Background: 177 LuPSMA is an effective treatment in metastatic castrate-resistant prostate cancer with trials adopting a standardised dose interval. Adjusting treatment intervals utilising early response biomarkers may improve patient outcomes. Objective: This study evaluated progression-free survival (PFS) and overall survival (OS) based on treatment interval adjustment utilising 177 LuPSMA 24-h SPECT/CT ( 177 Lu-SPECT) and early prostate-specific antigen (PSA) response. Design: Retrospective analysis of a clinical 177 Lu-PSMA-I&T treatment programme. Methods: In all, 125 men were treated with 6-weekly 177 LuPSMA-I&T [median 3 cycles, interquartile range (IQR): 2–4], median dose 8.0 GBq [95% confidence interval (CI): 7.5–8.0]. Imaging screening involved 68 GaPSMA-11 PET/diagnostic CT. 177 Lu-SPECT/diagnostic CT was acquired following each therapy, and clinical assessments 3-weekly. Following dose 2 (week 6), a composite PSA and 177 Lu-SPECT/CT imaging response [partial response (PR), stable disease (SD), and progressive disease (PD)] determined ongoing management. Response group (RG) 1 (marked reduction in PSA/imaging PR) break in treatment until subsequent PSA rise, then re-treatment. RG 2 (stable or reduced PSA and/or imaging SD) 6-weekly treatments until six doses, or no longer clinically benefitting. RG 3 (rise in PSA and/or imaging PD) recommended for an alternative treatment. Results: Overall PSA50% response rate (PSARR) was 60% (75/125), median PSA-PFS 6.1 months (95%CI: 5.5–6.7), and median OS 16.8 months (95%CI: 13.5–20.1). 35% (41/116) were classified as RG 1, 34% (39/116) RG 2, and 31% (36/116) RG 3. PSARRs by RG were 95% (38/41), 74% (29/39), and 8% (3/36); median PSA-PFS rates were 12.1 months (95%CI: 9.3–17.4), 6.1 months (95%CI: 5.8–9.0), and 2.6 months (95%CI: 1.6–3.1); and OS rates were 19.2 months (95%CI: 16.8–20.7), 13.2 months (95%CI: 12.0–18.8), and 11.2 months (95%CI: 8.7–15.6) for RG 1, 2, and 3, respectively. The median months of ‘treatment holiday’ for RG 1 was 6.1 months (IQR: 3.4–8.7). Nine men had received prior 177 LuPSMA-617 and were retreated with 177 LuPSMA-I&T, with a PSARR of 56% on re-treatment. Conclusion: Personalising dosing regimens using early response biomarkers with 177 LuPSMA has the potential to achieve similar treatment responses to continuous dosing while allowing treatment breaks or intensification. Further evaluation of early response biomarker-guided treatment regimens in prospective trials is warranted. Plain Language Summary Lutetium-PSMA therapy is a new therapy for metastatic prostate cancer that is well tolerated and effective. However, not all men respond equally, with some responding very well and others progressing early. Personalising treatments require tools that can accurately measure treatment responses, preferably early in the treatment course, so adjustments to treatment can be made. Lutetium-PSMA can measure tumour sites after each therapy by taking whole body 3D images at 24 h using a small radiation wave from the treatment itself. This is called a SPECT scan. Previous work has shown that both prostate-specific antigen (PSA) response and changes in tumour volume on a SPECT scan can predict how patients will respond to treatment as early as dose 2. This study demonstrates that stratifying how men are treated based on the results of the 6-week SPECT scan and PSA response potentially allows a third of men to have break in treatment and that these men have both longer time to disease progression and OS. Men with an increase in tumour volume and increase in PSA early in treatment (6 weeks) had shorter time to disease progression and OS. Men with early biomarker disease progression were offered alternative treatments early in an attempt to allow the opportunity to allow a more effective potential therapy, if one was available. The study is an analysis of a clinical programme, and was not a prospective trial. As such, there are potential biases that could influence results. Hence, while the study is encouraging for the use of early response biomarkers to guide better treatment decisions, this must be validated in a well-designed clinical trial.

