Non-invasive PET imaging of liver fibrogenesis using a RESCA-conjugated Affibody molecule

Non-invasive assessment of fibrogenic activity, rather than fibrotic scars, could significantly improve the management of fibrotic diseases and the development of anti-fibrotic drugs. This study explores the potential of an Affibody molecule (Z09591) labeled with the Al(18)F-restrained complexing agent (RESCA) method as a tracer for the non-invasive detection of fibrogenic cells. Z09591 was functionalized with the RESCA chelator for direct labeling with [18F]AlF. In vivo positron emission tomography/magnetic resonance imaging scans on U-87 tumor-bearing mice exhibited high selectivity of the resulting radiotracer, [18F]AlF-RESCA-Z09591, for platelet-derived growth factor receptor β (PDGFRβ), with minimal non-specific background uptake. Evaluation in a mouse model with carbon tetrachloride-induced fibrotic liver followed by a disease regression phase, revealed the radiotracer's high affinity and specificity for fibrogenic cells in fibrotic livers (standardized uptake value [SUV] 0.43 ± 0.05), with uptake decreasing during recovery (SUV 0.29 ± 0.03) (p < 0.0001). [18F]AlF-RESCA-Z09591 accurately detects PDGFRβ, offering non-invasive assessment of fibrogenic cells and promising applications in precise liver fibrogenesis diagnosis, potentially contributing significantly to anti-fibrotic drug development.

Uncovering the armpit of SBRT: An institutional experience with stereotactic radiation of axillary metastases

Purpose/objectives

The growing use of stereotactic body radiotherapy (SBRT) in metastatic cancer has led to its use in varying anatomic locations. The objective of this study was to review our institutional SBRT experience for axillary metastases (AM), focusing on outcomes and process.

Materials/methods

Patients treated with SBRT to AM from 2014 to 2022 were reviewed. Cumulative incidence functions were used to estimate the incidence of local failure (LF), with death as competing risk. Kaplan-Meier method was used to estimate progression-free (PFS) and overall survival (OS). Univariate regression analysis examined predictors of LF.

Results

We analyzed 37 patients with 39 AM who received SBRT. Patients were predominantly female (60 %) and elderly (median age: 72). Median follow-up was 14.6 months. Common primary cancers included breast (43 %), skin (19 %), and lung (14 %). Treatment indication included oligoprogression (46 %), oligometastases (35 %) and symptomatic progression (19 %). A minority had prior overlapping radiation (18 %) or surgery (11 %). Most had prior systemic therapy (70 %).Significant heterogeneity in planning technique was identified; a minority of patient received 4-D CT scans (46 %), MR-simulation (21 %), or contrast (10 %). Median dose was 40 Gy (interquartile range (IQR): 35-40) in 5 fractions, (BED10 = 72 Gy). Seventeen cases (44 %) utilized a low-dose elective volume to cover remaining axilla.At first assessment, 87 % had partial or complete response, with a single progression. Of symptomatic patients (n = 14), 57 % had complete resolution and 21 % had improvement. One and 2-year LF rate were 16 % and 20 %, respectively. Univariable analysis showed increasing BED reduced risk of LF. Median OS was 21.0 months (95 % [Confidence Interval (CI)] 17.3-not reached) and median PFS was 7.0 months (95 % [CI] 4.3-11.3). Two grade 3 events were identified, and no grade 4/5.

Conclusion

Using SBRT for AM demonstrated low rates of toxicity and LF, and respectable symptom improvement. Variation in treatment delivery has prompted development of an institutional protocol to standardize technique and increase efficiency. Limited followup may limit detection of local failure and late toxicity.

Brachytherapy for high grade prostate cancer induces distinct changes in circulating CD4 and CD8 T cells - Implications for systemic control

This exploratory study is a follow up to our previous investigation of immune response in the circulation of high-grade Gleason 9 prostate cancer patients treated with EBRT + BT compared to EBRT alone. Notably, EBRT + BT demonstrates the potential to elicit an effect on CD4/CD8 ratio which may have attributed to improved clinical response to therapy. Our findings show promise for leveraging circulating immune cells as predictive biomarkers for radiotherapy response.

Noninvasive PET Detection of CD69-Positive Immune Cells Before Signs of Clinical Disease in Inflammatory Arthritis

Rheumatoid arthritis (RA) is the most common inflammatory joint disease, and early diagnosis is key for effective disease management. CD69 is one of the earliest cell surface markers seen at the surface of activated immune cells, and CD69 is upregulated in synovial tissue in patients with active RA. In this study, we evaluated the performance of a CD69-targeting PET agent, [68Ga]Ga-DOTA-ZCAM241, for early disease detection in a model of inflammatory arthritis. Methods: A model of inflammatory arthritis was induced by transferring splenocytes from KRN T-cell receptor transgenic B6 mice into T-cell-deficient I-Ag7 major histocompatibility complex class II-expressing recipient mice. The mice were examined longitudinally by [68Ga]Ga-DOTA-ZCAM241 PET/CT before and 3, 7, and 12 d after induction of arthritis. Disease progression was monitored by clinical parameters, including measuring body weight and scoring the swelling of the paws. The uptake of [68Ga]Ga-DOTA-ZCAM241 in the paws was analyzed and expressed as SUVmean Tissue biopsy samples were analyzed for CD69 expression by flow cytometry or immunostaining for a histologic correlate. A second group of mice was examined by a nonbinding, size-matched Affibody molecule as the control. Results: Clinical symptoms appeared 5-7 d after induction of arthritis. The uptake of [68Ga]Ga-DOTA-ZCAM241 in the joints was negligible at baseline but increased gradually after disease induction. An elevated PET signal was found on day 3, before the appearance of clinical symptoms. The uptake of [68Ga]Ga-DOTA-ZCAM241 correlated with the clinical score and disease severity. The presence of CD69-positive cells in the joints and lymph nodes was confirmed by flow cytometry and immunostaining. The uptake of the nonbinding tracer that was the negative control also increased gradually with disease progression, although to a lesser extent than with [68Ga]Ga-DOTA-ZCAM241 Conclusion: The uptake of [68Ga]Ga-DOTA-ZCAM241 in the inflamed joints preceded the clinical symptoms in the KRN T-cell transfer model of inflammatory arthritis, in accordance with immunostaining for CD69. [68Ga]Ga-DOTA-ZCAM241 is thus a promising PET imaging marker of activated immune cells in tissue during RA onset.

Introduction of a fatty acid chain modification to prolong circulatory half-life of a radioligand towards glucose-dependent insulinotropic polypeptide receptor

BACKGROUND

The beneficial role of glucose-dependent insulinotropic polypeptide receptor (GIPR) in weight control and maintaining glucose levels has led to the development of several multi-agonistic peptide drug candidates, targeting GIPR and glucagon like peptide 1 receptor (GLP1R) and/or the glucagon receptor (GCGR). The in vivo quantification of target occupancy by these drugs would accelerate the development of new drug candidates. The aim of this study was to evaluate a novel peptide (GIP1234), based on previously reported ligand DOTA-GIP-C803, modified with a fatty acid moiety to prolong its blood circulation. It would allow higher target tissue exposure and consequently improved peptide uptake as well as in vivo PET imaging and quantification of GIPR occupancy by novel drugs of interest.

METHOD

A 40 amino acid residue peptide (GIP1234) was synthesized based on DOTA-GIP-C803, in turn based on the sequences of endogenous GIP and Exendin-4 with specific amino acid modifications to obtain GIPR selectivity. A palmitoyl fatty acid chain was furthermore added at Lys14 via a glutamic acid linker to prolong its blood circulation time by the interaction with albumin. GIP1234 was conjugated with a DOTA chelator at the C-terminal cysteine residue to achieve 68Ga radiolabeling. The resulting PET probe, [68Ga]Ga-DOTA-GIP1234 was evaluated for receptor binding specificity and selectivity using HEK293 cells transfected with human GIPR, GLP1R, or GCGR. Blocking experiments with tirzepatide (2 μM) were conducted using huGIPR HEK293 cells to investigate binding specificity. Ex vivo and in vivo organ distribution of [68Ga]Ga-DOTA-GIP1234 was studied in rats and a pig in comparison to [68Ga]Ga-DOTA-C803-GIP. Binding of [68Ga]Ga-DOTA-GIP1234 to albumin was assessed in situ using polyacrylamide gel electrophoresis (PAGE). The stability was tested in formulation buffer and rat blood plasma.

