In the past decade, there has been a proliferation of novel neoadjuvant treatment modalities in non-small cell lung cancer (NSCLC) (1). The publication of the CheckMate 816 trial results in 2022 marked the beginning of a new era for neoadjuvant immunochemotherapy in resectable NSCLC (2). Shortly thereafter, the NCCN updated its guidelines based on these findings, recommending nivolumab in combination with platinum-based doublet chemotherapy as a neoadjuvant immunotherapy regimen for specific patient populations (those with tumors ≥ 4 cm or lymph node positivity, and without contraindications to immune checkpoint inhibitors) (3). The efficacy and safety of neoadjuvant treatment modalities have been validated through phase III clinical trials. However, there remains no consensus on the optimal duration for neoadjuvant therapy. Both the CheckMate-159 and LCMC3 trials have utilized two-cycle immunotherapy regimens (4, 5). Additionally, three-cycle neoadjuvant immunotherapy regimens have been extensively employed in clinical trials (1). Regarding the optimal treatment duration for neoadjuvant therapy, specifically whether to use 2 or 3 cycles, Miner Shao et al. conducted the neoSCORE clinical trial in 2023. The study reported firstly that 3 cycles of neoadjuvant therapy resulted in a numerically higher major pathological response (MPR) rate compared to 2 cycles (41.4% vs 26.9%; P = 0.26) (6). Given these findings, additional evidence is required to further elucidate this issue. To address this gap, the author employed propensity score matching (PSM) and inverse probability weighting (IPW) to compare pathological remission, perioperative safety, and survival outcomes between 2-cycle and 3-cycle neoadjuvant therapy regimens.

Neoadjuvant therapy is now frequently used for NSCLC (2, 9–13). This approach was classically defined as systemic treatment administered before local therapy. Potential advantages of neoadjuvant therapy include: providing a favorable microenvironment for immune responses, achieving better treatment compliance, enabling direct assessment of therapeutic efficacy, facilitating minimally invasive surgery for organ preservation through tumor downstaging, and improving both distant and local control (14, 15). However, disadvantages encompass potential delays in initiating definitive treatment, increased treatment toxicity, challenges in accurate pathological staging, and elevated surgical complexity compared to patients not receiving neoadjuvant therapy (14–16).

Given the potential disadvantage of neoadjuvant therapy delaying definitive surgery, the selection of treatment cycles becomes a critical clinical decision requiring meticulous consideration. Based on the significant efficacy of neoadjuvant immunochemotherapy demonstrated in clinical trials such as CheckMate 816 (2) and CheckMate 77T (13) the NCCN now recommends a 4-cycle neoadjuvant treatment regimen for NSCLC patients who meet preoperative criteria (17). Although the efficacy of neoadjuvant therapy using 3 or 4 cycles has been validated by numerous Phase III clinical trials (2, 13, 18–20), uniformly applying a 4-cycle neoadjuvant regimen to all NSCLC patients does not align with the current trend toward individualized treatment. Furthermore, numerous clinical trials of preoperative single-agent immunotherapy have opted for two-cycle treatment regimens (4, 5, 21). In clinical trials, it is essential to ensure that patients in both the control and experimental groups undergo the same number of treatment cycles to achieve a scientifically valid evaluation of therapeutic efficacy. However, the current selection of neoadjuvant treatment cycle numbers appears to be influenced by the personal experience of trial investigators and their confidence in the chosen treatment regimen. The efficacy of neoadjuvant immunochemotherapy in NSCLC has been remarkable. Therefore, the selection of treatment cycle numbers must be approached with greater caution and supported by robust evidence demonstrating the differences between various cycle regimens and their impacts on different patient populations. This will help maximize the benefits of neoadjuvant therapy for NSCLC patients while striving to minimize or even prevent adverse outcomes associated with this treatment.

neoSCORE, as the first known clinical trial to investigate the differences in neoadjuvant treatment cycle numbers, provides invaluable insights for optimizing the selection of treatment cycles (6). In this study, Miner Shao et al. reported that compared with two cycles of neoadjuvant therapy, three cycles resulted in a higher MPR rate (41.4% vs 26.9%; P = 0.260). Numerically, the three-cycle neoadjuvant chemotherapy-immunotherapy regimen appeared more favorable for achieving MPR. However, the data safety monitoring board (DSMB) halted the trial after enrolling 60 participants, as it determined that the MPR rate in the three-cycle group was unlikely to show significant superiority over the two-cycle group (6).

We must acknowledge the significant contribution and pivotal role of the neoScore study in informing the selection of neoadjuvant treatment cycles. However, given the insights provided by the neoScore results, additional reports are warranted to further investigate this issue until a definitive conclusion can be reached. In this study, we compared the MPR rate, pCR rate, OS, and DFS between the 2-cycle and 3-cycle regimens. However, no statistically significant differences were observed across these endpoints. From a quantitative standpoint, it is noteworthy that although the pathological complete response (pCR) rate was elevated in the 3-cycle group relative to the 2-cycle group, the major pathological response (MPR) rate was diminished in the 3-cycle group compared to the 2-cycle group. The observed inconsistency in the numerical results may be ascribed to random variations, which could also suggest that the number of neoadjuvant treatment cycles does not exert a significant influence on pathological remission.

