Biomarker-Oriented Therapy in Bladder and Renal Cancer.

Treatment of patients with urothelial carcinoma (UC) of the bladder or renal cancer has changed significantly during recent years and efforts towards biomarker-directed therapy are being investigated. Immune checkpoint inhibition (ICI) or fibroblast growth factor receptor (FGFR) directed therapy are being evaluated for non-muscle invasive bladder cancer (NMIBC) patients, as well as muscle-invasive bladder cancer (MIBC) patients. Meanwhile, efforts to predict tumor response to neoadjuvant chemotherapy (NAC) are still ongoing, and genomic biomarkers are being evaluated in prospective clinical trials. Currently, patients with metastatic UC (mUC) are usually treated with second-line ICI, while cisplatin-ineligible patients with programmed death-ligand 1 (PD-L1) positive tumors can benefit from first-line ICI. Platinum-relapsed UC patients harboring FGFR2/3 mutations can be treated with erdafitinib, while enfortumab vedotin has emerged as a novel third-line treatment option for mUC. In metastatic (clear cell) renal cell carcinoma (RCC), ICI was first introduced as second-line treatment after vascular endothelial growth factor receptor-tyrosine kinase inhibition (VEGFR-TKI). Currently, ICIs have also been introduced as first-line treatment in metastatic RCC. Although there is no evidence up to now for beneficial adjuvant treatment after surgery with VEGFR-TKIs in high-risk non-metastatic RCC, several trials are underway investigating the potential beneficial effect of ICIs in this setting.

Identifying cystogenic paracrine signaling molecules in cyst fluid of patients with polycystic kidney disease.

In autosomal dominant polycystic kidney disease (ADPKD) paracrine signaling molecules in cyst fluid can induce proliferation and cystogenesis of neighboring renal epithelial cells. However, the identity of this cyst-inducing factor is still unknown. The aim of this study was to identify paracrine signaling proteins in cyst fluid using a 3D in vitro cystogenesis assay. We collected cyst fluid from 15 ADPKD patients who underwent kidney or liver resection (55 cysts from 13 nephrectomies, 5 cysts from 2 liver resections). For each sample, the ability to induce proliferation and cyst formation was tested using the cystogenesis assay (RPTEC/TERT1 cells in Matrigel with cyst fluid added for 14 days). Kidney cyst fluid induced proliferation and cyst growth of renal epithelial cells in a dose-dependent fashion. Liver cyst fluid also induced cystogenesis. Using size exclusion chromatography, 56 cyst fluid fractions were obtained of which only the fractions between 30 and 100 kDa showed cystogenic potential. Mass spectrometry analysis of samples that tested positive or negative in the assay identified 43 candidate cystogenic proteins. Gene ontology analysis showed an enrichment for proteins classified as enzymes, immunity proteins, receptors, and signaling proteins. A number of these proteins have previously been implicated in ADPKD, including secreted frizzled-related protein 4, S100A8, osteopontin, and cysteine rich with EGF-like domains 1. In conclusion, both kidney and liver cyst fluids contain paracrine signaling molecules that drive cyst formation. Using size exclusion chromatography and mass spectrometry, we procured a candidate list for future studies. Ultimately, cystogenic paracrine signaling molecules may be targeted to abrogate cystogenesis in ADPKD.

Bosniak Classification for Complex Renal Cysts Reevaluated: A Systematic Review.

PURPOSE: We systematically evaluated the Bosniak classification system with malignancy rates of each Bosniak category, and assessed the effectiveness related to surgical treatment and oncologic outcome based on recurrence and/or metastasis. MATERIALS AND METHODS: In a systematic review according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies) criteria, we selected 39 publications for inclusion in this analysis and categorized them into 1) surgical cohorts-all cysts treated surgically and 2) radiological cohorts-cysts with surgical treatment or radiological followup. RESULTS: A total of 3,036 complex renal cysts were categorized into Bosniak II, IIF, III and IV. In surgical and radiological cohorts pooled estimates showed a malignancy prevalence of 0.51 (0.44, 0.58) in Bosniak III and 0.89 (0.83, 0.92) in Bosniak IV cysts, respectively. Stable Bosniak IIF cysts showed a malignancy rate of less than 1% during radiological followup (surveillance). Bosniak IIF cysts, which showed reclassification to the Bosniak III/IV category during radiological followup (12%), showed malignancy in 85%, comparable to Bosniak IV cysts. The estimated surgical number needed to treat to avoid metastatic disease of Bosniak III and IV cysts was 140 and 40, respectively. CONCLUSIONS: The effectiveness of the Bosniak classification system for complex renal cysts was high in categories II, IIF and IV, but low in category III, and 49% of Bosniak III cysts was overtreated because of a benign outcome. This surgical overtreatment combined with the excellent outcome for Bosniak III cysts may suggest that surveillance is a rational alternative to surgery. This will require further study to assess whether surveillance of Bosniak III cysts will prove safe.

