Abstract 944: Chemokine receptor signaling as a new tool to improve lung cancer diagnostics and therapy

Background: The tumor microenvironment plays a critical role in cancer development, progression, and control. We demonstrated in vitro and in vivo that a bidirectional crosstalk between tumor-associated macrophages and cancer cells via CCR2-CCL2 and CX3CR1-CXCL1 signaling is fundamental for lung cancer growth and metastasis offers new treatment concepts.

Aim: Our working hypothesis is to develop a new platform for specific chemokine receptor (CCR2) PET imaging and a range of theranostic applications in lung cancer. For this purpose, we planned to define the CCR2 expression in NSCLC as well as in SCLC, tumor cells as well as immune/inflammatory cells.

Material and Methods: This is a multicenter trial with patients from Zentralklinik Bad Berka GmbH (n =100 NSCLC, n=100 SCLC). All patients gave informed consent according to the declaration of Helsinki. FFPE material was available in all cases. CCR2 CXCR4 and CX3CR1 expression was determined by immunohistochemistry with the avidin-biotin-peroxidase-complex.

Results: Analyzing 96 NSCLC (47 adenocarcinoma, 49 squamous cell carcinoma) and 45 SCLC tumor samples, we found CXCR4 and CCR2 chemokine receptor expression in tumor, immune and inflammatory cells. In NSCLC, co-expression between CCR2 and CXCR4 staining was very high concerning their expression on tumor cells rising with higher tumor stages, proliferation rate and grading. CCR2 expression in immune cells was restricted to lower stages; the same pattern could be observed in 45 SCLC tumor samples where CCR2 expression on immune cells was found especially in limited disease rather than in metastatic disease; CXCR4 expression in tumor cells was found to be high in all stages of SCLC. To evaluate the therapeutic efficacy of CCR2 antagonism in vivo, we injected LLC1 s.c. into WT mice treated with CCR2 antagonist (RS504393) or vehicle. Notably, tumor growth was significantly inhibited in CCR2 antagonist-treated mice as compared with vehicle-treated mice.

Discussion: Our preliminary results show a significant portion of CCR2 positive tumors - NSCLC as well as SCLC which would qualify for a CCR2-based imaging as well as - demonstrated in our mice models - CCR2 inhibitory strategies. This should be evaluated in further preclinical trials.

Citation Format: Katalin Nagy-Major, Jörg Sänger, Harshad R. Kulkarni, Peter Fix, Almut Kunze, Amelie Lupp, Reiner Bonnet, Werner Seeger, Richard P. Baum, Patricia Grabowski, Rajkumar Savai. Chemokine receptor signaling as a new tool to improve lung cancer diagnostics and therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 944. doi:10.1158/1538-7445.AM2017-944

CEA, CA15.3 and 18-FDG PET in the follow-up of early breast cancer (BC) patients (pts): A prospective, multicentric, randomized trial—KRONOS patient-oriented new surveillance study Italy

TPS11627

Background: Current recommendations for breast cancer (BC) surveillance in asymptomatic patients (pts) include only mammography and physical examination and arise from two trials conducted in the 80’s. Since then new findings about BC biology, treatment and the introduction of cutting-edge diagnostic technologies such as 18-FDG PET have deeply modified our clinical scenarios. The aim of this prospective randomized trial is to verify if the serial measurement of CEA and CA15-3 followed by 18-FDG PET can anticipate the diagnosis of BC recurrence compared to control arm by estimation of the difference of restricted mean survival time (RMST) between the two arms. If the end-point will be met a subsequent extension trial will investigate the impact of the earlier diagnosis of distant metastases on survival. Methods: Pts diagnosed with stage I-III BC, who underwent adequate surgery are eligible. Special histologies and low-risk cases according to St. Gallen criteria are excluded. The study includes pts at the beginning of the follow-up after the conclusion of primary treatment (cohort 1), and pts that have concluded without relapse the first 5 years of follow-up (cohort 2). Eligible pts will be randomized in a 1:1 ratio to follow-up according to local practice (control arm) or to three-monthly serial dosing of CEA and CA15-3 and subsequent 18 FDG-PET only in case of an increase of CEA and/or CA 15.3 greater than a critical difference compared to baseline (experimental arm). The following stratification factors will be used: node negative vs positive, HER2 negative vs positive, ER positive vs negative. Eight-hundred pts will be enrolled over 3 years. For such a calculation, we made the assumption of a 20% baseline 5-year incidence of relapse. The target reduction of three months in RMST implies a median time of diagnostic anticipation, conditional on having BC recurrence, of 10 months. The follow-up will continue until 10 years from surgery. Since 23rd October 2014 573 pts have been enrolled. The present trial was approved by the Ethical Committee of each participating centre and is registered on Clinical trial information: NCT02261389.

