A study protocol of a single-arm, prospective, open-label, non-controlled, phase II study of neoadjuvant BL-B01D1 combined with aumolertinib in resectable stage II-IIIB non-small cell lung cancer patients with mutation.

Introduction
Approximately 30% of lung cancer patients present with surgically resectable disease at diagnosis (1). Despite curative-intent surgery, the 5-year overall survival (OS) remains suboptimal—ranging from 65% in stage IIA to 24% in stage IIIB (2)—primarily due to high rates of occult micrometastases and postoperative recurrence. Perioperative therapy has emerged as a crucial strategy to improve survival outcomes in this population.
Neoadjuvant therapy has demonstrated potential to downstage tumors, enhance surgical resectability for borderline cases, eliminate micrometastases, and reduce the risk of preoperative disease progression, thereby improving surgical outcomes and survival. While neoadjuvant or adjuvant chemotherapy was historically utilized in resectable non-small cell lung cancer (NSCLC), its 5-year survival benefit remained modest, with only ~5% improvement in OS and a major pathological response (MPR) rate of 10% compared to surgery alone (3-5). Recent breakthroughs in multiple trials have established immune checkpoint inhibitors (ICIs) as a paradigm-shifting approach, with neoadjuvant chemoimmunotherapy achieving pathological complete response (pCR) rates of 20–40% in resectable NSCLC, establishing it as a standard approach (6-8). However, ICIs show limited efficacy in epidermal growth factor receptor (EGFR)-mutant NSCLC, the most prevalent driver alteration (40–60% in Asian populations). Therefore, most related studies excluded patients with EGFR mutations, and even a few trials that included such patients failed to demonstrate the definite efficacy of neoadjuvant immunotherapy combined with chemotherapy in the EGFR mutation subgroup (9). Critically, neither neoadjuvant chemotherapy nor chemoradiotherapy has demonstrated significant OS improvements in this population.
EGFR tyrosine kinase inhibitors (TKIs) have proven effective in advanced and adjuvant settings for EGFR-mutant NSCLC, but neoadjuvant monotherapy consistently yields suboptimal pCR rates (0–16%) (4,10). Yet, pCR correlates strongly with prolonged OS (11), underscoring its prognostic value. The NeoADAURA study reported superior MPR rates with osimertinib-based regimens (26% for osimertinib plus chemotherapy, 25% for osimertinib monotherapy) vs. chemotherapy alone (2%), with pCR rates of 9% and 4% respectively, in the combination and monotherapy arms. These findings may support third-generation EGFR-TKI efficacy in neoadjuvant settings while suggesting limited additive benefit from chemotherapy combination, highlighting the need for more synergistic combinations. The superior response in Chinese patients (41% MPR) underscores the potential for greater clinical benefit with third-generation TKI neoadjuvant therapy in this population.
BL-B01D1, a first-in-class EGFR/human EGFR 3 (HER3) bispecific antibody-drug conjugate (ADC), demonstrated promising efficacy and favorable safety in a phase I trial across multiple epithelial malignancies, including NSCLC (12,13). Another ongoing phase II study evaluating efficacy and safety of the BL-B01D1 monotherapy and combination with osimertinib in first-line treatment in patients with locally advanced or metastatic NSCLC showed encouraging antitumor activity with favourable safety. Aumolertinib is China’s first self-developed third-generation EGFR-TKI, which is active against EGFR-sensitive mutations and T790M resistance mutations, showing good efficacy and safety (14). According to the ARTS clinical study, aumolertinib as an adjuvant treatment significantly prolonged disease-free survival (DFS) compared to placebo, and the improvement in 2-year DFS rate was statistically significant [2-year DFS rate 88.2% vs. 40.6%; hazard ratio (HR) =0.17, P<0.001]. Currently, this drug has been approved for use as an adjuvant treatment for adult patients with EGFR exon 19 deletion or exon 21 (L858R) substitution mutation-positive NSCLC after surgery in China.
Building on this foundation, this open-label phase II trial evaluates the safety and efficacy of neoadjuvant BL-B01D1 combined with aumolertinib, followed by postoperative adjuvant aumolertinib, for stage II–IIIB EGFR-sensitive mutant NSCLC. The primary objectives are: (I) to assess the antitumor activity of this regimen in the neoadjuvant setting; (II) to evaluate its safety and tolerability profile in the neoadjuvant setting; (III) to explore predictive/prognostic biomarkers correlated with treatment response. We present this article in accordance with the SPIRIT reporting checklist (available at https://tlcr.amegroups.com/article/view/10.21037/tlcr-2025-829/rc).