Intermittent versus continuous cyproterone acetate in bone metastatic prostate cancer: results of a randomized trial.

BACKGROUND: To compare intermittent treatment (IT) versus continuous treatment (CT) using cyproterone acetate (CPA) in bone metastatic prostate cancer patients, we conducted an open-label, multicenter randomized trial. Continuous androgen deprivation therapy is the standard treatment in metastatic prostate cancer. Intermittent treatment might maintain efficacy while toxicity and costs are reduced. METHODS: Patients received CPA 100 mg tid in the prephase. Patients with a PSA decline of ≥ 90 % or PSA <4 ng/ml were randomized. If patients were progressive, LHRH analogues were added. Primary end point was time to PSA progression. RESULTS: A total of 366 patients were recruited; 258 reached a good response after 3 or 6 months and were randomized. A total of 131 patients randomized to IT and 127 to CT. Patients on IT had an average of 1.7 episodes on CPA, before LHRH analogues were started. The mean time without treatment in IT was 463 days versus 422 days on treatment. There were statistical significant differences between IT and CT in 3 of the 5 functional scales of EORTC QLQ C 30; however, the clinical relevance of this finding appears modest. Symptom and potency scales showed significant advantages for IT. There were no differences in time to PSA progression on CPA, time to PSA and/or clinical progression on LHRH analogues and time to cancer-specific and overall survival. CONCLUSIONS: IT by CPA is associated with less symptoms and modest advantages in QOL domains. There were no differences in time to PSA progression, clinical progression or survival.

Surgical anatomy of the 10th and 11th intercostal, and subcostal nerves: prevention of damage during lumbotomy.

PURPOSE: In a descriptive, inventorial anatomical study we mapped the course of the 10th and 11th intercostal nerves, and the subcostal nerve in the abdominal wall to determine a safe zone for lumbotomy. MATERIALS AND METHODS: We dissected 11 embalmed cadavers, of which 10 were analyzed. The 10th and 11th intercostal nerves, and the subcostal nerve were dissected from the intercostal space to the rectus sheath. Analysis was done using computer assisted surgical anatomy mapping. A safe zone and an incision line with a minimum of nerve crossings were determined. RESULTS: The 10th and 11th intercostal nerves were invariably positioned subcostally. The subcostal nerve lay subcostally but caudal to the rib in 4 specimens. The main branches were located between the internal oblique and transverse abdominal muscles. The nerves branched and extensively varied in the abdominal wall. A straight line extended from the superior surface of the 11th and 12th ribs indicated a zone with lower nerve density. In 5 specimens the 10th and 11th intercostal nerves crossed this line from the superior surface of the 11th rib. In 5 specimens neither the 11th intercostal nerve nor the subcostal nerve crossed this extended line from the superior surface of the 12th rib up to 15 cm from the tip of the rib. CONCLUSIONS: Damage is inevitable to branches of the 10th or 11th intercostal nerve, or the subcostal nerve during lumbotomy. However, an incision extending from the superior surface of the 11th or 12th rib is less prone to damage these nerves. Closing the abdominal wall in 3 layers with the transverse abdominal muscle separately might prevent damage to neighboring nerves.

Patient-reported Quality of Life in Patients with Primary Metastatic Prostate Cancer Treated with Androgen Deprivation Therapy with and Without Concurrent Radiation Therapy to the Prostate in a Prospective Randomised Clinical Trial; Data from the HORRAD Trial.

