Pilot study of HER2 targeted 64 Cu-DOTA-tagged PET imaging in gastric cancer patients.

OBJECTIVE: Human epidermal growth factor receptor 2 (HER2) is an important biomarker for targeted gastric cancer (GC) immunotherapy. However, heterogeneous HER2 overexpression in GC, loss of HER2 expression during therapy, and inability to non-invasively identify HER2 overexpressing tumors impede effective targeting therapies. Improved HER2-specific functional imaging can address these challenges. Trastuzumab is a HER2-directed mAb to treat HER2 overexpressing cancers. The 64 Cu-DOTA-trastuzumab radiotracer is used to detect HER2+ metastatic breast cancer. We aimed to develop 64 Cu-DOTA-trastuzumab PET-CT to detect and characterize tumor uptake in HER2+ or - GC patients. METHODS: We conducted a single-arm phase II pilot study exploring the feasibility of 64 Cu-DOTA-trastuzumab for PET imaging of HER2 overexpressing GC compared to HER2 non-expressing tumors. Eight patients with biopsy-confirmed gastric adenocarcinoma were included. Immunohistochemistry was used to evaluate primary tumor biopsies for HER2 overexpression. Patients were injected with 45 mg of cold trastuzumab followed by 5 mg of 64 Cu-DOTA-trastuzumab. PET-CT scans were performed 24-48 h post radiotracer injection and compared to standard staging CT scans. RESULTS: We observed limited toxicity following 64 Cu-DOTA-trastuzumab injections. While there was uptake of the radiotracer in portions of HER2+ lesions, there was no statistically significant distinction between tumor and background by standardized uptake value analysis. CONCLUSION: Despite the potential of 64 Cu-DOTA-trastuzumab PET imaging of HER2+ metastatic breast cancer, a 5 mg dose of this radiotracer injected 24-48 h before imaging was insufficient to identify HER2+ GC. These results inform future GC imaging studies to optimize biomarker-targeted therapies based on dosage and timing for more clinically relevant imaging.

First-In-Human Pilot PET Immunoimaging Study of 64Cu-Anti-Carcinoembryonic Antigen Monoclonal Antibody (hT84.66-M5A) in Patients with Carcinoembryonic Antigen-Producing Cancers.

Background: PET imaging using radiolabeled immunoconstructs shows promise in cancer detection and in assessing tumor response to therapies. The authors report the first-in-human pilot study evaluating M5A, a humanized anti-carcinoembryonic antigen (CEA) monoclonal antibody (mAb), radiolabeled with 64Cu in patients with CEA-expressing malignancies. The purpose of this pilot study was to identify the preferred patient population for further evaluation of this agent in an expanded trial. Methods: Patients with CEA-expressing primary or metastatic cancer received 64Cu-DOTA-hT84.66-M5A with imaging performed at 1 and 2 days postinfusion. 64Cu-DOTA-hT84.66-M5A PET scan findings were correlated with CT, MRI, and/or FDG PET scans and with histopathologic findings from planned surgery or biopsy performed postscan. Results: Twenty patients received 64Cu-DOTA-hT84.66-M5A. Twelve patients demonstrated positive images, which were confirmed in 10 patients as tumor by standard-of-care (SOC) imaging, biopsy, or surgical findings. Four of the 8 patients with negative imaging were confirmed as true negative, with the remaining 4 patients having disease demonstrated by SOC imaging or surgery. All 5 patients with locally advanced rectal cancer underwent planned biopsy or surgery after 64Cu-DOTA-hT84.66-M5A imaging (4 patients imaged 6-8 weeks after completing neoadjuvant chemotherapy and radiation therapy) and demonstrated a high concordance between biopsy findings and 64Cu-DOTA-hT84.66-M5A PET scan results. Three patients demonstrated positive uptake at the primary site later confirmed by biopsy and at surgery as residual disease. Two patients with negative scans each demonstrated complete pathologic response. In 5 patients with medullary thyroid cancer, 64Cu-DOTA-hT84.66-M5A identified disease not seen on initial CT scans in 3 patients, later confirmed to be disease by subsequent surgery or MRI. Conclusions: 64Cu-DOTA-hT84.66-M5A demonstrates promise in tumor detection, particularly in patients with locally advanced rectal cancer and medullary thyroid cancer. A successor trial in locally advanced rectal cancer has been initiated to further evaluate this agent's ability to define tumor extent before and assess disease response after neoadjuvant chemotherapy and radiotherapy. clinical trial.gov (NCT02293954).

