The circadian timing system is composed of molecular clocks, which drive 24-h changes in xenobiotic metabolism and detoxification, cell cycle events, DNA repair, apoptosis, and angiogenesis. The cellular circadian clocks are coordinated by endogenous physiological rhythms, so that they tick in synchrony in the host tissues that can be damaged by anticancer agents. As a result, circadian timing can modify 2- to 10-fold the tolerability of anticancer medications in experimental models and in cancer patients. Improved efficacy is also seen when drugs are given near their respective times of best tolerability, due to (a) inherently poor circadian entrainment of tumors and (b) persistent circadian entrainment of healthy tissues. Conversely, host clocks are disrupted whenever anticancer drugs are administered at their most toxic time. On the other hand, circadian disruption accelerates experimental and clinical cancer processes. Gender, circadian physiology, clock genes, and cell cycle critically affect outcome on cancer chronotherapeutics. Mathematical and systems biology approaches currently develop and integrate theoretical, experimental, and technological tools in order to further optimize and personalize the circadian administration of cancer treatments.

Systemic chemotherapy typically converts previously unresectable liver metastases (LM) from colorectal cancer to curative intent resection in ∼15% of patients. This European multicenter phase II trial tested whether hepatic artery infusion (HAI) with triplet chemotherapy and systemic cetuximab could increase this rate to 30% in previously treated patients. Participants had unresectable LM from wt KRAS colorectal cancer. Main non-inclusion criteria were advanced extra hepatic disease, prior HAI and grade 3 neuropathy. Irinotecan (180 mg/m²), oxaliplatin (85 mg/m²) and 5-fluorouracil (2800 mg/m²) were delivered via an implanted HAI access port and combined with i.v. cetuximab (500 mg/m²) every 14 days. Multidisciplinary decisions to resect LM were taken after every three courses. The rate of macroscopic complete resections (R0 + R1) of LM, progression-free survival (PFS) and overall survival (OS) were computed according to intent to treat. The patient population consisted of 42 men and 22 women, aged 33–76 years, with a median of 10 LM involving a median of six segments. Up to 3 extrahepatic lesions of <1 cm were found in 41% of the patients. A median of six courses was delivered. The primary end point was met, with R0–R1 hepatectomy for 19 of the 64 previously treated patients, 29.7% (95% confidence interval 18.5–40.9). Grade 3–4 neutropenia (42.6%), abdominal pain (26.2%), fatigue (18%) and diarrhea (16.4%) were frequent. Objective response rate was 40.6% (28.6–52.3). Median PFS and OS reached 9.3 (7.8–10.9) and 25.5 months (18.8–32.1) respectively. Those with R0-R1 hepatectomy had a median OS of 35.2 months (32.6–37.8), with 37.4% (23.6–51.2) alive at 4 years. The coordination of liver-specific intensive chemotherapy and surgery had a high curative intent potential that deserves upfront randomized testing. EUDRACT 2007-004632-24, NCT00852228.

Background: Tolerability and antitumour efficacy of chemotherapy and radiation therapy can vary largely according to their time of administration along the 24-h time scale, due to the moderation of their molecular and cellular mechanisms by circadian rhythms. Recent clinical data have highlighted a striking role of dosing time for cancer immunotherapy, thus calling for a critical evaluation. Methods: Here, we review the clinical data and we analyse the mechanisms through which circadian rhythms can influence outcomes on ICI therapies. We examine how circadian rhythm disorders can affect tumour immune microenvironment, as a main mechanism linking the circadian clock to the 24-h cycles in ICIs antitumour efficacy. Results: Real-life data from 18 retrospective studies have revealed that early time-of-day (ToD) infusion of immune checkpoint inhibitors (ICIs) could enhance progression-free and/or overall survival up to fourfold compared to late ToD dosing. The studies involved a total of 3250 patients with metastatic melanoma, lung, kidney, bladder, oesophageal, stomach or liver cancer from 9 countries. Such large and consistent differences in ToD effects on outcomes could only result from a previously ignored robust chronobiological mechanism. The circadian timing system coordinates cellular, tissue and whole-body physiology along the 24-h timescale. Circadian rhythms are generated at the cellular level by a molecular clock system that involves 15 specific clock genes. The disruption of circadian rhythms can trigger or accelerate carcinogenesis, and contribute to cancer treatment failure, possibly through tumour immune evasion resulting from immunosuppressive tumour microenvironment. Conclusions and perspective: Such emerging understanding of circadian rhythms regulation of antitumour immunity now calls for randomised clinical trials of ICIs timing to establish recommendations for personalised chrono-immunotherapies with current and forthcoming drugs.

