PURPOSE HER2 exon 20 insertions and point mutations are oncogenic drivers found in 1%-2% of patients with non–small-cell lung cancer (NSCLC). No targeted therapy is approved for this subset of patients. We prospectively evaluated the effectiveness of the combination of two antibodies against human epidermal growth factor 2 (HER2 [HER2] trastuzumab and pertuzumab with docetaxel; trastuzumab and pertuzumab) and docetaxel. METHODS The IFCT 1703-R2D2 trial is a multicenter, nonrandomized phase II study. Patients with HER2-mutated, advanced NSCLC who progressed after ≥ 1 platinum-based treatment were enrolled. Patients received pertuzumab at a loading dose of 840 mg and 420 mg thereafter; trastuzumab at an 8 mg/kg loading dose and 6 mg/kg thereafter; and docetaxel at a dose of 75 mg/m² every 3 weeks. The primary outcome was the objective response rate (ORR). Other end points included the duration of response, progression-free survival, and safety ( NCT03845270 ). RESULTS Forty-five patients were enrolled and treated. The median age was 64.5 years (range, 31-84 years), 35% were smokers, 72% were females, 15% had an Eastern Cooperative Oncology Group performance status of 2, and 30% had brain metastases. The objective response rate was 29% (n = 13), and 58% had stable disease (n = 26). The median progression-free survival was 6.8 months (95% CI, 4.0 to 8.5). The median duration of response in patients with a confirmed response (n = 13) was 11 months (95% CI, 2.9 to 14.9). Grade 3/4 treatment-related adverse events were observed in 64% of the patients. No patient discontinued treatment because of toxicity. The most frequent grade ≥ 3 treatment-related adverse events were neutropenia (33%), diarrhea (13%), and anemia (9%). CONCLUSION Triple therapy with trastuzumab, pertuzumab, and docetaxel is feasible and effective for HER2-mutated pretreated advanced NSCLC. These results highlight the effectiveness of the HER2 antibody-based strategy, which should be considered for these patients.