PET-CT-based host metabolic (PETMet) features are associated with pathologic response in gastroesophageal adenocarcinoma.

Background: F-FDG PET-CT-based host metabolic (PETMet) profiling of non-tumor tissue is a novel approach to incorporate the patient-specific response to cancer into clinical algorithms.

Materials And Methods: A prospectively maintained institutional database of gastroesophageal cancer patients was queried for pretreatment PET-CTs, demographics, and clinicopathologic variables. F-FDG PET avidity was measured in 9 non-tumor tissue types (liver, spleen, 4 muscles, 3 fat locations).

Theranostic GPA33-Pretargeted Radioimmunotherapy of Human Colorectal Carcinoma with a Bivalent Lu-Labeled Radiohapten.

Radiolabeled small-molecule DOTA-haptens can be combined with antitumor/anti-DOTA bispecific antibodies (BsAbs) for pretargeted radioimmunotherapy (PRIT). For optimized delivery of the theranostic γ- and β-emitting isotope Lu with DOTA-based PRIT (DOTA-PRIT), bivalent Gemini (DOTA-Bn-thiourea-PEG4-thiourea-Bn-DOTA, aka (3,6,9,12-tetraoxatetradecane-1,14-diyl)bis(DOTA-benzyl thiourea)) was developed. Gemini was synthesized by linking 2 -2-(4-isothiocyanatobenzyl)-DOTA molecules together via a 1,14-diamino-PEG4 linker.

Patient metabolic profile defined by liver and muscle F-FDG PET avidity is independently associated with overall survival in gastric cancer.

Background: PET-CT-based patient metabolic profiling is a novel concept to incorporate patient-specific metabolism into gastric cancer care.

Methods: Staging PET-CTs, demographics, and clinicopathologic variables of gastric cancer patients were obtained from a prospectively maintained institutional database. PET-CT avidity was measured in tumor, liver, spleen, four paired muscles, and two paired fat areas in each patient.

Engineering CAR-T cells for radiohapten capture in imaging and radioimmunotherapy applications.

The dynamics of CAR-T cells remain incompletely understood. Novel methods are urgently needed to longitudinally monitor transferred cells non-invasively for biodistribution, functionality, proliferation, and persistence and for improving their cytotoxic potency in case of treatment failure. Here we engineered CD19 CAR-T cells ("Thor"-cells) to express a membrane-bound scFv, huC825, that binds DOTA-haptens with picomolar affinity suitable for labeling with imaging or therapeutic radionuclides.

Efficacy of HER2-Targeted Intraperitoneal Ac α-Pretargeted Radioimmunotherapy for Small-Volume Ovarian Peritoneal Carcinomatosis.

Epithelial ovarian cancer (EOC) is often asymptomatic and presents clinically in an advanced stage as widespread peritoneal microscopic disease that is generally considered to be surgically incurable. Targeted α-therapy with the α-particle-emitting radionuclide Ac (half-life, 9.92 d) is a high-linear-energy-transfer treatment approach effective for small-volume disease and even single cells.

Quantitative In Vivo Imaging of the Androgen Receptor Axis Reveals Degree of Prostate Cancer Radiotherapy Response.

Unlabelled: Noninvasive biomarkers for androgen receptor (AR) pathway activation are urgently needed to better monitor patient response to prostate cancer therapies. AR is a critical driver and mediator of resistance of prostate cancer but currently available noninvasive prostate cancer biomarkers to monitor AR activity are discordant with downstream AR pathway activity. External beam radiotherapy (EBRT) remains a common treatment for all stages of prostate cancer, and DNA damage induced by EBRT upregulates AR pathway activity to promote therapeutic resistance.

Phase 1 study of intraventricular I-omburtamab targeting B7H3 (CD276)-expressing CNS malignancies.

Background: The prognosis for metastatic and recurrent tumors of the central nervous system (CNS) remains dismal, and the need for newer therapeutic targets and modalities is critical. The cell surface glycoprotein B7H3 is expressed on a range of solid tumors with a restricted expression on normal tissues. We hypothesized that compartmental radioimmunotherapy (cRIT) with the anti-B7H3 murine monoclonal antibody omburtamab injected intraventricularly could safely target CNS malignancies.

