Evaluation of 177Lu-Dotatate treatment in patients with metastatic neuroendocrine tumors and prognostic factors

Challenges in developing response evaluation criteria for peptide receptor radionuclide therapy: A consensus report from the European Neuroendocrine Tumor Society Advisory Board Meeting 2022 and the ENETS Theranostics Task Force

Assessing the response to systemic therapy in neuroendocrine tumors (NET) is challenging since morphological imaging response is often delayed and not necessarily reflective of clinical benefit. Peptide receptor radionuclide therapy (PRRT) has a complex mechanism of action, further complicating response assessment. In response to these challenges, the European Neuroendocrine Tumor Society (ENETS) Theranostics Task Force conducted a statement-based survey among experts to identify the current landscape and unmet needs in PRRT response assessment. The survey, presented at the 2022 ENETS Advisory Board (AB) meeting in Vienna, was completed by 70% of AB members, most of whom (81%) were from ENETS Centers of Excellence (CoE). It comprised a set of 13 questions with two substatements in three questions. Six (46%) of the statements achieved more than 75% agreement, while five (39%) additional statements reached over 60% consensus. Key points from the survey include: AB members agreed that lesions deemed equivocal on computed tomography (CT) or magnetic resonance imaging (MRI) should be characterized by somatostatin receptor (SST) positron emission tomography (PET)/CT before being designated as target lesions. It was agreed that interim response assessments should occur after the second or third PRRT cycle. Over half (54%) preferred using both conventional cross-sectional imaging (CT and/or MRI) and hybrid imaging (SST PET/CT) for this purpose. Almost all AB members supported further response assessment 3 months after the final PRRT cycle. A majority (62%) preferred using a combination of conventional cross-sectional imaging and SST PET/CT. For cases showing equivocal progression (ambiguous lesions or nontarget lesions) on CT and/or MRI, further confirmation using SST PET/CT was recommended. A significant majority (74%) preferred assessing pseudo-progression and delayed response by combining SST PET with diagnostic CT and/ or MRI. Though just below the 75% consensus threshold, there was substantial agreement on selecting target lesions based on SST PET/CT uptake intensity and homogeneity. Sixty-nine percent noted the importance of documenting and closely following heterogeneity in lesions in liver, lymph nodes, primary tumors, or other organs. As to the statement on parameters for new response criteria, AB members recommended exploring maximum standard unit value, tumor-to-background ratio, Hounsfield Unit (Choi Criteria), total tumor burden, and novel serum or molecular markers for future response evaluation criteria. Sixty-five percent supported the use of a single SST PET/CT for response assessment of NET lesions treated with PRRT. These findings highlight the importance of integrating advanced imaging techniques and recognizing the need for more nuanced criteria in assessing the efficacy of PRRT in NET patients. This approach aims to enhance the accuracy of treatment monitoring and improve patient outcomes.

Radiomics Analysis for Clinical Decision Support in 177Lu-DOTATATE Therapy of Metastatic Neuroendocrine Tumors using CT Images

Background

Radiomics is the computation of quantitative image features extracted from medical imaging modalities to help clinical decision support systems, which could ultimately meliorate personalized management based on individual characteristics.

Objective

This study aimed to create a predictive model of response to peptide receptor radionuclide therapy (PRRT) using radiomics computed tomography (CT) images to decrease the dose for patients if they are not a candidate for treatment.

Material and Methods

In the current retrospective study, 34 patients with neuroendocrine tumors whose disease is clinically confirmed participated. Effective factors in the treatment were selected by eXtreme gradient boosting (XGBoost) and minimum redundancy maximum relevance (mRMR). Classifiers of decision trees (DT), random forest (RF), and K-nearest neighbors (KNN) with selected quantitative and clinical features were used for modeling. A confusion matrix was used to evaluate the performance of the model.

Results

Out of 866 quantitative and clinical features, nine features with the XGBoost method and ten features with the mRMR pattern were selected that had the most relevance in predicting response to treatment. Selected features of the XGBoost method in integration with the RF classifier provided the highest accuracy (accuracy: 89%), and features selected by the mRMR method in combination with the RF classifier showed satisfactory performance (accuracy: 74%).