RESULTS

[68Ga]Ga-DOTA-GIP1234 was synthesized with non-decay corrected radiochemical yield of 88 ± 3.7 % and radiochemical purity of 97.8 ± 0.8 %. The molar activity for the radiotracer was 8.1 ± 1.1 MBq/nmol. [68Ga]Ga-DOTA-GIP1234 was stable and maintained affinity to huGIPR HEK293 cells (dissociation constant (Kd) = 40 ± 12.5 nM). The binding of [68Ga]Ga-DOTA-GIP1234 to huGCGR and huGLP1R cells was insignificant. Pre-incubation of huGIPR HEK293 cell sections with tirzepatide resulted in the decrease of [68Ga]Ga-DOTA-GIP1234 binding by close to 90 %. [68Ga]Ga-DOTA-GIP1234 displayed slow blood clearance in pigs with SUV = 3.5 after 60 min. Blood retention of the tracer in rat was 2-fold higher than that of [68Ga]Ga-DOTA-C803-GIP. [68Ga]Ga-DOTA-GIP1234 also demonstrated strong liver uptake in both pig and rat combined with decreased renal excretion. The concentration dependent binding of [68Ga]Ga-DOTA-GIP1234 to albumin was confirmed in situ by PAGE.

CONCLUSION

[68Ga]Ga-DOTA-GIP1234 demonstrated nanomolar affinity and selectivity for huGIPR in vitro. Addition of a fatty acid moiety prolonged blood circulation time and tissue exposure in both rat and pig in vivo. However, the liver uptake was also increased which may make PET imaging of abdominal tissues such as pancreas challenging. The investigation of the influence of fatty acid moiety on the biological performance of the peptide ligand paved the way for further rational design of GIPR ligand analogues with improved characteristics.

Preclinical evaluation of Affibody molecule for PET imaging of human pancreatic islets derived from stem cells

BACKGROUND

Beta-cell replacement methods such as transplantation of isolated donor islets have been proposed as a curative treatment of type 1 diabetes, but widespread application is challenging due to shortages of donor tissue and the need for continuous immunosuppressive treatments. Stem-cell-derived islets have been suggested as an alternative source of beta cells, but face transplantation protocols optimization difficulties, mainly due to a lack of available methods and markers to directly monitor grafts survival, as well as their localization and function. Molecular imaging techniques and particularly positron emission tomography has been suggested as a tool for monitoring the fate of islets after clinical transplantation. The integral membrane protein DGCR2 has been demonstrated to be a potential pancreatic islet biomarker, with specific expression on insulin-positive human embryonic stem-cell-derived pancreatic progenitor cells. The candidate Affibody molecule ZDGCR2:AM106 was radiolabeled with fluorine-18 using a novel click chemistry-based approach. The resulting positron emission tomography tracer [18F]ZDGCR2:AM106 was evaluated for binding to recombinant human DGCR2 and cryosections of stem-cell-derived islets, as well as in vivo using an immune-deficient mouse model transplanted with stem-cell-derived islets. Biodistribution of the [18F]ZDGCR2:AM106 was also assessed in healthy rats and pigs.

RESULTS

[18F]ZDGCR2:AM106 was successfully synthesized with high radiochemical purity and yield via a pretargeting approach. [18F]ZDGCR2:AM106 retained binding to recombinant human DCGR2 as well as to cryosectioned stem-cell-derived islets, but in vivo binding to native pancreatic tissue in both rat and pig was low. However, in vivo uptake of [18F]ZDGCR2:AM106 in stem-cell-derived islets transplanted in the immunodeficient mice was observed, albeit only within the early imaging frames after injection of the radiotracer.

CONCLUSION

Targeting of DGCR2 is a promising approach for in vivo detection of stem-cell-derived islets grafts by molecular imaging. The synthesis of [18F]ZDGCR2:AM106 was successfully performed via a pretargeting method to label a site-specific covalently bonded fluorine-18 to the Affibody molecule. However, the rapid washout of [18F]ZDGCR2:AM106 from the stem-cell-derived islets graft indicates that dissociation kinetics can be improved. Further studies using alternative binders of similar classes with improved binding potential are warranted.

Uncovering the Armpit of Axillary SBRT

PURPOSE/OBJECTIVE(S)

The growing use of stereotactic body radiotherapy (SBRT) in metastatic cancer has led to applications in new and unique anatomic locations, highlighting the importance of effective, safe, reproducible treatment delivery. The objective of this study was to review our institutional SBRT experience for axillary metastases (AM), focusing on outcomes, safety and process.

MATERIALS/METHODS

In this ethics approved single-institution retrospective review, patients treated with SBRT to AM from 2014-2022 had tumor, treatment planning, and dosimetric variables abstracted. Toxicity was assessed per Common Terminology for Adverse Events V5.0. Cumulative incidence functions were used to estimate the incidence of local failure (LF), with death as competing risk. Kaplan-Meier method was used to estimate progression-free (PFS) and overall survival (OS).

RESULTS

We analyzed 37 patients with 39 AM who received SBRT. Patients were predominantly female (60%), Eastern Cooperative Oncology Group performance status 0-1 (62%), and elderly (median age: 72), with a median follow-up of 14.6 months. Common primary sites included breast (n = 16, 43%), skin (n = 7, 19%), and lung (n = 5, 14%). Treatment indication included oligoprogression (n = 18, 46%), oligometastases (n = 14, 36%) and symptomatic progression (n = 7, 18%). A minority had prior overlapping radiation (n = 7, 18%) or regional surgery (n = 4, 11%), while most had prior systemic therapy (n = 26, 70%). Significant heterogeneity in simulation, planning and treatment was identified. Immobilization included 5-point thermoplastic mask (n = 12, 32%), Vacloc (n = 12, 32%) arms-up thorax bag (n = 11, 30%). 4-D CT scans were obtained in 46%, MR simulation in 21%, and intravenous contrast in 10%. Median dose was 40 Gy (interquartile range (IQR): 35-40) in 5 fractions, (BED10 = 72 Gy), over a median of 12 days (IQR: 9-14). Seventeen cases (44%) utilized a low-dose elective volume to cover remaining axilla; 14% used a high dose clinical target volume. Median planning target volume margin was 5mm (range: 3-10mm), and plans were generated with 5 different dose constraint protocols. At first radiographic assessment, 87% had partial or complete response, with a single progression. Of symptomatic patients (n = 14), 57% had complete symptom resolution and 21% had improvement. One and 2-year LF rate were 19% and 31%, respectively. Median OS was 21.0 months (95% [Confidence Interval (CI)] 17.3-not reached) and median PFS was 7.0 months (95% [CI] 4.3-11.3). Acute and late toxicities were uncommon, with two grade 3 events (1 plexopathy in a case with tumor involving brachial plexus, 1 skin ulceration) identified, and no grade 4/5.

CONCLUSION

In this series of AM SBRT, low rates of toxicity, and good rates of LF and symptom improvement were observed. As treatment was delivered with a variety of individual treatment differences, an institutional protocol is under development to standardize technique, optimize efficiency and improve evaluability.

Safety and Efficacy of Stereotactic Body Radiotherapy for Ultra-Central Thoracic Tumors

PURPOSE/OBJECTIVE(S)

Stereotactic body radiotherapy (SBRT) is increasingly utilized in the management of ultra-central thoracic tumors, although concerns regarding significant toxicity remain. We sought to evaluate the toxicity and efficacy of SBRT to these tumors at our institution.

