Characteristics of patients included in the RADIOHEAD cohort
| Pretreatment characteristic | Full cohort, No. (%) | Any irAE incidence (Grade I–IV), No. (%) | Severe irAE incidence (Grade III–IV), No. (%) |
| All subjects, No. (%) | 1070 | 272 (25.4) | 65 (6.1) |
| Age, years, median (IQR) | 69 (62–77) | 68 (61–76) | 67 (62–77) |
| Sex, No. (%) | |||
| Female | 468 (43.7) | 119 (25.4) | 27 (5.8) |
| Male | 602 (56.3) | 153 (25.4) | 38 (6.3) |
| ICI treatment groups, No. (%) | |||
| Anti-PD-(L)1 antibody | 980 (91.6) | 223 (22.8) | 49 (5) |
| Anti-PD-(L)1 and anti-CTLA-4 combination | 90 (8.4) | 49 (54.4) | 16 (17.8) |
| ICI combinations, No. (%) | |||
| Anti-PD-(L)1 monotherapy | 717 (67) | 173 (24.1) | 37 (5.2) |
| Anti-PD-(L)1 combined with chemotherapy | 240 (22.4) | 41 (17.1) | 10 (4.2) |
| Anti-PD-(L)1 other combination* | 23 (2.1) | 9 (39.1) | 2 (8.7) |
| Anti-PD-(L)1 and anti-CTLA-4 combination | 87 (8.1) | 49 (56.3) | 16 (18.4) |
| Anti-PD-(L)1 and anti-CTLA-4 with chemotherapy | 3 (0.3) | 0 (0) | 0 (0) |
| Cancer type, No. (%) | |||
| Non-small cell lung cancer (NSCLC) | 398 (37.2) | 94 (23.6) | 23 (5.8) |
| Melanoma | 128 (12) | 56 (43.8) | 15 (11.7) |
| Renal cell carcinoma (RCC) | 94 (8.8) | 31 (33) | 8 (8.5) |
| Urothelial carcinoma (UC) | 89 (8.3) | 19 (21.3) | 3 (3.4) |
| Small cell lung cancer | 68 (6.4) | 12 (17.6) | 3 (4.4) |
| Head and neck squamous cell cancer (HNSCC) | 58 (5.4) | 10 (17.2) | 2 (3.4) |
| Gastroesophageal cancer | 36 (3.4) | 5 (13.9) | 1 (2.8) |
| Hepatocellular carcinoma | 36 (3.4) | 6 (16.7) | 1 (2.8) |
| Breast cancer | 26 (2.4) | 7 (26.9) | 3 (11.5) |
| Colorectal cancer | 24 (2.2) | 2 (8.3) | 0 (0) |
| Endometrial cancer | 23 (2.1) | 4 (17.4) | 0 (0) |
| Prostate cancer | 17 (1.6) | 5 (29.4) | 2 (11.8) |
| Non-melanoma skin cancer | 10 (0.9) | 4 (40) | 0 (0) |
| Lymphoma | 9 (0.8) | 3 (33.3) | 0 (0) |
| Merkel cell carcinoma (MCC) | 7 (0.7) | 2 (28.6) | 2 (28.6) |
| Cervical cancer | 6 (0.6) | 1 (16.7) | 0 (0) |
| Other | 41 (3.8) | 11 (26.8) | 2 (4.9) |
| Cancer stage, No. (%) | |||
| 0 | 6 (0.6) | 1 (16.7) | 1 (16.7) |
| I | 28 (2.6) | 5 (17.9) | 0 (0) |
| II | 40 (3.7) | 13 (32.5) | 5 (12.5) |
| III | 257 (24) | 81 (31.5) | 18 (7) |
| IV | 735 (68.7) | 170 (23.1) | 40 (5.4) |
| Unknown | 4 (0.4) | 2 (50) | 1 (25) |
| Clinical site region, No. (%) | |||
| Midwest | 385 (36) | 108 (28.1) | 32 (8.3) |
| Northeast | 506 (47.3) | 113 (22.3) | 24 (4.7) |
| South | 152 (14.2) | 40 (26.3) | 7 (4.6) |
| West | 27 (2.5) | 11 (40.7) | 2 (7.4) |
| Race (NIH categories), No. (%) | |||
| White | 970 (90.7) | 257 (26.5) | 61 (6.3) |
| Black | 57 (5.3) | 6 (10.5) | 2 (3.5) |
| Asian | 23 (2.1) | 5 (21.7) | 0 (0) |
| American Indian/Alaskan Native | 3 (0.3) | 1 (33.3) | 0 (0) |
| Hawaiian/Pacific Islander | 3 (0.3) | 0 (0) | 0 (0) |
| Other | 14 (1.3) | 3 (21.4) | 2 (14.3) |
| Ethnicity, No. (%) | |||
| Hispanic | 54 (5) | 13 (24.1) | 2 (3.7) |
| Non-Hispanic | 969 (90.6) | 241 (24.9) | 58 (6) |
| Unknown | 47 (4.4) | 18 (38.3) | 5 (10.6) |
| Corticosteroid use within 30 days, No. (%) | |||
| Any corticosteroid | |||
| Yes | 308 (28.8) | 68 (22.1) | 19 (6.2) |
| No | 762 (71.2) | 204 (26.8) | 46 (6) |
| If yes, route of administration | |||
| Systemic | 69 (6.4) | 13 (18.8) | 4 (5.8) |
| Non-systemic | 134 (12.5) | 29 (21.6) | 9 (6.7) |
| Unclear | 182 (17.0) | 41 (22.5) | 11 (6.0) |
| Vaccination history, No. (%) | |||
| Pneumococcal vaccine, ever | |||
| Yes | 368 (34.4) | 105 (28.5) | 20 (5.4) |
| No | 400 (37.4) | 86 (21.5) | 21 (5.3) |
| Unknown | 302 (28.2) | 81 (26.8) | 24 (7.9) |
| Zoster vaccine, ever | |||
| Yes | 151 (14.1) | 60 (39.7) | 12 (7.9) |
| No | 525 (49.1) | 114 (21.7) | 26 (5) |
| Unknown | 394 (36.8) | 98 (24.9) | 27 (6.9) |
| Influenza vaccine within 1 year | |||
| Yes | 536 (50.1) | 145 (27.1) | 29 (5.4) |
| No | 293 (27.4) | 60 (20.5) | 15 (5.1) |
| Unknown | 241 (22.5) | 67 (27.8) | 21 (8.7) |
| Antibiotic use, No. (%) | |||
| Any antibiotics within 30 days | |||
| Yes | 121 (11.3) | 38 (31.4) | 6 (5) |
| No | 949 (88.7) | 234 (24.7) | 59 (6.2) |
| Any antibiotics within 1 year | |||
| Yes | 381 (35.6) | 99 (26) | 19 (5) |
| No | 496 (46.4) | 117 (23.6) | 27 (5.4) |
| Unknown | 193 (18) | 56 (29) | 19 (9.8) |
*Other combination category includes TKIs, anti-VEGF, and other targeted treatments.
ICI, immune checkpoint inhibitor; irAE, immune-related adverse event; NIH, National Institute for Health; PD-(L)1, programmed death (ligand) 1; RADIOHEAD, Resistance Drivers for Immuno-Oncology Patients Interrogated by Harmonized Molecular Datasets; TKIs, tyrosine kinase inhibitors.