First clinical trial of Lu-177-PSMA-617 in recurrent, hormone-sensitive men


While we expect only a few months of extra survival from the VISION trial of Lu-177-PSMA-617 in heavily pretreated, metastatic, castration-resistant men (see this link), we hope to get more out of the radiopharmaceutical if used earlier.

Privé et al. reported the results of a pilot trial in 10 recurrent men treated with Lu-177-PSMA-617 at Radboud University in Nijmegen, The Netherlands. They were all:

  • Recurrent after prostatectomy ± salvage radiation (PSA > 0.2 ng/ml)
  • Rapid PSA doubling time (< 6 months)
  • Between 1-10 metastases detectable on a PSMA PET scan or USPIO MRI
  • At least 1 metastasis > 1 cm
  • Unable to receive SBRT to metastases
  • No visceral metastases
  • Have not begun salvage ADT
  • Treated with a low dose (3 GBq) on day 1; second treatment (~6 GBq) after 8 weeks (compared to dose in VISION trial of 7.4 GBq in each of 4 to 6 cycles)

After 24 weeks of follow-up after Cycle 2:

  • 5 patients had PSA reduced by > 50 percent (1 undetectable)
  • 2 patients had stable PSA
  • 3 patients had PSA progression
  • 6 patients had a radiographic response
  • 4 patients had radiographic progression
  • ADT-deferred survival was 9.5 months (median)
  • Those with lymph node only metastases had the best response
  • Those with any bone metastases had lesser response

After a second dose, comparing their 24-week PSA to their 12-week PSA:

  • PSA was continuing to decline in 3 patients
  • PSA was rising again in 6 patients
  • Side effects were mild (no grade 3) and transient:
    • Fatigue in 7;nausea in 3
    • Dry mouth (xerostomia) in 2

There are lots more questions than answers:

  • Would a higher dose and more treatments be more effective?
  • Would a higher dose and more treatments be more toxic?
  • Is it like Xofigo in that it’s more effective with micrometatases? If so, would a combination with SBRT targeted at the larger metastases be more effective?
  • Since it was more effective on lymph nodes, would it make a good combination with Xofigo for patients who have both lymph node and bone metastases? (See also Th-227-PSMA.)
  • Because there seems to be a continued abscopal effect for some patients, would combining it with Provenge be optimal?
  • Would pretreatment with ADT or a new anti-androgen (Xtandi, Erleada or Nubeqa) increase expression of PSMA, and increase radiosensitivity?
  • Can we predict who will benefit?

Use in other patient populations remains to be explored: high-risk, newly diagnosed metastatic, castration-resistant but chemo-naive. Optimal sequencing with other therapies remains to be explored.

Editorial note: This commentary was written by Alan Edel for The “New” Prostate Cancer InfoLink.

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