Surgery in combination with peptide receptor radionuclide therapy is effective in metastatic neuroendocrine tumors and is definable by blood gene transcript analysis

e15697

Background: Neuroendocrine tumours (NET) of the pancreas (PNET) or small bowel (SBNET) frequently present with metastases at initial diagnosis, undermining the efficacy of surgical treatment. Peptide receptor radionuclide therapy (PRRT) with radiolabelled somatostatin analogues, 90Y-DOTATOC and 177Lu-DOTATATE, has been shown to achieve prolonged progression-free survival (PFS) in a substantial number of non-surgical patients with advanced NET. Our aim was to prospectively determine the efficacy of a combination of radical loco-regional surgery and PRRT in patients with metastasised NET. Methods: A set of inclusion criteria was defined (e.g. G1/G2 NET, initial tumour diagnosis, treatment naïve patient, stage IV NET, positivity on 68Ga DOTA- PET/CT, eligibility for surgery and PRRT). Patients underwent PRRT within 3 months following surgery. Follow-up included biochemistry and imaging. In a sub-cohort, blood-based neuroendocrine gene transcript analysis of 51 genes (NETest) was used to define the effectiveness of treatment. Outcome measures included 5-year overall survival (OS) and PFS from initial diagnosis. Results: Twenty-five patients (5 PNET, 20 SBNET) met eligibility criteria and were included. There were 13 men (52%) and mean age was 57.1 years. All patients with SB NET underwent right hemicolectomy, terminal ileal resection and mesenteric lympadenectomy. In all PNET patients only limited pancreatic resection was required. The median number of PRRT cycles was 4 (range 2-6). Post-treatment mortality was 0%. Surgical morbidity was 12% (all Clavien-Dindo grade 1). Transient grade 1 toxicity occurred post-PRRT in 40%. NETest scores were increased in 8 patients (100%) pre-operatively and decreased in all following treatment. NETest decreases correlated with diminished tumour volume (R2=0.37, p=0.02). Median follow-up was 48 months (range 12-72months). Five-year OS was 90% and 5-year PFS was 84.3%. Conclusions: Radical loco-regional surgery for primary tumours combined with PRRT provides a novel, highly efficacious approach in metastasised NET. The NETest accurately measures the effectiveness of treatment.

Blood measurements of neuroendocrine tumor (NET) transcripts and gene cluster analysis to predict efficacy of peptide radioreceptor therapy

4091

Background: Peptide receptor radionuclide therapy (PRRT) capitalizes on somatostatin receptor (SSR) overexpression on NETs to deliver targeted isotope therapy. Objective prediction of efficacy remains to be established. Functional imaging of SSR expression (SRE) is used as a predictor of efficacy. Biomarkers e.g. circulating CgA, are ineffective. Circulating NET transcript analysis (NETest) integrated with tumor grade provides a Predictive Quotient Index (PQI) of PRRT. We validated the utility of this PRRT complementary diagnostic in a prospective, blinded study. Methods: 177Lu-PRRT (29.1±2.2 GBq). NETs ( n= 35); with progressive disease (66%). Baseline evaluations: Clinical status, Grade (Ki67), SRE, CgA (NeoLisa, ULN > 108ng/ml), and NETest (qRT-PCR - multianalyte algorithmic analyses, ULN > 14%). PQI: “omic” NETest gene expression (regulating metabolism and growth factor signaling) mathematically combined with Ki67 index. PQI has two prediction outputs: “responder” (R) vs “non-responder” (NR). Disease control was by RECIST criteria (R vs NR). All samples were blinded. Statistics: Cox proportional multiple regression, Kaplan-Meier survival, & McNemar-test. Results: At restaging, the overall response (disease control rate) was 77%; median PFS not reached (follow-up 4-13 months). Histology: GI: 5; GII: 21; GIII 1; and lung: TC: 2; AC: 5. SRE was Grade 3 (80%). Baseline CgA was 1556±1454ng/ml (89% elevated) and NETest was 60±21% (100% elevated) respectively. Predictive accuracies of SRE, clinical status, CgA levels ( > 2ULN) and NETest ranged from 25-54% (not-significant). PQI was the only predictive marker by multivariate analysis ( p= 0.002). The PQI diagnostic was 92% concordant with outcome and significantly more accurate than all other markers (McNemar: p< 0.002). Cox-proportional modeling confirmed PQI utility (OR: 9.1, p< 0.004). K-MS analysis identified significantly different mPFS between R (not reached) and NR (9.3 months; HR: 8.3, p< 0.0005). Conclusions: A pre-PRRT analysis of circulating NET genes, the predictive quotient index comprising “omic” analysis and grading, is validated to predict the efficacy of PRRT therapy in GEP and lung NETs.