Conclusion

This exploratory analysis shows that radiomic features with high accuracy can effectively predict response to personalize treatment.

Short-Term Biological Toxicity Prediction of [177Lu]Lutetium-Oxodotreotide: An Original Retrospective Analysis

Introduction: [177Lu]Lutetium (Lu)-oxodotreotide is a radiopharmaceutical drug used as peptide receptor radionuclide therapy (PRRT) for somatostatin receptor-expressing neuroendocrine neoplasms. It provides an additional effective alternative treatment for these rare cancers. Although well tolerated, its safety profile must continue to be characterized to support its use as a first-line treatment or for additional cycles. This study evaluated factors associated with the occurrence of [177Lu]Lu-oxodotreotide induced short-term toxicity. Materials and Methods: A retrospective observational monocentric study was carried out from July 2013 to October 2021. Inclusion criteria were defined as follows: patients who received at least four cycles of [177Lu]Lu-oxodotreotide and were followed up for 6 months after the last injection. Graduated toxicity was defined using the National Cancer Institute Common Terminology Criteria for Adverse Events 5.0. Cox regression was used in the analysis. Results: Forty patients were included. The most frequent toxicities occurred during the first cycle and were graded as G1 or G2. As expected, toxicities were predominantly hematological and hepatic, with incomplete reversibility after each cycle. The following factors were significantly related to the occurrence of hematological or hepatic toxicity during PRRT: gastrointestinal primary tumor diagnosis, bone metastases, peritoneal metastases, pancreatic metastases or pulmonary metastases, and high tumor grade. Conclusion: Knowledge and consideration of these factors in adjusting [177Lu]Lu-oxodotreotide treatment regimen could help prevent or reduce the severity of these toxicities. Further studies are still warranted to refine these results and improve treatment management.

Efficacy and tolerability of somatostatin analogues according to gender in patients with neuroendocrine tumors

As the incidence of neuroendocrine tumors has been rising, gender differences in epidemiology and clinical behavior have emerged, and interest into a gender-driven management of these tumors has grown with the aim to improve survival and quality of life of these patients. Somatostatin Analogues represent the first line of systemic treatment of both functional and non-functional neuroendocrine tumors, through the expression of somatostatin receptors (SSTRs) in the tumor cells, and proved effective in controlling hormonal hypersecretion and inhibiting tumor growth, improving progression-free survival and overall survival of these patients. Aim of the present review is to investigate any differences by gender in efficacy and safety of SSTS-targeted therapies, that represent the mainstay treatment of neuroendocrine tumors, as they emerge from studies of varying design and intent. Although preclinical studies have provided evidence in favor of differences by gender in tumor expression of SSTR, as well as of the role of sex hormones and related receptors in modulating SSTRs expression and function, the clinical studies conducted so far have not shown substantial differences between males and females in either efficacy or toxicity of SSTR-targeted therapies, even if with sometimes inconsistent results. Moreover, in most studies gender was not a predictor of response to treatment. Studies specifically designed to address this issue are needed to develop gender-specific therapeutic algorithms, improving patients' prognosis and quality of life.

Hypoalbuminemia, but not derived neutrophil to lymphocyte ratio (dNLR), predicts overall survival in neuroendocrine tumours undergoing peptide receptor radionuclide therapy: A retrospective, cohort study of 557 patients

Several inflammation scores have shown association with survival outcomes for patients with neuroendocrine tumours (NET) treated with peptide receptor radionuclide therapy (PRRT). However, whether these scores add value to established prognostic factors remains unknown. In this retrospective, cohort study of 557 NET patients undergoing PRRT in a tertiary referral centre from 2005 to 2015, we examined inflammatory markers and scores previously associated with cancer outcomes, using Cox proportional hazard models and Akaike's information criterion. Lower albumin (hazard ratio [95% confidence interval], .91 [.87-.95] per unit), as well as higher C-reactive protein (CRP; 1.02 [1.01-1.02]), Glasgow Prognostic Score (GPS; 1 vs. 0: 1.67 [1.14-2.44], 2 vs. 0 3.60 [2.24-5.79]), CRP/albumin ratio (1.84 [1.43-2.37]) and platelet count (Plt) × CRP, but not white blood cell, neutrophil and thrombocyte counts or derived neutrophil to lymphocyte ratio (dNLR), were associated with shorter median overall survival (OS) in an adjusted analysis. The addition of parameters based on albumin and CRP, but not dNLR, to a base model including age, chromogranin A, the cell proliferation marker Ki-67, performance status, tumour site and previous treatments improved the predictive accuracy of the base model. In an exploratory analysis of patients with available erythrocyte sedimentation rate (ESR) and CRP, ESR emerged as the most powerful predictor. When added to a prognostic model for OS in NET patients treated with PRRT, most inflammation scores further improved the model. Albumin was the single marker adding most value to the set of established prognostic markers, whereas dNLR did not seem to improve the model's prognostic ability.