Methods

Study design and participants
The Phase II BL-B01D1-206 study (NCT06951464), will evaluate efficacy and safety of BL-B01D1 combined with aumolertinib neoadjuvant therapy and postoperative aumolertinib adjuvant therapy in patients with stage II–IIIB EGFR-sensitive mutated NSCLC.

Key eligibility criteria
Patients must have histologically/cytologically confirmed NSCLC deemed completely resectable [stage II–IIIB, International Association for the Study of Lung Cancer (IASLC) 8th ed.], harbor EGFR mutations. Radical surgery (15) (radical pulmonary lobectomy with systematic lymphadenectomy) must be deemed feasible or possibly feasible as determined by a multidisciplinary team, and patients have an Eastern Cooperative Oncology Group (ECOG) performance status of 0–1. Adequate organ function and other criteria are required (see Table 1).

Objectives
The primary objective is to evaluate the efficacy of BL-B01D1 combined with aumolertinib in the neoadjuvant treatment of patients with NSCLC harboring EGFR-sensitive mutations. The primary endpoints are pCR and MPR in the neoadjuvant setting. Secondary endpoints include objective response rate (ORR), event-free survival (EFS), DFS, OS, and R0 resection rate in the neoadjuvant setting.
The secondary objective is to assess the safety and tolerability of BL-B01D1 combined with aumolertinib in neoadjuvant setting. This includes monitoring the types, frequencies, and severities of treatment-emergent adverse events (TEAEs) and treatment-related adverse events (TRAEs) during the treatment course.
Additionally, the study aims to explore the potential relationship between predictive and prognostic biomarkers and treatment response to the investigational drugs. This encompasses evaluating biomarker levels in preserved or newly collected tumor tissue samples alongside blood specimens collected at various treatment stages, including prior to, throughout, or following therapeutic interventions, as well as during instances of disease progression. The biomarkers under investigation encompass, but are not limited to, the detection of EGFR, HER3, other relevant markers and the correlation between these biomarkers and minimal residual disease (MRD) in relation to therapeutic efficacy.

Study procedures
BL-B01D1-206 is a Phase II, open-label, non-controlled, single-arm study that comprises two stages: dose escalation and dose expansion (Figure 1). Patients will be screened at West China Hospital, Sichuan University. Ethical approval for the study protocol and informed consent framework was granted by the Sichuan University West China Hospital Ethics Committee (No. 2025-245), with written informed consent to be obtained from all enrolled participants. Research activities will strictly adhere to the Declaration of Helsinki and its subsequent amendments and comply with Good Clinical Practice (GCP) standards throughout all study phases. The first patient was enrolled on 25 June 2025 and the recruitment is currently in progress.

Neoadjuvant therapy phase
During the dose escalation phase, we designed two dose cohorts. Initially, three patients meeting eligibility criteria will be enrolled to receive BL-B01D1 2.2 mg/kg on Day 1 and Day 8 of each 3-week cycle for a total of 2 cycles, in combination with aumolertinib (110 mg, once a day). If no dose-limiting toxicity (DLT) is observed in 21 days after the first dose, the study will progress to the BL-B01D1 2.5 mg/kg dose level. Based on integrated safety and preliminary efficacy data, one dose cohort will be selected for expansion in subsequent study phases. Tumor assessment will be conducted 6 weeks ± 3 days after the first administration of BL-B01D1. Administration of aumolertinib will continue until tumor assessment, at which point, if the patient achieves a complete response (CR), partial response (PR), or stable disease (SD) (indicating benefit) as assessed by the investigator, aumolertinib may continue to be administered until surgery. If progressive disease (PD) is observed or SD is assessed without benefit by the investigator, the decision to continue aumolertinib or adjust the treatment plan will be made by the investigator.

Surgical treatment phase
Patients who respond to neoadjuvant therapy (CR + PR) and those who do not respond but are still eligible for surgery (SD and PD) will undergo radical lobectomy with systematic lymph node dissection 4–6 weeks after the last administration of BL-B01D1. For patients with postoperative pathological confirmation of N2+ disease or positive surgical margins, postoperative radiotherapy (PORT) is recommended prior to starting adjuvant therapy or observational follow-up. PORT should commence within 30–90 days after surgery and should adhere to relevant guidelines.