Novel Radiolabeled Bisphosphonates for PET Diagnosis and Endoradiotherapy of Bone Metastases

Bone metastases, often a consequence of breast, prostate, and lung carcinomas, are characterized by an increased bone turnover, which can be visualized by positron emission tomography (PET), as well as single-photon emission computed tomography (SPECT). Bisphosphonate complexes of ^99mTc are predominantly used as SPECT tracers. In contrast to SPECT, PET offers a higher spatial resolution and, owing to the ⁶⁸Ge/⁶⁸Ga generator, an analog to the established ^99mTc generator exists. Complexation of Ga(III) requires the use of chelators. Therefore, DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), NOTA (1,4,7-triazacyclododecane-1,4,7-triacetic acid), and their derivatives, are often used. The combination of these macrocyclic chelators and bisphosphonates is currently studied worldwide. The use of DOTA offers the possibility of a therapeutic application by complexing the β-emitter ¹⁷⁷Lu. This overview describes the possibility of diagnosing bone metastases using [⁶⁸Ga]Ga-BPAMD (⁶⁸Ga-labeled (4-{[bis-(phosphonomethyl))carbamoyl]methyl}-7,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl)acetic acid) as well as the successful application of [¹⁷⁷Lu]Lu-BPAMD for therapy and the development of new diagnostic and therapeutic tools based on this structure. Improvements concerning both the chelator and the bisphosphonate structure are illustrated providing new ⁶⁸Ga- and ¹⁷⁷Lu-labeled bisphosphonates offering improved pharmacological properties.

Advances in the Diagnosis of Neuroendocrine Neoplasms

Somatostatin receptor PET/CT using (68)Ga-labeled somatostatin analogs, is a mainstay for the evaluation of the somatostatin receptor status in neuroendocrine neoplasms. In addition, the assessment of glucose metabolism by (18)F-FDG PET/CT at diagnosis can overcome probable shortcomings of histopathologic grading. This offers a systematic theranostic approach for the management of neuroendocrine neoplasms, that is, patient selection for the appropriate treatment-surgery, somatostatin analogs, peptide receptor radionuclide therapy, targeted therapies like everolimus and sunitinib, or chemotherapy-and also for therapy response monitoring. Novel targets, for example, the chemokine receptor CXCR4 in higher-grade tumors and glucagon like peptide-1 receptor in insulinomas, appear promising for imaging. Scandium-44 and Copper-64, especially on account of their longer half-life (for pretherapeutic dosimetry) and cyclotron production (which favors mass production), might be the potential alternatives to (68)Ga for PET/CT imaging. The future of molecular imaging lies in Radiomics, that is, qualitative and quantitative characterization of tumor phenotypes in correlation with tumor genomics and proteomics, for a personalized cancer management.

PSMA-Based Radioligand Therapy for Metastatic Castration-Resistant Prostate Cancer: The Bad Berka Experience Since 2013

A potential milestone in personalized nuclear medicine is theranostics of metastatic castration-resistant prostate cancer (mCRPC) based on molecular imaging using PET/CT with ⁶⁸Ga-labeled prostate-specific membrane antigen (PSMA) ligands and molecular radiotherapy using PSMA-targeted radioligand therapy (PRLT) with ¹⁷⁷Lu-PSMA ligands. ⁶⁸Ga-PSMA PET/CT enables accurate detection of mCRPC lesions with high diagnostic sensitivity and specificity and provides quantitative and reproducible data that can be used to select patients for PRLT and therapeutic monitoring. Our comprehensive experience over the last 3 years using different radioligands indicates that PRLT is highly effective for the treatment of mCRPC, even in advanced cases, and potentially lends a significant benefit to overall and progression-free survival. Additionally, significant improvement in clinical symptoms and excellent palliation of pain can be achieved.