Advancements in the development of radiopharmaceuticals for nuclear medicine applications in the treatment of bone metastases

Bone metastases are a painful and complex condition that overwhelmingly impacts the prognosis and quality of life of cancer patients. Over the years, nuclear medicine has made remarkable progress in the diagnosis and management of bone metastases. This review aims to provide a comprehensive overview of the recent advancements in nuclear medicine for the diagnosis and management of bone metastases. Furthermore, the review explores the role of targeted radiopharmaceuticals in nuclear medicine for bone metastases, focusing on radiolabeled molecules that are designed to selectively target biomarkers associated with bone metastases, including osteocytes, osteoblasts, and metastatic cells. The applications of radionuclide-based therapies, such as strontium-89 (Sr-89) and radium-223 (Ra-223), are also discussed. This review also highlights the potential of theranostic approaches for bone metastases, enabling personalized treatment strategies based on individual patient characteristics. Importantly, the clinical applications and outcomes of nuclear medicine in osseous metastatic disease are discussed. This includes the assessment of treatment response, predictive and prognostic value of imaging biomarkers, and the impact of nuclear medicine on patient management and outcomes. The review identifies current challenges and future perspectives on the role of nuclear medicine in treating bone metastases. It addresses limitations in imaging resolution, radiotracer availability, radiation safety, and the need for standardized protocols. The review concludes by emphasizing the need for further research and advancements in imaging technology, radiopharmaceutical development, and integration of nuclear medicine with other treatment modalities. In summary, advancements in nuclear medicine have significantly improved the diagnosis and management of osseous metastatic disease and future developements in the integration of innovative imaging modalities, targeted radiopharmaceuticals, radionuclide production, theranostic approaches, and advanced image analysis techniques hold great promise in improving patient outcomes and enhancing personalized care for individuals with bone metastases.

Role of systemic inflammatory factors in gastroenteropancreatic neuroendocrine tumors (GEP-NETs) treated with peptide receptor radionuclide therapy (PRRT): From biology to theragnosis

AIM

Systemic inflammatory factors have been validated as indicators of ongoing systemic inflammation that could be predictive markers of poor prognosis for oncological outcomes. However, the prognostic impact of systemic inflammation markers is unknown in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) treated with peptide receptor radionuclide therapy (PRRT).

METHODS

We conducted an observational, retrospective, multicentric study of 40 patients with GEP or unknown origin NETs treated with PRRT between 2016 and 2020. The systemic inflammatory markers were calculated as follows: neutrophil to lymphocyte ratio (NLR)=neutrophil count/lymphocyte count, monocyte to lymphocyte ratio (MLR)=monocyte count/lymphocyte count, platelet to lymphocyte ratio (PLR)=platelet count/lymphocyte count, albumin to lymphocyte ratio (ALR)=albumin levels/lymphocyte count and derived Neutrophil to Lymphocyte ratio (dNLR)=neutrophil count/(leucocytes count - neutrophils count). Baseline analysis and after the second dose were used for the calculation of different ratios.

RESULTS

The median age was 63 years (range 41-85), 55% were male. The baseline cut-off values for NLR were 2.61, for MLR 0.31, for PLR 110.14, for ALR 2.39 and for dNLR 1.71. The cut-off values after the 2° dose were, for NLR 2.3, for MLR 0.3, for PLR 131.61, ALR 4.16, and dNLR 1.48. Median progression-free survival (PFS) was 21.7 months (95% CI 10.7-32.8 months) and overall survival (OS) was 32.1 months (95% CI 19.6-44.7 months), PFS was shorter in patients with elevated NLR (p=0.001), ALR (0.03), and dNLR (p=0.001) in baseline analysis. DCR was 81% and ORR 18%.