MATERIALS/METHODS

Patients with ultra-central lung tumors or nodes treated at our institution with SBRT between 2009 and 2019 were retrospectively reviewed. Ultra-central was defined as having the planning target volume (PTV) overlapping or abutting the central bronchial tree and/or esophagus. All SBRT plans were generated with homogenous dose distributions using target coverage objectives of ITV V100% >99%, PTV V95% >99%, and an ideal PTV Dmax <105% (strict <120%). All plans were reviewed in quality assurance rounds by a team of dosimetrists, physicists, and radiation oncologists. The primary endpoint was incidence of severe toxicity (ST), defined as SBRT-related grade ≥3 toxicities, graded using the Common Terminology Criteria for Adverse Events V5.0. Secondary endpoints included local failure (LF), progression-free survival (PFS) and overall survival (OS). Competing risk analysis was used to estimate incidence and predictors of ST and LF, with death as a competing risk. Kaplan-Meier method was used to estimate PFS and OS.

RESULTS

A total of 154 patients who received 162 ultra-central courses of SBRT were included, with a median follow-up of 21.5 months. Treatment intent was most commonly for oligoprogression (46%), oligometastasis (30%), followed by curative (20%). The most frequent tumor histologies were NSCLC (41%) and RCC (26%). SBRT prescription doses ranged from 30-55 Gy in 5 fractions (BED10 range 48-115 Gy). The most common prescription was 50 Gy in 5 fractions (42%). The cumulative incidence of ST was 8.9% at 3-years. The most common ST was pneumonitis (n = 4). Notable toxicities included bronchopleural fistula (n = 2, grade 3 and 4), bronchial stricture (n = 1, grade 3), and esophagitis leading to bleeding (n = 1, grade 4). There were no esophageal strictures or perforations, and no bronchial bleeds. There was 1 possible treatment related death from pneumonitis/pneumonia. Predictors of any ST included increased lung V5 Gy, decreased PTV V95%, and not having prior radiation therapy to the chest. The cumulative incidence of LF was 4.8%, 11% and 14% at 1-, 2-, and 3-years respectively. Predictors of LF included younger age, and greater volume of overlap between the PTV and esophagus. Median PFS was 8.4 months, while median OS was 3.7 years.

CONCLUSION

In one of the largest case series of ultra-central thoracic SBRT reported to date, homogenously prescribed SBRT plans were associated with relatively low rates of ST and LF across a variety of treatment indications. Predictors of ST should be interpreted recognizing the heterogeneity in toxicities observed. Identified predictors of both ST and LF can contribute to future work to optimize the therapeutic ratio in treatment of ultra-central thoracic tumors.

Dosimetric Parameters Predictive of Treatment-Related Toxicity in High Dose-Rate Brachytherapy as Monotherapy for Prostate Cancer

PURPOSE/OBJECTIVE(S)

High dose-rate (HDR) brachytherapy as monotherapy is an effective treatment for patients with low- and intermediate-risk prostate cancer and is increasingly being offered as a 2-fraction protocol. There is a lack of consensus on the optimal dosimetric planning parameters to use, or whether there is any benefit summating dosimetric parameters from more than one implant. Our goal is to determine planning parameters associated with disease control, toxicity and health-related quality of life (HRQOL).

MATERIALS/METHODS

Data were collected on 83 patients with low- and intermediate-risk prostate cancer who received 2 fractions of 13.5 Gy HDR brachytherapy without androgen-deprivation therapy as part of a randomized phase II clinical trial. An in-house deformable, registration algorithm was used to co-register and dose-summate the plans from both implants for each patient. Acute and late GU and GI toxicities were measured using CTCAE 4.0 and HRQOL was measured in urinary, bowel, sexual and hormonal domains using the EPIC scores. Treatment efficacy was assessed through PSA measurement and imaging with or without biopsy where indicated. Covariates included baseline clinical factors, disease characteristics and treatment dosimetric parameters. Cox proportional hazards was performed to evaluate covariates impact on treatment toxicity and efficacy, and logistic regression analysis evaluated covariates impact on HRQOL.

RESULTS

Among the 83 patients, median prostate volume was 46.7cm3. Median summated planning target volume receiving 100% prescription dose (PTV V100%) was 97.4%, median PTV V150% 42.4% and median PTV V200% 15.5%. Median highest dose to the 1cm3 rectum (D1cc) was 66.9% of the prescription dose and median rectum V80% was 0.008cm3. Median urethral D1cc was 99.0% of the prescription dose, median urethral Dmax 121.7% and median urethral D10% 116.2%. Grade ≥2 GI toxicity was uncommon (3.7% acute and 8.5% late), but grade ≥2 GU toxicity was reported in 73.2% (acute) and 46.3% (late) patients. Rectum D1cc and V80% were found to be significantly associated with grade 2 or higher acute GI toxicity, while use of a-blocker at baseline was associated with grade ≥2 acute GU toxicity. Similarly, use of a-blocker was associated with late grade ≥2 GU toxicity, but with no dosimetric associations. No other variables were associated with treatment-related toxicities. Only rectum D1cc was significantly associated with changes in bowel EPIC scores. Estimated 5-year biochemical disease-free survival was 93.9% and 5-year cumulative incidence of local failure was 3.8%.

CONCLUSION

HDR monotherapy with 27 Gy delivered in 2 fractions in treatment of prostate cancer is well tolerated with high rates of disease control and minimal toxicity. Dose summation between 2 fractions of HDR brachytherapy is feasible, with rectal dose predicting acute GI toxicity. The lack of association between dose metrics and urinary toxicity raises the potential for further dose escalation.

Dosimetric Predictors of Toxicities and Quality of Life Following Two-Fraction Stereotactic Body Radiotherapy for Prostate Cancer

PURPOSE/OBJECTIVE(S)

There is emerging interest in two-fraction stereotactic body radiotherapy (2#SBRT) for localized prostate cancer. However, there is limited data to guide organs at risk (OAR) dose constraints in 2#SBRT. We aim to identify dosimetric predictors of toxicities and quality of life (QoL) using real life patient data from two prospective 2#SBRT trials.

MATERIALS/METHODS

We included 60 patients who had 2#SBRT in the 2STAR (NCT02031328) and 2SMART (NCT03588819) phase 2 trials. The prescribed dose was 26Gy to the prostate +/- focal boost of 32Gy to the dominant intraprostatic lesions. Toxicities and QoL data were prospectively collected using CTCAEv4 and EPIC26 questionnaires. For QoL, we reported the minimal clinical important changes (MCIC), defined as changes in QoL score of >0.5 standard deviation from baseline QoL score. We evaluated the bladder, urethra, rectum, and penile bulb dosimetry (urethra dosimetry only available in 30 patients in 2SMART trial). Some of the dosimetric parameters were log-transformed to normalize the distribution. Cox regression was used to identify dosimetric predictors for acute and late grade ≥2 GU toxicities. Logistic regression was used to identify dosimetric predictors for late MCIC in urinary, bowel and sexual QoL domains. Backward stepwise selection was used to identify significant dosimetric parameters. For GU toxicities and urinary QoL, three additional clinical factors (age, prostate volume and IPSS) were included in the final model as confounding factors. Receiver operating characteristics curve was used to identify cut-off for significant dosimetric parameters.