Lu-PSMA-617 therapy has shown high prostate-specific antigen (PSA) response rates in men with metastatic castration-resistant pros-tate cancer. However, early treatment resistance is common. This LuPIN substudy aimed to determine the prognostic value of posttreatment quantitative PET for PSA progression-free survival (PFS) and overall survival (OS) with 177Lu-PSMA-617 therapy.Methods: Fifty-six men with progressive metastatic castration-resistant prostate cancer were enrolled in the LuPIN trial and received up to 6 doses of 177Lu-PSMA-617 and a radiation sensitizer (NOX66). 68Ga-PSMA-11 and 18F-FDG PET/CT, diagnostic CT, and bone scanning were performed at study entry and exit. Quantitative analysis tracked change in total tumor vol-ume (TTV) and SUV. Univariable and multivariable analyses were con-ducted to examine the association of change in TTV (continuous and >30%), SUVmax, PSA, and radiographic progression with PSA PFS and OS.Results: All men (37/56) who underwent both screening and post-treatment molecular imaging were analyzed; 70% (26/37) had a PSA response of more than 50%. Median PSA PFS was 8.6 mo, and median OS was 22 mo. Clinical progression had occurred at trial exit in 54% (20/37). In response to treatment, a reduced PSMA SUVmax was demon-strated in 95% (35/37) and a reduced PSMA TTV in 68% (25/37). An increase in PSMA TTV by at least 30% was associated with worse OS (median, 10.2 vs. 23.6 mo; P = 0.002). Change in PSMA SUVmax was not associated with PSA PFS or OS. 18F-FDG SUVmax was reduced in 51% (18/35) and 18F-FDG TTV in 67% (22/35). An increased 18F-FDG SUVmax was associated with worse OS (median, 20.7 vs. 25.7 mo; P < 0.01). An 18F-FDG TTV increase by more than 30% was associated with a short PSA PFS (median, 3.5 vs. 8.6 mo; P < 0.001) but not OS. Both PSA and radiographic progression were associated with shorter OS (median, 14.5 vs. 25.7 mo [P < 0.001] and 12.2 vs. 23.6 mo [P = 0.002]). On multivariable analysis, only increased PSMA TTV and PSA progression remained independently prognostic of OS (hazard ratio, 5.1 [95% CI, 1.5-17.1; P = 0.008] and 3.5 [95% CI, 1.1-10.9; P = 0.03], respectively).Conclusion: Change in quantitative PSMA TTV has strong potential as a prognostic biomarker with 177Lu-PSMA-617 therapy, independent of 18F-FDG PET parameters, PSA, or radiographic progres-sion. Further research into the value of posttreatment PET as an imaging biomarker is warranted.

177Lu-PSMA-617 is an effective and novel treatment in metastatic cas-tration-resistant prostate cancer (mCRPC). Our ability to assess response rates and therefore efficacy may be improved using predic-tive tools. This study investigated the predictive value of serial 177Lu-PSMA-617 SPECT/CT (177Lu SPECT) imaging in monitoring treatment response. Methods: Fifty-six men with progressive mCRPC previ-ously treated with chemotherapy and novel androgen signaling inhibi-tor were enrolled into the LuPIN trial and received up to 6 doses of 177Lu-PSMA-617 and a radiation sensitizer (3-(4-hydroxyphenyl)-2H-1-benzopyran-7-ol [NOX66]). 68Ga-PSMA-11 and 18F-FDG PET/CT were performed at study entry and exit, and 177Lu SPECT from vertex to mid thighs was performed 24 h after each treatment. SPECT quanti-tative analysis was undertaken at cycles 1 (baseline) and 3 (week 12) of treatment. Results: Thirty-two of the 56 men had analyzable serial 177Lu SPECT imaging at both cycle 1 and cycle 3. In this subgroup, median prostate-specific antigen (PSA) progression-free survival (PFS) was 6.3 mo (95% CI, 5-10 mo) and median overall survival was 12.3 mo (95% CI, 12-24 mo). The PSA 50% response rate was 63% (20/32). 177Lu SPECT total tumor volume (SPECT TTV) was reduced in 68% (22/32; median, -0.20 m3 [95% CI, -1.4 to -0.001]) and increased in 31% (10/32; median, 0.36 [95% CI, 0.1-1.4]). Any increase in SPECT TTV was associated with shorter PSA PFS (hazard ratio, 4.1 [95% CI, 1.5-11.2]; P = 0.006). An increase of 30% or more in SPECT TTV was also associated with a shorter PSA PFS (hazard ratio, 3.3 [95% CI, 1.3-8.6]; P =0.02). Tumoral SUVmax was reduced in 91% (29/32) and SUVmean in 84% (27/32); neither was associated with PSA PFS or overall survival outcomes. PSA progres-sion by week 12 was also associated with a shorter PSA PFS (hazard ratio, 26.5 [95% CI, 5.4-131]). In the patients with SPECT TTV pro-gression at week 12, 50% (5/10) had no concurrent PSA progression (median PSA PFS, 4.5 mo [95% CI, 2.8-5.6 mo]), and 5 of 10 men had both PSA and SPECT TTV progression at week 12 (median PSA PFS, 2.8 mo [95% CI, 1.8-3.7 mo]). Conclusion: Increasing SPECT TTV on quantitative 177Lu SPECT predicts a short PFS and may play a future role as an imaging response biomarker.