Hypothesis: Prior experimental and human studies have demonstrated the circadian organization of immune cells’ proliferation, trafficking, and antigen recognition and destruction. Nivolumab targets T(CD8) cells, the functions, and trafficking of which are regulated by circadian clocks, hence suggesting possible daily changes in nivolumab’s efficacy. Worse progression-free survival (PFS), and overall survival (OS) were reported for malignant melanoma patients receiving more than 20% of their immune checkpoint inhibitor infusions after 16:30 as compared to earlier in the day. Methods: Consecutive metastatic non-small-cell cancer (NSCLC) patients received nivolumab (240 mg iv q 2 weeks) at a daily time that was ‘randomly’ allocated for each course on a logistical basis by the day-hospital coordinators. The median time of all nivolumab administrations was computed for each patient. The study population was split into two timing groups based upon the median value of the median treatment times of all patients. CTCAE-toxicity rates, iRECIST-tumor responses, PFS and OS were computed according to nivolumab timing. PFS and OS curves were compared and hazard ratios (HR) were computed for all major categories of characteristics. Multivariable and sensitivity analyses were also performed. Results: The study accrued 95 stage-IV NSCLC patients (PS 0–1, 96%), aged 41–83 years. The majority of nivolumab administrations occurred between 9:27 and 12:54 for 48 patients (‘morning’ group) and between 12:55 and 17:14 for the other 47 (‘afternoon’ group). Median PFS (95% CL) was 11.3 months (5.5–17.1) for the ‘morning’ group and 3.1 months (1.5–4.6) for the ‘afternoon’ one (p < 0.001). Median OS was 34.2 months (15.1–53.3) and 9.6 months (4.9–14.4) for the ‘morning’ group and the ‘afternoon’ one, respectively (p < 0.001). Multivariable analyses identified ‘morning’ timing as a significant predictor of longer PFS and OS, with respective HR values of 0.26 (0.11–0.58) and 0.17 (0.08–0.37). The timing effect was consistent across all patient subgroups tested. Conclusions: Nivolumab was nearly four times as effective following ‘morning’ as compared to ‘afternoon’ dosing in this cohort of NSCLC patients. Prospective timing-studies are needed to minimize the risk of resistance and to maximize the benefits from immune checkpoint inhibitors.

Immune checkpoint inhibitors (ICIs) have become the standard of care for numerous malignancies. Emerging evidence suggests that the time of day (ToD) of ICI administration could impact the outcomes of patients with cancer. The consistency of ToD effects on ICI efficacy awaits initial evaluation. This meta-analysis integrates progression-free survival (PFS) and overall survival (OS) data from studies with a defined 'cut-off' ToD. Hazard ratios (HRs) [95% confidence interval (CI)] of an earlier progression or death according to 'early' or 'late' ToD of ICIs were collected from each report and pooled. Thirteen studies involved 1663 patients (Eastern Cooperative Oncology Group performance status 0-1, 83%; males/females, 67%/33%) with non-small-cell lung cancer (47%), renal cell carcinoma (24%), melanoma (20%), urothelial cancer (5%), or esophageal carcinoma (4%). Most patients received anti-programmed cell death protein 1 or anti-programmed death-ligand 1 (98%), and a small proportion also received anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) (18%). ToD cut-offs were 13:00 or 14:00 (i.e. ICI median infusion time), for six studies, and 16:00 or 16:30 (i.e. reported threshold for weaker vaccination responses) for seven studies. Pooled analyses revealed that the early ToD groups had longer OS (HR 0.50, 95% CI 0.42-0.58; P < 0.00001) and PFS (HR 0.51, 95% CI 0.42-0.61; P < 0.00001) compared with the late ToD groups. Patients with selected metastatic cancers seemed to largely benefit from early ToD ICI infusions, which is consistent with circadian mechanisms in immune-cell functions and trafficking. Prospective randomized trials are needed to establish recommendations for optimal circadian timing of ICI-based cancer therapies.