medwireNews: Radionuclide treatment with lutetium-177 [177Lu]-prostate-specific membrane antigen (PSMA)-617 shows potential for men with metastatic castration-resistant prostate cancer (mCRPC) that has progressed after standard therapy, researchers report.
Among 30 men treated with up to four cycles of the radiolabeled small molecule, 57% achieved a prostate-specific antigen (PSA) decline of 50% or more from baseline, while all 27 who reported pain at baseline experienced clinically meaningful improvements in both severity and interference scores on the brief pain inventory for at least 3 months.
“In view of the almost ubiquitous nature of PSMA expression in most metastatic castration-resistant prostate cancers, [177Lu]-PSMA-617 offers a potential additional treatment option for men with metastatic castration-resistant prostate cancer,” Michael Hofman (Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia) and co-authors remark.
During the phase 2 prospective trial, 97% of patients experience some degree of PSA decline: 70% of patients achieved a decline of at least 30%, while 20% had a decline of 96% or higher.
Nearly all (87%) patients had received at least one line of previous chemotherapy, typically docetaxel, and 83% had received prior abiraterone acetate, enzalutamide, or both.
The researchers also report that 82% of 17 patients with measurable nodal or visceral disease had an objective response at these sites (29% complete response).
In addition, 37% of study participants reported at least a 10-point improvement in global health score within two cycles of treatment.
At the time of data analysis, 27 (90%) patients had experienced PSA progression and 22 (73%) had died. The median PSA progression-free survival and overall survival times were 7.6 and 13.2 months, respectively.
Hofman and team note that the treatment “was well tolerated, with no immediate adverse effects recorded during injection and no treatment-related deaths.”
Writing in The Lancet Oncology, the authors say that a lack of control group means their findings should be “interpreted with caution.”
Nonetheless, they add that “any sustained response to further treatment in this [heavily pretreated patient cohort] is promising, especially if the treatment improves quality of life without significant toxic effects.”
Hofman et al conclude that [177Lu]-PSMA-617 “could represent a new life-prolonging treatment for men with metastatic castration-resistant prostate cancer,” and a multicentre randomised comparing it with cabazitaxel chemotherapy is now underway.
By Laura Cowen
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