Table 1. Demographics, clinical, and survival characteristics of patients with Merkel cell carcinoma treated with an immune checkpoint inhibitor (univariate analyses).
| Characteristic | All
(%)A, N = 45 |
ResponseB
(%), N = 17 |
No response
(%), N = 22 |
p-value |
|---|---|---|---|---|
| Median age in years (range) | 71 (39–89) | 71 (50–89) | 71 (50–89) | 0.90 |
| Sex | ||||
| Male | 31 (69) | 12 (71) | 14 (64) | 0.27 |
| Female | 14 (31) | 5 (29) | 8 (36) | |
| Immune suppressionC | ||||
| Yes | 7 (16) | 2 (12) | 4 (18) | 0.29 |
| No | 38 (84) | 15 (88) | 18 (82) | |
| Primary site of disease | ||||
| Limb | 19 (42) | 8 (47) | 10 (45) | - |
| Head and neck | 15 (33) | 5 (29) | 8 (36) | |
| Unknown | 8 (18) | 3 (18) | 4 (18) | |
| Trunk | 3 (7) | 1 (6) | 0 (0) | |
| Initial staging at diagnosisD | ||||
| Stage I | 9 (20) | 5 (29) | 2 (9) | - |
| Stage II | 3 (7) | 0 (0) | 3 (14) | |
| Stage III | 28 (62) | 11 (65) | 14 (64) | |
| Stage IV | 5 (11) | 1 (6) | 3 (14) | |
| Initial treatment regimen | ||||
| Surgery and RT | 20 (44) | 7 (41) | 10 (45) | 0.435D |
| ChemoRT | 10 (22) | 4 (24) | 4 (18) | |
| RT alone | 6 (13) | 2 (12) | 4 (18) | |
| Surgery + ChemoRT | 3 (7) | 1 (6) | 2 (9) | |
| Surgery alone | 2 (4) | 2 (12) | 0 (0) | |
| Chemotherapy alone | 2 (4) | 0 (0) | 1 (5) | |
| Surgery + Chemotherapy | 1 (2) | 1 (6) | 0 (0) | |
| None | 1 (2) | 0 (0) | 1 (5) | |
| Number experiencing recurrence | 36 (80) | 13 (76) | 18 (82) | 0.19 |
| Medianime to recurrence (months) | 4.8 (0.6–21.1) | 3.7 (0.6–12.2) | 6.3 (0.9–21.1) | 0.10 |
| Initial staging at diagnosis of R/M diseaseE | ||||
| Stage III | 13 (29) | 7 (41) | 6 (27) | - |
| Stage IV | 32 (71) | 10 (59) | 16 (73) | |
| CPI line of therapy | ||||
| Adjuvant | 2 (4) | 2 (12) | 0 (0) | - |
| 1 | 25 (56) | 11 (65) | 13 (59) | |
| 2 | 13 (31) | 3 (18) | 7 (32) | |
| 3 | 2 (4) | 0 (0) | 1 (5) | |
| 4 | 2 (4) | 1 (6) | 1 (5) | |
| CPI therapy | ||||
| PD-1 inhibitor monotherapy | 23 (51) | 9 (53) | 10 (45) | 0.22 F |
| PD-L1 inhibitor monotherapy | 21 (47) | 7 (41) | 12 (55) | |
| PD-1/CTLA-4 dual therapy | 1 (2) | 1 (6) | 0 (0) | |
| Median baseline ALC (× 106/L) (range) | 780 (0–16,660) | 680 (390–16,660) | 875 (310–2,030) | 0.30 |
| Immune-related adverse eventsG | ||||
| Grade 2 or lower | 37 (82) | 12 (71) | 20 (91) | 0.09 |
| Grade 3 or above | 8 (18) | 5 (29) | 2 (9) | |
Student’s t-test for continuous variables (age, number experiencing recurrence, and median baseline ALC), Fisher exact test for categorical variables (all other variables). All tests were univariate and two-sided. AExcept for continuous variables (age, time to recurrence, baseline absolute lymphocyte count); BResponse evaluation criteria in solid tumors, RECIST v1.1, 39 patients evaluable for radiographic response; CIncludes three patients with hematologic malignancy, two patients on treatment for autoimmune disease, one with history of kidney transplant, and one with active tuberculosis; DRadiotherapy versus no radiotherapy EAmerican Joint Committee on Cancer (AJCC) 8th edition staging; FPD-1 vs. PD-L1; GUsing Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. ALC = absolute lymphocyte count, ChemoRT = concurrent chemoradiation, CPI = immune checkpoint inhibitor, R/M = recurrent/metastatic, RT = radiotherapy.