From September 2016 to June 2019, 14 patients with advanced solid tumors (5 breast cancer, 3 NSCLC, 2 colorectal cancer, 1 ovarian cancer, 1 esophageal cancer, 1 soft tissue sarcoma, 1 pancreatic cancer) were included in this study, the median age of these patients was 55 (ranging from 45 to 82) years old. Previously, all these patients had received several cycles of standard therapies, including surgical resection, traditional chemotherapy, radiotherapy and immune therapy.
In the first phase of this study, 9 patients received NK cell therapy, and all of them completed at least 2 courses of infusion (4 completed a full cycle of infusion, 2 received multi-cycle infusions, 3 patients received 2 or 3 courses of infusion). The median dose of NK cells was 10.6×109 cells.
In the second phase, 5 patients received NK cell and Keytruda therapy. Among them, 3 patients (P10, P11 and P12) received 2 cycles of infusions and 2 patient (P13 and P14) received 2 courses of infusion. The median dose of NK cells was 10.9×109 cells. The Keytruda was administrated at 200 mg each course for adult patients. The specific details were provided in the Table 1.
As shown in Figure 1C, the major phonotype of NK cells was CD3-CD56+, which was significant higher than the percentage of CD3+CD56- and CD3+CD56+ cells (median, 72.6% vs. 17.5% and 9.4%, P< 0.0001).
In the first phase, 3 of 9 patients achieved a stable disease (SD) 4 weeks after NK cell therapy; 5 patients experienced progressive disease (PD) after treatment; 1 patient (P4) was response non-evaluable (NE) as he refused to accept the second course of infusion and withdraw from the study. Among the 3 patients who achieved SD after treatment, P2 was a 64 years old man with a diagnosis of esophageal cancer (stage Ⅲb) accompanying lymph nodes and left pleura metastasis. After infusion of 2 courses of NK cells, the tumor remained the primary size for 4 weeks detected by CT and ultrasound test. Besides, the tumor makers (CA-199 and CA-242) had a significant decrease after treatment. Especially, the CA-242 evidently decreased from over 200 KU/L to 143 KU/L 4 weeks after infusion (Figure 2A and B). For patient 7 who was diagnosed as soft tissue sarcoma with lung and colon metastasis, a stable disease was achieved after treatment. As shown in Figure 3A and B, the lung metastasis remained the primary size 4 weeks after NK cells infusion. For 2 patients (P8 and P9) with advanced breast cancer, 3 and 2 cycles of infusion were conducted in them respectively. For patient 8, she had a stable disease after each cycle of infusion, and this SD remained for about 8 weeks after treatment. However, for patient 9, the disease had a significant progression after 2 cycles of infusion, and the patient finally died of it.
In the second stage of this study, 5 patients received NK cell and Keytruda therapy, and 1 of them (P12) achieved partial remission (PR), 4 patients (P10, P11, P13 and P14) achieved SD after treatment. For patient 10, she had received anti-CEA chimeric antigen receptor (CAR)-T cell therapy for refractory/relapsed rectal cancer 4 months ago, and a stable disease was achieved after CAR-T. However, the disease had a progression 2 months after CAR-T therapy and this patients turned to this study accepting NK and Keytruda treatment. After 2 cycles of treatment, her tumor remained stable, the metastasis in the lung was no longer progressed (Figure 3C and D). Patient 11 was diagnosed as stage Ⅳ NSCLC with lymph nodes and spine metastasis, receiving 2 cycles of NK and Keytruda treatment. As shown in Figure 2C-F, although the tumor markers had some slight fluctuations after treatment, they still remained at the normal range. The metastasis in the spine was no longer progressed and remained stable for 4 months after treatment (Figure 3E-H).
For patient 12, he was diagnosed as NSCLC (stage Ⅳ) with metastases in the lymph nodes, bone and brain, and accepted anti-CEA CAR-T cell therapy 5 months before this study. After CAR-T, his disease remained stable for about 3 months but rapidly progressed afterwards. In this study, he accepted 2 cycles of NK and Keytruda treatment. Surprisingly, levels of the tumor markers including CA-125, CA-199, CA-242 and CEA had an evident decrease after 2 cycles of infusion (Figure 2G-J). Besides, the primary lesions in the lungs showed apparent attenuation and almost disappeared after treatment (Figure 4).
In the NK cell group, all fusions of NK cells were well tolerated by all patients. The mild fever was the most common adverse event observed in this group, and only one patient (P8) experienced high fever (>39℃). All symptoms were quickly relieved after conventional treatments.
In the NK cell and Keytruda group, the degree of adverse events was relatively more serious than that in NK cell group. 4 patients (P10, P11, P12 and P14) experienced mild to moderate fever and chills after infusion, especially after Keytruda administration. Besides, mild local erythroderma (grade 1) was observed after Keytruda administration in P11 and P12, which was relieved after symptomatic treatments and did not have a negative effect on the overall treatment schedule in this study. No obvious adverse event was observed in P13.