Table 1 Characteristics of patients at baseline. ECOG Eastern Cooperative Oncology Group, NOS not otherwise specified, Tmab Trastuzumab, DTX docetaxel, PTX paclitaxel, CDDP Cisplatin, CBDCA carboplatin, FP fluorouracil–cisplatin, Cmab Cetuximab, SDC salivary duct carcinoma, CPS combined positive score, TPS tumor proportion score, NLR neutrophil–lymphocyte ratio, PLR platelet-lymphocyte ratio, LMR lymphocyte-monocyte ratio, mGPS modified Glasgow Prognostic Score.

Sex

 Male

20

(74)

12

(80)

 Female

7

(26)

3

(20)

Age (years)

 Median (range)

65 (47–85)

63 (47–85)

  < 65

13

(48)

8

(53)

 ≥ 65

14

(52)

7

(47)

Duration of follow up (month), median (range)

6.9 (2.1–58.8)

6.9 (2.1–14.0)

ECOG performance status

 0

19

(70)

11

(73)

 1

8

(30)

4

(27)

Primary site

 Parotid gland

17

(63)

11

(73)

 Submandibular gland

6

(22)

4

(27)

 Sublingual gland

1

(4)

0

(0)

 Minor salivary gland

3

(11)

0

(0)

Tumor type

 Salivary duct carcinoma

15

(56)

15

(100)

 Adenoid cystic carcinoma

6

(22)

 Myoepithelial carcinoma

3

(11)

Adenocarcinoma NOS

1

(4)

 Acinic cell carcinoma

1

(4)

 Lymphoepithelial carcinoma

1

(4)

With distant metastasis-yes

22

(81)

13

(87)

Previous therapy

 Non

1

(4)

1

(7)

 Surgery

18

(67)

9

(60)

 Radiotherapy

19

(70)

9

(60)

Number of prior lines of systemic therapy

 0

11

(41)

4

(27)

 1

7

(26)

4

(27)

 2

6

(22)

4

(27)

 3 or more

3

(11)

3

(20)

Prior systemic therapy regimen

 Leuprorelin + bicalutamide

10

(37)

9

(60)

 Tmab/DTX

6

(22)

5

(33)

 Tmab/S1

3

(11)

3

(20)

 Tmab monotherapy

2

(7)

2

(13)

 PTX + CBDCA

2

(7)

1

(7)

 DTX + CBDCA

2

(7)

2

(13)

 S1

2

(7)

0

(0)

 CDDP

1

(4)

0

(0)

 CBDCA

1

(4)

1

(7)

 PTX

1

(4)

0

(0)

 T-DM1

1

(4)

1

(7)

A biraterone

1

(4)

1

(7)

Following receipt of systemic therapy

 Yes

12

(44)

10

(67)

Following systemic therapy regimen

 Cmab + PTX

6

(22)

6

(40)

 PTX

2

(7)

1

(7)

 DTX + CBDCA

2

(7)

2

(13)

 PTX + CBDCA

1

(4)

1

(7)

 FP + Cmab

1

(4)

 PD-L1

All (N = 25)

N = 14

 CPS (%)

Median (range)

5 (0–180)

10 (< 1–100)

  < 1

7

(28)

2

(14)

 1 ≤ , < 20

11

(44)

7

(50)

 20 ≤ 

7

(28)

5

(36)

TPS (%)

 median (range)

 < 1 (0–100)

 < 1 (< 1–70)

  < 1

16

(64)

9

(64)

 1 ≤ , < 50

7

(28)

4

(29)

 50 ≤ 

2

(8)

1

(7)

HER2 status

 Negative

–

–

9

(60)

 Positive

–

–

6

(40)

AR IHC

 Negative

–

–

2

(13)

 Positive

–

–

13

(87)

 NLR

 Median (range)

3.3 (1.1–12.7)

3.2 (1.1–12.7)

 High^a

17

(63)

4

(68)

Low

10

(37)

11

(32)

PLR

 Median (range)

194.1 (68.3–1331.2)

188.9 (68.3–1331.2)

 High^b

9

(33)

6

(40)

 Low

18

(67)

9

(60)

LMR

 Median (range)

3.1 (1.1–12.9)

3.4 (1.1–12.9)

 High^c

9

(33)

9

(60)

 Low

18

(67)

6

(40)

mGPS

 0

24

(89)

14

(93)

 1

3

(11)

1

(7)

 2

0

(0)

0

(0)