3.1 Clinical characteristics of Adeno-NEPC and Adeno-PCa
Figure 1 shows the two groups into which patients with Adeno-NEPC and those with Adeno-PCa were further divided according to their initial treatments (prostatectomy and ADT).
The median age at PCa diagnosis was 67.86 ± 7.05 years: 68.65 ± 7.23 years for Adeno-NEPC and 67.52 ± 7.02 years for Adeno-PCa (P = 0.837). Nine (45.0%) patients with Adeno-NEPC underwent prostatectomy, whereas 11 (55.0%) received primary ADT. Among patients with Adeno-PCa, 30 (65.2%) underwent prostatectomy, whereas 16 (34.8%) received primary ADT. Seventeen (85.0%) patients with Adeno-NEPC and 35 (76.1%) with Adeno-PCa presented with T3 and T4 at the time of diagnosis. Eleven (55.0%) patients with Adeno-NEPC and 18 (39.1%) with Adeno-PCa presented with pelvic lymph node involvement at the time of diagnosis. Eight (40.0%) patients with Adeno-NEPC and 14 (30.4%) with Adeno-PCa presented with metastases at the time of diagnosis. Seventeen (85.0%) patients with Adeno-NEPC and 24 (52.2%) with Adeno-PCa presented with high-grade Gleason scores (>7) for their primary tumors. Eighteen (90.0%) patients with Adeno-NEPC and 27 (58.7%) with Adeno-PCa had high prostate-specific antigen (PSA) levels > 20 ng/L) at the time of diagnosis. Five (25.0%) patients with Adeno-NEPC and four (8.7%) with Adeno-PCa had lactate dehydrogenase (LDH) levels ≥ 250 U/L at the time of diagnosis. Three (15.0%) patients with Adeno-NEPC and five (10.9%) with Adeno-PCa had alkaline phosphatase levels ≥ 125 U/L at the time of diagnosis. Detailed clinicopathological manifestations of patients with Adeno-NEPC and Adeno-PCa at the time of diagnosis are summarized in Table 1.
Table 1. Clinicopathological characteristics of patients with primary PCa.
Characteristic
|
All
n=66
|
Adeno-NEPC
n=20
|
Adeno-PCa
n=46
|
P
|
Age (years)
|
67.86±7.05
|
68.65±7.23
|
67.52±7.02
|
0.837
|
Prostatectomy
|
|
|
|
0.308
|
No
|
27(40.9%)
|
11(55.0%)
|
16(34.8%)
|
|
Yes
|
39(59.1%)
|
9(45.0%)
|
30(65.2%)
|
|
Primary ADT
|
|
|
|
0.308
|
No
|
39(59.1%)
|
9(45.0%)
|
30(65.2%)
|
|
Yes
|
27(40.9%)
|
11(55.0%)
|
16(34.8%)
|
|
T staging
|
|
|
|
0.982
|
T1
|
1(1.5%)
|
0(0.00%)
|
1(2.2%)
|
|
T2
|
13(19.7%)
|
3(15.0%)
|
10(21.7%)
|
|
T3
|
41(62.1%)
|
14(70.0%)
|
27(58.7%)
|
|
T4
|
11(16.7%)
|
3(15.0%)
|
8(17.4%)
|
|
N staging
|
|
|
|
0.490
|
N0
|
37(56.1%)
|
9(45.0%)
|
28(60.9%)
|
|
N1
|
29(43.9%)
|
11(55.0%)
|
18(39.1%)
|
|
M staging
|
|
|
|
0.751
|
M0
|
44(66.7%)
|
12(60.0%)
|
32(69.6%)
|
|
M1
|
22(33.3%)
|
8(40.0%)
|
14(30.4%)
|
|
Gleason Score
|
|
|
|
0.168
|
<7
|
1(1.5%)
|
0(0.00%)
|
1(2.2%)
|
|
7
|
24(36.4%)
|
3(15.0%)
|
21(45.6%)
|
|
>7
|
41(62.1%)
|
17(85.0%)
|
24(52.2%)
|
|
PSA (ng/L)
|
|
|
|
0.177
|
<10
|
9(13.6%)
|
1(5.0%)
|
8(17.4%)
|
|
10–20
|
12(18.2%)
|
1(5.0%)
|
11(23.9%)
|
|
>20
|
45(68.2%)
|
18(90.0%)
|
27(58.7%)
|
|
LDH (U/L)
|
|
|
|
0.207
|
<250
|
57(86.4%)
|
15(75.0%)
|
42(91.3%)
|
|
≥250
|
9(13.6%)
|
5(25.0%)
|
4(8.7%)
|
|
ALP (U/L)
|
|
|
|
0.894
|
<125
|
58(87.9%)
|
17(85.0%)
|
41(89.1%)
|
|
≥125
|
8(12.1%)
|
3(15.0%)
|
5(10.9%)
|
|
Abbreviations: PCa, prostate cancer; NEPC, neuroendocrine prostate cancer; ADT, androgen deprivation therapy; PSA, prostate-specific antigen; LDH, lactate dehydrogenase; ALP, alkaline phosphatase.
