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Exhibit 99.1 xencor Xencor Reports Thirds Quarter 2021 Financial Results and Announces Encouraging Preliminary Data from Ongoing Phase 1 Study of Potency - reduced IL15 - Fc Cytokine , XmAb306 -- Management to Host Conference Call at 4:30 p.m. ET Today -- MONROVIA , Calif .-- Nov . 8 , 2021-- Xencor , Inc. ( NASDAQ : XNCR ) , a clinical - stage biopharmaceutical company developing engineered monoclonal antibodies and cytokines for the treatment of cancer and autoimmune diseases , today reported financial results for the third quarter ended September 30 , 2021 and provided a review of recent business and portfolio highlights , including initial data from the Phase 1 study of XmAb306 , an IL15 - Fc cytokine , in patients with advanced solid tumors . " This year we have significantly advanced our portfolio of clinical - stage XmAbⓇ drug candidates , establishing Phase 2 development plans for vudalimab , plamotamab and tidutamab . In the coming weeks , we will present new clinical data from the Phase 1 studies of vudalimab at SITC and plamotamab at ASH , ” said Bassil Dahiyat , Ph.D. , president and chief executive officer at Xencor . " Looking ahead to next year , we are on track to initiate first - in - human studies for additional XmAb drug candidates , such as XmAb819 , our first 2 + 1 bispecific antibody , which targets the underexplored kidney tumor target ENPP3 , and XmAb808 , our first tumor - selective , co - stimulatory CD28 bispecific antibody , which targets the broadly expressed tumor antigen B7 - H3 . " " Today we have announced encouraging initial dose - escalation data from our first clinical - stage cytokine , XmAb306 , which is co - developed in collaboration with Genentech , a member of the Roche Group . Exceptional NK cell expansion of 40- to 100 - fold increases compared to baseline , with good tolerability to date , has been observed . As we continue to escalate , we are now observing signs of effector T cell proliferation in the periphery . XmAb306's safety profile , biological activity and preliminary signs of anti - tumor activity at this early stage provide initial validation for our reduced - potency approach to engineering XmAb cytokine therapeutics , and we are considering new trials to study combinations with a range of NK and T- cell recruiting therapies . " Portfolio Highlights and Upcoming Data Presentations • Plamotamab ( CD20 x CD3 ) : Xencor entered a collaboration with Janssen to advance plamotamab and XmAb CD28 bispecific antibody combinations for the treatment of patients with B - cell malignancies , which expands the Company's strategy to develop multiple highly active , chemotherapy - free regimens to treat patients with B - cell cancers . Janssen received worldwide exclusive development and commercial rights to plamotamab , and the Company will collaborate with Janssen on further clinical development of plamotamab , with Xencor paying 20 % of costs , including those for a subcutaneous formulation study anticipated to enter clinical trials in 2022. The Company will continue , at its own expense , the combination study of plamotamab , tafasitamab and lenalidomide . The Company will present updated clinical results from the Phase 1 study of plamotamab in patients with non - Hodgkin lymphoma during the American Society of Hematology Annual Meeting in December 2021 . Vudalimab ( PD - 1 x CTLA - 4 ) : The Company will announce updated clinical results from expansion cohorts in the Phase 1 study in patients with prostate cancer , renal cell carcinoma and