BACKGROUND: A survival benefit was demonstrated for patients with low-volume metastatic prostate cancer (mPCa) when local radiotherapy was added to androgen deprivation therapy (ADT). OBJECTIVE: To determine the effect of ADT combined with external beam radiotherapy (EBRT) to the prostate on health-related quality of life (HRQoL) of patients with primary bone mPCa. DESIGN, SETTING, AND PARTICIPANTS: The HORRAD trial is a multicentre randomised controlled trial recruiting 432patients with primary bone mPCa between 2004 and 2014. INTERVENTION: Patients were randomised to ADT with EBRT or to ADT alone. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Patients completed two validated HRQoL questionnaires (European Organization for Research and Treatment of Cancer [EORTC] Quality of Life Questionnaire Core Module (QLQ-C30) and EORTC Quality of Life Questionnaire Prostate Module [QLQ-PR25]) at baseline and at 3, 6, 12, and24 mo after the initiation of treatment. The effect of both treatments was evaluated based on mixed-effect models. RESULTS AND LIMITATIONS: Patient characteristics and HRQoL scores at baseline were similar in both arms. At baseline, 98% of patients completed the questionnaires, compared with 58% at 24 mo. Patients reported significantly more diarrhoea (difference between the groups 10.8; 95% confidence interval [CI] 7.3-14.2), bowel symptoms (4.5; 95% CI 2.1-6.8), and urinary symptoms (11.9; 95% CI 8.9-14.8) after EBRT and ADT compared with ADT alone (all between-arm difference p < 0.001). Urinary complaints levelled at 6 mo. At 2 yr, only bowel symptom scores were significantly different (8.0; 95% CI 4.8-11.1, p ≤ 0.001), but 68% of patients in the radiotherapy group did not report clinically relevant worsening of their bowel symptom scores. CONCLUSIONS: Patients with bone mPCa reported temporary modest urinary and bowel symptoms after combined treatment with EBRT of the prostate and ADT compared with ADT alone. For some patients (22%), deterioration of bowel functions remains at 2 yr, whereas general HRQoL does not deteriorate.. PATIENT SUMMARY: This study investigated the effect of radiotherapy to the prostate added to hormonal therapy on patient-reported health-related quality of life (HRQoL) in patients with primary bone metastatic prostate cancer. Most patients reported only temporary urinary and bowel symptoms. In 22% of patients, bowel symptoms remained at 2 yr, whereas general HRQoL did not deteriorate.

Kidney and urinary tract imaging: triple-bolus multidetector CT urography as a one-stop shop--protocol design, opacification, and image quality analysis.

PURPOSE: To retrospectively evaluate renal, vascular, and urinary tract visualization following a single postcontrast multidetector computed tomographic (CT) urographic sequence performed with three limited-volume bolus injections. MATERIALS AND METHODS: The institutional review board approved this retrospective study. Patient informed consent was waived. Triple-bolus multidetector CT urography was performed in 110 patients. Triple-bolus protocol consisted of 30 mL of contrast material at 2 mL/sec at 0 seconds, 50 mL at 1.5 mL/sec at 435 seconds, 65 mL at 3 mL/sec at 488 seconds, with total abdominal scanning time of 510 seconds. Two independent readers rated urinary tract opacification and qualitatively and quantitatively assessed renal parenchymal and vascular contrast enhancement. Upper urinary tract (UUT) distention was measured by one reader. Interobserver agreement was assessed by using kappa statistics. RESULTS: Complete opacification of the intrarenal collecting system and proximal ureter was achieved in 91% (184 of 202) (kappa = 0.62) and 82% (166 of 202) (kappa = 0.94) of segments, respectively. The distal ureter was not opacified in 21% of the cases (kappa = 0.92), and the bladder was not opacified in 20% of the cases. Mean distention was higher for proximal (3.9 mm) than for distal (3.7 mm) segments. Image quality of renal parenchymal enhancement was excellent in 76% of cases. Arteries showed better contrast enhancement than veins (excellent rating in 89% vs 59% of the cases). Radiation dose calculated for triple-bolus acquisition was 9.8 mSv. CONCLUSION: Triple-bolus multidetector CT urography is a dose-efficient protocol acquiring corticomedullary-nephrographic-excretory and vascular enhancement phases in a single acquisition and provides sufficient opacification and distention of the UUT. Simultaneously, adequate image quality of renal parenchyma and vascular anatomy is achieved.

