J Nucl Med. 2008; 49 (Supplement 1):144P
Oncology-Basic Science: Therapy, Metrics & InterventionImaging for Assesment of Response or Therapy Planning |
177Lu-J591 monoclonal antibody (Lu-J591) therapy in metastatic castrate-resistant prostate cancer (metCRPC): Correlation of antibody-tumor targeting and treatment response
Robert Hynecek1,
Stanley Goldsmith1,
Shankar Vallabhajosula1,
David Nanus1,
Scott Tagawa1 and
Neil Bander1
1 Radiology, Medicine and Urology, New York Presbyterian Hospital and Weill Cornell Medical College, Cornell University, New York, New York
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Objectives: Response to treatment with Lu-J591 varies among patients (pts) with metCRPC. Imaging studies performed one week post therapy dose confirmed tumor targeting. Correlation between tumor targeting and treatment response was investigated.
Methods: 24 metCRPC pts received a single Lu-J591 dose, 65-70mCi/m2. The intensity of Lu-J591 tumor uptake per pt was graded using a 0-3 score (liver activity = 3). 99mTc-MDP bone scans were used to identify bone metastasis. Semi-quantitative tumor targeting index (TTI) values (177Lu tumor counts corrected for background/total body counts) were measured in a total of 64 lesions. Pt response to therapy was determined by % reduction (>10% baseline) or stabilization (+10% of baseline) of prostate specific antigen (PSA) at 2 months post treatment.
Results: PSA reduction or stabilization occured in 64% of pts. Responders had a mean PSA nadir of 67±24% of baseline. The greatest reduction in PSA was 87%. Of 13 pts with scores 
2, 7 had PSA reduction (54%), 3 had stabilization (23%). Of 9 pts with scores <2, 2 had PSA reduction (22%), 2 had stabilization (22%). The relationship between TTI values of the 64 lesions and treatment response (changes in PSA values) is shown in the table.
Conclusions: LuJ591 antibody-tumor targeting correlates with improvement in PSA. LuJ591 targeting intensity may ultimately guide pt selection or serve as a prognostic indicator.
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TTI Vs. PSA Response
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