CONCLUSIONS

In GEP or unknown origin NETs treated with PRRT, we have identified the predictive and prognostic impact of baseline systemic inflammatory factors.

Long-Term Outcomes of Submaximal Activities of Peptide Receptor Radionuclide Therapy with 177Lu-DOTATATE in Neuroendocrine Tumor Patients

In the literature, up to 45% of neuroendocrine tumor (NET) patients who are treated with ¹⁷⁷Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) do not receive the intended cumulative activity of 29.6 GBq (800 mCi). The aim of this study was to analyze the efficacy of submaximal activities of PRRT in patients who discontinued treatment for non-disease-related reasons. Methods: We retrospectively included patients with well-differentiated and advanced NETs who underwent PRRT from 2000 until 2019 and did not receive 29.6 GBq of ¹⁷⁷Lu-DOTATATE. For comparison, we selected control NET patients who received the intended cumulative activity of 29.6 GBq of ¹⁷⁷Lu-DOTATATE between 2000 and 2012. Primary outcomes were progression-free survival (PFS) and tumor response, and the secondary outcome was overall survival (OS). Results: In total, 243 patients received 3.7-27.8 GBq. In 130 patients, the submaximal activity was unrelated to disease (e.g., bone marrow and renal toxicity in 48% and maximal renal absorbed dose in 23%), and they were included. Patients receiving a reduced activity had more bone metastases, a lower body mass index and albumin level, a higher alkaline phosphatase level, and fewer grade 1 tumors than the 350 patients included in the control group. The disease control rate in the reduced-activity group was 85%, compared with 93% for the control group (P = 0.011). The median PFS (95% CI) was 23 mo (range, 21-26 mo) for the reduced-activity group and 31 mo (range, 27-35 mo) for the control group (P = 0.001), and the median OS (95% CI) was 34 mo (range, 28-40 mo) and 60 mo (range, 53-67 mo), respectively (P < 0.0001). With adjustment for relevant confounders in the multivariable Cox regression analyses, cumulative activity was an independent predictor of both PFS and OS. Conclusion: In NET patients treated with a cumulative activity of less than 29.6 GBq of ¹⁷⁷Lu-DOTATATE, PRRT was less efficacious in tumor response and survival than in patients who received 29.6 GBq.

Neutrophil to lymphocyte ratio as a prognosis biomarker of PRRT in NET patients

PURPOSE

Peptide Receptor Radionuclide Therapy (PRRT) with 177Lu-DOTATATE is a palliative therapeutic option for advanced Neuroendocrine Tumors (NETs). Prognostic factors can predict long-term outcomes and determine response to therapy. Among those already explored, biomarkers from full blood count, including neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) has shown value for other solid tumors and for NETs patients submitted to other forms of therapy. However, its relation to PRRT response and patients' prognosis is still to be determined.

METHODS

Medical records from 96 patients submitted to PRRT between 2010 and 2017 were reviewed, median NLR and PLR were calculated from baseline flood blood count and dichotomized as high or low. Progression-free survival (PFS) and Overall Survival (OS) were calculated.

RESULTS

NLR and PLR median values were 1.8 and 123, respectively. Patients with low NLR had a significantly longer OS (estimated median of 77.5 months, 95% CI: 27.3-127.7) when compared to patients with high NLR (estimated median of 47.7 months, 95% CI: 34.7-60.8); p = 0.04. Patients with low NLR had a trend toward a longer median PFS when compared to patients with high NLR [estimated medians of 77 months (95% CI: 27.3-127.7), and 47.7 months, (95% CI: 34.7-60.7)], respectively, p = 0.08.

CONCLUSION

Patients with advanced-stage NET with NLR higher than 1.8 have worse long term clinical outcomes after PPRT. Larger studies are needed to validate the optimal cutoff for this biomarker.