Safety and efficacy of 177lu-PSMA-617 radioligand therapy in patients with mCRPC: A multicenter study

155

Background: Prostate specific membrane antigen (PSMA) is a promising target for imaging and therapy of prostate cancer. Small cohorts trials have shown promising results for response and tolerability of 177Lu-PSMA-617 radioligand therapy (RLT) in patients with metastatic castration-resistant disease. The aim of this multicenter study was to investigate safety and efficacy of this new therapy in a large, multicenter cohort. Methods: Data of 145 patients with metastatic castration resistant prostate cancer treated with at least a single dose of 177Lu-PSMA-617 at 12 therapy centers in Germany (median age 73 years, range 43-88) were collected. Up to 4 therapy cycles (range of administered activity 2 – 8 GBq) were given. Toxicity was categorized by the common toxicity criteria for adverse events based on serial blood tests and the physician’s report. Biochemical response was defined by a PSA decline ≥ 50% from baseline. Results: 248 therapy cycles were performed. Data for biochemical response were available in 99 patients and data for physician-reported and lab-based toxicity in 145 and 121 patients. The median follow-up was 16 weeks (range 2-30 weeks). Nineteen patients died during the observation period. Grade 3 to 4 hematotoxicity occurred in 18 patients: 10%, 4% and 3% of the patients experienced anemia, thrombocytopenia and leukopenia, respectively. Xerostomia occurred in 8%. Overall biochemical response rate was 45% following all therapy cycles. Elevated alkaline phosphatase and presence of visceral metastases were negatively correlated and the total number of therapy cycles correlated positively with biochemical response. 22 of 31 patients with no PSA decline > 50% after the first cycle did not respond to the second therapy cycle. Conclusions: Radioligand therapy with 177Lu-PSMA-617 shows promising response rates and a low toxicity in extensively pretreated patients with prostate cancer. Future prospective trials have to evaluate the effect of RLT on survival and potentially be considered in earlier stages of prostate cancer.

Quality-of-life findings in patients with midgut neuroendocrine tumors: Results of the NETTER-1 phase III trial

348

Background: Neuroendocrine tumor progression is associated with decline in quality of life, both due to tumor and hormone-related symptoms. The Phase III NETTER-1 trial randomized patients with advanced, progressive midgut NETs to receive treatment with 177Lu-DOTATATE (177Lu; Lutathera) versus high-dose (60 mg) Octreotide LAR (Oct). EORTC questionnaires C30 and GINET21 were assessed during the trial in order to determine the impact of treatment on health-related quality of life (HRQoL). Methods: Patients completed EORTC QLQ-30 and QLQ-G.I.NET21 questionnaires at baseline and every 12 weeks thereafter until disease progression. Raw scores were converted to a 100-point scale and individual changes from baseline scores were assessed. Clinically relevant ( ≥ 10 point) deterioration/improvement was considered clinically significant. Results: Clinically and statistically significant improvements in QoL were observed in the 177Lu arm versus the Oct arm at certain time points in key domains of HRQoL including global health status and diarrhea. In mean, global health status improved in 28% of patients on 177Lu arm vs. 15% on Oct, and worsened in 18% of patients on 177Lu vs. 26% on Oct. Diarrhea improved in 39% of patients on 177Lu vs. 23% on Oct, and worsened in 19% of patients on 177Lu vs. 23% on Oct. There was a trend towards improvement in pain that was not statistically significant. Flushing appeared to improve compared to baseline in both arms of the study with no clear advantage to treatment with 177Lu vs. Oct. Conclusions: QoL analysis suggests benefit in important domains associated with 177Lu treatment compared to high-dose octreotide in patients with advanced midgut NETs, and confirms the treatment value of 177Lu on patient QoL, in addition to the meaningful increase in progression-free survival already reported. Clinical trial information: NCT01578239.

