Neoadjuvant anti-programmed Death-1 immunotherapy by Pembrolizumab in resectable nodal positive stage II/IIIa non-small-cell lung cancer (NSCLC): the NEOMUN trial

Lung cancer is one of the leading causes of death worldwide with approximately 230.000 new diagnoses per year in the United States and 410.000 in Europe [1, 2]. Non-small cell histology (NSCLC) accounts for 80% of all lung cancer patients [3]. Less than two thirds of all patients with a newly diagnosed NSCLC have the chance of a curative treatment. Only about 25% are diagnosed in a very early stage (stages IA to IB) [4, 5]. In these early stages, 5-year-survival ranges from 60 to 80% after radical surgical treatment [6]. Patients with locally advanced (T2-T4) tumors or limited nodal disease (N1, unilevel N2) do profit from a multimodal therapy including surgery followed by adjuvant cisplatin duplet chemotherapy. Nevertheless, survival of patients in stages IIA and IIB with nodal tumor involvement (N1) is estimated between 55 and 35% at five years and is even worse (15 to 40%) for patients with locally resectable tumors but limited nodal N2-disease. Following complete microscopic resection (R0), adjuvant chemotherapy may improve survival benefit of only approximately 5% [7, 8]. Until now, the recommendation for adjuvant treatment in resectable stages IIA to IIIA NSCLC is based on a meta-analysis of few studies that have been conducted up to 20 years ago [9].

In contrast to standard cisplatin based chemotherapy, novel drugs modulating the patient’s immune-system unleashing the anti-tumor immunity have been implemented into modern treatment strategies. Special interest has been raised by so-called regulatory immune-inhibitory pathways including the programmed death-receptor 1 (PD-1) and its ligand (PD-L1). Besides others, these molecules are expressed on the tumor cell surface (PD-L1) or the patients activated T-cells (PD-1). Ligation of PD1/PD-L1 suppresses activated T-cells, thus resulting in impaired anti-tumor immunity [10, 11].

Antibodies blocking the ligation of PD-1/PD-L1 have been investigated in recent clinical trials in NSCLC stage IV patients (KEYNOTE-trials). Treatment of selected patients (PD-L1 expression on at least 50% of the tumor-cells, no EGF-receptor mutation or ALK-translocation) with a monoclonal humanized antibody against PD-1 (Pembrolizumab, KEYTRUDA©) correlated with an increased progression-free survival (median 10.3 months vs. 6.0 months, p < 0.001) and an overall survival of 80.2% at 6 months compared to 72.4% in patients receiving standard chemotherapy (p < 0.005). These findings resulted in the recent approval of Pembrolizumab as first line-treatment for patients with a PD-L1 expression > 50%. Nevertheless, the KEYNOTE study population consisted of patients with advanced or metastatic NSCLC [10].

The feasibility and safety of neoadjuvant immunotherapy prior to tumor resection has been proven in a recently published study by Forde et al. Preliminary data shows encouraging results in clinical and pathological response evaluation [12]. Based on these experiences, aim of the NEOMUN investigator initiated trial (NCT03197467; EudraCT No.: 2017–000105-20) is to assess feasibility and safety of neoadjuvant anti PD-1 immunotherapy followed by curative intent surgery. Monitoring clinical and radiological response will be supplemented by a translational interdisciplinary research program. Assessing the induction of tumor specific immunity will help to more intensively explore potential immunotherapy-associated changes in the tumor and its microenvironment.

Patients with NSCLC and nodal N1 and/or N2 disease suffer from an overall relapse rate of 52% even when multimodality treatment including curative intent surgery with chemo- and/or radiotherapy is administered. The overall 5-year survival benefit in these patients accounts of only 4 to 5% [22, 23]. In terms of efficacy, no difference between a pre- or postoperative chemotherapy approach can be determined [24]. In the light of the efficacy results it is clear, that new multimodal treatment strategies are direly needed in order to improve long term survival following curative intent surgery.

Recently, immunotherapies targeting the PD-1/PD-L1 pathway have had significant impact on survival in patients with advanced stages of NSCLC in comparison to standard chemotherapy [10]. A correlation between PD-L1-expression (> 50%) and survival or response to immunotherapy has been shown in recent anti-PD-1 trials [25, 26]. However, the efficacy of Pembrolizumab as a first-line treatment in advanced and/or metastatic NSCLC patients with PD-L1 expression below 50% is under debate. Based upon preliminary promising results from the KEYNOTE-trials, the combination of Pembrolizumab and pemetrexed/carboplatin chemotherapy has been recently approved as first-line treatment for metastatic or advanced NSCLC regardless of the PD-L1 expression [27]. Further results are eagerly awaited to define more subgroups that are suitable for anti-PD-1 therapy.

