Imaging tumor variation in response to photodynamic therapy in pancreatic cancer xenograft models.
OBJECTIVE
A treatment monitoring study investigated the differential effects of orthotopic pancreatic cancer models in response to interstitial photodynamic therapy (PDT), and the validity of using magnetic resonance imaging as a surrogate measure of response was assessed.


METHODS
Different orthotopic pancreatic cancer xenograft models (AsPC-1 and Panc-1) were used to represent the range of pathophysiology observed in human beings. Identical dose escalation studies (10, 20, and 40J/cm) using interstitial verteporfin PDT were performed, and magnetic resonance imaging with T2-weighted and T1-weighted contrast were used to monitor the total tumor volume and the vascular perfusion volume, respectively.


RESULTS
There was a significant amount of necrosis in the slower-growing Panc-1 tumor using high light dose, although complete necrosis was not observed. Lower doses were required for the same level of tumor kill in the faster-growing AsPC-1 cell line.


CONCLUSIONS
The tumor growth rate and vascular pattern of the tumor affect the optimal PDT treatment regimen, with faster-growing tumors being relatively easier to treat. This highlights the fact that therapy in human beings shows a heterogeneous range of outcomes, and suggests a need for careful individualized treatment outcomes assessment in clinical work.
Samkoe
Kimberley S
KS
Thayer School of Engineering, Dartmouth College, Hanover, NH, USA. samkoe@dartmouth.edu; pogue@dartmouth.edu
Chen
Alina
A
Rizvi
Imran
I
O'Hara
Julia A
JA
Hoopes
P Jack
PJ
Pereira
Stephen P
SP
Hasan
Tayyaba
T
Pogue
Brian W
BW
D000818:Animals; D045744:Cell Line, Tumor; D003287:Contrast Media; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009336:Necrosis; D010190:Pancreatic Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology; D010778:Photochemotherapy / Q000379:methods* / Q000401:mortality; D017319:Photosensitizing Agents / Q000008:administration & dosage*; D011166:Porphyrins / Q000008:administration & dosage*; D011879:Radiotherapy Dosage; D047368:Tumor Burden; D000077362:Verteporfin; D023041:Xenograft Model Antitumor Assays
D003287:Contrast Media; D017319:Photosensitizing Agents; D011166:Porphyrins; D000077362:Verteporfin