RESULTS

The median follow-up for the cohort was 56 months (range: 39-78 months). The cumulative acute and late grade ³2 GU toxicities were 62% (37/60) and 57% (34/60) respectively. No bladder or urethra dosimetric parameter was associated with acute grade ≥2 GU toxicities. Bladder D0.5cc was significant predictor of late grade ≥2 GU toxicities in univariate model (P = 0.05), but not in multivariate model. Baseline IPSS score was the single strongest predictor for late grade ≥2 GU toxicities (HR = 1.9; 95% CI = 1.1-3.4; P = 0.03). For late QoL outcomes, there were 36% (21/58), 28% (16/58), and 29% (17/58) of patients with MCIC in urinary, bowel and sexual QoL domains respectively. Bladder V10Gy was associated with late urinary MCIC in multivariate model after adjusting for clinical confounders (HR = 2.6, 95% CI = 1.1-6.6; P = 0.04). 48% (14/29) and 24% (7/29) of patients with bladder V10Gy>13.9% and V10Gy≤13.9% respectively had late urinary MCIC. No rectum and penile bulb dosimetry parameters was identified to be associated with late bowel or sexual QoL.

CONCLUSION

Using real life patient data from prospective clinical trials with medium term follow-up, we identified statistically significant bladder dosimetry parameter predictive of late urinary QoL. This finding could be useful to guide OAR dose constraints in prostate 2#SBRT trials.

Imaging of fibrogenesis in the liver by [18F]TZ-Z09591, an Affibody molecule targeting platelet derived growth factor receptor β

BACKGROUND

Platelet-derived growth factor receptor beta (PDGFRβ) is a receptor overexpressed on activated hepatic stellate cells (aHSCs). Positron emission tomography (PET) imaging of PDGFRβ could potentially allow the quantification of fibrogenesis in fibrotic livers. This study aims to evaluate a fluorine-18 radiolabeled Affibody molecule ([18F]TZ-Z09591) as a PET tracer for imaging liver fibrogenesis.

RESULTS

In vitro specificity studies demonstrated that the trans-Cyclooctenes (TCO) conjugated Z09591 Affibody molecule had a picomolar affinity for human PDGFRβ. Biodistribution performed on healthy rats showed rapid clearance of [18F]TZ-Z09591 through the kidneys and low liver background uptake. Autoradiography (ARG) studies on fibrotic livers from mice or humans correlated with histopathology results. Ex vivo biodistribution and ARG revealed that [18F]TZ-Z09591 binding in the liver was increased in fibrotic livers (p = 0.02) and corresponded to binding in fibrotic scars.

CONCLUSIONS

Our study highlights [18F]TZ-Z09591 as a specific tracer for fibrogenic cells in the fibrotic liver, thus offering the potential to assess fibrogenesis clearly.

PET Imaging of Neutrophil Elastase with 11C-GW457427 in Acute Respiratory Distress Syndrome in Pigs

Today, there is a lack of clinically available imaging techniques to detect and quantify specific immune cell populations. Neutrophils are one of the first immune cells at the site of inflammation, and they secrete the serine protease neutrophil elastase (NE), which is crucial in the fight against pathogens. However, the prolonged lifespan of neutrophils increases the risk that patients will develop severe complications, such as acute respiratory distress syndrome (ARDS). Here, we evaluated the novel radiolabeled NE inhibitor 11C-GW457427 in a pig model of ARDS, for detection and quantification of neutrophil activity in the lungs. Methods: ARDS was induced by intravenous administration of oleic acid to 5 farm pigs, and 4 were considered healthy controls. The severity of ARDS was monitored by clinical parameters of lung function and plasma biomarkers. Each pig was studied with 11C-GW457427 and PET/CT, before and after pretreatment with the NE inhibitor GW311616 to determine in vivo binding specificity. PET image data were analyzed as SUVs and correlated with immunohistochemical staining for NE in biopsies. Results: The binding of 11C-GW457427 was increased in pig lungs with induced ARDS (median SUVmean, 1.91; interquartile range [IQR], 1.67-2.55) compared with healthy control pigs (P < 0.05 and P = 0.03, respectively; median SUVmean, 1.04; IQR, 0.66-1.47). The binding was especially strong in lung regions with high levels of NE and ongoing inflammation, as verified by immunohistochemistry. The binding was successfully blocked by pretreatment of an NE inhibitor drug, which demonstrated the in vivo specificity of 11C-GW457427 (P < 0.05 and P = 0.04, respectively; median SUVmean, 0.60; IQR, 0.58-0.77). The binding in neutrophil-rich tissues such as bone marrow (P < 0.05 and P = 0.04, respectively; baseline median SUVmean, 5.01; IQR, 4.48-5.49; block median SUVmean, 1.57; IQR, 0.95-1.85) and spleen (median SUVmean, 2.14; IQR, 1.19-2.36) was also high in all pigs. Conclusion: 11C-GW457427 binds to NE in a porcine model of oleic acid-induced lung inflammation in vivo, with a specific increase in regional lung, bone marrow, and spleen SUV. 11C-GW457427 is a promising tool for localizing, tracking, and quantifying neutrophil-facilitated inflammation in clinical diagnostics and drug development.

Accelerated Hypofractionated Radiotherapy for Centrally Located Lung Tumours Not Suitable for Stereotactic Body Radiotherapy or Chemoradiotherapy

AIMS

Accelerated hypofractionated radiotherapy is used at our institution for non-small cell lung cancer (NSCLC) patients not eligible for stereotactic body radiotherapy or chemoradiotherapy. The purpose of this study was to report clinical outcomes of delivering 60 Gy in 15 fractions for these patients.

MATERIALS AND METHODS

All NSCLC patients who received 60 Gy in 15 fractions were reviewed. Outcomes of interest were local failure, regional failure, distant progression, overall survival and treatment-associated toxicities.

RESULTS

In total, 111 patients were included. The median age was 78.8 years and most tumours were adenocarcinoma (n = 55, 49.6%). Sixty-five patients (58.6%) were N0. The cumulative incidence of local failure at 12 and 24 months in the N0 cohort was 5.2% and 14.2%, respectively, compared with 11.5% and 14.8% for N+ patients. Tumour size >35 mm predicted for local failure (hazard ratio 2.706, 95% confidence interval 1.002-7.307, P = 0.0494). Distant progression at 12 and 24 months in N0 patients was 13.7% and 24.3% compared with 24.6% and 33.5% in N+ patients. In N0 patients, larger tumour size was associated with increased risk of distant progression. The median overall survival was 38.1 months in N0 patients versus 31.7 months in N+ patients. The most common toxicity was radiation pneumonitis (n = 6, 6.4%). The incidence of any grade 3 toxicity was 10.3% at ≥1 year. There were no deaths or hospitalisations attributed to treatment.

CONCLUSIONS

Accelerated hypofractionated radiotherapy is well tolerated and resulted in favourable clinical outcomes in various stages of NSCLC patients.

Stereotactic Body Radiotherapy for Renal Cell Carcinoma: Oncological and Renal Function Outcomes

AIMS

To evaluate oncological and renal function outcomes of stereotactic body radiotherapy (SBRT) for medically inoperable patients with localised renal cell carcinoma.

MATERIALS AND METHODS

Consecutive patients treated with curative intent SBRT (30-45 Gy in five fractions or 42 Gy in three fractions) were included. Data on local control (Response Evaluation Criteria in Solid Tumors [RECIST] v1.1), distant metastasis, impact on estimated glomerular filtration rate (eGFR) and proportional ipsilateral and contralateral renal functions (measured through renal scans) were collected. Univariate and multivariable analyses were conducted to determine association of variables with oncological and renal function outcomes.

RESULTS

Seventy-four patients were analysed. The median follow-up was 27.8 months (interquartile range 17.6-41.7). Fifty-seven per cent had tumours ≥ T1b. One-, 2- and 4-year cumulative incidence of local failure was 5.85, 7.77 and 7.77%, respectively. The cumulative incidence of distant metastasis at 2 years was 4.24%. On multivariable analysis, a lower planning target volume (PTV) mean dose (P = 0.019) and a larger PTV (P = 0.005) were significantly associated with the risk of developing local failure. A lower PTV maximum dose (P = 0.039) was significantly associated with the risk of developing distant metastasis. The median change in global eGFR (ml/min) from pre-SBRT levels was -7.0 (interquartile range -14.5 to -1.0) at 1 year and -11.5 (interquartile range -19.5 to -4.0) at 2 years. The proportion of ipsilateral (differential) renal function decreased over time from 47% of overall renal function pre-SBRT to 36% at 2 years, whereas the proportion of contralateral renal function correspondingly improved. On multivariable analysis, a higher volume of uninvolved renal cortex (P < 0.0001) was significantly associated with a smaller decrease in eGFR over time.

