Table 1 –
Patient sample demographics and clinical characteristics at the time of blood draw overall and by drug class assigned a
| Overall | Pre-ARSI | Pre-Taxane | p value | |
|---|---|---|---|---|
| Samples (n) | 255 | 132 | 123 | |
| Unique patients (n) b | 193 | 124 | 111 | |
| Sampling point, n (%) | <0.0001 | |||
| Before 2nd-line Tx | 100 (39) | 74 (56) | 26 (21) | |
| Before 3rd-line Tx | 75 (29) | 33 (25) | 42 (34) | |
| Before ≥4th-line Tx | 80 (31) | 25 (19) | 55 (45) | |
| Median age at Tx decision, yr (IQR) | 69 (62.5–75) | 70 (63–77.25) | 69 (62–73.5) | 0.13 |
| Metastatic sites, n (%) | ||||
| Lymph nodes | 169 (66) | 83 (63) | 86 (70) | 0.23 |
| Bone | 226 (89) | 111 (84) | 115(93) | 0.018 |
| Lung | 29 (11) | 12 (9) | 17 (14) | 0.23 |
| Liver | 29 (11) | 8 (6) | 21 (17) | 0.0055 |
| Blood analytes, median (IQR) | ||||
| Prostate-specific antigen (ng/ml) | 50.4 (18.2–211.2) | 30.7 (11.6–80.6) | 99.4 (28.7–517.1) | <0.0001 |
| Alkaline phosphatase (IU/l) | 111 (80–199.5) | 97.5 (76–134) | 139 (94–233.5) | 0.00012 |
| Lactate dehydrogenase (U/l) | 235 (187–294) | 211.5 (180.5–264.2) | 248 (206–347) | 0.0087 |
| Hemoglobin (g/dl) | 11.7 (10.3–12.9) | 12 (10.675–13.1) | 11.4 (10–12.35) | 0.0035 |
| Albumin (g/dl) | 4.2 (4–4.3) | 4.2 (4–4.3) | 4.2 (3.9–4.3) | 0.98 |
| Last prior Tx was ARSI, n (%) | 168 (66) | 80 (61) | 88 (72) | 0.066 |
| Pre-Tx clinical data unavailable to physician for AR-V7–positive men, n (%) | 57 (22) | 21 (16) | 36 (29) | 0.010 |
ARSI = androgen receptor signaling inhibitor; IQR = interquartile range; Tx = treatment.
All percentages are calculated using total number of samples per group as the denominator. Of the 133 samples taken before second-line or later treatment with an ARSI, 59 were taken before abiraterone, 66 before enzalutamide, and eight before apalutamide. Of the 123 samples taken before second-line or later treatment with a taxane, 85 were taken before docetaxel, 36 before cabazitaxel, and two before paclitaxel.
An individual patient could be counted more than once if, during the study, he began more than one course of therapy that was eligible for inclusion in the study.