$XBIT Phase III Findings for its Antibody Therapy for Colorectal Cancer

Data Show Reduced Disease Progression and Improved Survival for Patients Achieving Primary Endpoint 

AUSTIN, Texas, June 01, 2017 – XBiotech Inc. (NASDAQ:XBIT) announced today that data from XBiotech’s European Phase III Study of advanced colorectal cancer patients treated with Hutruo (MABp1) will be presented at the 2017 American Society of Clinical Oncology (ASCO) meeting in Chicago, Illinois. The abstract entitled, “MABp1 improves clinical outcomes of patients with symptomatic refractory metastatic colorectal cancer patients: Per-Protocol Population analysis of Phase III Study (PT026)” will be presented during the Gastrointestinal Colorectal Cancer poster session on June 3, 2017 from 8am-11:30am. Dr. Lucjan Wyrwicz from the Maria Sklodowska-Curie Memorial Cancer Centre, Institute of Oncology, Warsaw, will be leading the poster session.

The poster will provide analysis of how patients performed during and after treatment with the prescribed 8 week treatment regimen. Patients that received the full 8 weeks of treatment are considered to have completed the study “per protocol” (i.e. did not leave the study early). Assessment of the treatment outcome for the per protocol group is particularly important, since due to the advanced stage of these patients, some are unable to complete the recommended treatment regimen and are not able to have the full potential benefit from therapy.

In the Phase III study, 82% of all patients that received at least one dose of study drug did complete the 8 week treatment regimen. For these per protocol patients, 40% of patients that received treatment with the antibody therapy achieved the primary endpoint, nearly double compared to placebo (40% vs 23%, relative risk 1.76, 95% CI 1.14 to 2.72, one-tailed p=0.003). Dr. Wyrwicz is providing an analysis showing how patients in this population that achieved the primary endpoint of the study had substantially improved survival outcomes, with a median survival of 11.7 months versus 5.7 months for those that did not (HR 0.39; p<0.0001). Other key findings include RECIST assessment of tumor progression, where radiographic evidence of stable disease was more than three-fold better (42% vs 12%; p<0.001) in this population.

Dr. Wyrwicz commented, “This analysis confirms our previous report that in an advanced cancer population, the combination of patient-reported symptoms and radiography used as the primary endpoint is a powerful measure of disease progression.” He further stated, “These findings show that the use of this endpoint to measure disease modifying anti-tumor therapies is a logical surrogate to assess new anti-cancer agents in chemorefractory patients.”

About True Human(TM) Therapeutic Antibodies
XBiotech’s True Human(TM) antibodies are derived without modification from individuals who possess natural immunity to certain diseases. With discovery and clinical programs across multiple disease areas, XBiotech’s True Human antibodies have the potential to harness the body’s natural immunity to fight disease with increased safety, efficacy and tolerability.

About XBiotech
XBiotech is a fully integrated global biosciences company dedicated to pioneering the discovery, development and commercialization of therapeutic antibodies based on its True Human(TM) proprietary technology. XBiotech currently is advancing a robust pipeline of antibody therapies to redefine the standards of care in oncology, inflammatory conditions and infectious diseases. Headquartered in Austin, Texas, XBiotech also is leading the development of innovative biotech manufacturing technologies designed to more rapidly, cost-effectively and flexibly produce new therapies urgently needed by patients worldwide. For more information, visit www.xbiotech.com.

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Contact
Ashley Otero
aotero@xbiotech.com
512-386-2930