Irrespective of the results in metastatic stage IV patients, the predictive value of the PD-L1 status might have a different impact in patients with non-metastatic earlier-stage lung cancer with less tumor burden. This hypothesis is supported by data recently published by Forde et al. [12]. Their trial (NCT02259621) investigated safety and feasibility of patients with early stage I-IIIa NSCLC treated neoadjuvantly with 2 doses of nivolumab. Major pathologic tumor response (defined as less than 10% viable tumor cells posttreatment) was observed in 9 of 21 (43%) resected tumors. Importantly, this tumor response did not correlate with the pre-treatment PD-L1 status assessed in tumor biopsies by immunohistochemistry.

Moreover, the techniques used to quantitatively assess the PDL-1 status in small pre-treatment biopsies are under critical debate. Several factors contributing to a false-negative or a false-low PD-L1 status have recently been identified [28]. From a biological point of view dynamic induction of PD-L1 expression and an intratumoral heterogeneity of PDL-1 expression may result in a false-negative PD-L1 status and may not be accurately investigated by small sample biopsies. This is supported by a comparative study investigating the PD-L1 status in surgically resected specimens and matched biopsies of NSCLC patients. The study revealed major discordances between biopsies and surgical specimens with an overall discordance rate of 48%. In all cases the biopsy specimens underestimated the PDL-1 status observed on the whole tissue sample [28]. Due to the points listed above, the authors believe that the benefit/risk ratio is not influenced by the pretreatment PDL-1 status and therefore the inclusion of an all-comers population is justifiable. The translational study research program will raise the opportunity to generate further data to elucidate the role of different PD-L1 expression levels in the context of neoadjuvant immunotherapy.

In addition to the PD-L1 status analysis, EGFR-mutation and ALK-translocation have been implemented in routine diagnostics and represent important prognostic parameters in the era of targeted therapy [29]. A correlation between positive EGFR-mutation and high PD-L1 expression in a historical cohort analysis of surgically resected NSCLC has been shown by Azuma et al. [30]. Several authors have also reported about rare concomitant expression of EGFR, ALK and/or PD-L1 and thus they so far refuted their mutual exclusiveness [31, 32]. Nevertheless, the NEOMUN-trial aims to include untreated patients with stage II/IIIA1–3 NSCLC. According to current guidelines surgical tumor resection is the primary treatment in this patient cohort. This also accounts for EGFR or ALK positive tumors. To date, there is no neoadjuvant or adjuvant EGFR- or ALK-TKI therapy authorized in this patient cohort. Based on this, the protocol does not include stratification after EGFR/ALK- mutation analysis and therefore does not exclude patients with positive mutations.

The question whether checkpoint blockade should be performed before or after surgery has been addressed by Liu et al. in a preclinical breast-cancer model. The authors reported about an increased tumor specific CD8+ T-cell response in patients after neoadjuvant immunotherapy [33]. Pircher et al. observed a reduction of regulatory T-cells (Tregs) in NSCLC patients that received neoadjuvant immune-chemotherapy (Cetuximab/Docetaxel/Cisplatin) before surgical resection [34]. Tregs play a relevant role in cancer-associated immune-escape mechanisms as they suppress cytotoxic T-lymphocytes and natural killer cells [35]. Taking this into account, it is uncontroversial that a profound interaction between the tumor and its autologous immune-system is necessary to induce tumorspecific t-cells to overcome tumor induced tolerance and to generate and activate T-cell memory. We hypothesize that the anti-neoplastic immune-stimulatory effect will be more effective in patients treated prior to tumor resection. Therefore, neoadjuvant immunotherapy by administration of anti-PD-1 targeting antibodies is very promising and has led to unforeseen therapeutic efficacy. The results of a number of ongoing clinical phase II and III trials addressing neoadjuvant immunotherapy before surgery in extrathoracic solid cancers are awaited with great interest (e.g. bladder cancer, melanoma, clinicaltrials.​gov).

In NSCLC, clinical data on neoadjuvant immunomodulatory treatment is scarce but few encouraging trials investigating anti-PD-1/PD-L1 checkpoint inhibition prior to surgery for NSCLC patients are currently ongoing (e.g. NCT02938624; NCT03217071; NCT02818920; NCT02259621). In a first interim analysis, Forde et al. recently published data on patients with NSCLC receiving neoadjuvant anti-PD-1 therapy (Nivolumab). They observed a major pathological response (less than 10% viable tumor cells) in 9 of 20 patients (45%) with neoadjuvant immunotherapy. These preliminary data and the results of the KEYNOTE-trials identified immunotherapy as a promising strategy in NSCLC treatment [10].

The scope of the enrolled NEOMUN trial is to generate pilot data on the efficacy, safety and the feasibility of a neoadjuvant anti-PD-1 immunotherapy with Pembrolizumab. The research endeavor will be flanked by a translational research program to elucidate potential predictive biomarkers and to investigate the mode of action of anti PD-1 treatment in NSCLC patients.