Table 2.
Baseline characteristics within HER2-0 and HER2-low-positive populations in PALOMA-3 trial.
| HER2-0b |
HER2-low-positiveb |
|||||||
|---|---|---|---|---|---|---|---|---|
| Overall (N = 153) | Palbociclib + Fulvestrant (N = 107) | Placebo + Fulvestrant (N = 46) | p valuea | Overall (N = 367) | Palbociclib + Fulvestrant (N = 239) | Placebo + Fulvestrant (N = 128) | p valuea | |
| Age | ||||||||
| Mean (SD)—yr | 57.8 (10.4) | 57.9 (11.1) | 57.7 (8.7) | 0.93 | 56.6 (11.6) | 56.6 (11.9) | 56.5 (10.9) | 0.99 |
| <65 yr—no. (%) | 117 (76.5) | 79 (73.8) | 38 (82.6) | 0.24 | 274 (74.7) | 181 (75.7) | 93 (72.7) | 0.52 |
| ≥65 yr—no. (%) | 36 (23.5) | 28 (26.2) | 8 (17.4) | 93 (25.3) | 58 (24.3) | 35 (27.3) | ||
| Race | 0.20 | 0.95 | ||||||
| White | 116 (75.8) | 77 (72.0) | 39 (84.8) | 268 (73.4) | 174 (73.1) | 94 (74.0) | ||
| Asian | 33 (21.6) | 26 (24.3) | 7 (15.2) | 72 (19.7) | 48 (20.2) | 24 (18.9) | ||
| Black or other | 4 (2.6) | 4 (3.7) | 0 (0.0) | 25 (6.8) | 16 (6.7) | 9 (7.1) | ||
| Menopausal status at study entry | 0.56 | 0.75 | ||||||
| Post-Menopausal | 124 (81.0) | 88 (82.2) | 36 (78.3) | 289 (78.7) | 187 (78.2) | 102 (79.7) | ||
| Pre/Peri-Menopausal | 29 (19.0) | 19 (17.8) | 10 (21.7) | 78 (21.3) | 52 (21.8) | 26 (20.3) | ||
| Sensitivity to previous hormonal therapy, yes—no. (%) | 114 (74.5) | 83 (77.6) | 31 (67.4) | 0.19 | 296 (80.7) | 191 (79.9) | 105 (82.0) | 0.62 |
| ECOG score at baseline—no. (%) | 0.33 | 0.22 | ||||||
| 0 | 84 (54.9) | 56 (52.3) | 28 (60.9) | 237 (64.6) | 149 (62.3) | 88 (68.8) | ||
| 1 | 69 (45.1) | 51 (47.7) | 18 (39.1) | 130 (35.4) | 90 (37.7) | 40 (31.2) | ||
| Hormone receptor status – no. (%) | 0.76 | 0.53 | ||||||
| ER-positive and PR-positive | 111 (75.5) | 80 (76.2) | 31 (73.8) | 240 (69.4) | 160 (70.5) | 80 (67.2) | ||
| ER-positive and PR-negative | 36 (24.5) | 25 (23.8) | 11 (26.2) | 106 (30.6) | 67 (29.5) | 39 (32.8) | ||
| Previous lines of therapies for metastatic disease—no. (%) | 0.18 | 0.49 | ||||||
| 0 | 30 (19.6) | 19 (17.8) | 11 (23.9) | 84 (22.9) | 55 (23.0) | 29 (22.7) | ||
| 1 | 73 (47.7) | 48 (44.9) | 25 (54.3) | 151 (41.1) | 92 (38.5) | 59 (46.1) | ||
| 2 | 37 (24.2) | 28 (26.2) | 9 (19.6) | 94 (25.6) | 66 (27.6) | 28 (21.9) | ||
| ≥3 | 13 (8.5) | 12 (11.2) | 1 (2.2) | 38 (10.4) | 26 (10.9) | 12 (9.4) | ||
| Site of metastatic disease—no. (%) | 0.44 | 0.52 | ||||||
| Visceral | 87 (56.9) | 63 (58.9) | 24 (52.2) | 224 (61.0) | 143 (59.8) | 81 (63.3) | ||
| Nonvisceral | 66 (43.1) | 44 (41.1) | 22 (47.8) | 143 (39.0) | 96 (40.2) | 47 (36.7) | ||
| Bone only, yes—no. (%) | 40 (26.1) | 28 (26.2) | 12 (26.1) | 0.99 | 83 (22.6) | 57 (23.8) | 26 (20.3) | 0.44 |
| Number of disease sites—no. (%) | 0.81 | 0.51 | ||||||
| 1–3 | 128 (83.7) | 89 (83.2) | 39 (84.8) | 295 (80.4) | 190 (79.8) | 105 (82.7) | ||
| ≥4 | 25 (16.3) | 18 (16.8) | 7 (15.2) | 70 (19.2) | 48 (20.2) | 22 (17.3) | ||
| Disease-free interval—no. (%) | 0.81 | 0.70 | ||||||
| ≤24 Months | 25 (25.0) | 17 (25.8) | 8 (23.5) | 37 (14.6) | 23 (13.9) | 14 (15.7) | ||
