systemic caffeine clearance by 17% (p = 0.04) and metoprolol clearance by 13% (p < 0.01), whereas S-warfarin clearance decreased by 19% (p < 0.01). Fasting did not affect bioavailability.

Conclusion

The study demonstrates that short-term fasting alters CYP-mediated drug metabolism in a non-uniform pattern without affecting oral bioavailability.

Fasting, Fats, and Physics: Combining Ketogenic and Radiation Therapy against Cancer

Radiotherapy (RT) is a mainstay in the treatment of solid tumors and works by physicochemical reactions inducing oxidative stress in cells. Because in practice the efficacy of RT is limited by its toxicity to normal tissues, any strategy that selectively increases the radiosensitivity of tumor cells or boosts the radioresistance of normal cells is a valuable adjunct to RT. In this review, I summarize preclinical and clinical data supporting the hypothesis that ketogenic therapy through fasting and/or ketogenic diets can be utilized as such an adjunct in order to improve the outcome after RT, in terms of both higher tumor control and lower normal-tissue complication probability. The first effect relates to the metabolic shift from glycolysis towards mitochondrial metabolism, which selectively increases reactive oxygen species (ROS) production and impairs adenoside triphosphate (ATP) production in tumor cells. The second effect is based on the differential stress resistance phenomenon describing the reprogramming of normal cells, but not tumor cells, from proliferation towards maintenance and stress resistance when glucose and growth factor levels are decreased and ketone body levels are elevated. Underlying both effects are metabolic differences between normal and tumor cells. Ketogenic therapy is a non-toxic and cost-effective complementary treatment option that exploits these differences and deserves further clinical investigation.

The influence of ketogenic therapy on the 5 R's of radiobiology

PURPOSE

Radiotherapy (RT) is a mainstay in the treatment of solid tumors and works by inducing free radical stress in tumor cells, leading to loss of reproductive integrity. The optimal treatment strategy has to consider damage to both tumor and normal cells and is determined by five factors known as the 5 R's of radiobiology: Reoxygenation, DNA repair, radiosensitivity, redistribution in the cell cycle and repopulation. The aim of this review is (i) to present evidence that these 5 R's are strongly influenced by cellular and whole-body metabolism that in turn can be modified through ketogenic therapy in form of ketogenic diets and short-term fasting and (ii) to stimulate new research into this field including some research questions deserving further study.

CONCLUSIONS

Preclinical and some preliminary clinical data support the hypothesis that ketogenic therapy could be utilized as a complementary treatment in order to improve the outcome after RT, both in terms of higher tumor control and in terms of lower normal tissue complication probability. The first effect relates to the metabolic shift from glycolysis toward mitochondrial metabolism that selectively increases ROS production and impairs ATP production in tumor cells. The second effect is based on the differential stress resistance phenomenon, which is achieved when glucose and growth factors are reduced and ketone bodies are elevated, reprogramming normal but not tumor cells from proliferation toward maintenance and stress resistance. Underlying both effects are metabolic differences between normal and tumor cells that ketogenic therapy seeks to exploit. Specifically, the recently discovered role of the ketone body β-hydroxybutyrate as an endogenous class-I histone deacetylase inhibitor suggests a dual role as a radioprotector of normal cells and a radiosensitzer of tumor cells that opens up exciting possibilities to employ ketogenic therapy as a cost-effective adjunct to radiotherapy against cancer.

Protective effects of short-term dietary restriction in surgical stress and chemotherapy

Reduced caloric intake including fasting, as well as the dietary composition or the timing of food intake, impact longevity, likely through a modification in the onset or the severity of chronic aging-related diseases such as cancer. As with pre- and post-operative dietary recommendations, evidence-based nutritional advice from healthcare professionals during and after cancer treatment is often vague or conflicting. We hypothesize that preventive dietary recommendations can help in the context of both chronic cancer treatment efficacy and the avoidance of development of secondary malignancies, as well as in the context of protection from the acute stress of surgery. In this perspective review, we will discuss the latest findings on the potential role of short-term dietary restriction in cancer treatment and improvement of surgical outcome.

Gut microbiota modulation of chemotherapy efficacy and toxicity

Evidence is growing that the gut microbiota modulates the host response to chemotherapeutic drugs, with three main clinical outcomes: facilitation of drug efficacy; abrogation and compromise of anticancer effects; and mediation of toxicity. The implication is that gut microbiota are critical to the development of personalized cancer treatment strategies and, therefore, a greater insight into prokaryotic co-metabolism of chemotherapeutic drugs is now required. This thinking is based on evidence from human, animal and in vitro studies that gut bacteria are intimately linked to the pharmacological effects of chemotherapies (5-fluorouracil, cyclophosphamide, irinotecan, oxaliplatin, gemcitabine, methotrexate) and novel targeted immunotherapies such as anti-PD-L1 and anti-CLTA-4 therapies. The gut microbiota modulate these agents through key mechanisms, structured as the 'TIMER' mechanistic framework: Translocation, Immunomodulation, Metabolism, Enzymatic degradation, and Reduced diversity and ecological variation. The gut microbiota can now, therefore, be targeted to improve efficacy and reduce the toxicity of current chemotherapy agents. In this Review, we outline the implications of pharmacomicrobiomics in cancer therapeutics and define how the microbiota might be modified in clinical practice to improve efficacy and reduce the toxic burden of these compounds.