Peptide Receptor Radionuclide Therapy Using 177Lu-DOTATATE in Advanced Neuroendocrine Tumors (NETs) in a Limited-Resource Environment

Background  This study was conducted to evaluate the clinical efficacy and safety of peptide receptor radionuclide therapy (PRRT) using ¹⁷⁷ Lu-DOTA0-Tyr3-octreotate (DOTATATE) in patients with neuroendocrine tumors (NETs).

Methods  Sixteen patients with pathologically verified NETs including eight females and eight males were enrolled in this study. Before PRRT, the patients underwent ⁶⁸ Ga-DOTATATE positron emission tomography/computed tomography or ^99m Tc-octreotide scintigraphy for evaluation of somatostatin receptor expression. Response to treatment was assessed according to the Response Evaluation Criteria In Solid Tumors (RECIST) classified as complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD). In addition, for evaluation of toxicity, monthly blood analysis was performed including hematology, renal function (creatinine) test, and liver function test. The Eastern Cooperative Oncology Group (ECOG) status performance was applied to estimate the patients' general condition in a scale of 0 (fully active) to 5 (dead). In addition, overall survival (OS) was calculated as the time interval from the start of PRRT to death from any reason.

Results  Sixteen patients including eight females and eight males with a median age of 60.5 years (range: 24–74) were enrolled in this study. The patients underwent PRRT with a median cycle of 3.5 (range: 1–7) and a median dose of 20.35 (range: 7.4–49.95 GBq). At the end of data collection, PR, CR, SD, and PD were seen in 11, 2, 1, and 2 patients according to the RECIST, respectively. Three patients expired during or after the PRRT period. The median ECOG and Karnofsky Performance Scale was 1.5 and 75 before PRRT, which improved significantly to 1 and 80 after PRRT, respectively ( p  < 0.05). According to the Kaplan–Meier test, the median OS was 23 months (95% confidence interval: 7.90–38.09). According to the National Cancer Institute's Common Terminology Criteria for Adverse Events, three patients showed grade I and three patients showed grade II leucopenia. Furthermore, three and seven patients had grade II and grade I anemia, respectively.

Conclusion  Since PRRT using ¹⁷⁷ Lu-DOTATATE has a favorable response rate and few adverse effects and improves the quality of life in NETs, it can be used as an effective therapeutic option, especially in nonoperative, metastatic, and progressive NETs.

Homomultimer strategy for improvement of radiolabeled peptides and antibody fragments in tumor targeting

A homomultimeric radioligand is composed of multiple identical ligands connected to the linker and radionuclide to detect a variety of overexpressed receptors on cancer cells. Multimer strategy holds great potential for introducing new radiotracers based on peptide and monoclonal antibody (mAb) derivatives in molecular imaging and therapy. It offers a reliable procedure for the preparation of biological-based targeting with diverse affinities and pharmacokinetics. In this context, we provide a useful summary and interpretation of the main results by a comprehensive look at multimeric radiopharmaceuticals in nuclear oncology. Therefore, there will be explanations for the strategy mechanisms and the main variables affecting the biodistribution results. The discussion is followed by highlights of recent work in the targeting of various types of receptors. The consequences are expressed based on comparing some parameters between monomer and multimer counterparts in each relevant section.

Treatment of neuroendocrine tumours with 177 Lu-peptide receptor radionuclide therapy: Challenging clinical scenarios and their management

Peptide receptor radionuclide therapy (PRRT) for the treatment of patients with neuroendocrine tumours is usually well tolerated, with selection based on existing guidelines. However, there are various scenarios where the risk-benefit analysis of PRRT needs to be evaluated to limit any complications associated with PRRT. This review looks at 11 key scenarios where the risk-benefit of PRRT needs to be closely evaluated.

