Extended Data Table 3.
Demographic and disease characteristics at baseline
| Efficacy population | Intention-to-treat population | |||
|---|---|---|---|---|
| characteristic | Pembrolizumab group (N=133) | Placebo group (N=131) | Pembrolizumab group (N=217) | Placebo group (N=217) |
|
| ||||
| Age | ||||
| Median (range) — yr | 62 (19–84) | 61 (32–83) | 62 (19–84) | 63 (32–83) |
| ≥65 yr — no. (%) | 55 (41.4) | 53 (40.5) | 89 (41.0) | 98 (45.2) |
| Male sex — no. (%) | 112 (84.2) | 104 (79.4) | 179 (82.5) | 174 (80.2) |
| Region of enrolment — no. (%) | ||||
| Australia/Europe/lsrael/North America | 41 (30.8) | 44 (33.6) | 67 (30.9) | 67 (30.9) |
| Asia | 40 (30.1) | 39 (29.8) | 76 (35.0) | 75 (34.6) |
| Rest of world | 52 (39.1) | 48 (36.6) | 74 (34.1) | 75 (34.6) |
| ECOG performance-status score — no. (%) | ||||
| 0 | 65 (48.9) | 59 (45.0) | 101 (46.5) | 89 (41.0) |
| 1 | 68 (51.1) | 72 (55.0) | 116(53.5) | 128 (59.0) |
| Primary location at diagnosis — no. (%) | ||||
| Gastroesophageal junction | 37 (27.8) | 42 (32.1) | 62 (28.6) | 75 (34.6) |
| Stomach | 96 (72.2) | 89 (67.9) | 155 (71.4) | 142 (65.4) |
| No. of metastatic sites — no. (%) | ||||
| 0–2 | 71 (53.4) | 77 (58.8) | 117(53.9) | 131 (60.4) |
| ≥3 | 62 (46.6) | 54 (41.2) | 100 (46.1) | 86 (39.6) |
| Histologic subtype — no. (%) | ||||
| Diffuse | 28 (21.1) | 26(19.8) | 48 (22.1) | 39(18.0) |
| Intestinal | 81 (60.9) | 63 (48.1) | 117(53.9) | 101 (46.5) |
| Indeterminate | 24(18.0) | 42 (32.1) | 52 (24.0) | 77 (35.5) |
| Previous gastrectomy or oesophagectomy — no. (%) | ||||
| Yes | 22 (16.5) | 25(19.1) | 34(15.7) | 44 (20.3) |
| No | 111 (83.5) | 106 (80.9) | 183 (84.3) | 173 (79.7) |
| PD-L1 combined positive score — no. (%) | ||||
| ≥1 | 117(88.0) | 112(85.5) | 184 (84.8) | 181 (83.4) |
| <1 | 16(12.0) | 19(14.5) | 33(15.2) | 36(16.6) |
| HER2 status — no. (%) | ||||
| IHC 1 + | 0 (0.0) | 0 (0.0) | 1 (0.5) | 1 (0.5) |
| IHC 2+ ISH equivocal | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (0.5) |
| IHC 2+ ISH positive | 24(18.0) | 27 (20.6) | 36(16.6) | 45 (20.7) |
| IHC 3+ | 109 (82.0) | 104 (79.4) | 180 (82.9) | 170 (78.3) |
| MSI status — no. (%) | ||||
| MSI-high | 1 (0.8) | 1 (0.8) | 2 (0.9) | 1 (0.5) |
| Non-MSI-high | 120 (90.2) | 120 (91.6) | 171 (78.8) | 174 (80.2) |
| Unknown | 12 (9.0) | 10(7.6) | 44 (20.3) | 42(19.4) |
| Sum of target lesions at baseline — no. (%) | ||||
| <Median | 62 (46.6) | 65 (49.6) | 98 (45.2) | 107 (49.3) |
| ≥Median | 62 (46.6) | 61 (46.6) | 107 (49.3) | 101 (46.5) |
| Missing | 9 (6.8) | 5 (3.8) | 12 (5.5) | 9(4.1) |
| Chosen chemotherapy regimen — no. (%) | ||||
| Capecitabine and oxaliplatin | 115(86.5) | 115(87.8) | 189 (87.1) | 187 (86.2) |
| 5-fluorouracil and cisplatin | 18(13.5) | 16(12.2) | 28 (12.9) | 30(13.8) |
The treatment regimen included trastuzumab and chemotherapy in both groups.