Adjuvant therapy phase
Patients who have undergone surgery and achieved CR, PR, or SD continue to receive aumolertinib at a dose of 110 mg once daily for 3 years or until disease recurrence, unacceptable adverse events (AE) occur, death, or when the patient and/or physician decides to discontinue study treatment or observational follow-up. Patients with SD or PD who are unable to undergo surgery, as well as those with PD who have undergone surgery, will receive comprehensive treatment.

Assessments
The tumor response status of patients will be evaluated using the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. During the screening period, mandatory contrast-enhanced imaging will assess tumors, including computed tomography (CT) scans of the chest and abdomen alongside magnetic resonance imaging (MRI) of the head, for disease staging and to establish a baseline for the presurgical scan. Subsequent scans will be acquired at the presurgical assessment (6 weeks after the first administration), and every 3 months ± 1 week post-surgery within 2 years, every 6 months ± 2 weeks since 3rd year and every 1 year ± 1 month since 5th year until any of the following occurs: EFS event documentation, patient demise, study discontinuation, or protocol-defined termination.
The pathological assessment includes pCR, MPR, and the R0 resection rate. Exploratory biomarker analyses, such as the expression of EGFR and HER3 using archived tumor tissues, will be conducted. In addition to the expression of EGFR and HER3, other exploratory biomarkers related to the clinical benefit of BL-B01D1 might also be evaluated. Quantitative analysis of MRD and/or circulating tumor DNA (ctDNA) dynamics will utilize plasma specimens obtained at 1, 3, and 6 months postoperatively.
Safety will be assessed by compiling and analyzing AE, laboratory tests, physical examination and vital signs, ECOG, echocardiography, electrocardiogram and concomitant medications. Throughout the entire study period and the safety follow-up phase, AEs and serious AEs will undergo continuous evaluation. The duration of the safety follow-up period is determined by surgical status: for patients not undergoing surgery, it spans 28 days after the last administration of the study drug; for surgical patients, it extends 90 days post-operatively. Additionally, interstitial lung disease (ILD) (including pneumonitis) will be a specific AE of interest requiring rigorous monitoring. All AEs will be categorized based on the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE), version 5.0, and indexed using the Medical Dictionary for Regulatory Activities (MedDRA). A comprehensive summary of the number and incidence of AEs will be presented, categorized according to human organ systems using pertinent terminology. Additionally, all serious AEs (SAEs), DLTs, and AEs resulting in discontinuation will be summarized. Investigators should estimate the relationship between AEs and the study drug.

Statistical analysis
Approximately 40 patients with resectable stage II–IIIB EGFR-mutant NSCLC will be enrolled. This sample size calculation assumes a 5% historical pCR rate and provides 80% statistical power to detect a 20% pCR using a one-sided significance level of 2.5%. Both pCR and MPR will undergo Cochran-Mantel-Haenszel analysis, stratified by disease stage and mutation subtype, with subsequent subgroup evaluations across these stratification factors.
EFS is defined from treatment initiation to the first occurrence of: (I) documented disease progression precluding surgery or requiring non-protocol therapy; (II) local/distant recurrence or new malignant lesion (excluding pathologically confirmed new primary malignancies); or (III) death from any cause. OS spans treatment commencement to all-cause mortality, while DFS measures time from surgery to first recurrence (local/distant) or death.
MRD assessment and molecular tumor profiling will evaluate progression biomarkers during adjuvant therapy, with correlative analyses examining associations with MPR, pCR, EFS, DFS outcomes and treatment effects. All endpoints except DFS will be analyzed in the full analysis set (all enrolled patients), whereas DFS assessment will utilize the resected cohort comprising patients achieving complete surgical resection following neoadjuvant therapy.