Phase 3 Trial of 177Lu-Dotatate for Midgut Neuroendocrine Tumors

BACKGROUND

Patients with advanced midgut neuroendocrine tumors who have had disease progression during first-line somatostatin analogue therapy have limited therapeutic options. This randomized, controlled trial evaluated the efficacy and safety of lutetium-177 (¹⁷⁷Lu)-Dotatate in patients with advanced, progressive, somatostatin-receptor-positive midgut neuroendocrine tumors.

METHODS

We randomly assigned 229 patients who had well-differentiated, metastatic midgut neuroendocrine tumors to receive either ¹⁷⁷Lu-Dotatate (116 patients) at a dose of 7.4 GBq every 8 weeks (four intravenous infusions, plus best supportive care including octreotide long-acting repeatable [LAR] administered intramuscularly at a dose of 30 mg) (¹⁷⁷Lu-Dotatate group) or octreotide LAR alone (113 patients) administered intramuscularly at a dose of 60 mg every 4 weeks (control group). The primary end point was progression-free survival. Secondary end points included the objective response rate, overall survival, safety, and the side-effect profile. The final analysis of overall survival will be conducted in the future as specified in the protocol; a prespecified interim analysis of overall survival was conducted and is reported here.

RESULTS

At the data-cutoff date for the primary analysis, the estimated rate of progression-free survival at month 20 was 65.2% (95% confidence interval [CI], 50.0 to 76.8) in the ¹⁷⁷Lu-Dotatate group and 10.8% (95% CI, 3.5 to 23.0) in the control group. The response rate was 18% in the ¹⁷⁷Lu-Dotatate group versus 3% in the control group (P<0.001). In the planned interim analysis of overall survival, 14 deaths occurred in the ¹⁷⁷Lu-Dotatate group and 26 in the control group (P=0.004). Grade 3 or 4 neutropenia, thrombocytopenia, and lymphopenia occurred in 1%, 2%, and 9%, respectively, of patients in the ¹⁷⁷Lu-Dotatate group as compared with no patients in the control group, with no evidence of renal toxic effects during the observed time frame.

CONCLUSIONS

Treatment with ¹⁷⁷Lu-Dotatate resulted in markedly longer progression-free survival and a significantly higher response rate than high-dose octreotide LAR among patients with advanced midgut neuroendocrine tumors. Preliminary evidence of an overall survival benefit was seen in an interim analysis; confirmation will be required in the planned final analysis. Clinically significant myelosuppression occurred in less than 10% of patients in the ¹⁷⁷Lu-Dotatate group. (Funded by Advanced Accelerator Applications; NETTER-1 ClinicalTrials.gov number, NCT01578239 ; EudraCT number 2011-005049-11 .).

Phase 3 Trial of 177Lu-Dotatate for Midgut Neuroendocrine Tumors

BACKGROUND

Patients with advanced midgut neuroendocrine tumors who have had disease progression during first-line somatostatin analogue therapy have limited therapeutic options. This randomized, controlled trial evaluated the efficacy and safety of lutetium-177 (¹⁷⁷Lu)-Dotatate in patients with advanced, progressive, somatostatin-receptor-positive midgut neuroendocrine tumors.

METHODS

We randomly assigned 229 patients who had well-differentiated, metastatic midgut neuroendocrine tumors to receive either ¹⁷⁷Lu-Dotatate (116 patients) at a dose of 7.4 GBq every 8 weeks (four intravenous infusions, plus best supportive care including octreotide long-acting repeatable [LAR] administered intramuscularly at a dose of 30 mg) (¹⁷⁷Lu-Dotatate group) or octreotide LAR alone (113 patients) administered intramuscularly at a dose of 60 mg every 4 weeks (control group). The primary end point was progression-free survival. Secondary end points included the objective response rate, overall survival, safety, and the side-effect profile. The final analysis of overall survival will be conducted in the future as specified in the protocol; a prespecified interim analysis of overall survival was conducted and is reported here.

RESULTS

At the data-cutoff date for the primary analysis, the estimated rate of progression-free survival at month 20 was 65.2% (95% confidence interval [CI], 50.0 to 76.8) in the ¹⁷⁷Lu-Dotatate group and 10.8% (95% CI, 3.5 to 23.0) in the control group. The response rate was 18% in the ¹⁷⁷Lu-Dotatate group versus 3% in the control group (P<0.001). In the planned interim analysis of overall survival, 14 deaths occurred in the ¹⁷⁷Lu-Dotatate group and 26 in the control group (P=0.004). Grade 3 or 4 neutropenia, thrombocytopenia, and lymphopenia occurred in 1%, 2%, and 9%, respectively, of patients in the ¹⁷⁷Lu-Dotatate group as compared with no patients in the control group, with no evidence of renal toxic effects during the observed time frame.