Fasting and Caloric Restriction in Cancer Prevention and Treatment

Cancer is the second leading cause of death in the USA and among the leading major diseases in the world. It is anticipated to continue to increase because of the growth of the aging population and prevalence of risk factors such as obesity, smoking, and/or poor dietary habits. Cancer treatment has remained relatively similar during the past 30 years with chemotherapy and/or radiotherapy in combination with surgery remaining the standard therapies although novel therapies are slowly replacing or complementing the standard ones. According to the American Cancer Society, the dietary recommendation for cancer patients receiving chemotherapy is to increase calorie and protein intake. In addition, there are no clear guidelines on the type of nutrition that could have a major impact on cancer incidence. Yet, various forms of reduced caloric intake such as calorie restriction (CR) or fasting demonstrate a wide range of beneficial effects able to help prevent malignancies and increase the efficacy of cancer therapies. Whereas chronic CR provides both beneficial and detrimental effects as well as major compliance challenges, periodic fasting (PF), fasting-mimicking diets (FMDs), and dietary restriction (DR) without a reduction in calories are emerging as interventions with the potential to be widely used to prevent and treat cancer. Here, we review preclinical and preliminary clinical studies on dietary restriction and fasting and their role in inducing cellular protection and chemotherapy resistance.

Ramadan Fasting and Patients with Cancer: State-of-the-Art and Future Prospects

Ramadan fasting represents one of the five pillars of the Islam creed. Even though some subjects (among which patients) are exempted from observing this religious duty, they may be eager to share this particular moment of the year with their family and peers. However, there are no guidelines or standardized protocols that can help physicians to properly address the issue of patients with cancer fasting in Ramadan and correctly advising them. Moreover, in a more interconnected and globalized society, in which more and more Muslim patients live in the Western countries, this topic is of high interest also for the general practitioner. For this purpose, we carried out a systematic review on the subject. Our main findings are that (1) very few studies have been carried out, addressing this issue, (2) evidence concerning quality of life and compliance to treatment is contrasting and scarce, and (3) generally speaking, few patients ask their physicians whether they can safely fast or not. For these reasons, further research should be performed, given the relevance and importance of this topic.

Fasting protects against the side effects of irinotecan treatment but does not affect anti-tumour activity in mice

BACKGROUND

The main limitation to the use of irinotecan in the treatment of colorectal cancer is the severity of side effects, including neutropaenia and diarrhoea. Here, we explored the effects of 3 days of fasting on irinotecan-induced toxicities, on plasma, liver and tumour pharmacokinetics and on anti-tumour activity in mice.

EXPERIMENTAL APPROACH

Male BALB/c mice received C26 colon carcinoma cells subcutaneously. They were randomized 1:1 into equally sized ad libitum fed and fasted groups after which they were treated with irinotecan. Weight and adverse side effects were recorded daily. At the end of the experiment, tumours were resected and weighed, and concentrations of irinotecan and its active metabolite SN-38 were determined in plasma and tumour.

KEY RESULTS

Fasting prevented the diarrhoea and visible signs of discomfort induced by irinotecan. Ad libitum fed animals developed leucopenia compared with untreated controls, whereas fasted mice did not. Irinotecan suppressed tumour growth equally in both treated groups, compared with untreated controls. Levels of the active irinotecan metabolite SN-38 9 (calculated as AUC values) were significantly lower in fasted mice in both plasma and liver, but not in tumour tissue.

CONCLUSIONS AND IMPLICATIONS

Fasting protected against irinotecan-induced side effects without interfering with its anti-tumour efficacy. Fasting induced a lower systemic exposure to SN-38, which may explain the absence of adverse side effects, while tumour levels of SN-38 remained unchanged. These data offer important new approaches to improve treatment with irinotecan in patients.

Biophysical and molecular docking insight into interaction mechanism and thermal stability of human serum albumin isoforms with a semi-synthetic water-soluble camptothecin analog irinotecan hydrochloride

In the present work, we have examined the binding parameters, thermodynamics, and stability of human serum albumin (HSA) isoforms at pH 7.4 and 9.0, using spectroscopic, calorimetric, and molecular docking methods in the presence of water-soluble camptothecin analog irinotecan hydrochloride (CPT-11). We observed that CPT-11 binds to HSA through a static quenching procedure of ground-state complex formation with N-isoform and B-isoform. Hydrogen bond and hydrophobic interactions are the major governing forces that participating in the formation of protein-drug complex. To determine the binding site of CPT-11 within HSA molecules, we also have performed molecular docking experiments. We explored the CPT-11-mediated stability and modulation of HSA by performing dynamic light scattering (DLS) and differential scanning calorimetry (DSC) experiments. DLS and DSC techniques are used to determine the size and the melting point (Tm) of HSA, which was decreased in the presence of CPT-11. Therefore, CPT-11 plays an important role in HSA stability and protein-ligand interactions. The present study provides valuable information in the field of pharmacokinetics, pharmaco-dynamics, and drug discovery.