Purpose <p>Prostate-specific membrane antigen (PSMA) radioligand therapy is a promising treatment for metastatic castration-resistant prostate cancer (mCRPC). Several beta or alpha particle-emitting radionuclide-conjugated small molecules have shown efficacy in late-stage mCRPC and one, [[177Lu]Lu]Lu-PSMA-617, is FDA approved. In addition to tumor upregulation, PSMA is also expressed in kidneys and salivary glands where specific uptake can cause dose-limiting xerostomia and potential for nephrotoxicity. The PSMA inhibitor 2-(phosphonomethyl)pentanedioic acid (2-PMPA) can prevent kidney uptake in mice, but also blocks tumor uptake, precluding its clinical utility. Preferential delivery of 2-PMPA to non-malignant tissues could improve the therapeutic window of PSMA radioligand therapy.</p> Methods <p>A tris(isopropoxycarbonyloxymethyl) (TrisPOC) prodrug of 2-PMPA, JHU-2545, was synthesized to enhance 2-PMPA delivery to non-malignant tissues. Mouse pharmacokinetic experiments were conducted to compare JHU-2545-mediated delivery of 2-PMPA to plasma, kidney, salivary glands, and C4-2 prostate tumor xenograft. Imaging studies were conducted in rats and mice to measure uptake of PSMA PET tracers in kidney, salivary glands, and prostate tumor xenografts with and without JHU-2545 pre-treatment.</p> Results <p>JHU-2545 resulted in approximately 3- and 53-fold greater exposure of 2-PMPA in rodent salivary glands (18.0 ± 0.97&#xa0;h*nmol/g) and kidneys (359 ± 4.16&#xa0;h*nmol/g) versus prostate tumor xenograft (6.79 ± 0.19&#xa0;h*nmol/g). JHU-2545 also blocked rodent kidneys and salivary glands uptake of the PSMA PET tracers [68Ga]Ga-PSMA-11 and [18&#xa0;F]F-DCFPyL by up to 85% with little effect on tumor.</p> Conclusions <p>JHU-2545 pre-treatment may enable greater cumulative administered doses of PSMA radioligand therapy, possibly improving safety and efficacy.</p>

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JHU-2545 preferentially shields salivary glands and kidneys during PSMA-targeted imaging

  • Michael T. Nedelcovych,
  • Ranjeet P. Dash,
  • Ying Wu,
  • Eun Yong Choi,
  • Rena S. Lapidus,
  • Pavel Majer,
  • Andrej Jančařík,
  • Diane Abou,
  • Marie-France Penet,
  • Anastasia Nikolopoulou,
  • Alex Amor-Coarasa,
  • John Babich,
  • Daniel L. Thorek,
  • Rana Rais,
  • Clemens Kratochwil,
  • Barbara S. Slusher

摘要

Purpose

Prostate-specific membrane antigen (PSMA) radioligand therapy is a promising treatment for metastatic castration-resistant prostate cancer (mCRPC). Several beta or alpha particle-emitting radionuclide-conjugated small molecules have shown efficacy in late-stage mCRPC and one, [[177Lu]Lu]Lu-PSMA-617, is FDA approved. In addition to tumor upregulation, PSMA is also expressed in kidneys and salivary glands where specific uptake can cause dose-limiting xerostomia and potential for nephrotoxicity. The PSMA inhibitor 2-(phosphonomethyl)pentanedioic acid (2-PMPA) can prevent kidney uptake in mice, but also blocks tumor uptake, precluding its clinical utility. Preferential delivery of 2-PMPA to non-malignant tissues could improve the therapeutic window of PSMA radioligand therapy.

Methods

A tris(isopropoxycarbonyloxymethyl) (TrisPOC) prodrug of 2-PMPA, JHU-2545, was synthesized to enhance 2-PMPA delivery to non-malignant tissues. Mouse pharmacokinetic experiments were conducted to compare JHU-2545-mediated delivery of 2-PMPA to plasma, kidney, salivary glands, and C4-2 prostate tumor xenograft. Imaging studies were conducted in rats and mice to measure uptake of PSMA PET tracers in kidney, salivary glands, and prostate tumor xenografts with and without JHU-2545 pre-treatment.

Results

JHU-2545 resulted in approximately 3- and 53-fold greater exposure of 2-PMPA in rodent salivary glands (18.0 ± 0.97 h*nmol/g) and kidneys (359 ± 4.16 h*nmol/g) versus prostate tumor xenograft (6.79 ± 0.19 h*nmol/g). JHU-2545 also blocked rodent kidneys and salivary glands uptake of the PSMA PET tracers [68Ga]Ga-PSMA-11 and [18 F]F-DCFPyL by up to 85% with little effect on tumor.

Conclusions

JHU-2545 pre-treatment may enable greater cumulative administered doses of PSMA radioligand therapy, possibly improving safety and efficacy.