Pretargeting: A Path Forward for Radioimmunotherapy.

Pretargeted radioimmunodiagnosis and radioimmunotherapy aim to efficiently combine antitumor antibodies and medicinal radioisotopes for high-contrast imaging and high-therapeutic-index (TI) tumor targeting, respectively. As opposed to conventional radioimmunoconjugates, pretargeted approaches separate the tumor-targeting step from the payload step, thereby amplifying tumor uptake while reducing normal-tissue exposure. Alongside contrast and TI, critical parameters include antibody immunogenicity and specificity, availability of radioisotopes, and ease of use in the clinic.

Prospective evaluation of F-FDG positron emission tomography in the preoperative staging of patients with hepatic colorectal metastases.

Background: Despite considerable advances in preoperative imaging, up to one-third of patients operatively explored for hepatic colorectal metastases are unexpectedly found to harbor unresectable intrahepatic or extrahepatic disease.

Methods: The current study is a prospective, blinded study comparing utility of [F]2-fluoro-2-deoxyglucose positron emission tomography (F-FDG-PET) to computed tomography (CT) and CT arterial portography (CTAP) as preoperative staging.

Results: The 125 planned subjects were enrolled.

Automated Bone Scan Index to Optimize Prostate Cancer Working Group Radiographic Progression Criteria for Men With Metastatic Castration-Resistant Prostate Cancer.

Introduction: Radiographic progression-free survival (rPFS) by Prostate Cancer Working Group (PCWG) criteria is a radiographic endpoint. The automated bone scan index (aBSI) quantifies osseous disease burden on bone scintigraphy as a percentage of total skeletal weight. Using the aBSI, we sought to quantify increase in tumor burden represented by PCWG progression criteria, and to determine the interval increase that best associates with overall survival (OS).

Treatment of Patients with Acute Myeloid Leukemia with the Targeted Alpha-Particle Nanogenerator Actinium-225-Lintuzumab.

Purpose: The anti-CD33 antibody lintuzumab has modest activity against acute myeloid leukemia (AML). To increase its potency, lintuzumab was conjugated to actinium-225 (225Ac), a radionuclide yielding 4 α-particles. This first-in-human, phase I trial was conducted to determine the safety, pharmacology, and biological activity of 225Ac-lintuzumab.

Enhancing Radioiodine Incorporation in -Mutant, Radioiodine-Refractory Thyroid Cancers with Vemurafenib and the Anti-ErbB3 Monoclonal Antibody CDX-3379: Results of a Pilot Clinical Trial.

Oncogenic activation of mitogen-activated protein kinase (MAPK) signaling is associated with radioiodine refractory (RAIR) thyroid cancer. Preclinical models suggest that activation of the receptor tyrosine kinase erbB-3 (HER3) mitigates the MAPK pathway inhibition achieved by BRAF inhibitors in mutant thyroid cancers. We hypothesized that combined inhibition of BRAF and HER3 using vemurafenib and the human monoclonal antibody CDX-3379, respectively, would potently inhibit MAPK activation and restore radioactive iodine (RAI) avidity in patients with mutant RAIR thyroid cancer.

Biodistribution and Radiation Dosimetry of Intraperitoneally Administered I-Omburtamab in Patients with Desmoplastic Small Round Cell Tumors.

The aim of this study was to assess the pharmacokinetics, biodistribution, and radiation dosimetry of I-omburtamab administered intraperitoneally in patients with desmoplastic small round cell tumor. Eligible patients diagnosed with desmoplastic small round cell tumor with peritoneal involvement were enrolled in a phase I trial of intraperitoneal radioimmunotherapy with I-omburtamab. After thyroid blockade and before radioimmunotherapy, patients received approximately 74 MBq of I-omburtamab intraperitoneally.

Intraperitoneal Pretargeted Radioimmunotherapy for Colorectal Peritoneal Carcinomatosis.

