Dosimetry and safety of 177Lu PSMA-617 along with polyglutamate parotid gland protector: preliminary results in metastatic castration-resistant prostate cancer patients

Targeted Alpha Therapy in mCRPC (Metastatic Castration-Resistant Prostate Cancer) Patients: Predictive Dosimetry and Toxicity Modeling of 225Ac-PSMA (Prostate-Specific Membrane Antigen)

“…Figure 1 compares our data with those of Kratochwil et al's study ( 8 ). The reduced absorbed dose observed with 177 Lu-PSMA dosimetry ( 11 , 12 ) was also confirmed for 225 Ac-PSMA predictive dosimetry, with a 53% decreased of predicted dose in salivary glands in our patient group [1.08 vs. 2.33 Sv RBE5 /MBq ( 8 ), mean values].…”

“…The predictive dosimetry of 225 Ac-PSMA confirms the reduction of absorbed dose previously reported in our protocol with 177 Lu-PSMA in combination with folic glutamate tablets and ice pack application as salivary gland protectors (11,12). The conversion from a β/γ emission to an α/β/γ emission could not be calculated with a global scaling factor between 177 Lu and 225 Ac emissions.…”

“…Polyglutamate tablets were orally administered as a substrate for PSMA receptors, and external ice packs were applied to the neck region (3). The dosimetry evaluation performed on 13 patients showed a lower absorbed dose in both parotid and submandibular glands compared with previously published data (11,12). The efficacy results of the protectors proposed in our study, especially for salivary glands, were encouraging in the context of TAT, as they could potentially improve treatment management, enabling wider use of this therapeutic approach.…”

“…Organ-specific drug protectors were administered to reduce organ-at-risk uptake ( 10 – 12 ). For the salivary glands, 30 min before, during, and 4 h after 177 Lu-PSMA infusion, ice packs were applied to the neck region ( 3 , 13 ), and patients were given polyglutamate folate tablets of plant origin (Morgan Pharma Monteviale, Italy).…”

“…Given that Kratochwil et al (8) did not perform any attenuation correction to their patents' data, no attenuation correction was applied in this study. Details on the dosimetry protocol were published in previous works (11,12). Structures of interest for dosimetry evaluation were kidneys, liver, parotid glands (PGs), submandibular glands (SGs), red marrow (RM), and whole body (WB).…”