RT Journal Article
SR Electronic
T1 Evaluation of <sup>177</sup>Lu-PSMA-617 SPECT/CT Quantitation as a Response Biomarker Within a Prospective <sup>177</sup>Lu-PSMA-617 and NOX66 Combination Trial (LuPIN)
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 221
OP 226
DO 10.2967/jnumed.122.264398
VO 64
IS 2
A1 Pathmanandavel, Sarennya
A1 Crumbaker, Megan
A1 Ho, Bao
A1 Yam, Andrew O.
A1 Wilson, Peter
A1 Niman, Remy
A1 Ayers, Maria
A1 Sharma, Shikha
A1 Hickey, Adam
A1 Eu, Peter
A1 Stockler, Martin
A1 Martin, Andrew J.
A1 Joshua, Anthony M.
A1 Nguyen, Andrew
A1 Emmett, Louise
YR 2023
UL http://jnm.snmjournals.org/content/64/2/221.abstract
AB 177Lu-PSMA-617 is an effective and novel treatment in metastatic castration-resistant prostate cancer (mCRPC). Our ability to assess response rates and therefore efficacy may be improved using predictive tools. This study investigated the predictive value of serial 177Lu-PSMA-617 SPECT/CT (177Lu SPECT) imaging in monitoring treatment response. Methods: Fifty-six men with progressive mCRPC previously treated with chemotherapy and novel androgen signaling inhibitor were enrolled into the LuPIN trial and received up to 6 doses of 177Lu-PSMA-617 and a radiation sensitizer (3-(4-hydroxyphenyl)-2H-1-benzopyran-7-ol [NOX66]). 68Ga-PSMA-11 and 18F-FDG PET/CT were performed at study entry and exit, and 177Lu SPECT from vertex to mid thighs was performed 24 h after each treatment. SPECT quantitative analysis was undertaken at cycles 1 (baseline) and 3 (week 12) of treatment. Results: Thirty-two of the 56 men had analyzable serial 177Lu SPECT imaging at both cycle 1 and cycle 3. In this subgroup, median prostate-specific antigen (PSA) progression-free survival (PFS) was 6.3 mo (95% CI, 5–10 mo) and median overall survival was 12.3 mo (95% CI, 12–24 mo). The PSA 50% response rate was 63% (20/32). 177Lu SPECT total tumor volume (SPECT TTV) was reduced in 68% (22/32; median, −0.20 m3 [95% CI, −1.4 to −0.001]) and increased in 31% (10/32; median, 0.36 [95% CI, 0.1–1.4]). Any increase in SPECT TTV was associated with shorter PSA PFS (hazard ratio, 4.1 [95% CI, 1.5–11.2]; P = 0.006). An increase of 30% or more in SPECT TTV was also associated with a shorter PSA PFS (hazard ratio, 3.3 [95% CI, 1.3–8.6]; P =0.02). Tumoral SUVmax was reduced in 91% (29/32) and SUVmean in 84% (27/32); neither was associated with PSA PFS or overall survival outcomes. PSA progression by week 12 was also associated with a shorter PSA PFS (hazard ratio, 26.5 [95% CI, 5.4–131]). In the patients with SPECT TTV progression at week 12, 50% (5/10) had no concurrent PSA progression (median PSA PFS, 4.5 mo [95% CI, 2.8–5.6 mo]), and 5 of 10 men had both PSA and SPECT TTV progression at week 12 (median PSA PFS, 2.8 mo [95% CI, 1.8–3.7 mo]). Conclusion: Increasing SPECT TTV on quantitative 177Lu SPECT predicts a short PFS and may play a future role as an imaging response biomarker.