166 Background: 177Lutetium PSMA-617 (LuPSMA) is an effective therapy for metastatic castrate-resistant prostate cancer (mCRPC). However, treatment resistance may occur. We developed a quantitative workflow for serial PSMA PET/CT to optimise predictive and prognostic imaging biomarker capability for progression free (PFS) and overall survival (OS). Methods: 56 men with mCRPC previously treated with taxane chemotherapy and androgen signaling inhibitor were enrolled, receiving up to 6 doses of LuPSMA and a radiation sensitizer idronoxil (NOX66). 68Ga-PSMA-11 PET/CT was performed at study entry and exit. Traffic Light (TL) quantification workflow was developed to track changes in both tumour volume and intensity at a total body and lesional level. Lesions were classified as responding in green (>30% decline in volume), stable in yellow (<30% change in volume/intensity), progressive in red (>30% increase in volume/intensity, or new). Overall response pattern was categorised as responding ( green/yellow), low volume red (<50% progressive disease) or high volume red (>50% progressive disease). TL workflow results were correlated with PFS and OS. Results: 37/56 men underwent both entry and exit imaging. The median PSA decline was 77% (IQR 34-92%), and 70% (26/37) achieved PSA response >50%. PSA progression occurred in 54% (20/37) at exit imaging. Median PFS was 8.6 months (95%CI 5.6-11.6) and median OS 22 months (95% CI 18.6-25.6). 95% (35/37) had reduction in PSMA SUVmax (-26.1 (IQR +11.7 to -89.4)) and SUVmean (-3.3 (+2.9 to -14.2)). PSMA total tumor volume reduced in 68% (25/37) (median -0.64 liters (range +1.44 to -1.1)). On TL workflow, 24% (9/37) had responding/stable disease ( green/ yellow), 76% (28/37) had progressive disease ( red) of whom 41% (15/37) had low volume progression and 35% (13/37) high volume progression. Men with high volume progression had worse OS compared to responders (HR 0.18 (0.05-0.59), p 0.005), and low volume progression (HR 0.30 (0.11-0.80), p 0.02). 68% (19/28) had progression on both TL workflow and PSA, while 32% (9/28) had progression on TL workflow without PSA progression. In multivariable analysis, TL workflow and PSA progression at time of exit scans were independent predictors of OS (Table). Conclusions: This study demonstrates the feasibility of characterizing lesional response on molecular imaging with a quantification TL workflow. TL workflow response independently correlated with survival outcomes, indicating serial PSMA PET has prognostic biomarker potential. Clinical trial information: ACTRN12618001073291.[Table: see text]

Lu-177-PSMA-617 is an effective therapy for metastatic castration-resistant prostate cancer (mCRPC). However, treatment resistance occurs frequently, and combination therapies may improve outcomes. We report the final safety and efficacy results of a phase I/II study combining Lu-177-PSMA-617 with idronoxil (NOX66), a radiosensitizer, and examine potential clinical, blood-based, and imaging biomarkers. Methods: Fifty-six men with progressive mCRPC previously treated with taxane chemotherapy and novel androgen signaling inhibitor (ASI) were enrolled. Patients received up to 6 doses of Lu-177-PSMA-617 (7.5 GBq) on day 1 in combination with a NOX66 suppository on days 1-10 of each 6-wk cycle. Cohort 1 (n = 8) received 400 mg of NOX66, cohort 2 (n = 24) received 800 mg, and cohort 3 (n = 24) received 1,200 mg. Ga-68-PSMA and F-18-FDG PET/CT were performed at study entry, and semiquantitative imaging analysis was undertaken. Blood samples were collected for analysis of blood-based bio-markers, including androgen receptor splice variant 7 expression. The primary outcomes were safety and tolerability; secondary outcomes included efficacy, pain scores, and xerostomia. Regression analyses were performed to explore the prognostic value of baseline clinical, blood-based, and imaging parameters. Results: Fifty-six of the 100 men screened were enrolled (56%), with a screening failure rate of 26% (26/100) for PET imaging criteria. All men had received prior treatment with ASI and docetaxel, and 95% (53/56) had received cab-azitaxel. Ninety-six percent (54/56) of patients received at least 2 cycles of combination NOX66 and Lu-177-PSMA-617, and 46% (26/56) completed 6 cycles. Common adverse events were anemia, fatigue, and xerostomia. Anal irritation attributable to NOX66 occurred in 38%. Forty-eight of 56 had a reduction in prostate-specific antigen (PSA) level (86%; 95% CI, 74%-94%); 34 of 56 (61%; 95% CI, 47%-74%) had a PSA reduction of at least 50%. Median PSA progression-free survival was 7.5 mo (95% CI, 5.9-9 mo), and median overall survival was 19.7 mo (95% CI, 9.5-30 mo). A higher PSMA SUVmean correlated with treatment response, whereas a higher PSMA tumor volume and prior treatment with ASI for less than 12 mo were associated with worse overall survival. Conclusion: NOX66 with Lu-177-PSMA-617 is a safe and feasible strategy in men being treated with third-line therapy and beyond for mCRPC. PSMA SUVmean, PSMA-avid tumor volume, and duration of treatment with ASI were independently associated with outcome.

BACKGROUND:Because management is very different, it is important to differentiate between small focal insulinomas and diffuse pancreatic dysplasia (nesidioblastosis) in patients with confirmed endogenous hyperinsulinaemic hypoglycaemia (EHH). Most insulinomas highly express glucagon-like peptide-1 receptors enabling positron emission tomography-computed tomography imaging with its radiolabelled analogue; 68 Ga-DOTA-Exendin-4 (Exendin).AIM:To determine: (i) the utility of Exendin in EHH patients in a clinical setting; and (ii) whether the degree of Exendin uptake differentiates non-insulinoma pancreatogenous hypoglycaemia syndrome (NIPHS) from post-gastric bypass hypoglycaemia (PGBH).METHODS:This retrospective study reviewed the clinical, biochemistry and prior imaging findings in confirmed EHH patients referred for Exendin. Accuracy of Exendin was based on surgical findings and treatment outcomes. Finally, average Exendin uptake (SUVmax) of five PGBH studies was compared with the SUVmax of a key NIPHS case report.RESULTS:Twenty of 25 consecutive patients had confirmed EHH. Exendin located insulinomas in eight of nine patients enabling successful surgical excision with rapid and durable cure. Exendin correctly identified diffuse nesidioblastosis in two of three cases requiring partial pancreatectomy for hypoglycaemia control. All three relapsed within 1.7 years with one needing completion pancreatectomy. Establishing the cause in the remainder relied on other investigations, clinical correlation and response to empirical treatment. Finally, Exendin SUVmax could not distinguish between NIPHS and PGBH.CONCLUSION:In EHH patients, Exendin accurately identifies the site of insulinoma and thereby differentiates it from nesidioblastosis but negative findings should not be ignored. Exendin is unlikely to differentiate between normal pancreatic uptake, NIPHS and PGBH.

