Efficacy and safety of arimoclomol in Niemann-Pick disease type C: Results from a double-blind, randomised, placebo-controlled, multinational phase 2/3 trial of a novel treatment.

Niemann-Pick disease type C (NPC) is a rare, genetic, progressive neurodegenerative disorder with high unmet medical need. We investigated the safety and efficacy of arimoclomol, which amplifies the heat shock response to target NPC protein misfolding and improve lysosomal function, in patients with NPC. In a 12-month, prospective, randomised, double-blind, placebo-controlled, phase 2/3 trial (ClinicalTrials.gov identifier: NCT02612129), patients (2-18 years) were randomised 2:1 to arimoclomol:placebo, stratified by miglustat use. Routine clinical care was maintained. Arimoclomol was administered orally three times daily. The primary endpoint was change in 5-domain NPC Clinical Severity Scale (NPCCSS) score from baseline to 12 months. Fifty patients enrolled; 42 completed. At month 12, the mean progression from baseline in the 5-domain NPCCSS was 0.76 with arimoclomol vs 2.15 with placebo. A statistically significant treatment difference in favour of arimoclomol of -1.40 (95% confidence interval: -2.76, -0.03; P = .046) was observed, corresponding to a 65% reduction in annual disease progression. In the prespecified subgroup of patients receiving miglustat as routine care, arimoclomol resulted in stabilisation of disease severity over 12 months with a treatment difference of -2.06 in favour of arimoclomol (P = .006). Adverse events occurred in 30/34 patients (88.2%) receiving arimoclomol and 12/16 (75.0%) receiving placebo. Fewer patients had serious adverse events with arimoclomol (5/34, 14.7%) vs placebo (5/16, 31.3%). Treatment-related serious adverse events (n = 2) included urticaria and angioedema. Arimoclomol provided a significant and clinically meaningful treatment effect in NPC and was well tolerated.

Safety, Tolerability, and EEG-Based Target Engagement of STP1 (PDE3,4 Inhibitor and NKCC1 Antagonist) in a Randomized Clinical Trial in a Subgroup of Patients with ASD.

This study aimed to evaluate the safety and tolerability of STP1, a combination of ibudilast and bumetanide, tailored for the treatment of a clinically and biologically defined subgroup of patients with Autism Spectrum Disorder (ASD), namely ASD Phenotype 1 (ASD-Phen1). We conducted a randomized, double-blind, placebo-controlled, parallel-group phase 1b study with two 14-day treatment phases (registered at clinicaltrials.gov as NCT04644003). Nine ASD-Phen1 patients were administered STP1, while three received a placebo. We assessed safety and tolerability, along with electrophysiological markers, such as EEG, Auditory Habituation, and Auditory Chirp Synchronization, to better understand STP1's mechanism of action. Additionally, we used several clinical scales to measure treatment outcomes. The results showed that STP1 was well-tolerated, with electrophysiological markers indicating a significant and dose-related reduction of gamma power in the whole brain and in brain areas associated with executive function and memory. Treatment with STP1 also increased alpha 2 power in frontal and occipital regions and improved habituation and neural synchronization to auditory chirps. Although numerical improvements were observed in several clinical scales, they did not reach statistical significance. Overall, this study suggests that STP1 is well-tolerated in ASD-Phen1 patients and shows indirect target engagement in ASD brain regions of interest.

Safety and efficacy of arimoclomol in patients with early amyotrophic lateral sclerosis (ORARIALS-01): a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial.

