Table 5. Cox proportional hazards regression analysis of clinical factors associated with PFS2 and OS2 in the rechallenged group.
| Variable | PFS2 | OS2 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Univariate analysis | Multivariate analysis | Univariate analysis | Multivariate analysis | ||||||||
| HR (95% CI) | P value | HR (95% CI) | P value | HR (95% CI) | P value | HR (95% CI) | P value | ||||
| Age ≥65 years | 1.47 (0.64–3.39) | 0.36 | – | – | 0.93 (0.26–3.30) | 0.91 | – | – | |||
| Male vs. female | 1.02 (0.34–3.08) | 0.97 | – | – | 1.59 (0.60–4.23) | 0.36 | – | – | |||
| Smoking (current or former vs. never) | 1.47 (0.64–3.39) | 0.37 | – | – | 1.08 (0.41–2.81) | 0.88 | – | – | |||
| Grade 1–2 of first CIP | 0.20 (0.06–0.62) | 0.005* | 0.70 (0.14–3.45) | 0.66 | 0.12 (0.04–0.39) | <0.001* | 1.57 (0.22–11.04) | 0.65 | |||
| ECOG PS (0–1) of first CIP | 0.24 (0.10–0.57) | 0.001* | 0.49 (0.12–1.98) | 0.32 | 0.19 (0.07–0.57) | 0.003* | 0.52 (0.12–2.26) | 0.38 | |||
| Clinical type of first CIP | |||||||||||
| Pure | Reference | Reference | |||||||||
| Induced | 1.93 (0.62–6.03) | 0.26 | – | – | 1.63 (0.44–6.11) | 0.47 | – | – | |||
| Mixed | 1.23 (0.46–3.26) | 0.68 | – | – | 1.84 (0.61–5.58) | 0.28 | – | – | |||
| GGO vs. non-GGO at first CIP | 0.99 (0.42–2.37) | 0.98 | – | – | 0.96 (0.35–2.64) | 0.93 | – | – | |||
| Treatment line of second ICI | 1.42 (0.60–3.32) | 0.42 | – | – | 0.91 (0.32–2.59) | 0.86 | – | – | |||
| Laboratory values at rechallenge | |||||||||||
| IL-6 (<8.08 pg/mL) | 0.33 (0.13–0.84) | 0.020* | 0.44 (0.13–1.47) | 0.18 | 0.15 (0.05–0.51) | 0.002* | 0.06 (0.01–0.58) | 0.015* | |||
| CRP (<30.62 mg/L) | 0.57 (022–1.49) | 0.26 | – | – | 0.24 (0.08–0.70) | 0.010* | 0.55 (0.09–3.19) | 0.50 | |||
| WBC (<8.61 K/μL) | 0.52 (0.20–1.33) | 0.17 | – | – | 0.62 (0.20–1.97) | 0.42 | – | – | |||
| ANC (<6.75 K/μL) | 0.33 (0.14–0.82) | 0.017* | 0.60 (0.12–3.05) | 0.54 | 0.57 (0.19–1.70) | 0.31 | – | – | |||
| CIP recurrence (no vs. yes) | 0.28 (0.11–0.73) | 0.009* | 1.03 (0.18–5.97) | 0.98 | 0.19 (0.06–0.57) | 0.003* | 0.98 (0.12–8.20) | 0.98 | |||
*, P<0.05. PFS2, progression-free survival from the rechallenge; OS2, overall survival from the rechallenge; ANC, absolute neutrophil count; CI, confidence interval; CIP, checkpoint inhibitor-related pneumonitis; CRP, C-reactive protein; ECOG PS, Eastern Cooperative Oncology Group performance status; GGO, ground-glass opacity; HR, hazard ratio; IL, interleukin; ICI, immune checkpoint inhibitor; WBC, absolute white blood cell count.