CONCLUSIONS

Treatment with ¹⁷⁷Lu-Dotatate resulted in markedly longer progression-free survival and a significantly higher response rate than high-dose octreotide LAR among patients with advanced midgut neuroendocrine tumors. Preliminary evidence of an overall survival benefit was seen in an interim analysis; confirmation will be required in the planned final analysis. Clinically significant myelosuppression occurred in less than 10% of patients in the ¹⁷⁷Lu-Dotatate group. (Funded by Advanced Accelerator Applications; NETTER-1 ClinicalTrials.gov number, NCT01578239 ; EudraCT number 2011-005049-11 .).

Rapid Synthesis of 68Ga-labeled macroaggregated human serum albumin (MAA) for routine application in perfusion imaging using PET/CT

^99mTc-labeled MAA is commonly used for single photon emission computed tomography SPECT. In contrast, positron emission tomography/CT (PET/CT) delivers images with significantly higher resolution. The generator produced radionuclide ⁶⁸Ga is widely used for PET/CT imaging agents and ⁶⁸Ga-labeled MAA represents an attractive alternative to ^99mTc-labeled MAA. We report a simple and rapid NaCl based labeling procedure for the labeling of MAA with ⁶⁸Ga using a commercially available MAA labeling kit for ^99mTc. The procedure delivers ⁶⁸Ga-labeled MAA with a high specific activity and a high labeling efficiency (>99%). The synthesis does not require a final step of separation or the use of organic solvents.

Clinical evaluation of the radiolanthanide terbium-152: first-in-human PET/CT with 152Tb-DOTATOC

The existence of theragnostic pairs of radionuclides allows the preparation of radiopharmaceuticals for diagnostic and therapeutic purposes.

German Multicenter Study Investigating 177Lu-PSMA-617 Radioligand Therapy in Advanced Prostate Cancer Patients

¹⁷⁷Lu-labeled PSMA-617 is a promising new therapeutic agent for radioligand therapy (RLT) of patients with metastatic castration-resistant prostate cancer (mCRPC). Initiated by the German Society of Nuclear Medicine, a retrospective multicenter data analysis was started in 2015 to evaluate efficacy and safety of ¹⁷⁷Lu-PSMA-617 in a large cohort of patients.

METHODS

One hundred forty-five patients (median age, 73 y; range, 43-88 y) with mCRPC were treated with ¹⁷⁷Lu-PSMA-617 in 12 therapy centers between February 2014 and July 2015 with 1-4 therapy cycles and an activity range of 2-8 GBq per cycle. Toxicity was categorized by the common toxicity criteria for adverse events (version 4.0) on the basis of serial blood tests and the attending physician's report. The primary endpoint for efficacy was biochemical response as defined by a prostate-specific antigen decline ≥ 50% from baseline to at least 2 wk after the start of RLT.

RESULTS

A total of 248 therapy cycles were performed in 145 patients. Data for biochemical response in 99 patients as well as data for physician-reported and laboratory-based toxicity in 145 and 121 patients, respectively, were available. The median follow-up was 16 wk (range, 2-30 wk). Nineteen patients died during the observation period. Grade 3-4 hematotoxicity occurred in 18 patients: 10%, 4%, and 3% of the patients experienced anemia, thrombocytopenia, and leukopenia, respectively. Xerostomia occurred in 8%. The overall biochemical response rate was 45% after all therapy cycles, whereas 40% of patients already responded after a single cycle. Elevated alkaline phosphatase and the presence of visceral metastases were negative predictors and the total number of therapy cycles positive predictors of biochemical response.

CONCLUSION

The present retrospective multicenter study of ¹⁷⁷Lu-PSMA-617 RLT demonstrates favorable safety and high efficacy exceeding those of other third-line systemic therapies in mCRPC patients. Future phase II/III studies are warranted to elucidate the survival benefit of this new therapy in patients with mCRPC.

