Binding of TS1, an anti-keratin 8 antibody, in small-cell lung cancer after 177Lu-DOTA-Tyr3-octreotate treatment: a histological study in xenografted mice

Radiolabeled Somatostatin Analogs for Cancer Imaging

Somatostatin receptors (SSTR) are expressed by many tumours especially those related to neuro-endocrine origin and molecular functional imaging of SSTR expression using radiolabelled somatostatin analogs have revolutionized imaging of patients with these group of malignancies. Coming a long way from the first radiolabelled somatostatin analog 123I-Tyr-3-octreotide, there has been significant developments in terms of radionuclides used, the ligands and somatostatin derivatives. 111In-Pentetreotide extensively employed for imaging NETs at the beginning has now been replaced by 68Ga-SSA based PET-CT. SSA-PET/CT performs superior to conventional imaging modalities and has evolved in the mainframe for NET imaging. The advantages were multiple: (i) superior spatial resolution of PET versus SPECT, (ii) quantitative capabilities of PET aiding in disease activity and treatment response monitoring with better precision, (iii) shorter scan time and (iv) less patient exposure to radiation. The modality is indicated for staging, detecting the primary in CUP-NETs, restaging, treatment planning (along with FDG: the concept of dual-tracer PET-CT) as well as treatment response evaluation and follow-up of NETs. SSA PET/CT has also been incorporated in the guidelines for imaging of Pheochromocytoma-Paraganglioma, Medullary carcinoma thyroid, Meningioma and Tumor induced osteomalacia. At present, there is rising interest on (a) 18F-labelled SSA, (b) 64Cu-labelled SSA, and (c) somatostatin antagonists. 18F offers excellent imaging properties, 64Cu makes delayed imaging feasible which has implications in dosimetry and SSTR antagonists bind with the SST receptors with high affinity and specificity, providing high contrast images with less background, which can be translated to theranostics effectively. SSTR have been demonstrated in non-neuroendocrine tumours as well in the peer-reviewed literature, with studies demonstrating the potential of SSA PET/CT in Neuroblastoma, Nasopharyngeal carcinoma, carcinoma prostate (neuroendocrine differentiation) and lymphoma. This review will focus on the currently available SSAs and their history, different SPECT/PET agents, SSTR antagonists, comparison between the various imaging tracers, and their utility in both neuroendocrine and non-neuroendocrine tumors.

68Ga-SSO-120 PET for Initial Staging of Small Cell Lung Cancer Patients: A Single-Center Retrospective Study

PET imaging using the somatostatin receptor 2 (SSTR2) antagonist satoreotide trizoxetan (SSO-120, previously OPS-202) could offer accurate tumor detection and screening for SSTR2-antagonist radionuclide therapy in patients with SSTR2-expressing small cell lung cancer (SCLC). The aim of this single-center study was to investigate tumor uptake and detection rates of 68Ga-SSO-120 in comparison to 18F-FDG PET in the initial staging of SCLC patients. Methods: Patients with newly diagnosed SCLC who underwent additional whole-body 68Ga-SSO-120 PET/CT during the initial diagnostic workup were retrospectively included. The mean administered activity was 139 MBq, and the mean uptake time was 60 min. Gold-standard staging 18F-FDG PET/CT was evaluated if available within 2 wk before or after 68Ga-SSO-120 PET if morphologic differences in CT images were absent. 68Ga-SSO-120- or 18F-FDG-positive lesions were reported in 7 anatomic regions (primary tumor, thoracic lymph node metastases, and distant metastases including pleural, contralateral pulmonary, liver, bone, and other) according to the TNM classification for lung cancer (eighth edition). Consensus TNM staging (derived from CT, endobronchial ultrasound-guided transbronchial needle aspiration, PET, and brain MRI) by a clinical tumor board served as the reference standard. Results: Thirty-one patients were included, 12 with limited and 19 with extensive disease according to the Veterans Administration Lung Study Group classification. 68Ga-SSO-120-positive tumor was detected in all patients (100%) and in 90 of the 217 evaluated regions (41.5%). Thirteen patients (42.0%) had intense average 68Ga-SSO-120 uptake (region-based mean SUVmax ≥ 10); 28 patients (90.3%) had average 68Ga-SSO-120 uptake greater than liver uptake (region-based mean peak tumor-to-liver ratio > 1). In 25 patients with evaluable 18F-FDG PET, primary tumor, thoracic lymph node metastases, and distant metastases were detected in 100%, 92%, and 64%, respectively, of all investigated patients by 68Ga-SSO-120 and in 100%, 92%, and 56%, respectively, by 18F-FDG PET. 68Ga-SSO-120 PET detected additional contralateral lymph node, liver, and brain metastases in 1, 1, and 2 patients, respectively (no histopathology available), and 18F-FDG PET detected additional contralateral lymph node metastases in 3 patients (1 confirmed, 1 systematic endobronchial ultrasound-guided transbronchial needle aspiration-negative, and 1 without available histopathology). None of these differences altered Veterans Administration Lung Study Group staging. The region-based monotonic correlation between 68Ga-SSO-120 and 18F-FDG uptake was low (Spearman ρ = 0.26-0.33). Conclusion: 68Ga-SSO-120 PET offers high diagnostic precision with comparable detection rates and additional complementary information to the gold standard, 18F-FDG PET. Consistent uptake in most patients warrants exploration of SSTR2-directed radionuclide therapy.

