Sunday, November 20, 2016

PD-L1 expression by tumor and response to Pembro - more expression = more response

Not really news here.  We're known this for sometime.  Patients with greater PD-L1 expression on their tumors respond better to anti-PD1, though those with lesser expression can still gain a response.

Programmed Death-Ligand 1 Expression and Response to the Anti-Programmed Death 1 Antibody Pembrolizumab in Melanoma.  Daud, Wolchok...Weber, Ribas, Hodi,... Hamid, et al.  J Clin Oncol. 2016 Dec;34.  

Expression of programmed death-ligand 1 (PD-L1) is a potential predictive marker for response and outcome after treatment with anti-programmed death 1 (PD-1). This study explored the relationship between anti-PD-1 activity and PD-L1 expression in patients with advanced melanoma who were treated with pembrolizumab in the phase Ib KEYNOTE-001 study (clinical trial information: NCT01295827). Six hundred fifty-five patients received pembrolizumab10 mg/kg once every 2 weeks or once every 3 weeks, or 2 mg/kg once every 3 weeks. Tumor response was assessed every 12 weeks per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 by independent central review. Primary outcome was objective response rate. Secondary outcomes included progression-free survival (PFS) and overall survival (OS). Membranous PD-L1 expression in tumor and tumor-associated immune cells was assessed by a clinical trial immunohistochemistry assay (22C3 antibody) and scored on a unique melanoma (MEL) scale of 0 to 5 by one of three pathologists who were blinded to clinical outcome; a score greater or = to 2 (membranous staining in greater or = to 1% of cells) was considered positive. Of 451 patients with evaluable PD-L1 expression, 344 (76%) had PD-L1-positive tumors. Demographic and staging variables were equally distributed among PD-L1-positive and -negative patients. An association between higher MEL score and higher response rate and longer PFS and OS  was observed. Objective response rate was 8%, 12%, 22%, 43%, 57%, and 53% for MEL 0, 1, 2, 3, 4, and 5, respectively. Conclusion PD-L1 expression in pretreatment tumor biopsy samples was correlated with response rate, PFS, and OS; however, patients with PD-L1-negative tumors may also achieve durable responses.

So....when are we going to actually USE this information?????  PD-L1 positive???? Which treatment is best???  This is from 2015 y'all...with links within to other posts from 2012! And, no....I still don't know the results of my tumor testing.

Hang in there ratties!!  The ride sometimes lasts longer than we wish....but we ARE getting there! - c 

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