German Multicenter Study Investigating 177Lu-PSMA-617 Radioligand Therapy in Advanced Prostate Cancer Patients

¹⁷⁷Lu-labeled PSMA-617 is a promising new therapeutic agent for radioligand therapy (RLT) of patients with metastatic castration-resistant prostate cancer (mCRPC). Initiated by the German Society of Nuclear Medicine, a retrospective multicenter data analysis was started in 2015 to evaluate efficacy and safety of ¹⁷⁷Lu-PSMA-617 in a large cohort of patients.

METHODS

One hundred forty-five patients (median age, 73 y; range, 43-88 y) with mCRPC were treated with ¹⁷⁷Lu-PSMA-617 in 12 therapy centers between February 2014 and July 2015 with 1-4 therapy cycles and an activity range of 2-8 GBq per cycle. Toxicity was categorized by the common toxicity criteria for adverse events (version 4.0) on the basis of serial blood tests and the attending physician's report. The primary endpoint for efficacy was biochemical response as defined by a prostate-specific antigen decline ≥ 50% from baseline to at least 2 wk after the start of RLT.

RESULTS

A total of 248 therapy cycles were performed in 145 patients. Data for biochemical response in 99 patients as well as data for physician-reported and laboratory-based toxicity in 145 and 121 patients, respectively, were available. The median follow-up was 16 wk (range, 2-30 wk). Nineteen patients died during the observation period. Grade 3-4 hematotoxicity occurred in 18 patients: 10%, 4%, and 3% of the patients experienced anemia, thrombocytopenia, and leukopenia, respectively. Xerostomia occurred in 8%. The overall biochemical response rate was 45% after all therapy cycles, whereas 40% of patients already responded after a single cycle. Elevated alkaline phosphatase and the presence of visceral metastases were negative predictors and the total number of therapy cycles positive predictors of biochemical response.

CONCLUSION

The present retrospective multicenter study of ¹⁷⁷Lu-PSMA-617 RLT demonstrates favorable safety and high efficacy exceeding those of other third-line systemic therapies in mCRPC patients. Future phase II/III studies are warranted to elucidate the survival benefit of this new therapy in patients with mCRPC.

64Cu-PSMA-617 PET/CT Imaging of Prostate Adenocarcinoma: First In-Human Studies

AIM

The prostate-specific membrane antigen (PSMA) is a cell surface protein, which is overexpressed in nearly all cases of prostate cancer (PCa). PET imaging with ⁶⁸Ga-PSMA-HBED-CC has recently found widespread application in the diagnosis of recurrent PCa. In this study, the diagnostic potential of ⁶⁴Cu-labeled PSMA ligand (PSMA-617) PET in patients with PCa has been investigated.

MATERIALS AND METHODS

The study was conducted simultaneously at two nuclear medicine centers, Austria (Vienna, Center 1) and Germany (Bad Berka, Center 2). The patients (n = 29) included in this study were referred for PET (Center 1, 21 patients) or PET/CT (Center 2, 8 patients) imaging with either a high suspicion of recurrent disease or for possible surgical or PSMA radioligand therapy planning. PET images of the whole body were performed at 1 hour p.i. and additional images of the pelvis at 2 hours p.i.

RESULTS

In 23 of 29 patients, at least one focus of pathological tracer uptake suspicious for primary disease in the prostate lobe or recurrent disease was detected. Among healthy organs, the salivary glands, kidneys, and liver showed the highest radiotracer uptake. Lesions suspicious for PCa were detected with excellent contrast as early as 1 hour p.i. with high detection rates even at low prostate-specific antigen (PSA) levels.

CONCLUSION

The preliminary results of this study demonstrate the high potential of ⁶⁴Cu-PSMA ligand PET/CT imaging in patients with recurrent disease and in the primary staging of selected patients with progressive local disease. The acquired PET images showed an excellent resolution of the detected lesions with very high lesion-to- background contrast. Furthermore, the long half-life of ⁶⁴Cu allows distribution of the tracer to clinical PET centers that lack radiochemistry facilities for the preparation of ⁶⁸Ga-PSMA ligand (satellite concept).

