Pembrolizumab plus allogeneic NK cells in advanced non-small cell lung cancer patients

Abstract

BACKGROUNDThe anti-programmed cell death 1 (anti-PD-1) antibody pembrolizumab is clinically active against non-small cell lung cancer (NSCLC). In addition to T cells, human natural killer (NK) cells, reported to have the potential to prolong the survival of patients with advanced NSCLC, also express PD-1. This study aimed to investigate the safety and efficacy of pembrolizumab plus allogeneic NK cells in patients with previously treated advanced NSCLC.METHODSIn total, 109 enrolled patients with a programmed death ligand 1 (PD-L1) tumor proportion score (TPS) of 1% or higher were randomly allocated to group A (n = 55 patients given pembrolizumab plus NK cells) or group B (n = 54 patients given pembrolizumab alone). The patients received i.v. pembrolizumab (10 mg/kg) once every 3 weeks and continued treatment until the occurrence of tumor progression or unacceptable toxicity. The patients in group A continuously received 2 cycles of NK cell therapy as 1 course of treatment.RESULTSIn our study, patients in group A had longer survival than did patients in group B (median overall survival [OS]: 15.5 months vs. 13.3 months; median progression-free survival [PFS]: 6.5 months vs. 4.3 months; P < 0.05). In group A patients with a TPS of 50% or higher, the median OS and PFS was significantly longer. Moreover, the patients in group A treated with multiple courses of NK cell infusion had better OS (18.5 months) than did those who received a single course of NK cell infusion (13.5 months).CONCLUSIONPembrolizumab plus NK cell therapy yielded improved survival benefits in patients with previously treated PD-L1+ advanced NSCLC.TRIAL REGISTRATIONClinicalTrials.gov NCT02843204.FUNDINGThis work was supported by grants from the National Natural Science Foundation of China (NSFC) - Guangdong Joint Foundation of China (no. U1601225); the NSFC (no. 81671965); the Guangdong Provincial Key Laboratory Construction Project of China (no. 2017B030314034); and the Key Scientific and Technological Program of Guangzhou City (no. 201607020016).

Keywords: Cancer immunotherapy; Immunology; Lung cancer; Therapeutics.

Conflict of interest statement

Conflict of interest: The authors have declared that no conflict of interest exists.

Figures

Figure 1. Clinical trial profile and treatment schedule.

(A) Clinical trial profile. In total, 379 patients were selected for enrollment, 249 (65.7%) of whom were assessed for PD-L1 expression. For the 186 (74.7%) PD-L1+ patients, 78 (31.3%) had PD-L1 expression on at least 50% of their tumor cells. The PD-L1+ patients were screened for the eligibility criteria, and 109 (58.6%) were enrolled in the study and randomly assigned to group A or B. (B) Clinical treatment schedule. Patients in group A received pembrolizumab plus 1–3 courses of allogeneic NK cells; 1 NK cell treatment course was designed to contain 2 cycles, totaling 6 NK cell infusions in 28 days, i.e., days 12, 13, and 14 for the first cycle and days 26, 27, and 28 for the second cycle. Patients in group B received regular therapy with i.v. injection of pembrolizumab (10 mg/kg) on day 1 of a 21-day cycle, and the treatment was continued until disease progression or unacceptable toxicity occurred. n = 109.

Figure 2. All-cause adverse events in the safety population.

(A) All-cause adverse events with a difference of no less than 5% between the study groups. (B) Proportions of patients with treatment-related adverse events presented by grade. There was no significant difference between the 2 groups. n = 109. P > 0.05, by χ2 test.

Figure 3. Evaluation of immune parameters, tumor markers, and CTCs before treatment and 90 days after treatment.

(A) Flow cytometric analysis was performed with 6-Color TBNK Reagent to detect lymphocytes in the blood. n = 109. Data are shown as box-and-whisker plots (bottom: 25%; top: 75%; line: median; whiskers: minimum to maximum). Comparison within groups: *P < 0.05 and **P < 0.01, for comparison within groups; #P < 0.05 and ##P < 0.01, for comparison between groups. Statistical significance was determined by 2-sided Student’s t test. (B) Flow cytometric analysis was performed with the Cytometric Bead Array Human Th1/Th2 Cytokine Kit II to detect cytokines in the blood. (C) The levels of tumor markers including CEA, Cyfra21-1, and CA125 were quantitated by chemiluminescence immunoassay. (D) The number of CD45–CK+CD326+ cells (CTCs) was determined with a FACSCanto II. Data are shown as scatter plots with the median and range. n = 109. ‡P < 0.05. ANCOVA was used to analyze the effect of combined treatment on the reduction in CTCs in 7.5 mL of blood compared with pembrolizumab alone.

Figure 4. Effect of combination therapy on tumor MTDs in patients with NSCLC.

Data are shown as scatter plots with the median and range. *P < 0.05, compared with before treatment; #P < 0.05, compared with group B patients. Statistical significance was determined by 2-sided Student’s t test. n = 109.

Figure 5. OS analysis.

(A) Kaplan-Meier analysis was used to estimate the OS of the total population. n = 109. *P < 0.05. (B) Multivariate Cox regression analysis of the OS for key subgroups. n = 109. (C) Kaplan-Meier analysis was used to estimate the OS of patients with a TPS of 50% or higher. n = 47. *P < 0.05. (D) Kaplan-Meier analysis was used to estimate the OS of group A patients who received a single course of NK cell infusion or multiple courses of NK cell infusions. n = 53. *P < 0.05.

Figure 6. PFS analysis.

(A) Kaplan-Meier analysis was used to estimate the PFS of the total population. n = 109. *P < 0.05. (B) Multivariate Cox regression analysis of PFS for key subgroups. n = 109. (C) Kaplan-Meier analysis was used to estimate the PFS of patients with a TPS of 50% or higher. n = 47. *P < 0.05. (D) Kaplan-Meier analysis was used to estimate the PFS of group A patients who received a single course of NK cell infusion or multiple courses of NK cell infusion. n = 53. P > 0.05.