Use of 64Cu-DOTA-Trastuzumab PET to Predict Response and Outcome of Patients Receiving Trastuzumab Emtansine for Metastatic Breast Cancer: A Pilot Study.

We hypothesized that functional imaging with 64Cu-DOTA-trastuzumab PET/CT would predict the response to the antibody-drug conjugate trastuzumab-emtansine (T-DM1). Methods: Ten women with metastatic human epidermal growth factor receptor 2-positive breast cancer underwent 18F-FDG PET/CT and 64Cu-DOTA-trastuzumab PET/CT on days 1 and 2 before treatment with T-DM1. Results: T-DM1-responsive patients had higher uptake than nonresponsive patients. Day 1 minimum SUVmax (5.6 vs. 2.8, P < 0.02), day 2 minimum SUVmax (8.1 vs. 3.2, P < 0.01), and day 2 average SUVmax (8.5 vs. 5.4, P < 0.05) for 64Cu-DOTA-trastuzumab all favored responding patients. Tumor-level response suggested threshold dependence on SUVmax Patients with a day 2 minimum SUVmax above versus below the threshold had a median time to treatment failure of 28 mo versus 2 mo (P < 0.02). Conclusion: Measurement of trastuzumab uptake in tumors via PET/CT is promising for identifying patients with metastatic breast cancer who will benefit from T-DM1.

Template-Catalyzed, Disulfide Conjugation of Monoclonal Antibodies Using a Natural Amino Acid Tag.

The high specificity and favorable pharmacological properties of monoclonal antibodies (mAbs) have prompted significant interest in re-engineering this class of molecules to add novel functionalities for enhanced therapeutic and diagnostic potential. Here, we used the high affinity, meditope-Fab interaction to template and drive the rapid, efficient, and stable site-specific formation of a disulfide bond. We demonstrate that this template-catalyzed strategy provides a consistent and reproducible means to conjugate fluorescent dyes, cytotoxins, or "click" chemistry handles to meditope-enabled mAbs (memAbs) and memFabs. More importantly, we demonstrate this covalent functionalization is achievable using natural amino acids only, opening up the opportunity to genetically encode cysteine meditope "tags" to biologics. As proof of principle, genetically encoded, cysteine meditope tags were added to the N- and/or C-termini of fluorescent proteins, nanobodies, and affibodies, each expressed in bacteria, purified to homogeneity, and efficiently conjugated to different memAbs and meFabs. We further show that multiple T-cell and Her2-targeting bispecific molecules using this strategy potently activate T-cell signaling pathways in vitro. Finally, the resulting products are highly stable as evidenced by serum stability assays (>14 d at 37 °C) and in vivo imaging of tumor xenographs. Collectively, the platform offers the opportunity to build and exchange an array of functional moieties, including protein biologics, among any cysteine memAb or Fab to rapidly create, test, and optimize stable, multifunctional biologics.

Tumor Uptake of 64Cu-DOTA-Trastuzumab in Patients with Metastatic Breast Cancer.