BACKGROUND: Amyotrophic lateral sclerosis is a progressive neurodegenerative disorder leading to muscle weakness and respiratory failure. Arimoclomol, a heat-shock protein-70 (HSP70) co-inducer, is neuroprotective in animal models of amyotrophic lateral sclerosis, with multiple mechanisms of action, including clearance of protein aggregates, a pathological hallmark of sporadic and familial amyotrophic lateral sclerosis. We aimed to evaluate the safety and efficacy of arimoclomol in patients with amyotrophic lateral sclerosis. METHODS: ORARIALS-01 was a multinational, randomised, double-blind, placebo-controlled, parallel-group trial done at 29 centres in 12 countries in Europe and North America. Patients were eligible if they were aged 18 years or older and met El Escorial criteria for clinically possible, probable, probable laboratory-supported, definite, or familial amyotrophic lateral sclerosis; had an ALS Functional Rating Scale-Revised score of 35 or more; and had slow vital capacity at 70% or more of the value predicted on the basis of the participant's age, height, and sex. Patients were randomly assigned (2:1) in blocks of 6, stratified by use of a stable dose of riluzole or no riluzole use, to receive oral arimoclomol citrate 1200 mg/day (400 mg three times per day) or placebo. The Randomisation sequence was computer generated centrally. Investigators, study personnel, and study participants were masked to treatment allocation. The primary outcome was the Combined Assessment of Function and Survival (CAFS) rank score over 76 weeks of treatment. The primary outcome and safety were analysed in the modified intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT03491462, and is completed. FINDINGS: Between July 31, 2018, and July 17, 2019, 287 patients were screened, 245 of whom were enrolled in the trial and randomly assigned. The modified intention-to-treat population comprised 239 patients (160 in the arimoclomol group and 79 in the placebo group): 151 (63%) were male and 88 (37%) were female; mean age was 57·6 years (SD 10·9). CAFS score over 76 weeks did not differ between groups (mean 0·51 [SD 0·29] in the arimoclomol group vs 0·49 [0·28] in the placebo group; p=0·62). Cliff's delta comparing the two groups was 0·039 (95% CI -0·116 to 0·194). Proportions of participants who died were similar between the treatment groups: 29 (18%) of 160 patients in the arimoclomol group and 18 (23%) of 79 patients in the placebo group. Most deaths were due to disease progression. The most common adverse events were gastrointestinal. Adverse events were more often deemed treatment-related in the arimoclomol group (104 [65%]) than in the placebo group (41 [52%]) and more often led to treatment discontinuation in the arimoclomol group (26 [16%]) than in the placebo group (four [5%]). INTERPRETATION: Arimoclomol did not improve efficacy outcomes compared with placebo. Although available biomarker data are insufficient to preclude future strategies that target the HSP response, safety data suggest that a higher dose of arimoclomol would not have been tolerated. FUNDING: Orphazyme.

Safety and efficacy of arimoclomol for inclusion body myositis: a multicentre, randomised, double-blind, placebo-controlled trial.

BACKGROUND: Inclusion body myositis is the most common progressive muscle wasting disease in people older than 50 years, with no effective drug treatment. Arimoclomol is an oral co-inducer of the cellular heat shock response that was safe and well-tolerated in a pilot study of inclusion body myositis, reduced key pathological markers of inclusion body myositis in two in-vitro models representing degenerative and inflammatory components of this disease, and improved disease pathology and muscle function in mutant valosin-containing protein mice. In the current study, we aimed to assess the safety, tolerability, and efficacy of arimoclomol in people with inclusion body myositis. METHODS: This multicentre, randomised, double-blind, placebo-controlled study enrolled adults in specialist neuromuscular centres in the USA (11 centres) and UK (one centre). Eligible participants had a diagnosis of inclusion body myositis fulfilling the European Neuromuscular Centre research diagnostic criteria 2011. Participants were randomised (1:1) to receive either oral arimoclomol 400 mg or matching placebo three times daily (1200 mg/day) for 20 months. The randomisation sequence was computer generated centrally using a permuted block algorithm with randomisation numbers masked to participants and trial staff, including those assessing outcomes. The primary endpoint was the change from baseline to month 20 in the Inclusion Body Myositis Functional Rating Scale (IBMFRS) total score, assessed in all randomly assigned participants, except for those who were randomised in error and did not receive any study medication, and those who did not meet inclusion criteria. Safety analyses included all randomly assigned participants who received at least one dose of study medication. This trial is registered with ClinicalTrials.gov, number NCT02753530, and is completed. FINDINGS: Between Aug 16, 2017 and May 22, 2019, 152 participants with inclusion body myositis were randomly assigned to arimoclomol (n=74) or placebo (n=78). One participant was randomised in error (to arimoclomol) but not treated, and another (assigned to placebo) did not meet inclusion criteria. 150 participants (114 [76%] male and 36 [24%] female) were included in the efficacy analyses, 73 in the arimoclomol group and 77 in the placebo group. 126 completed the trial on treatment (56 [77%] and 70 [90%], respectively) and the most common reason for treatment discontinuation was adverse events. At month 20, mean IBMFRS change from baseline was not statistically significantly different between arimoclomol and placebo (-3·26, 95% CI -4·15 to -2·36 in the arimoclomol group vs -2·26, -3·11 to -1·41 in the placebo group; mean difference -0·99 [95% CI -2·23 to 0·24]; p=0·12). Adverse events leading to discontinuation occurred in 13 (18%) of 73 participants in the arimoclomol group and four (5%) of 78 participants in the placebo group. Serious adverse events occurred in 11 (15%) participants in the arimoclomol group and 18 (23%) in the placebo group. Elevated transaminases three times or more of the upper limit of normal occurred in five (7%) participants in the arimoclomol group and one (1%) in the placebo group. Tubulointerstitial nephritis was observed in one (1%) participant in the arimoclomol group and none in the placebo group. INTERPRETATION: Arimoclomol did not improve efficacy outcomes, relative to placebo, but had an acceptable safety profile in individuals with inclusion body myositis. This is one of the largest trials done in people with inclusion body myositis, providing data on disease progression that might be used for subsequent clinical trial design. FUNDING: US Food and Drug Administration Office of Orphan Products Development and Orphazyme.

