ERBB2 and neoplasm: Figure 6 shows the chemical structure of lapatinib. A previous study found lapatinib showed high efficacy to halt tumor progression when used as a first-line therapy for HER2+ BC. The result showed about 24% patients (n = 138) who received treatment of lapatinib for 17.6 weeks demonstrated an overall response (OR) of 31%, and progression-free survival (PFS) rate of 63% at Month 4 and 43% at Month 6. The most common adverse events caused by lapatinib were diarrhea, rash, pruritus, and nausea. However, these events were primarily graded at mild level as 1 or 2 [85].