Investigating the Effect of Ligand Amount and Injected Therapeutic Activity: A Simulation Study for 177Lu-Labeled PSMA-Targeting Peptides

In molecular radiotherapy with ¹⁷⁷Lu-labeled prostate specific membrane antigen (PSMA) peptides, kidney and/or salivary glands doses limit the activity which can be administered. The aim of this work was to investigate the effect of the ligand amount and injected activity on the tumor-to-normal tissue biologically effective dose (BED) ratio for ¹⁷⁷Lu-labeled PSMA peptides. For this retrospective study, a recently developed physiologically based pharmacokinetic model was adapted for PSMA targeting peptides. General physiological parameters were taken from the literature. Individual parameters were fitted to planar gamma camera measurements (¹⁷⁷Lu-PSMA I&T) of five patients with metastasizing prostate cancer. Based on the estimated parameters, the pharmacokinetics of tumor, salivary glands, kidneys, total body and red marrow was simulated and time-integrated activity coefficients were calculated for different peptide amounts. Based on these simulations, the absorbed doses and BEDs for normal tissue and tumor were calculated for all activities leading to a maximal tolerable kidney BED of 10 Gy_2.5/cycle, a maximal salivary gland absorbed dose of 7.5 Gy/cycle and a maximal red marrow BED of 0.25 Gy₁₅/cycle. The fits yielded coefficients of determination > 0.85, acceptable relative standard errors and low parameter correlations. All estimated parameters were in a physiologically reasonable range. The amounts (for 2⁵−2⁹ nmol) and pertaining activities leading to a maximal tumor dose, considering the defined maximal tolerable doses to organs of risk, were calculated to be 272±253 nmol (452±420 μg) and 7.3±5.1 GBq. Using the actually injected amount (235±155 μg) and the same maximal tolerable doses, the potential improvement for the tumor BED was 1–3 fold. The results suggest that currently given amounts for therapy are in the appropriate order of magnitude for many lesions. However, for lesions with high binding site density or lower perfusion, optimizing the peptide amount and activity might improve the tumor-to-kidney and tumor-to-salivary glands BED ratio considerably.

A Delphic consensus assessment: imaging and biomarkers in gastroenteropancreatic neuroendocrine tumor disease management

The complexity of the clinical management of neuroendocrine neoplasia (NEN) is exacerbated by limitations in imaging modalities and a paucity of clinically useful biomarkers. Limitations in currently available imaging modalities reflect difficulties in measuring an intrinsically indolent disease, resolution inadequacies and inter-/intra-facility device variability and that RECIST (Response Evaluation Criteria in Solid Tumors) criteria are not optimal for NEN. Limitations of currently used biomarkers are that they are secretory biomarkers (chromogranin A, serotonin, neuron-specific enolase and pancreastatin); monoanalyte measurements; and lack sensitivity, specificity and predictive capacity. None of them meet the NIH metrics for clinical usage. A multinational, multidisciplinary Delphi consensus meeting of NEN experts (n = 33) assessed current imaging strategies and biomarkers in NEN management. Consensus (>75%) was achieved for 78% of the 142 questions. The panel concluded that morphological imaging has a diagnostic value. However, both imaging and current single-analyte biomarkers exhibit substantial limitations in measuring the disease status and predicting the therapeutic efficacy. RECIST remains suboptimal as a metric. A critical unmet need is the development of a clinico-biological tool to provide enhanced information regarding precise disease status and treatment response. The group considered that circulating RNA was better than current general NEN biomarkers and preliminary clinical data were considered promising. It was resolved that circulating multianalyte mRNA (NETest) had clinical utility in both diagnosis and monitoring disease status and therapeutic efficacy. Overall, it was concluded that a combination of tumor spatial and functional imaging with circulating transcripts (mRNA) would represent the future strategy for real-time monitoring of disease progress and therapeutic efficacy.

[177Lu-PSMA-617 therapy, dosimetry and follow-up in patients with metastatic castration-resistant prostate cancer]

Radioligand therapy (RLT) using 177Lu labelled inhibitors of the prostate-specific membrane antigen (177Lu-PSMA) is performed in patients with metastatic castration-resistant prostate cancer (mCRPC) after exhaustion of other options. German University Clinics offer RLT since 2013 on a compassionate use basis. The present consensus document includes recommendations for RLT with 177Lu-PSMA-617. These consensus statements were developed by an expert panel formed by the German Society of Nuclear Medicine (DGN) in December 2015. Statements include recommendations for indication, baseline tests, therapy protocol, concomitant therapy, dosimetry, and follow-up. Consensus recommendations aim to inform the attending medical staff, standardize 177Lu-PSMA-617 RLT, and improve quality of individual patient care.