| >24 Months | 75 (75.0) | 49 (74.2) | 26 (76.5) | 217 (85.4) | 142 (86.1) | 75 (84.3) | ||
| Measurable disease, yes—no. (%) | 117 (76.5) | 83 (77.6) | 34 (73.9) | 0.62 | 289 (78.7) | 185 (77.4) | 104 (81.2) | 0.39 |
| Histopathological classification—no. (%)c | 0.31 | 0.053 | ||||||
| Ductal | 113 (73.9) | 82 (76.6) | 31 (67.4) | 276 (75.2) | 188 (78.7) | 88 (68.8) | ||
| Lobular | 17 (11.1) | 12 (11.2) | 5 (10.9) | 45 (12.3) | 28 (11.7) | 17 (13.3) | ||
| Other or unknown | 23 (15.0) | 13 (12.1) | 10 (21.7) | 46 (12.5) | 23 (9.6) | 23 (18.0) | ||
| Type of previous chemotherapy—no. (%) | 0.31 | 0.42 | ||||||
| Neoadjuvant or adjuvant treatment only | 65 (42.5) | 42 (39.3) | 23 (50.0) | 149 (40.6) | 98 (41.0) | 51 (39.8) | ||
| Treatment for metastatic disease | 50 (32.7) | 35 (32.7) | 15 (32.6) | 126 (34.3) | 77 (32.2) | 49 (38.3) | ||
| None | 38 (24.8) | 30 (28.0) | 8 (17.4) | 92 (25.1) | 64 (26.8) | 28 (21.9) | ||
| Disease stage at study entry—no. (%)d | 0.65 | 0.71 | ||||||
| Metastatic | 130 (86.7) | 91 (85.8) | 39 (88.6) | 311 (85.2) | 204 (85.7) | 107 (84.3) | ||
| Recurrent locally advanced | 20 (13.3) | 15 (14.2) | 5 (11.4) | 54 (14.8) | 34 (14.3) | 20 (15.7) | ||
| Type of most recent therapy—no. (%) | 0.34 | 0.94 | ||||||
| Neoadjuvant or adjuvant | 30 (19.7) | 19 (17.8) | 11 (24.4) | 84 (22.9) | 55 (23.0) | 29 (22.7) | ||
| Advanced disease | 122 (80.3) | 88 (82.2) | 34 (75.6) | 283 (77.1) | 184 (77.0) | 99 (77.3) | ||
| Prior endocrine therapy—no. (%) | 0.42 | 0.68 | ||||||
| Aromatase inhibitors only | 69 (45.1) | 51 (47.7) | 18 (39.1) | 138 (37.6) | 86 (36.0) | 52 (40.6) | ||
| Tamoxifen only | 23 (15.0) | 17 (15.9) | 6 (13.0) | 50 (13.6) | 33 (13.8) | 17 (13.3) | ||
| Aromatase inhibitors and tamoxifen | 61 (39.9) | 39 (36.4) | 22 (47.8) | 179 (48.8) | 120 (50.2) | 59 (46.1) | ||
| HER2 sample site—no. (%) | 0.75 | 0.22 | ||||||
| Primary tumour | 73 (48.0) | 50 (47.2) | 23 (50.0) | 139 (38.1) | 96 (40.3) | 43 (33.9) | ||
| Metastasis | 79 (52.0) | 56 (52.8) | 23 (50.0) | 226 (61.9) | 142 (59.7) | 84 (66.1) | ||
Abbreviations: ER, oestrogen receptor; PR, progesterone receptor.
Wilcoxon rank sum test; Pearson's Chi-squared test; Fisher's exact test.
All the HER2 testing results were based on local laboratory test using FDA-approved assays. Among HER2-low-positive group, 148 (40.3%) patients had immunohistochemistry (IHC) 1+ and 219 (59.7%) patients had IHC 2+/in situ hybridization (ISH)-negative. Specifically, in Palbociclib + Fulvestrant arm, 100 (41.8%) patients had IHC 1+ and 139 (58.2%) patients had IHC 2+/ISH-negative. While in Placebo + Fulvestrant arm, 48 (37.5%) patients had IHC 1+ and 80 (62.5%) patients had IHC 2+/ISH-negative.
Ductal carcinoma includes diffuse adenocarcinoma, mixed adenocarcinoma, adenocarcinoma and ductal carcinoma. “Other” and “Unknown” were options for the site to select on the clinical report form.
Recurrent locally advanced disease included local and regional involvement and data on disease stage at study entry were missing or unknown for five patients.