CONCLUSION

In this large institutional cohort, oncological outcomes of renal cell carcinoma treated with SBRT were favourable and a longitudinal decline in renal function in the ipsilateral kidney and compensatory increase in the contralateral kidney were observed. Clinical and dosimetric factors were significantly associated with oncological and renal function outcomes.

POS0200 POST-mRNA VACCINE FLARES IN AUTOIMMUNE INFLAMMATORY RHEUMATIC DISEASES: INTERIM RESULTS FROM THE CORONAVIRUS NATIONAL VACCINE REGISTRY FOR IMMUNE DISEASES SINGAPORE (CONVIN-SING)

Background

Published data suggest no increased rate of flare of autoimmune inflammatory rheumatic diseases (AIIRD) after COVID-19 mRNA vaccination; however, the studies are limited by small sample size, short follow up or at risk of selection bias (voluntary physician reports or patient surveys).

Objectives

To study flares of AIIRD within three months of the first dose of an anti-SARS-COV2 mRNA vaccine.

Methods

A retrospective cohort study of consecutive AIIRD patients ≥ 12 years old, across six public hospitals in Singapore who received at least one dose of an mRNA (Pfizer/BioNTech or Moderna) vaccine. Data were censored at the first post-vaccine clinic visit when the patient had flared or if ≥ three months had elapsed since the first dose of the vaccine, whichever came first. Predictors of flare were determined by Cox proportional hazards analysis and time to flare was examined using a Nelson Aalen cumulative hazard estimate (Figure 1).

Figure 1.

Nelson-Aalen curve of flares over time

Results

2339 patients (74% Chinese, 72% female) of median (IQR) age 64 (53, 71) years were included in the interim analysis (Table 1). 2112 (90%) had the Pfizer/BioNTech vaccine and 195 (8%) had Moderna, with a median (IQR) interval of 21 (21, 23) days between the two doses. The most common AIIRD diagnoses were Rheumatoid arthritis (1063, 45%), Psoriatic arthritis (296, 12.6%) and Systemic lupus erythematosus (SLE) (288, 12.3%). 186 (8%) were treated with biologics/ targeted disease modifying agents. 2125 (91%) patients were in low disease activity or remission. Treatment was interrupted for vaccination in only 18 (0.8%) patients. Seven (0.3%) patients had previous COVID-19 infection.

Table 1.

Patient characteristics

Baseline characteristicsNo flares(n = 1887, %)Flares within 0—3 months of 1st vaccine dose (n= 272, %)Flares outside of 0 – 3 months after 1st vaccine dose (n = 180, %)Age (median years, IQR)64 (53, 71)61 (50, 69)65 (55, 71)RaceChinese1386 (73)206 (76)129 (72)Malay193 (10)28 (10)20 (11)Indian195 (10)27 (10)26 (14)GenderFemale1367 (72)200 (74)117 (65)Vaccine typePfizer/BioNTech1713 (92)239 (90)160 (90)Moderna149 (8)28 (10)18 (10)DiagnosisRheumatoid Arthritis831 (44)139 (51)93 (52)Systemic Lupus Erythematosus269 (14)20 (7)9 (5)Psoriatic Arthritis225 (12)42 (15)29 (16)Spondyloarthropathies141 (7)21 (7)17 (9)Sjogren’s Syndrome114 (6)15 (6)8 (4)Systemic sclerosis94 (5)4 (1)6 (3)Baseline Physician Disease ActivityRemission1007 (53)99 (36)63 (35)Low Disease Activity731 (39)128 (47)97 (54)Moderate Disease Activity134 (7)40 (15)20 (11)High Disease Activity15 (1)5 (2)0

452 (19%) flares were recorded during 9798.8 patient-months [4.6/100 patient-months, median (IQR) follow up duration 4.2 (3.3, 5.3) months], of which 272 (11.6%) patients flared within the 3-month period of interest and 180 (7.7%) flared outside of the 3-month period (Table 1). Median (IQR) time-to-flare was 40.5 (18, 56.6) days. 60 (22.1%) were mild and self-limiting, 170 (62.5%) were mild-moderate and 42 (15.4%) were severe. 190 (69.8%) of those who flared required escalation of treatment and 15 (5.5%) required hospital admission. 239 (10.2%) had improved disease activity after the vaccine.

On multivariate Cox regression analysis, patients in the oldest age tertile [median (IQR) 74 (71, 79) years] were less likely to flare [HR 0.80 (95% CI 0.63, 1.00), p = 0.05] Patients with inflammatory arthritis (compared with connective tissue disease, vasculitis and others) and patients with baseline active disease were more likely to flare [HR 1.72 (95% CI 1.35, 2.20), p < 0.001 and 1.82 (95% CI 1.39, 2.39), p < 0.001 respectively]

Conclusion

There was a moderately high rate of AIIRD flares after mRNA vaccination; however, there was no clustering of flares in the immediate post-vaccine period to suggest causality. Older patients were less likely to flare, while those with inflammatory arthritis and active disease at baseline were more likely to flare.

Disclosure of Interests

Margaret Ma Grant/research support from: Support grant from multiple companies for the Singapore Biologics registry, Amelia Santosa Speakers bureau: Amgen Talk, Consultant of: Pfizer ad board, Kok Ooi Kong: None declared, Chuanhui Xu: None declared, Johnston Tang Gin Xiang: None declared, Gim Gee Teng Speakers bureau: Boehringer Ingleheim, Anselm Mak Speakers bureau: J&J and GSK, Grant/research support from: GSK - the supported studies programme, Sen Hee Tay: None declared, Victoria Wei Wen Ng: None declared, Joshua Zhi En Koh: None declared, Warren Fong Speakers bureau: speaker for Abbvie, DKSH, GSK, Novartis, Li-Ching Chew Speakers bureau: pfizer and Abbvie, Consultant of: Pfizer and Abbvie Advisory Board meeting, Grant/research support from: Abbvie educational grant for ultrasound conference, Andrea Low Speakers bureau: Boehringer Ingeilheim, Consultant of: Consultant/steering group committee for BI and J&J, annie law: None declared, Yih Jia Poh: None declared, Siaw Ing Yeo Grant/research support from: Multiple pharmaceutical companies for the support of the National Biologics Registry, Ying Ying Leung Speakers bureau: Abbvie, DKSH, Jassen, Novartis and Pfizer, Wei-Rui Goh: None declared, Chuah Tyng Yu: None declared, Nur Emillia Roslan: None declared, Stanley Angkodjojo Speakers bureau: Boehringer Ingeilheim, Consultant of: Abbvie and DKSH, Kee Fong Phang: None declared, Thaschawee Arkachaisri: None declared, Melonie Sriranganathan: None declared, Teck Choon TAN: None declared, Peter Cheung Consultant of: Ad board for Boehringer Ingleheim, novartis, janssen and abbvie, Grant/research support from: Novartis, Manjari Lahiri Speakers bureau: J&J, DSKH, Consultant of: DSKH, Gilead, Grant/research support from: Multiple pharma companies contributed to the Singapore Biologics registry

Novartis

The Current State of Beta-Cell-Mass PET Imaging for Diabetes Research and Therapies

Diabetes is a chronic metabolic disease affecting over 400 million people worldwide and one of the leading causes of death, especially in developing nations. The disease is characterized by chronic hyperglycemia, caused by defects in the insulin secretion or action pathway. Current diagnostic methods measure metabolic byproducts of the disease such as glucose level, glycated hemoglobin (HbA1c), insulin or C-peptide levels, which are indicators of the beta-cell function. However, they inaccurately reflect the disease progression and provide poor longitudinal information. Beta-cell mass has been suggested as an alternative approach to study disease progression in correlation to beta-cell function, as it behaves differently in the diabetes physiopathology. Study of the beta-cell mass, however, requires highly invasive and potentially harmful procedures such as pancreatic biopsies, making diagnosis and monitoring of the disease tedious. Nuclear medical imaging techniques using radiation emitting tracers have been suggested as strong non-invasive tools for beta-cell mass. A highly sensitive and high-resolution technique, such as positron emission tomography, provides an ideal solution for the visualization of beta-cell mass, which is particularly essential for better characterization of a disease such as diabetes, and for estimating treatment effects towards regeneration of the beta-cell mass. Development of novel, validated biomarkers that are aimed at beta-cell mass imaging are thus highly necessary and would contribute to invaluable breakthroughs in the field of diabetes research and therapies. This review aims to describe the various biomarkers and radioactive probes currently available for positron emission tomography imaging of beta-cell mass, as well as highlight the need for precise quantification and visualization of the beta-cell mass for designing new therapy strategies and monitoring changes in the beta-cell mass during the progression of diabetes.