The goal of this study was to characterize the relationship between tumor uptake of 64Cu-DOTA-trastuzumab as measured by PET/CT and standard, immunohistochemistry (IHC)-based, histopathologic classification of human epidermal growth factor receptor 2 (HER2) status in women with metastatic breast cancer (MBC). Methods: Women with biopsy-confirmed MBC and not given trastuzumab for 2 mo or more underwent complete staging, including 18F-FDG PET/CT. Patients were classified as HER2-positive (HER2+) or -negative (HER2-) based on fluorescence in situ hybridization (FISH)-supplemented immunohistochemistry of biopsied tumor tissue. Eighteen patients underwent 64Cu-DOTA-trastuzumab injection, preceded in 16 cases by trastuzumab infusion (45 mg). PET/CT was performed 21-25 (day 1) and 47-49 (day 2) h after 64Cu-DOTA-trastuzumab injection. Radiolabel uptake in prominent lesions was measured as SUVmax Average intrapatient SUVmax (pt) was compared between HER2+ and HER2- patients. Results: Eleven women were HER2+ (8 immunohistochemistry 3+; 3 immunohistochemistry 2+/FISH amplified), whereas 7 were HER2- (3 immunohistochemistry 2+/FISH nonamplified; 4 immunohistochemistry 1+). Median pt for day 1 and day 2 was 6.6 and 6.8 g/mL for HER 2+ and 3.7 and 4.3 g/mL for HER2- patients (P < 0.005 either day). The distributions of pt overlapped between the 2 groups, and interpatient variability was greater for HER2+ than HER2- disease (P < 0.005 and 0.001, respectively, on days 1 and 2). Conclusion: By 1 d after injection, uptake of 64Cu-DOTA-trastuzumab in MBC is strongly associated with patient HER2 status and is indicative of binding to HER2. The variability within and among HER2+ patients, as well as the overlap between the HER2+ and HER2- groups, suggests a role for 64Cu-DOTA-trastuzumab PET/CT in optimizing treatments that include trastuzumab.

Diagnostic PET Imaging of Mammary Microcalcifications Using 64Cu-DOTA-Alendronate in a Rat Model of Breast Cancer.

The development of improved breast cancer screening methods is hindered by a lack of cancer-specific imaging agents and effective small-animal models to test them. The purpose of this study was to evaluate 64Cu-DOTA-alendronate as a mammary microcalcification-targeting PET imaging agent, using an ideal rat model. Our long-term goal is to develop 64Cu-DOTA-alendronate for the detection and noninvasive differentiation of malignant versus benign breast tumors with PET. Methods: DOTA-alendronate was synthesized, radiolabeled with 64Cu, and administered to normal or tumor-bearing aged, female, retired breeder Sprague-Dawley rats for PET imaging. Mammary tissues were subsequently labeled and imaged with light, confocal, and electron microscopy to verify microcalcification targeting specificity of DOTA-alendronate and elucidate the histologic and ultrastructural characteristics of the microcalcifications in different mammary tumor types. Tumor uptake, biodistribution, and dosimetry studies were performed to evaluate the efficacy and safety of 64Cu-DOTA-alendronate. Results:64Cu-DOTA-alendronate was radiolabeled with a 98% yield. PET imaging using aged, female, retired breeder rats showed specific binding of 64Cu-DOTA-alendronate in mammary glands and mammary tumors. The highest uptake of 64Cu-DOTA-alendronate was in malignant tumors and the lowest uptake in benign tumors and normal mammary tissue. Confocal analysis with carboxyfluorescein-alendronate confirmed the microcalcification binding specificity of alendronate derivatives. Biodistribution studies revealed tissue alendronate concentrations peaking within the first hour, then decreasing over the next 48 h. Our dosimetric analysis demonstrated a 64Cu effective dose within the acceptable range for clinical PET imaging agents and the potential for translation into human patients. Conclusion:64Cu-DOTA-alendronate is a promising PET imaging agent for the sensitive and specific detection of mammary tumors as well as the differentiation of malignant versus benign tumors based on absolute labeling uptake.

Functional imaging of human epidermal growth factor receptor 2-positive metastatic breast cancer using (64)Cu-DOTA-trastuzumab PET.

