Clinical Outcomes of Patients with HER2 Positive Metastatic Breast Cancer to the Brain, with First-Line Trastuzumab, Pertuzumab and Chemotherapy, in a Real-World Setting

Figures & data

Figure 1 Study design.

Table 1 Baseline Characteristics of Patients Diagnosed with HER2 Positive Metastatic Breast Cancer from January 2013 to June 2021 That Initiated Systemic 1L Treatment (n = 61)

Characteristic	Cohort, n = 61
Age
Median (IQR)	50.0 (44.0–63.0)
Sex
Female	60 (98.4%)
Residential district
Center	34 (55.7%)
North	19 (31.1%)
South	8 (13.1%)
Socio-economic status
Low	23 (37.7%)
Medium	14 (23.0%)
High	24 (39.3%)
Diabetes mellitus	7 (11.5%)
Cardiovascular disease	3 (4.9%)
Hypertension	16 (26.2%)
Smoking status
Ever (current/past)	20 (32.8%)
Never	41 (67.2%)
Unknown	0 (0.0%)
Body mass index, continuous
Mean (SD)	27.02 (5.94)
Histology
Invasive ductal	52 (85.2%)
Other	9 (14.8%)
ECOG performance status
0–1	31 (50.8%)
2	6 (9.8%)
3–4	5 (8.2%)
Missing	19 (31.1%)
Hormone sensitivity^#
Positive	27 (44.3%)
Negative/ Unknown	34 (55.7%)
Lymph node metastases	43 (70.5%)
Bone metastases	45 (73.8%)
Visceral metastases*	38 (62.3%)

Notes: Data are n (%) unless otherwise indicated. ^#Hormone sensitivity positive includes estrogen receptor positive and/or progesterone receptor positive. *Visceral includes lung, liver, abdomen, or skin metastases.

Abbreviation: ECOG, Eastern Cooperative Oncology Group.

Table 2 Time on Treatment from First-Line and Second-Line Treatment Initiation for Patients Diagnosed with HER2 Positive Metastatic Breast Cancer with Brain Metastases Diagnosed during Their Metastatic Disease, from January 2013 to June 2021 (n = 61)

Outcome
Time on treatment from 1L treatment initiation
N	61
Discontinuation, N (%)	55 (90.2%)
Median ToT (95% CI)	16.9 (13.9–27.7)
At 12 months, %	65.6%
At 24 months, %	41.0%
At 36 months, %	26.1%
At 48 months, %	19.2%
Time on treatment from 2L treatment initiation
N	44
Discontinuation, N (%)	41 (93.2%)
Median ToT (95% CI)	7.9 (5.6–10.7)
At 12 months, %	27.0%
At 24 months, %	9.8%
At 36 months, %	4.9%
At 48 months, %	2.5%

Note: 1L, first-line; 2L, second-line.

Abbreviation: ToT, time on treatment.

Figure 2 Time on treatment and overall survival from first-line treatment initiation for patients diagnosed with HER2 positive metastatic breast cancer with brain metastases diagnosed during their metastatic disease, from January 2013 to June 2021 (n = 61).

Table 3 Overall Survival from First-Line Treatment Initiation, and Overall Survival from Brain Metastases Diagnosis for Patients Diagnosed with HER2 Positive Metastatic Breast Cancer with Brain Metastases Diagnosed during Their Metastatic Disease, from January 2013 to June 2021 (n = 61)

Outcome	N = 61
Overall survival from 1L treatment initiation
Died, N (%)	40 (65.6%)
Median OS (95% CI)	45.5 (35.4–71.2)
At 12 months, %	88.5%
At 24 months, %	80.1%
At 36 months, %	59.1%
At 48 months, %	48.2%
Overall survival from brain metastases diagnosis
Died, N (%)	40 (65.6%)
Median OS (95% CI)	25.1 (17.0–34.6)
At 12 months, %	76.3%
At 24 months, %	52.6%
At 36 months, %	32.6%
At 48 months, %	24.8%

Note: 1L, first-line.

Abbreviation: OS, overall survival.

Table 4 Overall Survival from First-Line Treatment Initiation, and Overall Survival from Brain Metastases Diagnosis, Stratified by Time of Brain Metastases Diagnosis, for Patients Diagnosed with HER2 Positive Metastatic Breast Cancer from January 2013 to June 2021 (n = 61)

	Brain Metastases Diagnosed
	Before 1L or within 6 Months of Initiation of 1L Treatment (n = 15)	More Than 6 Months After Initiating 1L Treatment to cessation of 1L Treatment (n = 25)	On Second-Line Treatment or During Subsequent Treatment (n = 21)
OS from 1L treatment initiation	36.3 (10.0, NR)	59.1 (32.5, NR)	40.8 (35.4, NR)
OS from brain metastases diagnosis	36.9 (15.8, NR)	27.2 (16.7, NR)	18.0 (12.4, NR)

Note: 1L, first-line.

Abbreviation: OS, overall survival.