Motexafin lutetium-photodynamic therapy of prostate cancer: short- and long-term effects on prostate-specific antigen.
OBJECTIVE
The time course of serum prostate-specific antigen (PSA) response to photodynamic therapy (PDT) of prostate cancer was measured.


METHODS
Seventeen patients were treated in a phase I trial of motexafin lutetium-PDT. PDT dose was calculated in each patient as the product of the ex vivo measured pre-PDT photosensitizer level and the in situ measured light dose. Serum PSA level was measured within 2 months before PDT (baseline), and at day 1; weeks 1 to 3; months 1, 2, and 3; months 4 to 6; and months 7 to 11 after PDT.


RESULTS
At 24 hours after PDT, serum PSA increased by 98% +/- 36% (mean +/- SE) relative to baseline levels (P = 0.007). When patients were dichotomized based on median PDT dose, those who received high PDT dose showed a 119% +/- 52% increase in PSA compared with a 54% +/- 27% increase in patients treated at low PDT dose. Patients treated with high versus low PDT dose showed a median biochemical delay of 82 versus 43 days (P = 0.024), with biochemical delay defined as the length of time between PDT and a nonreversible increase in PSA to a value greater than or equal to baseline.


CONCLUSIONS
Results show PDT to induce large, transient increases in serum PSA levels. Patients who experienced high PDT dose showed greater short-term increase in PSA and a significantly more durable PSA response (biochemical delay). These data strongly promote the need for individualized delivery of PDT dose and assessment of treatment effect in PDT of prostate cancer. Information gained from such patient-specific measurements could facilitate the introduction of multiple PDT sessions in patients who would benefit.
Patel
Hiral
H
Department of Radiation Oncology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6072, USA.
Mick
Rosemarie
R
Finlay
Jarod
J
Zhu
Timothy C
TC
Rickter
Elizabeth
E
Cengel
Keith A
KA
Malkowicz
S Bruce
SB
Hahn
Stephen M
SM
Busch
Theresa M
TM
D004305:Dose-Response Relationship, Drug; D006801:Humans; D008027:Light; D008297:Male; D008665:Metalloporphyrins / Q000627:therapeutic use*; D008954:Models, Biological; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D017430:Prostate-Specific Antigen / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy*; D011874:Radiometry; D012008:Recurrence; D013997:Time Factors; D016896:Treatment Outcome
D008665:Metalloporphyrins; D017319:Photosensitizing Agents; C102825:motexafin lutetium; D017430:Prostate-Specific Antigen