Clinical Data
The data being reported are from HER2-expressing GEA patients who received zanidatamab either as monotherapy (n=35) or in combination with chemotherapies (n=28). The groups had a median of two to three (range 0-7) prior therapies, with a high percentage (88-91%) having received prior HER2-targeted therapies. The data continue to demonstrate that zanidatamab is well tolerated with the majority of treatment-related AEs considered mild to moderate in severity (Grade 1 or 2) and manageable in the outpatient setting.
In 33 response-evaluable patients who received zanidatamab as monotherapy (10 mg/kg weekly or 20 mg/kg every two weeks), the objective response rate (ORR) was 39% (13/33), 11 (33%) of which were confirmed by a subsequent scan. The disease control rate (DCR) was 61% (20/33) and median duration of response (DOR) was six months.
In 10 response-evaluable patients who received zanidatamab (20 mg/kg every two weeks) plus paclitaxel, the ORR was 60% (6/10), five (50%) of which were confirmed by a subsequent scan including one patient who experienced a complete response. The DCR was 90% (9/10) for this group. In 14 response-evaluable patients who received zanidatamab (20 mg/kg every two weeks or 30 mg/kg every three weeks) plus capecitabine, the confirmed ORR was 57% (8/14) and the DCR was 71% (10/14). Overall the median DOR for zanidatamab plus chemotherapy was 8.9 months and the median progression-free survival (PFS) was 5.6 months with eight (29%) patients still on study at the time of data cut-off.