Clinical characteristics of enrolled patients at diagnosis
| CIP type | Steroid-refractory | Steroid-response | P value | Initial refractory | Late refractory | P value |
| n (%) | n (%) | n (%) | n (%) | |||
| No of patients | 28 | 38 | 19 | 9 | ||
| Demographic characteristic | ||||||
| Mean age (range), years | 64.3 (38–76) | 63.6 (29–78) | 0.584 | 63.3 (38–76) | 68.0 (61–71) | 0.156 |
| Sex | ||||||
| Male | 23 (82.1) | 32 (84.2) | 1.000 | 14 (73.7) | 9 (100.0) | 0.144 |
| Female | 5 (17.9) | 6 (15.8) | 5 (26.3) | 0 (0.0) | ||
| Smoking status | ||||||
| Current/former | 17 (60.7) | 23 (60.5) | 0.988 | 10 (52.6) | 7 (77.8) | 0.249 |
| Never | 11 (39.3) | 15 (39.5) | 9 (47.4) | 2 (22.2) | ||
| Cancer and anticancer therapy | ||||||
| Primary malignancy | ||||||
| Lung cancer | 24 (85.7) | 27 (71.1) | 0.160 | 15 (78.9) | 9 (100.0) | 0.273 |
| Others | 4 (14.3) | 11 (28.9) | 4 (21.1) | 0 (0.0) | ||
| Metastasis | ||||||
| Yes | 20 (71.4) | 30 (78.9) | 0.481 | 15 (78.9) | 5 (55.6) | 0.371 |
| No | 8 (28.6) | 8 (21.1) | 4 (21.1) | 4 (34.4) | ||
| Previous RT* | ||||||
| Yes | 5 (17.9) | 8 (21.1) | 0.747 | 4 (21.1) | 1 (11.1) | 0.626 |
| No | 23 (82.1) | 30 (78.9) | 15 (78.9) | 8 (88.9) | ||
| ICIs type | ||||||
| Anti-PD-1 | 25 (89.3) | 36 (94.7) | 0.721 | 17 (89.5) | 8 (88.9) | 1.000 |
| Anti-PD-L1 | 3 (10.0) | 2 (5.2) | 2 (10.5) | 1 (11.1) | ||
| Combination therapy | ||||||
| Chemotherapy | 23 (82.1) | 33 (86.8) | 0.858 | 16 (84.2) | 7 (77.8) | 1.000 |
| TKI | 3 (10.7) | 6 (15.8) | 0.817 | 2 (10.5) | 1 (11.1) | 1.000 |
| Treatment line† | ||||||
| 1 | 17 (60.7) | 19 (50.0) | 0.608 | 11 (57.9) | 6 (66.7) | 1.000 |
| ≥2 | 11 (39.3) | 16 (45.5) | 8 (42.1) | 3 (33.3) | ||
| ICI treatment duration, days (range) | 143 (7–513) | 191 (8–542) | 0.125 | 149 (7–513) | 128 (13–281) | 0.679 |
| Previous disease and steroid using | ||||||
| Previous chest disease‡ | ||||||
| ILD | 19 (67.9) | 16 (42.1) | 0.015 | 13 (68.4) | 6 (66.7) | 1.000 |
| Emphysema | 13 (46.4) | 10 (26.3) | 0.052 | 7 (36.8) | 6 (66.7) | 0.236 |
| Previous irAEs | ||||||
| Yes | 4 (14.3) | 1 (2.6) | 0.194 | 3 (15.8) | 1 (11.1) | 1.000 |
| No | 24 (85.7) | 37 (97.4) | 16 (84.2) | 8 (88.9) | ||
| Pervious steroids use | ||||||
| Yes | 5 (17.9) | 4 (10.5) | 0.621 | 4 (21.1) | 1 (11.1) | 1.000 |
| No | 23 (82.1) | 34 (89.5) | 15 (78.9) | 8 (88.9) | ||
| Clinical characteristic of CIP | ||||||
| Initial grade | ||||||
| Grade 2 | 10 (35.7) | 34 (89.5) | <0.001 | 2 (10.5) | 7 (77.8) | 0.001 |
| Grade 3 | 10 (35.7) | 2 (5.3) | 9 (47.4) | 2 (22.2) | ||
| Grade 4 | 8 (28.6) | 2 (5.3) | 8 (42.1) | 0 (0.0) | ||
| Concurrent infection§ | ||||||
| Yes | 9 (32.1) | 5 (13.2) | 0.051 | 7 (36.8) | 2 (22.2) | 0.676 |
| No | 18 (64.3) | 33 (86.8) | 12 (63.2) | 6 (66.7) | ||
| Concurrent irAEs | ||||||
| Yes | 8 (28.6) | 7 (18.4) | 0.331 | 7 (36.8) | 1 (11.1) | 0.214 |
| No | 20 (71.4) | 31 (81.6) | 12 (63.2) | 8 (88.9) | ||
P value was bolded if it was less than 0.05.
*Radiotherapy to the chest, not to other sites.
†Three patients received neoadjuvant or adjuvant therapy were not included.
‡Two patients did not have chest CT images before CIP.
§Infection condition was not known in 1 patient of the steroid-refractory group.
CIP, checkpoint-inhibitor pneumonitis; ICI, immune-checkpoint inhibitor; ILD, interstitial lung disease; irAEs, immune-related adverse events; PD-1, programmed death-1; PD-L1, programmed death ligand-1; RT, radiotherapy; TKI, tyrosine kinase inhibitor.