Peptide receptor radionuclide therapy implementation and results in a predominantly gastrointestinal neuroendocrine tumor population: A two-year experience in a nonuniversity setting

Neuroendocrine tumors (NETs) are rare, but the incidence and prevalence of NETs are increasing in the United States. While surgery is the preferred treatment for NETs, it is not a viable option for metastatic disease. Lutathera (177Lu-DOTATATE) is approved by the United States Food and Drug Administration and the European Medicines Agency for the treatment of gastroenteropancreatic (GEP)-NETs in adults. There is limited information on GEP-NET treatment responses to Lutathera.Our institution launched a peptide receptor radionuclide therapy (PRRT) service line using Lutathera with involvement from a multidisciplinary team and complete collaboration between hospital administration and clinical providers. A prospective registry study was also established in order to collect patient demographics and clinical data regarding the treatment of GEP primary NETs with Lutathera.Between August 2018 and July 2020, 35 GEP-NET patients were treated with Lutathera, of which 65.71% received 4 complete cycles and 25.71% received 3 cycles; 5.71% and 2.86% received 2 and 1 cycles of PRRT, respectively. Most adverse events during the course of our study were low grade using the common terminology criteria for adverse events system. Of the patients who completed all 4 cycles: 22% showed partial response to Lutathera, 44% showed stable disease, and 13% showed disease progression based on a qualitative assessment of positron emission tomography/computed tomography imaging.From our experience, Lutathera was well tolerated in patients with GEP-NET. Additional studies are needed to examine long-term clinical and patient-reported outcomes associated with GEP-NET treatment as well as financial considerations for hospitals embarking on a PRRT program.

Bio-vehicles of cytotoxic drugs for delivery to tumor specific targets for cancer precision therapy

Abnormal structural and molecular changes in malignant tissues were thoroughly investigated and utilized to target tumor cells, hence rescuing normal healthy tissues and lowering the unwanted side effects as non-specific cytotoxicity. Various ligands for cancer cell specific markers have been uncovered and inspected for directional delivery of the anti-cancer drug to the tumor site, in addition to diagnostic applications. Over the past few decades research related to the ligand targeted therapy (LTT) increased tremendously aiming to treat various pathologies, mainly cancers with well exclusive markers. Malignant tumors are known to induce elevated levels of a variety of proteins and peptides known as cancer "markers" as certain antigens (e.g., Prostate specific membrane antigen "PSMA", carcinoembryonic antigen "CEA"), receptors (folate receptor, somatostatin receptor), integrins (Integrin αvβ3) and cluster of differentiation molecules (CD13). The choice of an appropriate marker to be targeted and the design of effective ligand-drug conjugate all has to be carefully selected to generate the required therapeutic effect. Moreover, since some tumors express aberrantly high levels of more than one marker, some approaches investigated targeting cancer cells with more than one ligand (dual or multi targeting). We aim in this review to report an update on the cancer-specific receptors and the vehicles to deliver cytotoxic drugs, including recent advancements on nano delivery systems and their implementation in targeted cancer therapy. We will discuss the advantages and limitations facing this approach and possible solutions to mitigate these obstacles. To achieve the said aim a literature search in electronic data bases (PubMed and others) using keywords "Cancer specific receptors, cancer specific antibody, tumor specific peptide carriers, cancer overexpressed proteins, gold nanotechnology and gold nanoparticles in cancer treatment" was carried out.

Survival predictors of 177Lu-Dotatate peptide receptor radionuclide therapy (PRRT) in patients with progressive well-differentiated neuroendocrine tumors (NETS)

Purpose

¹⁷⁷Lu-Dotatate is an emerging treatment modality for patients with unresectable or metastatic well-differentiated NETs. This study examines survival predictors in patients who received ¹⁷⁷Lu-Dotatate.

Methods

A retrospective single-center review was conducted, examining 47 individuals with progressive well-differentiated NETs treated with ¹⁷⁷Lu-Dotatate (four induction cycles of 5.5 GBq at 10-week intervals followed by eight maintenance cycles of 3.7 GBq at 6-month intervals).

Results

Median follow-up was 63.1 months with a median progression-free survival (PFS) of 34.1 months. However, median overall survival (OS) was not reached at the time of analysis. The presence of ≥ 5 bone metastases (hazard ratio HR 4.33; p = 0.015), non-gastroenteropancreatic (non-GEP) NETs (HR 3.22; p = 0.025) and development of interim ascites (HR 3.15; p = 0.047) independently predicted a worse OS. Patients with chromogranin A of ≥ 4 × upper limit of normal (ULN) had shorter OS (p < 0.001) and PFS (p = 0.004). Similarly, those with pre-existing ascites demonstrated a worse OS (p = 0.009) and PFS (p = 0.026). Liver metastases involving greater than 50% liver volume and the existence of unusual metastatic locations had a negative impact on OS (p = 0.033) and PFS (p = 0.026), respectively.

