New Insights on Treatment Timing in Lung Cancer Patients
Researchers recently conducted an intriguing experiment involving individuals diagnosed with the same type of lung cancer. They subjected these patients to similar treatments aimed at boosting their immune responses, but with one key difference: half of them received their medications before 3 p.m., while the other half had their treatments later in the day.
The outcome was quite surprising. Those who received their treatments in the morning had, on average, about five additional months before their cancers progressed—this is known in the medical world as progression-free survival. Furthermore, they lived nearly a year longer compared to those treated later. The results were notable, with better survival rates observed by the end of the two-year study.
For a long time, scientists have been fascinated by the body’s internal clock, or circadian rhythm. This clock influences many biological processes, from hormone release to hunger, energy levels, and even blood pressure. Interestingly, numerous smaller clocks exist throughout our body, governed by this central clock, affecting various cellular functions.
Recent studies have shown that the immune system may be particularly sensitive to timing. There’s increasing evidence suggesting that the timing of vaccine administration can affect effectiveness, as well as the risk of complications following heart surgery. For instance, surgeries performed in the afternoon appeared to carry less risk for patients.
This new study, spearheaded by researchers in China, is unique in that it experimentally verifies findings that previous observational research had suggested. Earlier studies focused on melanoma and kidney cancer patients indicated similar benefits from earlier treatment times in the day, where patients responded better to immunotherapy when treated in the morning.
Even though many experts are enthusiastic about these findings, they express a note of caution. “The results are remarkably compelling,” noted Dr. Zach Buchwald, an oncologist who wasn’t involved in the study. “If this were a new drug, it would be regarded as a groundbreaking discovery.” Yet, questions remain regarding why treatment timing would play such a crucial role when these immunotherapies remain active in the body for weeks after infusion. This uncertainty is acknowledged by the study authors.
Dr. Paolo Tarantino, a medical oncologist, labeled the findings as potentially controversial. “The significance of the effect is hard to accept, but randomized-controlled trials are generally persuasive. We really need a collective effort to explore this further,” he stated.
Researchers are also eager for additional studies. Dr. Christoph Scheiermann, one of the study’s co-authors, emphasized the dramatic nature of the findings. “The strength of these results in patients is noteworthy,” he remarked, while also agreeing that further replication in diverse cohorts is essential.
In fact, a follow-up study is already in the works. Buchwald and colleagues are enrolling participants in a similar trial testing the timing of immunotherapy in melanoma patients, aiming to include 100 individuals at both Emory University and Massachusetts General Hospital.
The recent study, published in the journal Nature Medicine, involved 210 patients with non-small-cell lung cancer. They were evenly divided into two groups, randomly assigned to receive their initial immunotherapy either before or after 3 p.m. This cutoff was based on previous research suggesting a slowdown in immune responsiveness between 2 and 3 p.m.
After tracking these patients for over 28 months, significant effects on cancer progression and overall survival were observed. Those treated early in the day survived nearly a year longer than their later-treated counterparts.
Moreover, patients in the early treatment group experienced almost double the duration of progression-free survival—averaging 11.3 months, compared to just 5.7 months for those treated later. By the end of the study, around 45% of patients in the early treatment group were still alive, versus about 15% in the later group. Researchers noted that as of late January 2026, 75 participants remain alive, with intentions to publish further survival analyses in the future.
Blood tests illustrated that those receiving morning treatment had more immune cells capable of attacking cancer than those treated later.
Prior to human trials, Scheiermann performed detailed studies in mice to understand how different biological clocks influence immune functions. Although mice and humans are fundamentally different, the studies revealed that T cells—immune cells targeting threats like cancer—are more active in the morning.
These specialized cells tend to cycle in and out of tumors at different times of the day, but cancer is adept at putting them on pause by producing proteins that hinder their action. “T cells in cancer become exhausted,” Buchwald explained. “They simply don’t function properly anymore as cancer learns to suppress the immune response.”
The PD-1 inhibitors used in this study counteract this suppression, allowing T cells to recognize and combat cancer cells effectively. “The assumption is that more T cells aggregation in tumors during morning treatment enhances the drug’s effectiveness in targeting and killing cancer cells,” noted Scheiermann, who is currently investigating the underlying biology of these phenomena in humans.
Interestingly, while the timing of initial immunotherapy exposure seems crucial, Scheiermann observed that the timing of subsequent treatments is less significant, although the reasons for this remain unclear.
Your Body’s Exquisitely Fine-Tuned Clock
Dr. Jeffrey Haspel, a pulmonologist studying circadian rhythms, remarked on the immune system’s intricate biological timing. His research indicates that CAR-T therapy—engineered T cells for fighting blood cancers—also yields better results and fewer side effects when administered in the morning.
Other cancer medications may also respond to timing, as a 2021 study indicated that many anticancer drugs were more effective at specific times of day. Dr. Amita Seghal, who leads the Chronobiology and Sleep Institute, expressed her excitement about the research, even though she did not participate in this particular study.
Haspel acknowledges the hesitance surrounding these findings, noting the complexities of scheduling treatment and the need for compelling justification before altering established practices. “If we’re reorganizing how patient care is delivered, we ought to consider if the benefits justify the effort,” Haspel questioned. “Is the potential patient benefit worth the considerable changes required for scheduling?”
“What’s fascinating is that these cancer immunotherapies seem to indeed show a meaningful effect with morning scheduling,” Haspel concluded.