UNLABELLED: Women with human epidermal growth factor receptor 2 (HER2)-positive breast cancer are candidates for treatment with the anti-HER2 antibody trastuzumab. Assessment of HER2 status in recurrent disease is usually made by core needle biopsy of a single lesion, which may not represent the larger tumor mass or other sites of disease. Our long-range goal is to develop PET of radiolabeled trastuzumab for systemically assessing tumor HER2 expression and identifying appropriate use of anti-HER2 therapies. The purpose of this study was to evaluate PET/CT of (64)Cu-DOTA-trastuzumab for detecting and measuring tumor uptake of trastuzumab in patients with HER2-positive metastatic breast cancer. METHODS: Eight women with biopsy-confirmed HER2-positive metastatic breast cancer and no anti-HER2 therapy for 4 mo or longer underwent complete staging, including (18)F-FDG PET/CT. For 6 of the 8 patients, (64)Cu-DOTA-trastuzumab injection (364-512 MBq, 5 mg of trastuzumab) was preceded by trastuzumab infusion (45 mg). PET/CT (PET scan duration 1 h) was performed 21-25 (day 1) and 47-49 (day 2) h after (64)Cu-DOTA-trastuzumab injection. Scan fields of view were chosen on the basis of (18)F-FDG PET/CT. Tumor detection sensitivity and uptake analyses were limited to lesions identifiable on CT; lesions visualized relative to adjacent tissue on PET were considered PET-positive. Radiolabel uptake in prominent lesions was measured as maximum single-voxel standardized uptake value (SUVmax). RESULTS: Liver uptake of (64)Cu was reduced approximately 75% with the 45-mg trastuzumab predose, without significant effect on tumor uptake. The study included 89 CT-positive lesions. Detection sensitivity was 77%, 89%, and 93% for day 1, day 2, and (18)F-FDG, respectively. On average, tumor uptake was similar for (64)Cu-DOTA-trastuzumab and (18)F-FDG (SUVmax and range, 8.1 and 3.0-22.5 for day 1 [n = 48]; 8.9 and 0.9-28.9 for day 2 [n = 38]; 9.7 and 3.3-25.4 for (18)F-FDG [n = 56]), but same-lesion SUVmax was not correlated between the 2 radiotracers. No toxicities were observed, and estimated radiation dose from (64)Cu-DOTA-trastuzumab was similar to (18)F-FDG. CONCLUSION: (64)Cu-DOTA-trastuzumab visualizes HER2-positive metastatic breast cancer with high sensitivity and is effective in surveying disseminated disease. A 45-mg trastuzumab predose provides a (64)Cu-DOTA-trastuzumab biodistribution favorable for tumor imaging. (64)Cu-DOTA-trastuzumab PET/CT warrants further evaluation for assessing tumor HER2 expression and individualizing treatments that include trastuzumab.

Combination therapy for non-Hodgkin's lymphoma: an opportunity for pharmaceutical care in a specialty practice.

OBJECTIVE: To describe the application of pharmaceutical care practices in the administration of new therapeutic radiopharmaceuticals used in the treatment of non-Hodgkin's lymphoma (NHL). PRACTICE DESCRIPTION: At the Antibody Labeling Facility at the University of Nebraska Medical Center, the nuclear pharmacist provides support in the formulation, preparation, and quality testing of radiopharmaceuticals. The nuclear pharmacist also provides direct patient care by assisting in the administration of radiopharmaceuticals, monitoring patients during their infusions, and counseling patients on radioimmunotherapy and radiation safety. PRACTICE INNOVATION: Expanding the role of the nuclear pharmacist in treating patients with NHL using radiolabeled monoclonal antibodies (MABs). INTERVENTIONS: The nuclear pharmacist provides specialized pharmaceutical care by being involved in planning patient care, administering diagnostic and therapeutic radiopharmaceuticals, performing individualized patient dose calculations, monitoring patients, and counseling patients. MAIN OUTCOME MEASURES: Number of patients treated with radiolabeled MABs. RESULTS: Since January 1996, 85 patients with NHL have been treated using 131I-tositumomab (Corixa, GlaxoSmithKline), an anti-B1 MAB, under various clinical research protocols requiring specialized pharmaceutical care. The nuclear pharmacist on the team provided direct patient care, assisting with the administration of diagnostic and therapeutic radiopharmaceuticals under a collaborative agreement with a nuclear medicine physician or a radiation oncologist. Other pharmaceutical care activities performed include calculating individual patient doses, obtaining medication histories, counseling patients on their therapy and on radiation safety after early release, and monitoring patients for adverse effects during medication infusion. Patients have responded favorably to nontraditional nuclear pharmacy activities. CONCLUSION: The nuclear pharmacist has become an important member of the health care team that provides a new and unique therapy for patients with NHL. To date, the nuclear pharmacist, in collaboration with the nuclear medicine physician or the radiation oncologist, has successfully administered the tositumomab and 131I-tositumomab combination therapy without significant incident.