103 Background: 177 LuPSMA – 617 is a promising therapy for metastatic castrate-resistant prostate cancer (mCRPC). However, treatment resistance occurs frequently and synergistic combination therapy may improve outcomes. We combined 177 LuPSMA – 617 with idronoxil (NOX66), an inhibitor of external NADH oxidase type 2 with radio-sensitizing properties. We present the final safety and efficacy results. Methods: Men with progressive mCRPC after androgen signalling inhibition (ASI) and taxane chemotherapy were enrolled. Key inclusion criteria were: PSMA PET/CT intensity SUV max > 15 with no discordant disease on FDG PET/CT, haemoglobin > 100g/L, platelets > 100x10 9 /L and eGFR > 40mls/min. Enrolled patients received up to six doses of 177 Lu-PSMA 617 (7.5Gbq) day 1 every 6 weeks in combination with NOX66 days 1-10 each cycle. Cohort 1 (n = 8) received 400mg NOX66. Following safety reviews the doses were escalated in cohorts 2 (n = 24) and 3 (n = 24) to 800mg and 1200mg of NOX66, respectively. Blood samples were prospectively collected for androgen receptor splice variant 7 (ARV7) expression. PSMA and FDG PET/CT were performed at study entry and on progression. The primary outcomes were safety and tolerability; the secondary outcomes evaluated were efficacy, pain scores, and quality of life. Results: Of the 56 men enrolled, all had received prior treatment with ASI and docetaxel, and 95% (53/56) had prior cabazitaxel. 96% (54/56) patients received ≥2 cycles and 46% (26/56) completed six cycles of treatment. Adverse events are summarized in the table below. PSA responses were as follows: 86% (48/56) had any PSA reduction and 61% (34/56) had > 50% PSA reduction. 84% (47/56) have had PSA progression to date with median follow up 18.9 months (95% CI 11.9-25.8). Median PSA PFS was 7.5 months (95% CI 6.0-9.0). 55% (31/56) have died and median overall survival was 19.7 months (95% CI 10.7-28.7). 34/56 men had baseline pain scores ≥3, of whom 53% (18/34) had significant reduction in pain indicators. There was no correlation between quantitative PET results and either PSA > 50% response, PSA PFS or OS. Conclusions: The combination of 177 Lu-PSMA 617 + NOX66 appears safe and efficacious in men with heavily pre-treated mCRPC. Exploratory analysis of ARV7 expression and quantitative PET imaging markers of treatment response and resistance is in progress. Clinical trial information: ACTRN12618001073291. [Table: see text]

Lung PET/CT is a promising imaging modality for regional lung function assessment. Our aim was to develop and validate a fast, simple, and fully automated GMP compliant [68Ga]Ga-MAA labeling procedure, using a commercially available [99mTc]Tc-MAA kit, a direct gallium-68 eluate and including a purification of the [68Ga]Ga-MAA. Method: The synthesis parameters (pH, heating temperature) were manually determined. Automated 68Ga-labeling of MAA was then developed on a miniAIO (Trasis®, Ans, Belgium) module. An innovative automated process was developed for the purification. The process was then optimized and adapted to automate both the [68Ga]Ga-MAA synthesis and the isolation of gallium-68 eluate required for the pulmonary ventilation PET/CT. Results: The 15-min process demonstrated high reliability and reproducibility, with high synthesis yield (>95 %). Mean [68Ga]Ga-MAA radiochemical purity was 99 % ± 0.6 %. The 68Ga-labeled MAA particles size and morphology remained unchanged. Conclusion: A fast, user friendly, and fully automated process to produce GMP [68Ga]Ga-MAA for clinical use was developed. This automated process combining the advantages of using a non-modified MAA commercial kit, a gallium-68 eluate without pre-purification and an efficient final purification of the [68Ga]Ga-MAA may facilitate the implementation of lung PET/CT imaging in nuclear medicine departments.

Peptide receptor radionuclide therapy (PRRT) is an important treatment option for patients with somatostatin receptor-2 (SSTR2)-expressing neuroendocrine tumour (NET) though tumour regression occurs in only a minority of patients. Therefore, novel PRRT regimens with improved therapeutic activity are needed. Radiation induced DNA damage repair is an attractive therapeutic target to increase PRRT efficacy and consequently, we have characterised a panel of preclinical models for their SSTR2 expression, in vivo growth properties and response to 177Lu-DOTA-octreotate (LuTate) PRRT to identify models with features suitable for evaluating novel therapeutic combinations. In vitro studies using the SSTR2 expressing AR42J model demonstrate that the combination of LuTate and the small molecule Poly(ADP-ribose) polymerase-1 (PARP) inhibitor, talazoparib led to increased DNA double strand breaks, as assessed by γ-H2AX foci formation, as compared to LuTate alone. Furthermore, using the AR42J tumour model in vivo we demonstrate that the combination of LuTate and talazoparib significantly improved the anti-tumour efficacy of LuTate alone. These findings support the clinical evaluation of the combination of LuTate and PARP inhibition in SSTR2-expressing NET.