Conclusion

High burden of skeletal and hepatic metastases, non-GEP-NETs, chromogranin A of ≥ 4 × ULN, unusual metastatic sites, pre-existing and interim ascites are predictors of poor outcomes in patients treated with ¹⁷⁷Lu-Dotatate. These common indicators can be used for the risk stratification and identification of patients most likely to benefit from PRRT.

Trial registration

ClinicalTrials.gov identifier: NCT02236910, Retrospectively registered on September, 2014.

177Lu-DOTATATE Peptide Receptor Radionuclide Therapy: Indigenously Developed Freeze Dried Cold Kit and Biological Response in In-Vitro and In-Vivo Models

Somatostatin receptors (SStR) based ¹⁷⁷Lu-DOTATATE therapy is known as one of the highly effective neuroendocrine tumors (NETs) treatment strategy. Development of DOTATATE freeze-dried kit for imaging and therapy of SStR positive NETs is a prime goal in neuroendocrine cancer research. The present work describes the development of ¹⁷⁷Lu-DOTATATE freeze dried cold kit for indigenous needs, through technology development fund (TDF) program offered by Higher Education Commission (HEC) Pakistan. The parameters for freeze dried kit production was optimized and tested the stored lyophilized cold kits for different time intervals after labeling with ¹⁷⁷Lu radioisotope. The effect of ligand to radionuclide ratio, pH and reaction time at 90°C was recorded. Five times greater molar concentration of ligand, pH 5 and 30 min reaction time were the effective reaction conditions for maximum radiochemical yield. The radiolabeling yield at 1 day, 1-week and 4-week post storing period showed ∼100% radiochemical yield. The biodistribution study using rat model depicted the absence of non-targeted accumulation while glomerular filtration rate also explains the rapid renal washout. Cytotoxicity study showed quite favorable results for subjecting the radiopharmaceutical to clinical practice in Pakistan.

Cardiotoxicity and cardiac monitoring following the use of radiotheranostics agents including 177Lu-PSMA for prostate cancer and 177Lu-DOTATATE for neuroendocrine tumors

BACKGROUND

 The aim of this study was to determine the probable cardiotoxicity following radionuclide therapy (RNT), specifically peptide receptor radionuclide therapy (PRRT) with ¹⁷⁷Lu-DOTATATE and radioligand therapy (RLT) with ¹⁷⁷Lu-PSMA by evaluation of serum troponin I and cardiac profile change during a follow-up time.

MATERIALS AND METHODS

 Patients with prostate cancer and neuroendocrine tumours (NETs) referred for PRRT and RLT, respectively, were enrolled in this study. The cardiac profiles of the patients were evaluated by a cardiologist and a cardiac history was obtained from all patients. Also, troponin I was measured before and 48 hours after treatment.

RESULTS

 In this retrospective study for assessment of RLT associated cardiotoxicity, 24 patients were evaluated with a median age of 64 years (27-99 years) including 13 NET patients and 11 prostate cancer patients. Patients were followed up for 4 to 31 months which no cardiovascular problem was observed. In evaluation of troponin I, 39 RNT cycles were evaluated. In all patients, the value of troponin I was in normal range. In all patients, the median values of serum troponin I before and after treatment were 0.2 ± 0.02 (range: 0.00-0.42) and 0.28 ± 0.02 (range: 0.00-0.46) ng/ml, respectively (p > 0.05). In the prostate cancer patients, the median values of serum troponin I before and after treatment were 0.26 ± 0.04 (0.04-0.42) and 0.30 ± 0.04 (0.00-0.41) ng/ml, respectively (p > 0.05). In the NET patients, the median values of serum troponin I before and after treatment were 0.18 ± 0.03 (0.00-0.42) and 0.17 ± 0.03 (0.00-0.46) ng/ml, respectively (p > 0.05).

CONCLUSION

 PRRT with ¹⁷⁷Lu-DOTATATE and RLT with ¹⁷⁷Lu-PSMA as emerging therapeutic modalities have no significant cardiotoxicity. However, further well-designed studies are recommended.