Peritoneal carcinomatosis (PC) is considered incurable, and more effective therapies are needed. Herein we test the hypothesis that GPA33-directed intracompartmental pretargeted radioimmunotherapy (PRIT) can cure colorectal peritoneal carcinomatosis. Nude mice were implanted intraperitoneally with luciferase-transduced GPA33-expressing SW1222 cells for aggressive peritoneal carcinomatosis (e.

Optimizing reconstruction parameters for quantitative I-PET in the presence of therapeutic doses of I.

Background: The goal of this work was to determine the quantitative accuracy and optimal reconstruction parameters for I-PET imaging in the presence of therapeutic levels of I. In this effort, images were acquired on a GE D710 PET/CT scanner using a NEMA IEC phantom with spheres containing I and increasing amounts of I activity in the background. At each activity level, two scans were acquired, one with the phantom centered in the field of view (FOV) and one 11.

Engineered Cells as a Test Platform for Radiohaptens in Pretargeted Imaging and Radioimmunotherapy Applications.

Pretargeted imaging and radioimmunotherapy approaches are designed to have superior targeting properties over directly targeted antibodies but impose more complex pharmacology, which hinders efforts to optimize the ligands prior to human applications. Human embryonic kidney 293T cells expressing the humanized single-chain variable fragment (scFv) C825 (huC825) with high-affinity for DOTA-haptens (293T-huC825) in a transmembrane-anchored format eliminated the requirement to use other pretargeting reagents and provided a simplified, accelerated assay of radiohapten capture while offering normalized cell surface expression of the molecular target of interest. Using binding assays, biodistribution, and imaging, we demonstrated that radiohaptens based on benzyl-DOTA and a second generation "Proteus" DOTA-platform effectively and specifically engaged membrane-bound huC825, achieving favorable tumor-to-normal tissue uptake ratios in mice.

A simple strategy to reduce the salivary gland and kidney uptake of PSMA-targeting small molecule radiopharmaceuticals.

Purpose: Peptide-based prostate-specific membrane antigen (PSMA) targeted radionuclide therapy (TRT) agent [Lu]-PSMA-617 has emerged as leading TRT candidate for treatment of castration-resistant prostate cancer (mCRPC). [Lu]-PSMA-617 and other small molecule-based PSMA ligands have shown efficacy in reducing the tumor burden in mCRPC patients but irradiation to the salivary gland and kidneys is a concern and dose-limiting factor. Therefore, methods to reduce non-target organ toxicity are needed to safely treat patients and preserve their quality of life.

PSA-Targeted Alpha-, Beta-, and Positron-Emitting Immunotheranostics in Murine Prostate Cancer Models and Nonhuman Primates.

Purpose: Most patients with prostate cancer treated with androgen receptor (AR) signaling inhibitors develop therapeutic resistance due to restoration of AR functionality. Thus, there is a critical need for novel treatment approaches. Here we investigate the theranostic potential of hu5A10, a humanized mAb specifically targeting free PSA ().

PET/MRI for neuroendocrine tumors: a match made in heaven or just another hype?

Purpose: To evaluate the current literature on technical feasibility and diagnostic value of PET/MRI in management of patients with neuroendocrine tumors (NETs).

Methods: A systematic literature search of the PubMed/MEDLINE database identified studies that evaluated the role of simultaneous PET/MRI for the evaluation of neuroendocrine tumors in human subjects. Exclusion criteria included studies lacking simultaneous PET/MRI, absence of other than attenuation-correction MRI pulse sequences, and case reports.

Alpha radioimmunotherapy using Ac-proteus-DOTA for solid tumors - safety at curative doses.

This is the initial report of an α-based pre-targeted radioimmunotherapy (PRIT) using Ac and its theranostic pair, In. We call our novel tumor-targeting DOTA-hapten PRIT system "proteus-DOTA" or "Pr." Herein we report the first results of radiochemistry development, radiopharmacology, and stoichiometry of tumor antigen binding, including the role of specific activity, anti-tumor efficacy, and normal tissue toxicity with the Pr-PRIT approach (as α-DOTA-PRIT).