Astatine-211 labelled a small molecule peptide: specific cell killing in vitro and targeted therapy in a nude-mouse model

Extensive interest in the development of α-emitting radionuclides astatine-211 (211At) stems from the potential superiority for the treatment of smaller tumors, disseminated disease, and metastatic disease. VP2, a small molecule fusion peptide, can specifically bind to the VPAC1 receptor which is over-expressed in malignant epithelial tumors. In our recent study, we performed the preparation of 211At labelled VP2 through a one-step method. In this work, we explored the targeted radionuclide therapy with [211At]At-SPC-VP2 in vitro and in vivo. The cytotoxicity and specific cell killing of [211At]At-SPC-VP2 were evaluated using the CCK-8 assay. Compared with the [211At]NaAt, the VPAC1-targeted radionuclide compound [211At]At-SPC-VP2 showed more effective cytotoxicity in vitro. Targeted radioactive therapy trial was carried out in non-small-cell lung cancer (NSCLC) xenograft mice. For the therapy experiment, 4 groups of mice were injected via the tail vein with 370 kBq, 550 kBq, 740 kBq, 3 × ∼246 kBq of [211At]At-SPC-VP2, of which the second and third injections were given 4 and 8 days after the first injection, respectively. As controls, animals were treated with saline or 550 kBq [211At]NaAt. The body weight and tumor size of mice were monitored before the administration and every 2 days thereafter. Cytotoxic radiation of partial tissue samples such as kidneys, liver and stomach of mice were assessed by immunohistochemical examination. The tumor growth was inhibited and significantly improved survival was achieved in mice treated with [211At]At-SPC-VP2, two-fold prolongation of survival compared with the control group, which received normal saline or 550 kBq [211At]NaAt. No renal or hepatic toxicity was observed in the mice receiving [211At]At-SPC-VP2, but gastric pathological sections showed 211At uptake in stomach resulting in later toxicity, highlighting the importance of further enhancing the stability of labelled compounds.

Biomarkers of tumor invasiveness in proteomics (Review)

Over the past two decades, quantitative proteomics has emerged as an important tool for deciphering the complex molecular events involved in cancers. The number of references involving studies on the cancer metastatic process has doubled since 2010, while the last 5 years have seen the development of novel technologies combining deep proteome coverage capabilities with quantitative consistency and accuracy. To highlight key findings within this huge amount of information, the present review identified a list of tumor invasive biomarkers based on both the literature and data collected on a biocollection of experimental cell lines, tumor models of increasing invasiveness and tumor samples from patients with colorectal or breast cancer. Crossing these different data sources led to 76 proteins of interest out of 1,245 mentioned in the literature. Information on these proteins can potentially be translated into clinical prospects, since they represent potential targets for the development and evaluation of innovative therapies, alone or in combination. Herein, a systematical review of the biology of each of these proteins, including their specific subcellular/extracellular or multiple localizations is presented. Finally, as an important advantage of quantitative proteomics is the ability to provide data on all these molecules simultaneously in cell pellets, body fluids or paraffin‑embedded sections of tumors/invaded tissues, the significance of some of their interconnections is discussed.