Discussion
For patients with EGFR-mutated resectable NSCLC, currently approved therapies fail to address the biological characteristics of this population. Neoadjuvant chemotherapy, EGFR-TKI monotherapy, and EGFR-TKI-chemotherapy combinations yield suboptimal outcomes, necessitating novel therapeutic approaches. The BL-B01D1-206 trial will evaluate an innovative perioperative strategy for resectable stage II–IIIB EGFR-mutant NSCLC, combining neoadjuvant BL-B01D1 (an EGFR/HER3 ADC) with aumolertinib, followed by adjuvant aumolertinib. This regimen addresses fundamental limitations of existing paradigms through mechanistically driven innovation. Unlike cytostatic EGFR-TKI monotherapy, which primarily suppresses tumor growth without direct cytotoxic effects, BL-B01D1 enables dual-pathway blockade while selectively delivering cytotoxic payloads to tumor cells. Preclinical evidence supports this mechanism, demonstrating synergistic antitumor activity of BL-B01D1 with osimertinib in xenograft models without significant toxicity escalation (unpublished data). Crucially, aumolertinib is selected as the combinatorial partner based on its differentiated safety profile—particularly lower incidence of ILD (grade ≥3: 0.5% in AENEAS vs. 3.9% for osimertinib in FLAURA)—thereby minimizing perioperative pulmonary risks, a critical consideration for surgical candidacy.
This therapeutic regimen fully harnesses the tumor-specific cytotoxicity of BL-B01D1 and the targeted inhibitory effects of aumolertinib, while maintaining a critical focus on the safety profile of their combination therapy. Given the limited clinical experience with this novel ADC-TKI combination, we have incorporated rigorous safety considerations throughout the trial design. Phase I data of BL-B01D1 monotherapy indicate a profile dominated by hematologic toxicities (12), including grade ≥3 neutropenia (47%), anemia (39%), and thrombocytopenia (32%), with a low but notable incidence of treatment-related ILD (0.5%). The most common adverse reactions of aumolertinib are rash, diarrhea, and liver function abnormalities. When combined with aumolertinib, the potential for overlapping toxicities—primarily encompassing BL-B01D1-induced hematologic toxicities, aumolertinib-related TKI-class AEs, and the critical risk of ILD—requires proactive management. In neoadjuvant therapy, ensuring that treatment-related toxic reactions do not interfere with or delay the surgical process constitutes a core consideration, as this factor is pivotal in determining the optimal timing for neoadjuvant treatment. Three key design elements optimize the efficacy-safety balance: (I) limiting neoadjuvant BL-B01D1 to two cycles (Day 1/Day 8, every 3 weeks) controls cumulative toxicity; (II) mandatory imaging at 6 weeks after first administration enables tumor response assessment and proactive pulmonary surveillance for early ILD detection; (III) surgery within 4–6 weeks post-BL-B01D1 cessation, with continuous aumolertinib until surgery, to prevent tumor progression and probable surgical delays from unresolved toxicities. IFCT0002 showed no improvement in pathologic response with four vs. two neoadjuvant chemotherapy cycles in resectable stage I–II NSCLC (16), while NeoADAURA adopted a 9-week neoadjuvant TKI regimen (17). In our trial, BL-B01D1 is administered for 2 cycles and aumolertinib for 8–10 weeks, reducing risks while maintaining therapeutic intensity. Furthermore, the dosing strategy involves dose escalation across two cohorts followed by selection of an optimal dose for expansion. To avoid compromising therapeutic efficacy in lower-dose cohorts while ensuring rigorous safety oversight, the trial design incorporates a two-tiered escalation strategy. The study adopts the recommended combination dose from the ongoing phase II trial of BL-B01D1 plus osimertinib (another third-generation TKI) in advanced NSCLC, with an additional lower-dose cohort preceding it as a safety precaution. Throughout the neoadjuvant phase, patients undergo frequent laboratory monitoring and are managed according to predefined dose modification guidelines to address emerging AEs promptly. This sequential approach enables systematic evaluation of dose-limiting toxicities while preserving the therapeutic potential of the empirically optimized regimen.
In this study, pCR and MPR are selected as primary endpoints based on the following evidence: pCR has been demonstrated as a predictor of long-term prognosis in NSCLC patients undergoing neoadjuvant therapy followed by surgical resection (11), showing strong correlation with OS. MPR serves as a surrogate endpoint for DFS in neoadjuvant studies of resectable NSCLC (4), and also correlates with OS. The project will additionally collect data on EFS, DFS, and OS as secondary endpoints to assess the long-term benefits of the investigational treatment.
The interpretability of the findings from this study must be considered in the context of its single-arm design. The absence of a randomized control group precludes definitive conclusions regarding the efficacy of the investigated regimen compared to the current standard of care. The observed outcomes may be influenced by patient selection factors. Furthermore, comparisons with historical controls should be made with caution due to potential differences in staging techniques, surgical expertise, and patient demographics. Therefore, while our results are promising and generate important hypotheses, they warrant validation in future randomized controlled trials.
By a precision ADC-TKI combination, this approach may establish a novel treatment paradigm for oncogene-driven resectable NSCLC. Integrated biomarker analysis exploring EGFR/HER3 expression and ctDNA dynamics may identify patient subsets most likely to benefit, addressing a persistent gap in targeted neoadjuvant therapy. Should this strategy demonstrate enhanced pathological response depth and manageable toxicity, it may establish a new standard for precision perioperative management in molecularly defined populations.

Supplementary
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