ObjectiveCurrent prevention and/or treatment options for respiratory syncytial virus (RSV) infections are limited as no vaccine is available. Prophylaxis with palivizumab is very expensive and requires multiple intramuscular injections over the RSV season. Here we present proof-of-concept data using nebulized palivizumab delivery as a promising new approach for the prevention or treatment of severe RSV infections, documenting both aerosol characteristics and pulmonary deposition patterns in the lungs of lambs.DesignProspective animal study.SettingBiosecurity Control Level 2-designated large animal research facility at the Murdoch Children’s Research Institute, Melbourne, Australia.SubjectsFour weaned Border-Leicester/Suffolk lambs at 5 months of age.InterventionsFour lambs were administered aerosolized palivizumab conjugated to Tc-99m, under gaseous anesthesia, using either the commercially available AeroNeb Go® or the investigational HYDRA device, placed in-line with the inspiratory limb of a breathing circuit. Lambs were scanned in a single-photon emission computed tomography (SPECT/CT) scanner in the supine position during the administration procedure.Measurements and Main ResultsBoth the HYDRA and AeroNeb Go® produced palivizumab aerosols in the 1–5 µm range with similar median (geometric standard deviation and range) aerosol droplet diameters for the HYDRA device (1.84 ± 1.40 μm, range = 0.54–5.41μm) and the AeroNeb Go® (3.07 ± 1.56 μm, range = 0.86–10 μm). Aerosolized palivizumab was delivered to the lungs at 88.79–94.13% of the total aerosolized amount for all lambs, with a small proportion localized to either the trachea or stomach. No difference between devices were found. Pulmonary deposition ranged from 6.57 to 9.25% of the total dose of palivizumab loaded in the devices, mostly in the central right lung.ConclusionsAerosolized palivizumab deposition patterns were similar in all lambs, suggesting a promising approach in the control of severe RSV lung infections.

Vitamin E, a natural antioxidant, is of interest to scientists, health care pundits and faddists; its nutritional and biomedical attributes may be validated, anecdotal or fantasy. Vitamin E is a mixture of tocopherols (TPs) and tocotrienols (T-3s), each class having four substitutional isomers (α-, β-, γ-, δ-). Vitamin E analogues attain only low concentrations in most tissues, necessitating exacting invasive techniques for analytical research. Quantitative positron emission tomography (PET) with an F-18-labeled molecular probe would expedite access to Vitamin E’s biodistributions and pharmacokinetics via non-invasive temporal imaging. (R)-6-(3-[18F]Fluoropropoxy)-2,7,8-trimethyl-2-(4,8,12-trimethyltrideca-3,7,11-trien-1-yl)-chromane ([18F]F-γ-T-3) was prepared for this purpose. [18F]F-γ-T-3 was synthesized from γ-T-3 in two steps: (i) 1,3-di-O-tosylpropane was introduced at C6-O to form TsO-γ-T-3, and (ii) reaction of this tosylate with [18F]fluoride in DMF/K222. Non-radioactive F-γ-T-3 was synthesized by reaction of γ-T-3 with 3-fluoropropyl methanesulfonate. [18F]F-γ-T-3 biodistribution in a murine tumor model was imaged using a small-animal PET scanner. F-γ-T-3 was prepared in 61% chemical yield. [18F]F-γ-T-3 was synthesized in acceptable radiochemical yield (RCY 12%) with high radiochemical purity (>99% RCP) in 45 min. Preliminary F-18 PET images in mice showed upper abdominal accumulation with evidence of renal clearance, only low concentrations in the thorax (lung/heart) and head, and rapid clearance from blood. [18F]F-γ-T-3 shows promise as an F-18 PET tracer for detailed in vivo studies of Vitamin E. The labeling procedure provides acceptable RCY, high RCP and pertinence to all eight Vitamin E analogues.

Background In the curative-intent treatment of locally advanced lung cancer, significant morbidity and mortality can result from thoracic radiation therapy. Symptomatic radiation pneumonitis occurs in one in three patients and can lead to radiation-induced fibrosis. Local failure occurs in one in three patients due to the lungs being a dose-limiting organ, conventionally restricting tumour doses to around 60 Gy. Functional lung imaging using positron emission tomography (PET)/CT provides a geographic map of regional lung function and preclinical studies suggest this enables personalised lung radiotherapy. This map of lung function can be integrated into Volumetric Modulated Arc Therapy (VMAT) radiotherapy planning systems, enabling conformal avoidance of highly functioning regions of lung, thereby facilitating increased doses to tumour while reducing normal tissue doses.Methods and analysis This prospective interventional study will investigate the use of ventilation and perfusion PET/CT to identify highly functioning lung volumes and avoidance of these using VMAT planning. This single-arm trial will be conducted across two large public teaching hospitals in Australia. Twenty patients with stage III non-small cell lung cancer will be recruited. All patients enrolled will receive dose-escalated (69 Gy) functional avoidance radiation therapy. The primary endpoint is feasibility with this achieved if ≥15 out of 20 patients meet pre-defined feasibility criteria. Patients will be followed for 12 months post-treatment with serial imaging, biomarkers, toxicity assessment and quality of life assessment.Discussion Using advanced techniques such as VMAT functionally adapted radiation therapy may enable safe moderate dose escalation with an aim of improving local control and concurrently decreasing treatment related toxicity. If this technique is proven feasible, it will inform the design of a prospective randomised trial to assess the clinical benefits of functional lung avoidance radiation therapy.Ethics and dissemination This study was approved by the Peter MacCallum Human Research Ethics Committee. All participants will provide written informed consent. Results will be disseminated via publications.Trials registration number NCT03569072; Pre-results