3.2 Heat map of NE biomarkers in Adeno-NEPC
Adeno-NEPC samples from 20 patients were stained for the analysis of NE biomarkers (SYN, CgA, CD56, and NSE). Co-expression of CgA, SYN, CD56, and NSE in Adeno-NEPC is demonstrated in Additional file 3: Supplementary Figure S3. We used a heat map to describe the distribution and expression of NE biomarkers in each sample (Figure 2). The expression ratios of SYN, CgA, CD56, and NSE in the samples were 100%, 25%, 25%, and 10%, respectively.
3.3 Comparison of the clinical characteristics of Adeno-NEPC
The Adeno-NEPC samples were divided into two groups based on the expression of NE markers. Twelve of the 20 Adeno-NEPC samples were positive for only SYN, whereas the remaining samples were positive for more than one NE biomarker. The clinical characteristics of the two groups are compared in Table 2. There was a significant difference in OS between the groups (Figure 3a).
Table 2. Clinicopathological characteristics of patients with Adeno-NEPC
Characteristic
|
Only SYN (+)
n=12
|
Not only SYN (+)
n=8
|
P
|
Age (years)
|
66.00 ± 2.00
|
72.63 ± 2.12
|
0.041
|
T staging
|
|
|
0.528
|
T2
|
3(25.0%)
|
1(12.5%)
|
|
T3
|
8(66.7%)
|
5(62.5%)
|
|
T4
|
1(8.3%)
|
2(25.0%)
|
|
N staging
|
|
|
0.142
|
N0
|
7(58.3%)
|
2(25.0%)
|
|
N1
|
5(41.7%)
|
6(75.0%)
|
|
M staging
|
|
|
0.852
|
M0
|
7(58.3%)
|
5(62.5%)
|
|
M1
|
5(41.7%)
|
3(37.5%)
|
|
Gleason Score
|
|
|
0.798
|
≤7
|
2(16.7%)
|
1(12.5%)
|
|
>7
|
10(83.3%)
|
7(87.5%)
|
|
PSA (ng/L)
|
|
|
0.224
|
≤20
|
2(16.7%)
|
0(0.0%)
|
|
>20
|
10(83.3%)
|
8(100.0%)
|
|
LDH (U/L)
|
|
|
0.999
|
<250
|
9(75.0%)
|
6(75.0%)
|
|
≥250
|
3(25.0%)
|
2(25.0%)
|
|
ALP (U/L)
|
|
|
0.798
|
<125
|
10(83.3%)
|
7(87.5%)
|
|
≥125
|
2(16.7%)
|
1(12.5%)
|
|
Abbreviations: SYN, synaptophysin; PSA, prostate-specific antigen; LDH, lactate dehydrogenase; ALP, alkaline phosphatase.
3.4 OS analyses
There was a significant difference in OS between patients with Adeno-NEPC and those with Adeno-PCa (median OS from PCa diagnosis: 46.0 months vs 65.0 months, P = 0.001). In the cohort of patients who received ADT, the time from the diagnosis of hormone-sensitive PCa (HSPC) to that of CRPC was not significantly different between the groups (P = 0.18). However, in the cohort of patients who underwent prostatectomy, we observed a significant difference in the time from prostatectomy to biochemical recurrence (BCR) between the groups (P = 0.0086) (Figure 3b–d).
3.5 Univariate Cox regression analysis for OS in patients with Adeno-NEPC and response to different treatments
Prostatectomy and normal LDH levels were clinical factors significantly associated with better outcomes in patients with Adeno-NEPC (Table 3).
Table 3. Univariate Cox regression analysis for overall survival in patients with Adeno-NEPC
Variable
|
Hazard ratio (95% CI)
|
P
|
Prostatectomy (yes vs. no)
|
0.177 [0.036–0.883]
|
0.013
|
T staging (<T3b vs. ≥T3b)
|
1.420 [0.299–6.739]
|
0.237
|
N staging (N0 vs. N1)
|
0.467 [0.106–2.066]
|
0.311
|
M staging (M0 vs. M1)
|
0.315 [0.048–2.073]
|
0.086
|
Gleason Score (≤8 vs. >8)
|
0.368 [0.074–1.822]
|
0.283
|
LDH (<250 vs. ≥250)
|
0.195 [0.031–1.218]
|
0.011
|
Abbreviations: LDH, lactate dehydrogenase.
Nine of the 20 patients with Adeno-NEPC (45.0%) underwent prostatectomy. Subsequently, 6 (30.0%) received ADT, 5 (25.0%) underwent radiotherapy, 2 (10.0%) received chemotherapy, and 2 (10.0%) received abiraterone (median OS = 48.0 months). Additionally, among the 20 patients, 11 (55.0%) received primary ADT, and subsequently, 5 (25.0%) received chemotherapy and 4 (20.0%) received abiraterone or enzalutamide (median OS = 21.0 months).
3.6 PD-L1 expression in Adeno-NEPC and its possible negative correlation with CD8+ T cell expression
Samples from the 20 patients with Adeno-NEPC were stained for PD-L1 analysis. The positive expression rate of PD-L1 in these cases was 75% (15/20). A heat map was used to describe the distribution and expression of PD-L1 in each sample (Figure 4a). The patients were divided into two groups according to their clinical stages. Metastatic PCa demonstrated a trend toward a higher PD-L1 score (2-4) than localized PCa (Figure 4b). In addition, patients with higher PD-L1 scores (2-4) demonstrated a trend toward lower expression of CD8+ T cells, whereas those with lower PD-L1 scores (0-1) demonstrated a trend toward higher expression of CD8+ T cells (Figure 4c).