Efficacy, patterns of use and cost of Pertuzumab in the treatment of HER2+ metastatic breast cancer in Singapore: The National Cancer Centre Singapore experience

Table 1 Patient and disease characteristics

Characteristics	Pertuzumab usage		Total (n = 304)	P value
	Yes (n = 50)	No (n = 254)
Age at MBC diagnosis				0.0133
Mean ± SD	54.5 ± 11.64	58.9 ± 11.53	58.1 ± 11.65
Range	32–79	23–95	23–95
Race, n (%)				0.0003
Chinese	29 (58.0)	167 (65.7)	196 (64.5)
Malay	4 (8.00)	57 (22.4)	61 (9.21)
Indian	5 (10.0)	14 (5.51)	19 (6.25)
Others	12 (24.0)	16 (6.30)	28 (20.1)
Hormone receptor status, n (%)
ER positive	32 (64.0)	125 (49.2)	157 (51.6)	0.0638
PR positive	18 (36.0)	82 (32.2)	102 (33.6)	0.3264
Grade, n (%)				0.8160
Grade 1	0 (0.00)	3 (1.83)	3 (1.515)
Grade 2	8 (23.53)	47 (28.7)	55 (27.8)
Grade 3	26 (76.5)	114 (69.5)	140 (70.7)
Histology, n (%)				0.0899
Invasive ductal carcinoma	48 (96.0)	220 (86.6)	268 (88.2)
Others	2 (4.00)	34 (13.4)	36 (11.8)
Site of metastases, n (%)
Brain	6 (12.0)	17 (6.69)	23 (7.57)	0.2369
Lung	18 (36.0)	115 (45.3)	133 (43.8)	0.2754
Liver	22 (44.0	98 (38.6)	120 (39.5)	0.5276
Bone	30 (60.0)	137 (53.9)	167 (54.9)	0.4425
Other	16 (32.0)	94 (37.0)	110 (36.2)	0.5249
Follow-up duration (yr)				0.8511
Median (IQR)	20.6 (21.6)	22.5 (29.5)	21.5 (27.8)
Range	1–74	0–92	0–92

MBC: Metastatic breast cancer; ER: Estrogen receptor; PR: Progesterone receptor; IQR: Interquartile range.

Table 2 Univariate and multivariate COX regression

Characteristics	Univariate analysis			Multivariable analysis
	HR	95%CI	P value	HR	95%CI	P value
Age	1.010	0.997 – 1.023	0.1330
Pertuzumab use	0.515	0.303 – 0.877	0.0145	0.468	0.271 – 0.809	0.0066
Positive ER status	0.722	0.531 – 0.981	0.0374	0.875	0.601 – 1.274	0.4871
Positive PR status	0.744	0.534 – 1.037	0.0806	0.770	0.511 – 1.161	0.2136
Presence of metastases
Brain	2.953	1.844 – 4.730	< 0.0001	3.620	2.229 – 5.879	< 0.0001
Lung	1.393	1.023 – 1.897	0.0352	1.520	1.107 – 2.086	0.0097
Liver	1.900	1.395 – 2.590	< 0.0001	2.051	1.495 – 2.815	< 0.0001
Bone	1.321	0.966 – 1.804	0.0808
Other sites	1.231	0.895 – 1.693	0.2007
Grade (Reference: Grade 1)
Grade 2	3.616	0.494 – 26.463	0.2056
Grade 3	2.799	0.388 – 20.202	0.3075
Race (Reference: Chinese)
Indian	1.184	0.636 – 2.204	0.5952
Malay	1.350	0.931 – 1.957	0.1135
Others	0.620	0.313 – 1.227	0.1701

Six variables were used for multivariate analyses based on the sample size. They are estrogen receptor status, progesterone receptor status, Pertuzumab use, presence of brain, lung and liver metastases. ER: Estrogen receptor; PR: Progesterone receptor.