5557 Background: There is no established standard of care post cabazitaxel in men with mCRPC. Ongoing trials in 177LuPSMA-617 have demonstrated good efficacy and safety, but synergistic combinations may further improve treatment responses. Idronoxil (NOX66) inhibits external NADH oxidase type 2 with downstream pro-apoptotic actions including radio-sensitization. Herein we present updated results and an additional cohort of a prospective single arm phase I/II dose escalation/expansion trial of LuPSMA-617 and NOX66 in mCRPC. Methods: Men with progressive mCRPC post androgen signalling inhibition (ASI) and 2 lines of taxane chemotherapy were considered eligible. Key inclusion criteria included PSMA PET/CT intensity SUV max > 15 with no discordant disease on FDG PET/CT, Hb >10, Platelets >100 and GFR >40mls/min. Enrolled patients received up to 6 doses of 177 Lu-PSMA 617 (7.5Gbq) day 1 every 6 weeks in combination with NOX66 days 1-10 each cycle. Cohort 1 (n=8) received 400mg NOX66. Cohorts 2 and 3 subsequently received 800mg and 1200mg of NOX66, respectively, following safety reviews. Data regarding safety, efficacy, pain scores, and QOL were collected. Results: 32 men were enrolled in cohorts 1&2 (November 2017 – June 2019) and 24 in cohort 3 (August 2019-February 2020). To date there have been no dose-limiting toxicities. Data for cohort 3 are immature. For cohorts 1 & 2: 31/32 men received ≥2 cycles, with 12/32 (47%) completing 6 cycles. Any PSA response was seen in 84% (27/32), with a PSA response > 50% in 62.5% (20/32). Median PSA PFS is 6.1 months Of men with increased baseline pain scores ≥3 (24/32), 50% (12/24) had a clinically significant reduction in pain indicators. Adverse events are summarized below. Updated results for cohorts 1 and 2 and preliminary results of cohort 3 will be presented. Conclusions: Combination LuPSMA-617 + NOX 66 appears safe and efficacious in men with heavily pre-treated end stage mCRPC. Clinical trial information: ACTRN12618001073291 .

228 Background: Lutetium-177 (177Lu)-PSMA-617 (LuPSMA) is a radiolabelled small molecule that binds with high affinity to prostate specific membrane antigen (PSMA) enabling targeted delivery of beta-radiation. We have previously reported favourable activity with low toxicity in a 30 patient study in men with metastatic castrate-resistant prostate cancer (mCRPC) and now report updated results including a twenty patient extension cohort. Methods: In this phase II trial, 50 pts with PSMA-avid mCRPC who had progressed after standard therapies received up to 4 cycles of LuPSMA every 6 weeks. The primary endpoints were PSA response (PCWG2) and toxicity (CTCAE v4). Other endpoints included imaging response, PSA PFS and OS. Cut-off for analysis 5 Oct 2018. Results: 76 men were screened to identify 50 patients eligible for treatment. Median PSA doubling time was 2.6 months. The majority of patients had received prior docetaxel (84%), cabazitaxel (48%), and abiraterone and/or enzalutamide (90%). The mean administered radioactivity was 7.5 GBq/cycle. PSA decline ≥ 50% was achieved in 32 of 50 patients (64%, 95% CI 50-77%), including 22 patients (44%, 95% CI 30-59%) with a PSA decline ≥ 80%. 27 patients had measurable soft tissue at baseline and 56% of these patients had a partial or complete response by RECIST 1.1. The most common toxicities attributed to LuPSMA were transient G1-2 dry mouth in 68%, G1-2 nausea in 48%, and G1-2 fatigue in 36%. G3-4 toxicities attributed to LuPSMA were infrequent with thrombocytopenia in 10% and anaemia in 10%. Median PSA PFS was 6.9 months (95% CI 6.0-8.7) and median OS was 13.3 months (95% CI 10.5-18.0). Upon subsequent progression, further LuPSMA was administered to 14 patients (median 2 cycles commencing 359 days from enrolment); PSA ≥ 50% response occurred in 9 patients (64%). Conclusions: This expanded 50 patient cohort confirms high response rates and low toxicity with LuPSMA in men who had progressed after standard therapies. In patients who subsequently progressed and were administered further LuPSMA, high response rates were also observed. These results have provided the basis for randomised controlled trials currently underway. Clinical trial information: ACTRN12615000912583.

