The immune response may be related to cancer chemotherapy in several ways. First, the patient with advanced cancer may have depressed immunological responsiveness prior to commencement of chemotherapy. Secondly, chemotherapy itself may markedly influence the immune response. Finally, chemotherapy and immunotherapy may be used together in the treatment of specific neoplasms. Before discussing these in detail, it is pertinent to review the immune response and the techniques by which it can be assessed.

Immunological Aspects of Cancer Chemotherapy

Trainees in medicine are taught to diagnose and administer treatment as needed; time-of-day is rarely considered. Yet accumulating evidence shows that ∼half of human genes and physiologic functions follow daily rhythms. Circadian medicine aims to incorporate knowledge of these rhythms to enhance diagnosis and treatment. Interest in this approach goes back at least six decades, but the path to the clinic has been marked by starts, stops, and ambiguity. How do we move the field forward to impact clinical practice? To gain insight into successful strategies, we studied the results of more than 100 human trials that evaluated time-of-administration of drugs.

Dosing Time Matters

Circadian clocks are biological timing mechanisms that generate 24-h rhythms of physiology and behavior, exemplified by cycles of sleep/wake, hormone release, and metabolism. The adaptive value of clocks is evident when internal body clocks and daily environmental cycles are mismatched, such as in the case of shift work and jet lag or even mistimed eating, all of which are associated with physiological disruption and disease. Studies with animal and human models have also unraveled an important role of functional circadian clocks in modulating cellular and organismal responses to physiological cues (ex., food intake, exercise), pathological insults (e.g. virus and parasite infections), and medical interventions (e.g. medication). With growing knowledge of the molecular and cellular mechanisms underlying circadian physiology and pathophysiology, it is becoming possible to target circadian rhythms for disease prevention and treatment. In this review, we discuss recent advances in circadian research and the potential for therapeutic applications that take patient circadian rhythms into account in treating disease.

Circadian Rhythms, Disease and Chronotherapy:

Timing chemotherapy on the basis of the body's intrinsic circadian clock-ie, chronomodulated chemotherapy-might improve efficacy and reduce treatment toxicity. This systematic review summarises the available clinical evidence on the effects of chronomodulated chemotherapy from randomised, controlled trials in adult patients with cancer, published between the date of database inception and June 1, 2021. This study complies with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered on the International Prospective Register of Systematic Reviews (CRD42020177878). The protocol was published on Oct 21, 2020, before study initiation. The primary outcome measures comprised toxicity incidence, overall survival, progression-free survival, and objective response rate. Of 1455 identified abstracts, 18 studies including 2547 patients were selected. Studies were heterogeneous in study design, treatment, and population. 14 (77%) of 18 studies reported differences among groups in toxicity. 11 (61%) studies reported that chronomodulated chemotherapy resulted in a significant decrease in toxicity while maintaining anti-cancer activity. Two (11%) studies showed that chronomodulated chemotherapy reduced some toxic effects but increased others, and one (6%) study reported worse toxicity outcomes than standard chemotherapy. Three (17%) studies reported improved efficacy (survival measures, objective response rate, or time to treatment failure) of chronomodulated chemotherapy, and no studies reported a decrease in efficacy. In conclusion, most studies provide evidence of the reduction of toxicity resulting from chronomodulated chemotherapy, while efficacy is maintained. More and larger, carefully designed, randomised, controlled trials are needed to provide recommendations for clinical practice. 

Toxicity and efficacy of chronomodulated chemotherapy: a systematic review.

Tailoring medical interventions to a particular patient and pathology has been termed personalized medicine. The outcome of cancer treatments is improved when the intervention is timed in accordance with the patient's internal time. Yet, one challenge of personalized medicine is how to consider the biological time of the patient. Prerequisite for this so-called chronotherapy is an accurate characterization of the internal circadian time of the patient. As an alternative to time-consuming measurements in a sleep-laboratory, recent studies in chronobiology predict circadian time by applying machine learning approaches and mathematical modelling to easier accessible observables such as gene expression. Embedding these results into the mathematical dynamics between clock and cancer in mammals, we review the precision of predictions and the potential usage with respect to cancer treatment and discuss whether the patient's internal time and circadian observables, may provide an additional indication for individualized treatment timing. Besides the health improvement, timing treatment may imply financial advantages, by ameliorating side effects of treatments, thus reducing costs. Summarizing the advances of recent years, this review brings together the current clinical standard for measuring biological time, the general assessment of circadian rhythmicity, the usage of rhythmic variables to predict biological time and models of circadian rhythmicity.

https://www.mdpi.com/2072-6694/12/11/3103/pdf

An Optimal Time for Treatment-Predicting Circadian Time by Machine Learning and Mathematical Modelling

Chronotherapy is no longer a novel concept in cancer treatment after approximately 20 years of development. Many clinical trials have provided strong supporting evidence that chronomodulated treatment yields better results than a traditional dosage regimen. This study aimed to evaluate the adverse reactions, effect on immune functions, and therapeutic efficacy of chronomodulated infusion versus flat intermittent infusion of cisplatin (DDP) combined with intensity-modulated radiation therapy (IMRT) in patients with locoregionally advanced nasopharyngeal carcinoma (NPC). A total of 148 patients with biopsy-diagnosed untreated stage III-IVb NPC were randomly assigned to undergo two cycles of chronomodulated infusion (study group) or flat intermittent infusion (control group) of DDP (100 mg/m2 on day 1, 21 days/cycle) synchronized with radical radiotherapy. Patients in the study group received chronomodulated infusion, with peak delivery of DDP at 16:00 pm. Patients in the control group received a routine constant rate of infusion. Both groups were treated with the same radiotherapy techniques. Over a median follow-up of 20 months, the study group had better outcomes for adverse effects and immune functions compared with the control group. During the phase of concurrent chemoradiotherapy, the incidence of nausea, vomiting, and oral mucositis in the study and control groups was 66.7% and 79.5% (p   0.05). Chronochemotherapy significantly reduced the incidence of adverse reactions and enhanced the tolerance for treatment without affecting survival. It is worth mentioning that reduced destruction of immune function is a novel area of exploration in chronotherapy research.

J Y Gan

Papers

A randomized phase II trial of induction chemotherapy followed by cisplatin chronotherapy versus constant rate delivery combined with radiotherapy