FDA has approved Margenza (margetuximab-cmkb) in combination with chemotherapy, for the treatment of adult patients with metastatic HER2-positive breast cancer who have received two or more prior anti-HER2 regimens, at least one of which was for metastatic disease.
Margenza is sponsored by MacroGenics.
Efficacy was evaluated in SOPHIA (NCT02492711), a randomized, multicenter, open-label trial of 536 patients with IHC 3+ or ISH-amplified HER2+ metastatic breast cancer who had received prior treatment with other anti-HER2 therapies. Patients were randomized (1:1) to margetuximab plus chemotherapy or trastuzumab plus chemotherapy. Randomization was stratified by chemotherapy choice (capecitabine, eribulin, gemcitabine, or vinorelbine), number of lines of therapy in the metastatic setting (≤ 2, > 2), and number of metastatic sites (≤ 2, > 2).
The main efficacy outcome measures were progression-free survival by blinded independent central review and overall survival. Additional efficacy outcome measures were objective response rate and duration of response assessed by BICR.
Median PFS in the margetuximab arm was 5.8 months (95% CI: 5.5, 7.0) compared with 4.9 months (95% CI: 4.2, 5.6) in the control arm (HR 0.76; 95% CI: 0.59, 0.98; p=0.033). Confirmed ORR was 22% (95% CI: 17, 27) with a median DOR of 6.1 months (95% CI: 4.1, 9.1) in the margetuximab arm compared to an ORR of 16% (95% CI: 12, 20) and median DOR of 6.0 months (95%CI: 4.0, 6.9) in the control arm.