Could Somatostatin Enhance the Outcomes of Chemotherapeutic Treatment in SCLC?

PURPOSE

Somatostatin is a peptide with a potent and broad antisecretory action, which makes it an invaluable drug target for the pharmacological management of pituitary adenomas and neuroendocrine tumors. Furthermore, somatostatin (SST) receptors (SSTR1, 2A and B, 3, 4 and 5) belong to the G protein coupled receptor family and are overexpressed in tumors. Since, human small-cell lung cancer overexpresses somatostatin receptors (STTR), they could be legitimate targets for treating SCLC.The aim of this study was the evaluation of cytotoxicity of somatostatin in combination with several anticancer drugs in HTB-175 cell line (Small Cell Lung Cancer Cell line that expresses neuron specific enolase).

METHODS

Docetaxel, Paclitaxel, Carboplatin, Cisplatin, Etoposide, Gemzar, Navelbine, Fluorouracil, Farmorubicin are the chemotherapeutic drugs that we used for the combination before and after adding somatostatin in SCLC cell culture. HTB-175 cell line was purchased from ATCC LGC Standards.At indicated time-point, 48h after the combination, cell viability and apoptosis were measured with Annexin V staining by flow cytometry.

RESULTS

Flow cytometry showed that Docetaxel, Paclitaxel, Gemzar and Cisplatin induced apoptosis more when they were added before somatostatin, whereas etoposide induced apoptosis more after somatostatin treatment. Navelbine alone or in combination with somatostatin showed no differences in apoptosis. Farmorubicin showed equal toxicity in all combinations. Fluorouracil and Carboplatin induced apoptosis more when added alone in HTB-175 cell line. However, increased apoptosis was also observed when Carboplatin was administered before somatostatin in higher concentrations.

CONCLUSION

Our results indicated that depending on the drug, somatostatin treatment before or after chemotherapeutic drugs increased apoptosis in small cell lung cancer cells. We suggest that long acting somatostatin analogues could be used as additive and maintenance therapy in combination to antineoplastic agents in SCLC patients.

Brief report on the use of radiolabeled somatostatin analogs for the diagnosis and treatment of metastatic small-cell lung cancer patients

INTRODUCTION

The demonstration of type 2 somatostatin receptors (SSTRs) in small-cell lung cancer (SCLC) represents the rationale for the use of positron emission tomography/computed tomography (PET/CT) to determine SSTR expression, and select patients suitable for peptide radioreceptor radionuclide therapy (PRRT) in extensive-disease stage (ED) SCLC.

METHODS

We evaluated 24 ED-SCLC patients with radiolabeled SST-analog PET/CT. Lesions at PET/CT scan were semiquantitatively scored (from 0 to 3+) and compared with contrast-enhanced CT findings. Patients scored as 3+ were admitted to PRRT after dosimetric evaluation. Average injected activity/cycle was 2.6 GBq (yttrium-PRRT) or 6.0 GBq (lutetium-PRRT). PRRT efficacy was clinically and radiologically assessed.

RESULTS

PET/CT was negative in four of 24 patients, whereas in the remaining 20 cases uptake was scored as 1+ in seven of 20, 2+ in one of 20, and 3+ in 12 of 20. Primary tumor lesions showed uptake in 16 of 24 patients. Uptake in metastatic lesions was observed in four of four adrenals, two of five brain, 12 of 16 bone, three of eight liver, and 17 of 20 lymph node lesions. Of the 12 patients eligible for PRRT, 11 were eventually treated and four of 11 patients received multiple PRRT administrations. Dosimetry resulted in a BED for kidney of 7.5 Gy (range, 4-21); bone marrow provisional dosage was 0.43 Gy (range, 0.1-1.7). Hematological PRRT toxicity occurred in three of 11 patients. No clinical or objective responses were observed with disease progression occurring approximately 48 days (range, 9-32) after PRRT.

CONCLUSION

Radiolabeled SST-analog PET/CT demonstrated enhanced SSTR expression in 50% of cases. Nevertheless, PRRT in ED-SCLC was ineffective, suggesting the need to anticipate or combine PRRT in a multimodality approach.