Diagnostic value of urinary dysmorphic erythrocytes in clinical practice.

BACKGROUND: In clinical practice, discriminating between glomerular and nonglomerular causes of hematuria is often difficult. Dysmorphic red blood cells (dRBC) in the urinary sediment are claimed to be effective, but the cutoff points in the literature vary. This follow-up study aimed to determine the diagnostic value of dRBC. METHODS: We investigated 134 hematuria patients in the departments of nephrology and urology. To diagnose the origin of hematuria, urological and/or nephrological examination was performed and the %dRBC identified by microscopy. Follow-up was performed after 3.5 years. RESULTS: The cause of hematuria was proven in 68 patients (35% glomerular; 65% nonglomerular). Patients with glomerular disease had significantly more albuminuria and dRBC than patients with nonglomerular disease, but the %dRBC ranged from 1 to 50% and no optimal cutoff could be identified. Logistic regression analysis showed that %dRBC had a predicted probability to diagnose glomerular disease of 77.9% (area under the curve, AUC, 0.85). When %dRBC was combined with other risk factors such as serum creatinine, sex, age, dipstick erythrocyte or proteinuria score and number of casts, the predictive probability increased to 90.6% (AUC 0.97). Follow-up of the included patients showed no benefit of dRBC to identify patients at risk for glomerular disease. CONCLUSIONS: The diagnostic value of routinely collected urinary dRBC to diagnose glomerular disease in patients presenting with hematuria is modest. However, including dRBC with other variables, such as age and erythrocyte score on dipstick testing may increase the sensitivity, but needs to be confirmed in another, preferably larger, population.

Cystic renal-epithelial derived induced pluripotent stem cells from polycystic kidney disease patients.

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease, leading to kidney failure in most patients. In approximately 85% of cases, the disease is caused by mutations in PKD1. How dysregulation of PKD1 leads to cyst formation on a molecular level is unknown. Induced pluripotent stem cells (iPSCs) are a powerful tool for in vitro modeling of genetic disorders. Here, we established ADPKD patient-specific iPSCs to study the function of PKD1 in kidney development and cyst formation in vitro. Somatic mutations are proposed to be the initiating event of cyst formation, and therefore, iPSCs were derived from cystic renal epithelial cells rather than fibroblasts. Mutation analysis of the ADPKD iPSCs revealed germline mutations in PKD1 but no additional somatic mutations in PKD1/PKD2. Although several somatic mutations in other genes implicated in ADPKD were identified in cystic renal epithelial cells, only few of these mutations were present in iPSCs, indicating a heterogeneous mutational landscape, and possibly in vitro cell selection before and during the reprogramming process. Whole-genome DNA methylation analysis indicated that iPSCs derived from renal epithelial cells maintain a kidney-specific DNA methylation memory. In addition, comparison of PKD1+/- and control iPSCs revealed differences in DNA methylation associated with the disease history. In conclusion, we generated and characterized iPSCs derived from cystic and healthy control renal epithelial cells, which can be used for in vitro modeling of kidney development in general and cystogenesis in particular.

Effect on Survival of Androgen Deprivation Therapy Alone Compared to Androgen Deprivation Therapy Combined with Concurrent Radiation Therapy to the Prostate in Patients with Primary Bone Metastatic Prostate Cancer in a Prospective Randomised Clinical Trial: Data from the HORRAD Trial.