The Drosophila melanogaster Levodopa-Induced Depression Model Exhibits Negative Geotaxis Deficits and Differential Gene Expression in Males and Females

More than 320 million people live with depression in the world, a disorder that severely limits psychosocial functioning and diminishes quality of life. The prevalence of major depression is almost two times higher in women than in men. However, the molecular mechanisms of its sex-specific pathophysiology are still poorly understood. Drosophila melanogaster is an established model for neurobiological research of depression-like states, as well as for the study of molecular and genetic sex differences in the brain. Here, we investigated sex-specific effects on forced-climbing locomotion (negative geotaxis) and gene expression of a fly model of depression-like phenotypes induced by levodopa administration, which was previously shown to impair normal food intake, mating frequency, and serotonin concentration. We observed that both males and females show deficits in the forced-climbing paradigm; however, modulated by distinct gene expression patterns after levodopa administration. Our results suggest that Drosophila models can be a valuable tool for identifying the molecular mechanisms underlying the difference of depressive disorder prevalence between men and women.

Longitudinal Assessment of 11C-5-Hydroxytryptophan Uptake in Pancreas After Debut of Type 1 Diabetes

The longitudinal alterations of the pancreatic β-cell and islet mass in the progression of type 1 diabetes (T1D) are still poorly understood. The objective of this study was to repeatedly assess the endocrine volume and the morphology of the pancreas for up to 24 months after T1D diagnosis (n = 16), by ¹¹C-5-hydroxytryptophan (¹¹C-5-HTP) positron emission tomography (PET) and MRI. Study participants were examined four times by PET/MRI: at recruitment and then after 6, 12, and 24 months. Clinical examinations and assessment of β-cell function by a mixed-meal tolerance test and fasting blood samples were performed in connection with the imaging examination. Pancreas volume has a tendency to decrease from 50.2 ± 10.3 mL at T1D debut to 42.2 ± 14.6 mL after 24 months (P < 0.098). Pancreas uptake of ¹¹C-5-HTP (e.g., the volume of the endocrine pancreas) did not decrease from T1D diagnosis (0.23 ± 0.10 % of injected dose) to 24-month follow-up, 0.21 ± 0.14% of injected dose, and exhibited low interindividual changes. Pancreas perfusion was unchanged from diagnosis to 24-month follow-up. The pancreas uptake of ¹¹C-5-HTP correlated with the long-term metabolic control as estimated by HbA_1c (P < 0.05). Our findings argue against a major destruction of β-cell or islet mass in the 2-year period after diagnosis of T1D.

Patient-reported Quality of Life following Stereotactic Body Radiation Therapy for Primary Kidney Cancer - Results from a Prospective Cohort Study

AIMS

We report on the first prospective series of patient-reported quality of life (QoL) following stereotactic body radiation therapy (SBRT) for primary kidney cancer.

MATERIALS AND METHODS

Patients were treated on a multi-institutional prospective cohort study with 30-42 Gy SBRT in three or five fractions. QoL assessments were carried out using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core-15 Palliative (EORTC-QLQ-C15-PAL), the Functional Assessment of Cancer Therapy-Kidney Symptom Index-19 (FACT FKSI-19) and the EuroQol-5D-3L tools at baseline, 1 week, and 1, 3 and 6 months post-treatment. QoL over time was analysed using linear mixed modelling, pairwise and anchor-based analyses.

RESULTS

Twenty-eight patients were included. No significant reduction in any QoL metric was observed on repeated measures. However, a trend to reduced EORTC global QoL and fatigue was observed at 1 week, with improvement over time in other symptom scores such as pain, appetite and nausea. On pairwise analysis, there were statistically significant reductions in global QoL at 1 week (with subsequent recovery) and dyspnoea at 6 months post-SBRT. Trends to improved pain, appetite and nausea were observed following SBRT. Less than half of patients reported stable or better EORTC global QoL at 1 week. For all other QoL and symptom scales, most patients had reported stable or better scores at all times, with a slight proportional improvement in emotional functioning, nausea, fatigue, pain and appetite, and a slight worsening of physical functioning and dyspnoea over time.

CONCLUSIONS

SBRT results in well-preserved QoL in the weeks to months following treatment for primary kidney cancer.

FRI0530 THE PREVALENCE AND DETERMINANTS OF SLEEP PROBLEMS IN PATIENTS ACROSS RHEUMATIC DISEASES AND THEIR CORRELATION WITH DISEASE INDICES USING THE ROUTINE ASSESSMENT OF PATIENT INDEX DATA 3 (RAPID3) QUESTIONNAIRE

Background:

Sleep problems are common in rheumatology patients. RAPID3 is a patient reported outcome measure (PROM) that efficiently screens for problems with sleep, anxiety or depression in routine care.

Objectives:

To study prevalence and determinants of self-reported sleep problems across rheumatic diseases in Rheumatology clinics in Singapore, and its correlation with disease indices.

Methods:

RAPID3 questionnaire was filled electronically over 6 months. Demographic data and SNOWMED diagnoses codes were matched through hospital electronic medical records. RAPID3 comprised of 3 questions measuring the extent of difficulty getting a good night’s sleep and dealing with anxiety or depression. Significant problems were considered if they had “much difficulty” or were “unable to do” the component. The relationship of sleep with anxiety, depression, physical function (measured by modified health assessment questionnaire, mdHAQ), pain and patient global assessment (using visual analogue scale, VAS), was evaluated using Pearson’s correlation. Factors associated with significant sleep problems were evaluated by logistic regression.

Results:

4078 patients [mean (SD) age 55.8 (16.3) years, 67.9% female, 70.6% Chinese] were invited to participate, of which 2625 (64.4%) responded. SNOMED diagnosis codes were available for 1570 (59.8%) patients- majority had inflammatory arthritides (n= 843, 53.7%) (Figure 1).

Mean mdHAQ was 0.3 (0.5), pain VAS was 2.4 (2.3) and global VAS was 2.6 (2.2). Data on disease duration, clinical features and medications were not available. 39.3%, 27.5% and 23.8% had problems with sleep, anxiety and depression respectively; and 7.3%, 4.5% and 4.3% had significant problems respectively. Sleep moderately correlated with anxiety (r=0.463, p<0.001) and depression (r=0.436, p<0.001) and weakly correlated with mdHAQ (r= 0.289, p<0.001), global (r=0.339, p<0.001) and pain VAS (r= 0.314, p<0.001).

In multivariable logistic regression, significant sleep problems were associated with anxiety (OR 4.733, CI 2.172-10.310, p<0.001), mdHAQ score ≥ 1 (OR 2.920, CI 1.691-5.043, p< 0.001) and pain VAS >3 (OR 1.884, CI 1.093-3.247, p=0.023). Patients with osteoarthritis and fibromyalgia were more likely than those with inflammatory arthritides to have significant sleep problems, though we were unable to adjust for body mass index as data were unavailable (Table 1).