Cancer has a high incidence and mortality rate worldwide, which continues to grow as millions of people are diagnosed annually. Metastatic disease caused by cancer is largely responsible for the mortality rates, thus early detection of metastatic tumours can improve prognosis. However, a large number of patients will also present with micrometastasis tumours which are often missed, as conventional medical imaging modalities are unable to detect micrometastases due to the lack of specificity and sensitivity. Recent advances in radiochemistry and the development of nucleic acid based targeting molecules, have led to the development of novel agents for use in cancer diagnostics. Monoclonal antibodies may also be used, however, they have inherent issues, such as toxicity, cost, unspecified binding and their clinical use can be controversial. Aptamers are a class of single-stranded RNA or DNA ligands with high specificity, binding affinity and selectivity for a target, which makes them promising for molecular biomarker imaging. Aptamers are presented as being a superior choice over antibodies because of high binding affinity and pH stability, amongst other factors. A number of aptamers directed to cancer cell markers (breast, lung, colon, glioblastoma, melanoma) have been radiolabelled and characterised to date. Further work is ongoing to develop these for clinical applications.

This pilot study assessed the independent and incremental value of 68Ga-V/Q PET/CT as compared with CT pulmonary angiography (CTPA) for the management of cancer patients with suspected acute pulmonary embolism (PE). All 24 cancer patients with suspected acute PE prospectively recruited underwent both 68Ga-V/Q PET/CT and CTPA within 24 h. PET/CT was acquired after inhalation of Galligas prepared using a Technegas generator and administration of 68Ga-macroaggregated albumin. Initially, PET/CT and CTPA scans were read independently with the reader blinded to the results of the other imaging study. CTPA and PET/CT were then coregistered and reviewed by consensus between a radiologist and nuclear medicine physician. The therapeutic management was established by the managing physician based on all available data. The diagnostic conclusion was concordantly negative in 18 patients (75%). Of the six discordant diagnoses on independent reading, combined interpretation of V/Q PET/CTPA enabled a consensus conclusion in two patients, excluding PE in one and confirming PE in the other, similar to the initial diagnostic conclusion of the V/Q PET/CT. Of the remaining four patients, three had a single subsegmental thrombus on CTPA but a negative V/Q PET/CT scan, and two of these did not receive long-term anticoagulation and did not have a venous thromboembolic event during a 3-year follow-up period. The third patient, along with a patient with a positive V/Q PET/CT scan but a negative CTPA scan, presented with acute complications preventing any conclusions with regard to the appropriateness of the V/Q PET/CT results in the management of PE. Overall, V/Q PET had an impact on management in four patients (17%). In this pilot study, we demonstrated the feasibility and potential utility of V/Q PET/CT for the management of patients with suspected PE. V/Q PET/CT may be of particular relevance in patients with equivocal findings or isolated subsegmental findings on CTPA, adding further discriminatory information to allow important decision-making regarding the use or withholding of anticoagulation. Given the other advantages of V/Q PET/CT (reduced acquisition time, low radiation dose), and with the increasing availability of 68Ga generators, PET/CT is a potential replacement for V/Q SPECT/CT imaging.

This study examined the value of Ga-68-HBEDD (PSMA-11; prostate-specific membrane antigen, PSMA) positron emission tomography (PET) in predicting treatment response and disease progression in Lu-177 PSMA-617 (Lu-PS MA) therapy within the context of a phase 2 prospective pilot trial. The study found that a minimum intensity of tumor activity is required on PSMA PET to get a treatment response to Lu-PSMA therapy. Background: Lu-177-PSMA-617 (Lu-PSMA) is an emerging therapy in men with metastatic castration-resistant prostate cancer. Paired theranostic agents have the potential to visually identify phenotypes that will respond to targeted therapy. This study examined the value of Ga-68-HBEDD PSMA-11; prostate-specific membrane antigen (PSMA) positron emission tomography (PET) in predicting treatment response and disease progression in Lu-PSMA therapy within the context of a phase 2 prospective pilot trial. Patients and Methods: Men with progressive, symptomatic metastatic castration-resistant prostate cancer previously treated with antiandrogens (abiraterone and/or enzalutamide) and taxane-based chemotherapy were prospectively enrolled. Eligibility criteria included uptake on PSMA PET above or equal to liver activity, with no F-18-Fluoro-deoxyglucose (FDG) PET-discordant disease. Men received up to 4 cycles of Lu-PSMA at 6 weekly intervals. Repeat FDG/PSMA PET imaging was performed after completion of therapy or at prostate-specific antigen (PSA) progression. The study assessed treatment response to Lu-PSMA using PSA response and correlated treatment response (PSA) to molecular imaging parameters at enrollment. Results: Fourteen of 18 men screened underwent Lu-PSMA therapy. Ten (71%) of 14 had a PSA response (mean reduction, 59%). A >= 50% reduction in PSA occurred in 5 (36%), and >= 30% in 9 (64%). PSMA PET standardized uptake value (SUV) at screening was predictive of >= 30% PSA reduction: SUV max value 17 +/- 9 versus 44 +/- 15 (P < .007), and PSMA SUV mean 6 +/- 4 versus 10 +/- 4 (P < .04). FDG parameters alone, and volume or site of disease did not predict PSA response. No imaging parameters predicted >= 50% PSA reduction. Nine of 14 men were reimaged after treatment, revealing 3 distinct patterns of progression. Conclusion: PSMA PET plays an important role in predicting treatment response to Lu-PSMA and in identifying subsequent patterns of failure, which may aid in determining the next best treatment options. (C) 2018 Elsevier Inc. All rights reserved.