BACKGROUND: The cornerstone of standard treatment for patients with primary bone metastatic prostate cancer (mPCa) is androgen deprivation therapy (ADT). Retrospective studies suggest a survival benefit for treatment of the primary prostatic tumour in mPCa, but to date, no randomised-controlled-trials (RCTs) have been published addressing this issue. OBJECTIVE: To determine whether overall survival is prolonged by adding local treatment of the primary prostatic tumour with external beam radiation therapy (EBRT) to ADT. DESIGN, SETTING, AND PARTICIPANTS: The HORRAD trial is a multicentre RCT recruiting 432 patients with prostate-specific antigen (PSA) >20ng/ml and primary bone mPCa on bone scan between 2004 and 2014. INTERVENTION: Patients were randomised to either ADT with EBRT (radiotherapy group) or ADT alone (control group). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Primary endpoint was overall survival. Secondary endpoint was time to PSA progression. Crude and adjusted analyses were applied to evaluate treatment effect. RESULTS AND LIMITATIONS: Median PSA level was 142ng/ml and 67% of patients had more than five osseous metastases. Median follow up was 47 mo. Median overall survival was 45 mo (95% confidence interval [CI], 40.4-49.6) in the radiotherapy group and 43 mo (95% CI: 32.6-53.4) in the control group (p=0.4). No significant difference was found in overall survival (hazard ratio [HR]: 0.90; 95% CI: 0.70-1.14; p=0.4). Median time to PSA progression in the radiotherapy group was 15 mo (95% CI: 11.8-18.2), compared with 12 mo (95% CI: 10.6-13.4) in the control group. The crude HR (0.78; 95% CI: 0.63-0.97) was statistically significant (p=0.02). CONCLUSIONS: The current RCT comparing ADT to ADT with EBRT to the prostate in patients with primary bone mPCa did not show a significant difference in overall survival, although the CI cannot exclude a substantial survival benefit. Further research is needed to confirm our findings. PATIENT SUMMARY: This study investigated the effect of adding radiation therapy to the prostate to hormonal therapy in prostate cancer patients with metastasis to the bone at diagnosis. In our patient group, additional radiotherapy did not improve overall survival. Further research is needed to confirm our findings. TWITTER SUMMARY: Adding radiotherapy to the prostate in patients with bone metastatic prostate cancer does not improve overall survival.

Long-term outcome of kidney transplantation in patients with a urinary conduit: a case-control study.

PURPOSE: To study the short- and long-term outcomes of kidney transplantation in patients with a bladder augmentation or urinary diversion compared to patients with a kidney transplantation in a normal functional bladder. PATIENTS AND METHODS: Between January 2000 and March 2011, 13 patients received 16 grafts into a reconstructed urinary tract. We performed a retrospective case-control study and matched each patient to 4 controls for donor and recipient gender and year of transplantation. RESULTS: Short- and long-term complications of kidney transplantation occurred in 12 patients, varying from urinary tract infections to medical hospitalization with or without surgical or radiological intervention. In 5 patients, a percutaneous nephrostomy (PCN) was placed followed by surgical re-intervention. In three patients, the grafts failed as a result of chronic rejection and were re-transplanted. There was no graft loss as a result of surgical complications or the reconstructed urinary tract. One-year patient and graft survival was 100 %. After five years, all patients were alive and seven of nine grafts (77.8 %) were functioning. Mean follow-up time was 4.3 years. Among the controls, 55 grafts were transplanted in 52 patients. Ten patients received a PCN. Five patients needed surgical re-intervention. In three patients, transplantectomy was performed for ongoing rejection. Three patients were re-transplanted. One patient had a failing graft 7.5 years post-transplantation and became dialysis dependent. CONCLUSION: Kidney transplantation in patients with a reconstructed urinary tract has an increased complication rate. Nevertheless, the long-term results are comparable to patients with a normal urinary bladder.

Does local treatment of the prostate in advanced and/or lymph node metastatic disease improve efficacy of androgen-deprivation therapy? A systematic review.

CONTEXT: Androgen-deprivation therapy (ADT) plays a pivotal role in the management of locally advanced and metastatic prostate cancer (PCa). When and for how long to apply ADT have remained controversial issues. OBJECTIVE: To review randomised studies of ADT (orchiectomy or luteinising hormone-releasing hormone analogues) in PCa-both immediate and deferred/adjuvant studies-to elucidate a possible interaction between local treatment and ADT. EVIDENCE ACQUISITION: Published randomised studies on ADT in various stages of PCa were included in this review. EVIDENCE SYNTHESIS: Studies of immediate versus deferred ADT without local treatment consistently showed only limited benefit for overall survival (OS; hazard ratio [HR]: 0.90; 95% confidence interval [CI], 0.83-0.97) and cancer-specific survival (CSS; HR: 0.79; 95% CI, 0.71-0.89). In contrast, ADT as an adjuvant to radiation therapy in patients with high-risk localised disease or locally advanced disease was associated with substantial OS and CSS benefits. A similar benefit was seen in patients with proven systemic disease (node-positive patients after radical prostatectomy). Overall, the data suggest a clinically important survival benefit (HR for OS: 0.69; 95% CI, 0.61-0.79) when a local treatment has been applied to the primary tumour. Possible mechanisms of this therapeutic effect are discussed. CONCLUSIONS: We conclude that an interaction between local treatment and ADT is suggested by this systematic review. In patients with advanced and aggressive disease who are at a high risk to die from PCa and who are treated for their primary tumour with curative intent, immediate and sustained ADT improves OS and CSS significantly. The local therapy in T3 and/or lymph node-positive disease is an essential part of the optimal treatment. However, this intensive treatment is unnecessary in a substantial number of patients with T3 and/or N1 disease with a slow natural history or high competing death risk.