Table 1.

Determinants of significant disturbances in sleep in patients with rheumatic diseases

VariablesUnivariableMultivariableOdds ratio (95% CI)p-valueOdds ratio (95% CI)p-valueGenderFemale1.79 (1.245-2.57)0.0021.49 (0.86-2.59)0.16EthnicityChineseRefRefMalay1.04 (0.62-1.73)0.890.73 (0.33-1.61)0.43Indian1.59 (1.03-2.44)0.040.97 (0.49-1.90)0.92Others1.05 (0.62-1.77)0.870.92 (0.43-2.00)0.84Age (years)1.00 (1.00-1.01)0.36--mdHAQ ≥16.25 (4.46-8.75)<0.0012.92 (1.69-5.04)0.001Pain VAS >34.15 (3.07-5.61)<0.0011.88 (1.09-3.25)0.02Global VAS > 34.25 (3.13-5.76)<0.0011.63 (0.95-2.80)0.07Significant anxiety15.99 (10.71- 23.89)<0.0014.73 (2.17-10.31)<0.001Significant depression15.58 (10.35-23.45)<0.0013.02 (1.29-7.10)0.11Primary rheuma-tological diagnosisInflammatory arthritidesRefRefConnective tissue diseases1.18 (0.73-1.90)0.510.9 (0.51-1.59)0.71Crystal arthritides1.06 (0.48-2.33)0.880.83 (0.34-2.03)0.68Osteoarthritis3.09 (1.31-7.32)0.012.96 (1.19-7.36)0.02Fibromyalgia9.05 (2.04-40.05)0.0049.62 (2.11-43.84)0.003Others1.63 (0.82-3.29)0.171.20 (0.58-2.47)0.63

Conclusion:

Sleep problems are common in rheumatology patients and correlate significantly with disease indices and psychological distress. Rheumatologists should routinely screen for sleep difficulties, especially in patients with osteoarthritis and fibromyalgia.

References: -

Acknowledgments:

Nil.

Disclosure of Interests:

Charlotte Tan: None declared, Peter Cheung: None declared, Manjari Lahiri Grant/research support from: Manjari Lahiri is the site principal investigator for the Singapore National Biologics Register, which is a multi-pharmaceutical funded register, in which industry sponsors provide support through the Chapter of Rheumatologists, Singapore. Dr Lahiri does not personally receive any remuneration.

FRI0033 ANTI-CARBAMYLATED PROTEIN POSITIVITY PREDICTS DAS28-REMISSION AT 12 MONTHS IN PATIENTS WITH EARLY RHEUMATOID ARTHRITIS: RESULTS FROM THE SINGAPORE EARLY ARTHRITIS COHORT

Background:

Anti-carbamylated protein antibody (anti-carp) positivity has been associated with poorer outcomes in Western cohorts of early rheumatoid arthritis; however, it is unknown if this applies to Asians.

Objectives:

We determined whether anti-carp predicted DAS28-remission, disability and radiographic progression in a multi-ethnic Asian ERA cohort.

Methods:

Patients with physician diagnosed ERA (symptom duration ≤1 year) were recruited from the Singapore Early Arthritis Cohort (n= 317) by convenience sampling. Serum anti-carp was measured cross-sectionally using a commercial ELISA (SincereBio). The test was repeated in 40 healthy individuals to establish the optimal sensitivity and specificity for the diagnosis of RA via a receiver operating curve. Disease activity (DAS28-ESR or DAS28-CRP) was recorded at baseline, 3, 6 and 12 months. Two independent accessors quantified the radiographic damage at baseline and at follow-up using the modified Sharp van der Heijde score (mSS). We used multivariable logistic regression to determine whether anti-carp predicted the following outcomes; (i) DAS-28 remission at 12 months, (ii) any disability (mHAQ>0) at 12 months and (iii) radiographic progression (any increase in the mSS). In each regression model, we chose covariates known to influence the dependent variable in our cohort or from literature.

Results:

One hundred patients were recruited, of mean age (SD) 49.8 (12.5) years, median (IQR) disease duration 10.2 (6.9-15.1) weeks at cohort entry and baseline median DAS-28 4.5 (2.9-5.9) (Table 1). The anti-carp assay was performed after a median (IQR) disease duration of 2.24 (1.82-3.14) years. 93 patients had baseline hand radiographs and 66 had follow-up hand radiographs after ≥ 12 months. Receiver operating characteristics curve yielded optimal sensitivity (95%) and specificity (60%) for the diagnosis of RA at 1.60OD. Therefore, 60 patients were anti-carp positive and 35 patients (37.2%) were positive for RF, ACPA and anti-carp (Figure 1). Anti-carp positivity independently predicted DAS28-remission at 12 months (OR 3.41, 95% CI 1.08-10.7,p=0.04) (Table 2). Anti-carp positivity did not predict disability at 12 months (OR 0.61, 95% CI 0.18-2.07,p=0.43) or radiographic progression (OR 0.23, 95% CI 0.03-2.03,p=0.18).

Table 1.

Predictors of DAS28-remission at 12 months

VariableN (%)Univariable Logistic RegressionMultivariable Logistic RegressionORpOR (CI)SEpAnti-carp60 (60)3.0 (1.31−6.88)0.013.41 (1.08−10.7)1.990.04SerologyRF and ACPA negative31 (33.0)RefEither RF or ACPA positive11 (11.7)0.99 (0.25−3.93)0.991.10 (0.17−7.04)1.040.92RF and ACPA positive52 (55.3)1.12 (0.45−2.75)0.800.89 (0.28−2.81)0.520.84Baseline DAS28Remission17 (17.4)RefLow DA10 (10.2)0.50 (0.05−4.67)0.540.13 (0.01−1.67)0.170.12Mod DA32 (32.7)0.29 (0.05−1.65)0.160.10 (0.02−0.68)0.100.02High DA39 (39.8)0.18 (0.04−0.90)0.040.06 (0.01−0.41)0.06<0.01Combination csDMARDs or biologic DMARD74 (74)1.13 (0.46−2.76)0.801.97 (0.58−6.67)1.230.28Radiographic damage at baseline11 (20)1.79 (0.65−4.95)0.261.27 (0.33-4.95)0.880.73Tertiary education23 (38.3)0.77 (0.34-1.77)0.540.42 (0.12-1.45)0.270.17EthnicityChinese42 (70)RefMalay39 (68.4)0.61 (0.22-1.71)0.350.56 (0.14-2.25)0.400.41Indian8 (13.3)0.60 (0.20-1.77)0.350.79 (0.20-3.13)0.560.74Females46 (76.7)0.43 (0.17-1.11)0.080.48 (0.13-1.85)0.330.29

Conclusion:

Contrary to previous studies done on Western cohorts where anti-carp predicted worse outcomes, anti-carp positivity predicted DAS28-remission at 12 months in our multi-ethnic Asian cohort. This suggests that different genetic and environmental determinants account for anti-carp expression in patients with RA.

Disclosure of Interests:

Jiacai Cho: None declared, Anselm Mak Speakers bureau: Professor Anselm Mak has been paid as a speaker for Johnson & Johnson., Sachin Agrawal: None declared, Preeti Dhanasekaran: None declared, Lay Kheng Teoh: None declared, Peter Cheung: None declared, Manjari Lahiri Grant/research support from: Manjari Lahiri is the site principal investigator for the Singapore National Biologics Register, which is a multi-pharmaceutical funded register, in which industry sponsors provide support through the Chapter of Rheumatologists, Singapore. Dr Lahiri does not personally receive any remuneration.