A case-control study of sporadic Creutzfeldt-Jakob disease in Switzerland: analysis of potential risk factors with regard to an increased CJD incidence in the years 2001-2004.

BACKGROUND: In 2001, the observed annual mortality from Creutzfeldt-Jakob disease (CJD) in Switzerland increased from less than 1.5 to 2.6 per million inhabitants. An underlying cause could not be identified. METHODS: To analyse potential risk factors for sCJD in Switzerland, close relatives of 69 sCJD-patients and 224 frequency age-matched controls were interviewed in a case-control study using a standardised questionnaire. 135 potential risk factors including socio-demographics, medical history, occupation and diet were analysed by logistic regression adjusting for age, sex and education. RESULTS: sCJD patients were more likely to have travelled abroad, worked at an animal laboratory, undergone invasive dental treatment, orthopaedic surgery, ophthalmologic surgery after 1980, regular GP visits, taken medication regularly, and consumed kidney. No differences between patients and controls were found for residency, family history, and exposure to environmental and other dietary factors. CONCLUSION: Although some factors were significantly more frequent among sCJD-cases, this study did not reveal specific explanations for the increased incidence of deaths due to sporadic CJD observed in Switzerland since 2001. Results have to be interpreted with caution due to multiple testing and possible recall bias in association with a long incubation period. The most plausible reason for the increase in Swiss sCJD cases after 2000 is an improved case ascertainment. Therefore, underreporting of cases might well have occurred before the year 2001, and the "real" yearly incidence of sCJD might not be lower than, but rather above 2 per million inhabitants.

Bitopertin in Negative Symptoms of Schizophrenia-Results From the Phase III FlashLyte and DayLyte Studies.

BACKGROUND: There is currently no standard of care for treatment of negative symptoms of schizophrenia, although some previous results with glutamatergic agonists have been promising. METHODS: Three (SunLyte [WN25308], DayLyte [WN25309], and FlashLyte [NN25310]) phase III, multicenter, randomized, 24-week, double-blind, parallel-group, placebo-controlled studies evaluated the efficacy and safety of adjunctive bitopertin in stable patients with persistent predominant negative symptoms of schizophrenia treated with antipsychotics. SunLyte met the prespecified criteria for lack of efficacy and was declared futile. Key inclusion criteria were age ≥18 years, DSM-IV-TR diagnosis of schizophrenia, score ≥40 on the sum of the 14 Positive and Negative Syndrome Scale negative symptoms and disorganized thought factors, unaltered antipsychotic treatment, and clinical stability. Following a 4-week prospective stabilization period, patients were randomly assigned 1:1:1 to bitopertin (5 mg and 10 mg [DayLyte] and 10 mg and 20 mg [FlashLyte]) or placebo once daily for 24 weeks. The primary efficacy end point was mean change from baseline in Positive and Negative Syndrome Scale negative symptom factor score at week 24. RESULTS: The intent-to-treat population in DayLyte and FlashLyte included 605 and 594 patients, respectively. At week 24, mean change from baseline showed improvement in all treatment arms but no statistically significant separation from placebo in Positive and Negative Syndrome Scale negative symptom factor score and all other end points. Bitopertin was well tolerated. CONCLUSIONS: These studies provide no evidence for superior efficacy of adjunctive bitopertin in any of the doses tested over placebo in patients with persistent predominant negative symptoms of schizophrenia.

Safety and efficacy of olesoxime in patients with type 2 or non-ambulatory type 3 spinal muscular atrophy: a randomised, double-blind, placebo-controlled phase 2 trial.