There is difference in Major Pathological Response (MPR) rates between our study and the neoSCORE trial. In the neoSCORE trial, the 3-cycle vs 2-cycle MPR rates were 41.4% (12/29) vs 26.9% (7/26), while our post-PSM results showed 70.4% (57/81) vs 66.7% (54/81). However, nearly all Relative Risk (RR) values >1 in the neoSCORE trial baseline comparisons (except stage IIIA) indicate the 3-cycle group had higher proportions of males, elevated PD-L1 expression, more stage III patients, more squamous histology cases, and more smokers (numerically higher but statistically non-significant) (6). Among these factors, trials including RATIONALLE-315 (22), AEGEAN (23), CheckMate-77T (13), and CheckMate-816 (2) demonstrate superior pathological response benefits in squamous NSCLC patients; higher PD-L1 expression correlates with improved outcomes (24); Stage III patients show enhanced response to neoadjuvant immunochemotherapy (2, 13); smoking history associates with immunotherapy benefit (25, 26); and males derive greater immunotherapy benefit than females (27). Thus, the neoSCORE trial’s 3-cycle group—enriched with high PD-L1 expressors, squamous histology, stage III patients, and smokers—may have contributed to outcome differences. In contrast, our study achieved near-perfect balance in these treatment-influencing confounders through PSM and IPW, minimizing confounding effects. This likely explains our study’s more comparable MPR rates. Additionally, our cohort received a variety of PD-1/PD-L1 inhibitors (e.g., Pembrolizumab, Nivolumab, Atezolizumab, Toripalimab, Camrelizumab, Sintilimab). This heterogeneity reflects real-world practice but introduces a variable not present in the single-agent neoSCORE trial (6). It is possible that the overall efficacy profile across this diverse group might differ slightly from the focused use of Sintilimab in a highly responsive tumor type. Finally, neoSCORE (6) utilize stringent eligibility criteria to enroll a homogenous cohort with defined disease stages, optimal performance status, preserved organ function, and limited comorbidities. This design enhances internal validity and identifies efficacy in an optimized population. Conversely, our real-world study intentionally captured the inherent heterogeneity of routine clinical practice. By including patients with diverse comorbidities, varying performance status, and broader disease characteristics, our findings reflect the “effectiveness” of the intervention across the spectrum of patients encountered by oncologists, thereby enhancing external validity and generalizability.

Our finding that there was no significant difference in pathological response (pCR/MPR) between the 2-cycle and 3-cycle groups suggests a potential mechanistic plateau in immune activation. We hypothesize that the first two cycles of chemotherapy, by inducing immunogenic cell death, creates a pro-inflammatory microenvironment and rapidly expands the pool of tumor-reactive T cells, as evidenced by the significant early surge in tumor-infiltrating lymphocytes (TILs) and CD8+ T cell proportions observed after just one cycle of neoadjuvant chemotherapy (NAC) (28). Concurrent checkpoint blockade is critical in this phase, likely acting to sustain the proliferation and effector differentiation of pre-existing PD-1– CD8+ TILs, particularly the Tcf7+ memory-precursor-like subset, which is essential for an effective anti-tumor response and expands upon immunotherapy (29). We posit that this first-two-cycle synergy achieves a maximal practical recruitment and activation of the available anti-tumor T cell repertoire. Consequently, a third cycle provides diminishing returns, as it may fail to mobilize new, potent T cell clones. Instead, persistent antigen exposure and inflammatory signals could push the early-activated T cells toward exhaustion, while the residual tumor microenvironment evolves toward a more immunosuppressive state, characterized by a decline in TIL density and an increase in immunosuppressive M2 macrophages at the end of treatment, as documented in NAC non-responders (28). Thus, the lack of additional benefit from one-cycle extension may stem from an inability to further amplify the cytotoxic immune response, coupled with the inadvertent promotion of T cell dysfunction and compensatory immunosuppression.

Regarding perioperative safety, our findings suggest that patients who received two cycles of neoadjuvant therapy experienced more favorable outcomes during the perioperative period compared to those who underwent three cycles. The extended operative interval (OI) associated with the three-cycle regimen may be attributed to the additional recovery time required following the third cycle of immunochemotherapy. This prolonged interval could potentially affect treatment schedules and resource allocation in clinical settings. Furthermore, when comparing other perioperative outcomes, increasing the neoadjuvant treatment from two to three cycles did not confer any advantages in perioperative safety indicators, indicating that the perioperative safety of the two regimens is approximately equivalent.

While precise quantification of surgery ineligibility per cycle remains elusive in retrospective cohorts, our integrative analysis of trial data and clinician consensus suggests marginally higher attrition after 2 cycles (12%) versus 3 cycles (10%). This underscores the need for prospective recording of discontinuation drivers in future studies. Furthermore, given the real-world nature of this study, adverse event (AE) monitoring was subject to delayed assessments, potentially compromising both AE grading accuracy and detection sensitivity. These limitations may have resulted in false-negative AE reporting for some patients. More robust data from prospective cohort studies are needed to further elucidate AE incidence patterns.

In conclusion, Our analysis demonstrated comparable pathological responses (pCR/MPR) and survival outcomes (DFS/OS) between 2-cycle and 3-cycle neoadjuvant immunochemotherapy, while the two-cycle regimen was associated with a significantly shorter neoadjuvant-to-surgery interval, potentially facilitating earlier surgical intervention.