177Lu-PSMA-617 is a radioligand with high affinity for prostate-specific membrane antigen (PSMA), enabling targeted β-irradiation of prostate cancer. We have previously reported favorable activity with low toxicity in a prospective phase II trial involving 30 men with metastatic castration-resistant prostate cancer. We now report their longer-term outcomes, including a 20-patient extension cohort and outcomes of subsequent systemic treatments after completion of trial therapy. Methods: Fifty patients with PSMA-avid metastatic castration-resistant prostate cancer who had progressed after standard therapies received up to 4 cycles of 177Lu-PSMA every 6 wk. Endpoints included prostate-specific antigen (PSA) response (Prostate Cancer Working Group 2), toxicity (Common Terminology Criteria for Adverse Events, version 4.03), imaging response, patient-reported health-related quality of life, progression-free survival, and overall survival. We also describe, as a novel finding, outcomes of men who subsequently progressed and had further systemic therapies, including 177Lu-PSMA. Results: Seventy-five men were screened to identify 50 patients eligible for treatment. Adverse prognostic features of the cohort included short median PSA doubling time (2.3 mo) and extensive prior treatment, including prior docetaxel (84%), cabazitaxel (48%), and abiraterone or enzalutamide (92%). The mean administered radioactivity was 7.5 GBq/cycle. A PSA decline of at least 50% was achieved in 32 of 50 patients (64%; 95% confidence interval [CI], 50%-77%), including 22 patients (44%; 95% CI, 30%-59%) with at least an 80% decrease. Of 27 patients with measurable soft-tissue disease, 15 (56%) achieved an objective response by RECIST 1.1. The most common toxicities attributed to 177Lu-PSMA were self-limiting G1-G2 dry mouth (66%), transient G1-G2 nausea (48%), G3-G4 thrombocytopenia (10%), and G3 anemia (10%). Brief Pain Inventory severity and interference scores decreased at all time points, including at the 3-mo follow-up, with a decrease of -1.2 (95% CI, -0.5 to -1.9; P = 0.001) and -1.0 (95% CI, -0.2 to -0.18; P = 0.013), respectively. At a median follow-up of 31.4 mo, median overall survival was 13.3 mo (95% CI, 10.5-18.7 mo), with a significantly longer survival of 18.4 mo (95% CI, 13.8-23.8 mo) in patients achieving a PSA decline of at least 50%. At progression after prior response, further 177Lu-PSMA was administered to 15 (30%) patients (median of 2 cycles commencing 359 d from enrollment), with a PSA decline of at least 50% in 11 patients (73%). Four of 21 patients (19%) receiving other systemic therapies on progression experienced a PSA decline of at least 50%. There were no unexpected adverse events with 177Lu-PSMA retreatment. Conclusion: This expanded 50-patient cohort of men with extensive prior therapy confirms our earlier report of high response rates, low toxicity, and improved quality of life with 177Lu-PSMA radioligand therapy. On progression, rechallenge 177Lu-PSMA demonstrated higher response rates than other systemic therapies.

177Lu-prostate-specific membrane antigen (PSMA)–617 enables targeted delivery of β-particle radiation to prostate cancer. We determined its radiation dosimetry and relationships to pretherapeutic imaging and outcomes. Methods: Thirty patients with prostate cancer receiving 177Lu-PSMA-617 within a prospective clinical trial (ACTRN12615000912583) were studied. Screening 68Ga-PSMA-11 PET/CT demonstrated high PSMA expression in all patients. After therapy, patients underwent quantitative SPECT/CT at 4, 24, and 96 h. Pharmacokinetic uptake and clearance at a voxel level were calculated and translated into absorbed dose using voxel S values. Volumes of interest were drawn on normal tissues and tumor to assess radiation dose, and a whole-body tumor dose was defined. Correlations between PSMA PET/CT parameters, dosimetry, and biochemical and therapeutic response were analyzed to identify relationships between absorbed dose, tumor burden, and patient physiology. Results: Mean absorbed dose to kidneys, submandibular and parotid glands, liver, spleen, and bone marrow was 0.39, 0.44, 0.58, 0.1, 0.06, and 0.11 Gy/MBq, respectively. Median whole-body tumor-absorbed dose was 11.55 Gy and correlated with prostate-specific antigen (PSA) response at 12 wk. A median dose of 14.1 Gy was observed in patients achieving a PSA decline of at least 50%, versus 9.6 Gy for those achieving a PSA decline of less than 50% (P < 0.01). Of 11 patients receiving a tumor dose of less than 10 Gy, only one achieved a PSA response of at least 50%. On screening PSMA PET, whole-body tumor SUVmean correlated with mean absorbed dose (r = 0.62), and SUVmax of the parotids correlated with absorbed dose (r = 0.67). There was an inverse correlation between tumor volume and mean dose to the parotids (r = −0.41) and kidneys (r = −0.43). The mean parotid dose was also reduced with increasing body mass (r = −0.41) and body surface area (r = −0.37). Conclusion:177Lu-PSMA-617 delivers high absorbed doses to tumor, with a significant correlation between whole-body tumor dose and PSA response. Patients receiving less than 10 Gy were unlikely to achieve a fall in PSA of at least 50%. Significant correlations between aspects of screening 68Ga-PET/CT and tumor and normal tissue dose were observed, providing a rationale for patient-specific dosing. Reduced salivary and kidney doses were observed in patients with a higher tumor burden. The parotid dose also reduced with increasing body mass and body surface area.