In this retrospective study, we analyzed the potential risk factors and their association with the incidence of CIP. No significant association was observed between COPD and CIP. To the best of our knowledge, this is the largest study to evaluate the impact of spirometry-defined COPD on the incidence and outcome of CIP in patients with NSCLC.
Lung cancer is the first cause of death in patients with COPD [22]. COPD is a disease associated with chronic inflammation of the airways and lung parenchyma, characterized by persistent lung injury, activates a regulatory mechanism that downgrades the immune response, including PD-L1/PD-1 [23], and thus opening a therapeutic window among patients with COPD who develop lung cancer. Despite the proven longer PFS in lung cancer patients with COPD [24,25,26], the uncertain safety may limit the use of ICIs. Since it is biologically plausible for immunotherapy to stimulate lymphocytes against healthy lung cancer cells, increasing lung tissue damage and COPD symptoms. Nair et al. reported a series of patients with prolonged and severe COPD exacerbations upon initiating immune checkpoint inhibitor therapy, indicating ICIs may aggravate CODP and irAE [27]. However, given the stringent eligibility criteria applied in clinical trials, healthier patients tend to be enrolled, and thus the real-world frequency of these events in the overall population is unknown. Findings from three recent studies indicated that COPD might associate with CIP [20, 28, 29]. However, these studies have not accounted for some crucial potential confounding factors. Atchley et al. [20] showed that obstructive lung disease was independently associated with CIP (aOR, 2.79; 95% CI, 1.07–7.29). It is noteworthy that the history of COPD is not a statistically significant risk factor for CIP in multivariate logistic regression analysis. Moreover, only 24.1% of these patients had documented baseline spirometry. Additionally, patients with ILD, connective tissue disease (CTD), and prior thoracic radiation history were included in the above research for CIP analysis, while the clinical variables mentioned above have been demonstrated as an independent risk factors for the development of CIP [6, 30, 31]. All the mentioned interfering factors above are difficult to distinguish from the risk conferred by COPD. Another study by Sul et al. [28] recapitulated this finding that CIP occurred more frequently in patients with a history of COPD and asthma than in patients without this history (5.4% vs. 3.1%). Unfortunately, in the study COPD and asthma were grouped together, which could be inappropriate given that the pathophysiology and dominant immunologic mechanisms involved differ [32]. A recent retrospective study reported that the presence of COPD was independently associated with a higher incidence of CIP, 70% of the patients in the CIP group had COPD. Unfortunately, the study investigated this association using physician-diagnosed COPD [29].
Notably, the incidence of CIP was similar in patients regardless of COPD status (18.0% vs. 13.1%, P = 0.618) in our study. The discrepancy might be partly attributed to the confounding factors in the previous study, and therefore, conclusions from these studies to be addressed with caution. Overcoming these limitations, the present study firstly showed that coexisting spirometry-defined COPD was not an independent risk factor for patients with lung cancer who have co-morbid COPD. In our study, the incidence of all CIP was 15.5% (19/122), and the incidence for grade ≥ 3 CIP was 3.3% (4/122), which is consistent with a prior report [6]. With timely and appropriate systemic corticosteroid treatment, the clinical symptoms and imaging changes of CIP can be improved in most patients (93.8%, 15/16). These results support the clinical observation that lung cancer patients can be treated safely with ICI in the context of COPD, and treatment-related irAEs were found to be manageable in COPD patients.
Pre-existing ILD has been reported to exist in approximately 15% of lung cancer patients at the time of initial diagnosis and is associated with a poor prognosis [33, 34]. Since patients with pre-existing pulmonary fibrosis are often excluded in clinical trials of immunotherapy to avoid CIP, the relationship between them needs to be further elucidated. Interstitial lung abnormalities (ILA) are defined as increased lung densities on chest computed tomography images of patients without previous history of ILD [35]. In our retrospective study, analysis according to the F score on baseline CT was analyzed in patients with ILA. The incidence of CIP was similar in two arms, which is inconsistent with previous studies [9, 11, 17]. This may partially attribute to the small sample size of patients with pre-existing pulmonary fibrosis in our study, and thus could not detect the group differences. Additionally, consideration is given to potential harms in the individual patients, physician may be more cautious to prescribe ICIs to patients with severe CT abnormalities (fibrosis/emphysema) in clinical practice. In our study, only 3 patients with F score 2 (presence of honeycomb lungs) received ICIs. According to the result of a phase 2 trial of atezolizumab for pretreated NSCLC with idiopathic interstitial pneumonitis, there is a particularly high risk of CIP in patients with a honeycomb lung on HRCT [11].
We also compared other clinical variables such as smoking history, older age, poor performance status, and underlying medical comorbidities, considered high-risk factors for drug-induced ILD [9, 30, 36]. No significant association was observed between groups according to the variables mentioned above.
Previous study indicated that some patients didn’t meet the spirometric standard of COPD have evidence of structural lung disease (emphysema, gas trapping) on chest imaging, these patients may experience a high risk of lung function decline and have potential to develop COPD in the future [37]. Previous studies reported that pre-existing pulmonary emphysema on baseline chest CT is not a risk factor for CIP [17, 20]. In our study, 24.6% (15/61) of patients in non-COPD group with emphysema in baseline CT scan, we also analyzed the relationship between E score and CIP. Consistent with previous studies, no relation between E score and CIP was revealed in our study.
Several retrospective studies suggest a longer PFS to ICIs in NSCLC patients with COPD compared to those without COPD [24, 26, 38]. However, there was also a limitation in the studies, only a small proportion of patients had documented spirometry in baseline and investigated COPD using physician-diagnosed COPD [24, 26]. In our study, we confirmed the conclusion in spirometry-defined COPD patients with co-morbid lung cancer. Moreover, the findings of previous studies were inconsistent regarding OS. A retrospective study in China was found a prolonged OS in the subgroup of patients with mixed ventilatory defects [26]. Nevertheless, numerous diseases are causing mixed ventilatory pulmonary, and the pathophysiology and underlying molecular mechanisms are different. Therefore, the difference in OS between groups cannot solely be attributed to COPD and the conclusion of the study should be treated with caution. Previous studies demonstrated patients with irAE, especially with lower-grade irAE was associated with better outcomes in patients with ICI treatment for NSCLC [39, 40]. In this study, 78.9% patients (15/19) with grade 1 or 2 CIP. Likewise, we observed that patients with CIP had longer median PFS and OS versus those without CIP in COPD subgroup, but the difference was not statistically significant given the limited sample size.
There are several limitations to this study, which should be addressed. First, the retrospective nature of this study is prone to biases from missing data and reliance on the documentation available for review. Second, the number of patients with CIP might not be sufficient to provide reliable information concerning the significance of the subgroup analysis according to COPD severity. Third, due to the scarcity of lung tissue from patients who received an ICIs, we lacked data regarding the PD-L1 expression and tumor mutational burden (TMB) of patients with COPD, unable to explore the potential interaction between COPD and immune profile. However, our data may be more informative in a real-world clinical setting, as clinical trials have demonstrated that patients achieved clinical benefit from ICI combined chemotherapy irrespective of PD-L1 expression [41], and patients who undergo palliative immunotherapy for NSCLC do not routinely undergo PD-L1 or TMB detection. Further prospective studies are needed to elucidate the complex relationship between the immune profile in tumor and the incidence of CIP in the context of COPD.