Expression of the androgen-regulated fusion gene TMPRSS2-ERG does not predict response to endocrine treatment in hormone-naïve, node-positive prostate cancer.

BACKGROUND: Fusion of the androgen-regulated gene transmembrane protease, serine 2, TMPRSS2, to the v-ets erythroblastosis virus E26 oncogene homolog (avian), ERG, of the erythroblast transformation-specific (ETS) family is the most common genetic alteration in prostate cancer (PCa). OBJECTIVE: To determine whether expression of androgen-regulated TMPRSS2-ERG predicts response to endocrine treatment in hormone-naïve, node-positive PCa. DESIGN, SETTING, AND PARTICIPANTS: Eighty-five patients with histologically confirmed, node-positive PCa who were without treatment at the moment of lymph node dissection were analysed. RNA was isolated from the paraffin-embedded lymph node metastases and complementary DNA (cDNA) was made. The quality of cDNA was tested by polymerase chain reaction (PCR) analysis of the expression of the housekeeping gene hydroxymethylbilane synthase, HMBS (formerly PBGD). TMPRSS2-ERG expression was analysed by PCR using a forward primer in TMPRSS2 exon 1 and a reverse primer in ERG exon 4. MEASUREMENTS: The primary end point was time from start of endocrine therapy to the occurrence of three consecutive rises in prostate-specific antigen (PSA) that were at least 2 wk apart and resulted in two 50% increases over the PSA nadir. Secondary end points were time to PSA nadir after start of endocrine treatment and cancer-specific and overall survival. RESULTS AND LIMITATIONS: TMPRSS2-ERG was expressed in 59% of the 71 patients who could be analysed. Median duration of response to endocrine therapy was 20.9 mo versus 24.1 mo for gene fusion-positive versus gene fusion-negative patients (95% confidence intervals: 18.6-23.1 vs 18.9-29.4, p=0.70). Furthermore, no significant differences were seen between the two groups for the secondary end points. CONCLUSIONS: Expression of TMPRSS2-ERG is frequent in lymph node metastases of patients with untreated PCa; however, expression of this androgen-regulated fusion gene did not correspond with duration of response to endocrine therapy. Our results suggest that expression of TMPRSS2-ERG is not a candidate marker to select for metastatic PCa patients who will benefit more from endocrine treatment.

Histoplasma-associated inflammatory pseudotumour of the kidney mimicking renal carcinoma.

A 56-year-old female, originally from Suriname, with an otherwise unremarkable previous medical history was found to have a renal mass highly suspicious for renal cancer for which a nephrectomy was performed. Within the kidney, a tumourous mass was found which, on histological examination, showed an inflammatory pseudotumour caused by Histoplasma capsulatum. Further investigations revealed an idiopathic CD4(+) lymphopenia. Mass lesions mimicking a malignant tumour caused by infection with Histoplasma have rarely been described. To the best of our knowledge, this is the first report of a Histoplasma-associated inflammatory pseudotumour mimicking cancer occurring in the kidney.

Reduction of serum prostate-specific antigen levels following varicella-zoster infection and valaciclovir treatment in prostate cancer.

We present two prostate cancer patients, including one with a castration-resistant cancer whose rising serum prostate-specific antigen (PSA) levels showed a remarkable drop after a reactivated varicella-zoster virus infection treated with valaciclovir. In one patient, we found a temporary decrease in serum PSA lasting for at least 4 mo. In the patient with castration-resistant prostate cancer, serum PSA decreased to <0.01 microg/l and has remained undetectable since.