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• zymeworks Zanidatamab Phase 2 Clinical Trial Demonstrates Promising Response Rate and Durability in First - Line HER2 - Positive Gastroesophageal Adenocarcinoma ( GEA ) at the European Society for Medical Oncology ( ESMO ) Annual Congress September 16 , 2021 • Confirmed objective response rate ( CORR ) of 75 % overall and 93 % for the proposed Phase 3 regimen ( zanidatamab + CAPOX / FP ) • Median duration of response ( mDOR ) of 16.4 months and median progression free survival ( mPFS ) of 12 months • Data support zanidatamab + chemotherapy as the foundation of a potential new standard of care in first - line HER2 - positive GEA • Global randomized Phase 3 trial scheduled to launch in fourth quarter ( Q4 ) of 2021 VANCOUVER , British Columbia -- ( BUSINESS WIRE ) -- Sep . 16 , 2021-- Zymeworks Inc. ( NYSE : ZYME ) , a clinical - stage biopharmaceutical company developing multifunctional biotherapeutics , today announced that new clinical data for zanidatamab , a HER2 - targeted bispecific antibody , demonstrate promising response rates and durability in first - line HER2 - positive GEA . These data were presented today by lead study investigator , Geoffrey Ku , M.D. , Medical Oncologist at Memorial Sloan Kettering Cancer Center ( MSK ) , at the ESMO Annual Congress . This press release features multimedia . View the full release here : https://www.businesswire.com/news/home/20210916005389/en/ Phase 2 Clinical Trial Demonstrates Promising Response Rate and Durability in First - Line HER2 - Positive Gastroesophageal Adenocarcinoma ( GEA ) at ESMO 2021 " Herceptin and chemotherapy have been the standard of care in first - line HER2 - positive GEA for over 10 years . The data presented today give us the confidence that we have developed a next - generation HER2 - targeted agent that has the potential to provide patients with an improved option in this setting . Neil Josephson , M.D. Interim Chief Medical Officer & SVP , Clinical Research ( Photo : Business Wire ) zymeworks Phase 2 Study Results The data presented at ESMO are from a clinical study of 36 patients with HER2 - expressing GEA who received zanidatamab in combination with either CAPOX ( capecitabine / oxaliplatin ; n = 14 ) , FP ( 5FU / cisplatin ; n = 2 ) , or mFOLFOX6 ( 5FU / leucovorin / oxaliplatin ; n = 20 ) . None of the patients had received prior HER2 - targeted therapies . In 28 response - evaluable patients with metastatic HER2 - positive GEA , zanidatamab plus chemotherapy resulted in a CORR of 75 % and disease control rate ( DCR ) of 89 % overall , with a CORR of 93 % and DCR of 100 % in the proposed Phase 3 regimen of zanidatamab + CAPOX / FP . All patients except one experienced a decrease in their tumor size . The mDOR is 16.4 months and the mPFS is 12.0 months across all treatment regimens with 61 % of patients still on study at the time of data cutoff . In addition , the data demonstrate that zanidatamab plus chemotherapy is generally well tolerated , with the majority of treatment - related adverse events ( TRAES ) considered mild to moderate in severity ( Grade 1 or 2 ) . The most common grade ≥ 3 TRAE was diarrhea which was manageable in the outpatient setting ; introduction of prophylactic loperamide reduced the incidence in cycle 1 from 44 % to 18 % . No severe ( grade ≥ 3 ) infusion- related reactions or cardiac events were observed . " Despite recent advances , metastatic HER2 - expressing GEA has high morbidity and mortality , and new treatment options are desperately needed , " said the principal investigator on the trial , Geoffrey Ku , M.D. , Medical Oncologist at MSK . " The data presented today at ESMO demonstrate the potential of zanidatamab in the first - line setting , highlighted by response rates and durability that compare favorably to the current standard of care as well as to emerging treatments . These data support further evaluation of zanidatamab plus chemotherapy in a randomized pivotal trial in first - line HER2 - positive GEA . " HER2 is overexpressed in approximately 20 % of GEA patients . For these patients , HerceptinⓇ ( trastuzumab ) is the only approved HER2 - targeted therapy in 1L treatment , and therapeutic options are currently limited if disease progression occurs . Zanidatamab's bispecific approach simultaneously binds two non - overlapping epitopes of HER2 , ECD2 and ECD4 , resulting in multiple mechanisms of action that provide potential therapeutic benefits beyond the combination of two monoclonal antibodies . " Herceptin and chemotherapy have been the standard of care in first - line HER2 - positive GEA for over 10 years . The data presented today give us the confidence that we have developed a next - generation HER2 - targeted agent that has the potential to provide patients with an improved option in this setting , " said Neil Josephson , M.D. , Zymeworks ' Interim Chief Medical Officer . " Based on these data , we will pursue a randomized , Phase 3 trial with