Comparison of facet joint violation in lumbar posterior spinal instrumentation using different techniques including cortical bone trajectory

Study background:

A retrospective study to compare the rate of facet joint violation (FJV) in lumbar posterior spinal instrumentation using open pedicle screw, percutaneous pedicle screw, and cortical bone trajectory (CBT) technique. CBT is a new posterior spinal instrumentation technique in which a more caudal entry point can minimize iatrogenic damage to the cranial facet joint. Only one recent study reports incidence of FJV of 11%; however, no previous reports comment on radiological outcomes comparing to traditional open and percutaneous screws.

Methods:

We reviewed 90 patients who underwent lumbar posterior spinal instrumentation from January 2016 to June 2017. Postoperative computer tomography scans were performed to evaluate FJV. Incidence of FJV was graded by three reviewers according to Seo classification.

Results:

Totally, 446 screws (open 43.4%, percutaneous 37.8%, CBT 18.9%) were inserted. Among these, 6.3% (28/446) had screw head or rod in contact with facet joint and 0.9% (4/446) had screws directly invaded the facet joint. Overall, FJV was 7.2% (CTB = 3.4%, open = 10.4%, and percutaneous = 4.5%, p = 0.075).

Conclusion:

CBT technique has potential advantage in reducing FJV. It has a unique entry site at lateral aspect of pars interarticular with a caudomedial to craniolateral pathway. It is a reasonable alternative to open or percutaneous techniques in lumbar posterior spinal instrumentation.

Results of 15 Gy HDR-BT boost plus EBRT in intermediate-risk prostate cancer: Analysis of over 500 patients

PURPOSE/OBJECTIVE

To report biochemical control associated with single fraction 15 Gy high-dose-rate brachytherapy (HDR-BT) boost followed by external beam radiation (EBRT) in patients with intermediate-risk prostate cancer.

MATERIALS AND METHODS

A retrospective chart review of all patients with intermediate-risk disease treated with a real-time ultrasound-based 15 Gy HDR-BT boost followed by EBRT between 2009 and 2016 at a single quaternary cancer center was performed. Freedom from biochemical failure (FFBF), cumulative incidence of androgen deprivation therapy use for biochemical or clinical failure post-treatment (CI of ADT) and metastasis-free survival (MFS) outcomes were measured.

RESULTS

518 patients met the inclusion criteria for this study. Median age at HDR-BT was 67 years (IQR 61-72). 506 (98%) had complete pathologic information available. Of these, 146 (28%) had favorable (FIR) and 360 (69%) had unfavorable (UIR) intermediate-risk disease. 83 (16%) received short course hormones with EBRT + HDR. Median overall follow-up was 5.2 years. FFBF was 91 (88-94)% at 5 years. Five-year FFBF was 94 (89-99)% and 89 (85-94)% in FIR and UIR patients, respectively (p = 0.045). CI of ADT was 4 (2-6)% at 5 years. Five-year CI of ADT was 1 (0-3)% and 5 (2-8)% in FIR and UIR patients, respectively (p = 0.085). MFS was 97 (95-98)% at 5 years. Five-year MFS was 100 (N/A-100)% and 95 (92-98)% in FIR and UIR patients, respectively (p = 0.020).

CONCLUSION

In this large cohort of intermediate-risk prostate cancer patients, 15 Gy HDR-BT boost plus EBRT results in durable biochemical control and low rates of ADT use for biochemical failure.

Prostate-specific Antigen Bounce After Stereotactic Body Radiotherapy for Prostate Cancer: A Pooled Analysis of Four Prospective Trials

AIMS

We conducted a pooled analysis of four prospective stereotactic body radiotherapy (SBRT) trials of low- and intermediate-risk prostate cancer to evaluate the incidence of prostate-specific antigen (PSA) bounce and its correlation with the time-dose-fraction schedule. The correlation between bounce with PSA response at 4 years (nadir PSA < 0.4 ng/ml) and biochemical failure-free survival (BFFS) was also explored.

MATERIALS AND METHODS

The study included four treatment groups: 35 Gy/five fractions once per week (QW) (TG-1; n = 84); 40 Gy/five fractions QW (TG-2; n = 100); 40 Gy/five fractions every other day (TG-3; n = 73); and 26 Gy/two fractions QW (TG-4; n = 30). PSA bounce was defined as a rise in PSA by 0.2 ng/ml (nadir + 0.2) or 2 ng/ml (nadir + 2.0) above nadir followed by a decrease back to nadir. Patients with fewer than three follow-up PSA tests were excluded from the pooled analysis.

RESULTS

In total, 287 patients were included, with a median follow-up of 5.0 years. The pooled 5-year cumulative incidence of bounce by nadir + 2.0 was 8%. The 2-year cumulative incidences of PSA bounce by nadir + 0.2 were 28.9, 21, 19.6 and 16.7% (P = 0.12) and by nadir + 2.0 were 7.2, 8, 2.7 and 6.7% (P = 0.32) for TG-1 to TG-4, respectively. Multivariable analysis revealed that for nadir + 2.0, pre-treatment PSA (odds ratio 0.49; 95% confidence interval 0.26-0.97) correlated with PSA bounce. Although PSA bounce by nadir + 0.2 (odds ratio 0.10; 95% confidence interval 0.04-0.24) and nadir + 2.0 (odds ratio 0.29; 95% confidence interval 0.09-0.93) was associated with a lower probability of PSA response at 4 years, there was no association between bounce by nadir + 0.2 (hazard ratio 0.36; 95% confidence interval 0.08-1.74) or nadir + 2 (hazard ratio 1.77; 95% confidence interval 0.28-11.07) with BFFS.

CONCLUSION

The incidence of PSA bounce was independent of time-dose-fraction schedule for prostate SBRT. One in 13 patients experienced a bounce high enough to be misinterpreted as biochemical failure, and clinicians should avoid early salvage interventions in these patients. There was no association between PSA bounce and BFFS.

Absolute percentage of biopsied tissue positive for Gleason pattern 4 disease (APP4) appears predictive of disease control after high dose rate brachytherapy and external beam radiotherapy in intermediate risk prostate cancer

BACKGROUND AND PURPOSE

To identify if, in intermediate risk prostate cancer (IR-PCa), the absolute percentage of biopsied tissue positive for pattern 4 disease (APP4) may be a predictor of outcome.

MATERIALS AND METHODS

411 patients with IR-PCa were retrospectively reviewed. APP4 was calculated based on biopsy reports. Multivariable competing risk analysis was then performed on optimized APP4 cutpoints to predict for biochemical failure (BF), androgen deprivation use for BF (ADT-BF) and development of metastases (MD).

RESULTS

Median follow-up for the cohort was 5.2 (Inter Quartile Range: 2.9-6.6) years. Median baseline PSA was 7.3 (5.3-9.8) ng/mL. 234 (56.9%) patients had T1 and 177 (43.1%) had T2 disease. Median APP4 was 2.00 (0.75-7.50)%. 38 (9.3%) patients experienced BF. The optimal cutpoint of APP4 for BF was >3.3% with an area under the curve (AUC) of 0.66. 17 (4.1%) received ADT-BF. The ADT-BF cutpoint was >6.6% with an AUC of 0.72. Eight (2.0%) developed MD. The MD cutpoint was >17.5% with an AUC of 0.86. Using APP4 >3.3 vs ≤ 3.3, log-transformed baseline PSA ln(PSA) (HR 2.5, 1.1-6.1; p = 0.037) and APP4 (HR 2.3, 1.1-4.7; p = 0.031) predicted for BF. Using APP4 >6.6 vs ≤ 6.6, ln(PSA) (HR 4.2, 1.4-12.4; p = 0.010) and APP4 (HR 3.7, 1.4-10.0; p = 0.009) were predictive of ADT-BF. APP4 >17.5 vs ≤ 17.5 alone was predictive of MD (HR 25.7, 4.9-135.3; p < 0.001).

CONCLUSION

APP4 cutpoints of >3.3%, >6.6% and >17.5% were strongly associated with increased risk of BF, ADT-BF and developing MD respectively. These findings may inform future practice when treating IR-PCa but require external validation.