BACKGROUND: Spinal muscular atrophy (SMA) is a progressive motor neuron disease causing loss of motor function and reduced life expectancy, for which limited treatment is available. We investigated the safety and efficacy of olesoxime in patients with type 2 or non-ambulatory type 3 SMA. METHODS: This randomised, double-blind, placebo-controlled, phase 2 study was done in 22 neuromuscular care centres in Belgium, France, Germany, Italy, Netherlands, Poland, and the UK. Safety and efficacy of olesoxime were assessed in patients aged 3-25 years with genetically confirmed type 2 or non-ambulatory type 3 SMA. A centralised, computerised randomisation process allocated patients (2:1 with stratification by SMA type and centre) to receive olesoxime (10 mg/kg per day) in an oral liquid suspension or placebo for 24 months. Patients, investigators assessing outcomes, and sponsor study personnel were masked to treatment assignment. The primary outcome measure was change from baseline compared with 24 months between the two treatment groups in functional domains 1 and 2 of the Motor Function Measure (MFM D1 + D2) assessed in the full analysis population. A shorter, 20-item version of the MFM, which was specifically adapted for young children, was used to assess patients younger than 6 years. Safety was assessed in all patients who received one or more doses of the study drug. The trial is registered with ClinicalTrials.gov, number NCT01302600. FINDINGS: The trial was done between Nov 18, 2010, and Oct 9, 2013. Of 198 patients screened, 165 were randomly assigned to olesoxime (n=108) or placebo (n=57). Five patients in the olesoxime group were not included in the primary outcome analysis because of an absence of post-baseline assessments. The change from baseline to month 24 on the primary outcome measure was 0·18 for olesoxime and -1·82 for placebo (treatment difference 2·00 points, 96% CI -0·25 to 4·25, p=0·0676). Olesoxime seemed to be safe and generally well tolerated, with an adverse event profile similar to placebo. The most frequent adverse events in the olesoxime group were pyrexia (n=34), cough (n=32), nasopharyngitis (n=25), and vomiting (n=25). There were two patient deaths (one in each group), but these were not deemed to be related to the study treatment. INTERPRETATION: Olesoxime was safe at the doses studied, for the duration of the trial. Although the primary endpoint was not met, secondary endpoints and sensitivity analyses suggest that olesoxime might maintain motor function in patients with type 2 or type 3 SMA over a period of 24 months. Based on these results, olesoxime might provide meaningful clinical benefits for patients with SMA and, given its mode of action, might be used in combination with other drugs targeting other mechanisms of disease, although additional evidence is needed. FUNDING: AFM Téléthon and Trophos SA.

Efficacy and safety of adjunctive bitopertin versus placebo in patients with suboptimally controlled symptoms of schizophrenia treated with antipsychotics: results from three phase 3, randomised, double-blind, parallel-group, placebo-controlled, multicentre studies in the SearchLyte clinical trial programme.

BACKGROUND: Many patients with schizophrenia require high doses of medication for their ongoing psychotic symptoms. Glutamate theories and findings from studies showing efficacy of sarcosine, an endogenous, non-selective glycine-reuptake inhibitor mediated by GlyT1, offer an alternative approach. We undertook the SearchLyte trial programme to examine the efficacy of bitopertin, a selective GlyT1-mediated glycine-reuptake inhibitor, as an adjunctive treatment to ongoing antipsychotic treatment. METHODS: SearchLyte consisted of three phase 3, randomised, double-blind, parallel-group, placebo-controlled, multicentre studies done in outpatient clinics in Asia, Europe, and North and South America (TwiLyte done at 109 sites, NightLyte at 84, and MoonLyte at 87). Participants were male and female outpatients, aged at least 18 years, meeting DSM-IV criteria for schizophrenia with suboptimally controlled positive symptoms despite treatment with antipsychotics. Inclusion criteria included a Positive and Negative Syndrome Scale (PANSS) total score of at least 70 and antipsychotic treatment stability for the past 12 weeks before randomisation. Key exclusion criteria included meeting criteria for symptomatic remission or previous treatment with a GlyT1 inhibitor or any other investigational drug. After a screening or 4-week prospective stabilisation period, we randomly assigned participants (1:1:1) to a 12-week, double-blind treatment of either placebo or one of two fixed doses of oral, once-daily bitopertin (10 or 20 mg in TwiLyte and NightLyte; 5 or 10 mg in MoonLyte) added to their current antipsychotic medicine. After completion of 12 weeks' treatment, the study design allowed for additional double-blind treatment for 40 weeks to assess maintenance of the effect, followed by a randomised 4-week washout period to assess withdrawal effects. Subsequently, all patients were offered the opportunity to receive bitopertin treatment in a 3-year follow-up. The primary efficacy endpoint was the mean change from baseline in the PANSS Positive Symptom Factor Score (PSFS) at week 12, analysed in the modified intention-to-treat population. The trials were registered at ClinicalTrials.gov (numbers NCT01235520 [TwiLyte], NCT01235585 [MoonLyte], and NCT01235559 [NightLyte]). FINDINGS: Between Nov 19, 2010, and Dec 12, 2014, we randomly assigned 1794 patients to treatment, of whom 1772 were treated and analysed. MoonLyte was discontinued in September, 2014, on the basis of results from futility analyses. Across studies and treatment arms, most patients completed 12 weeks of treatment (505 in TwiLyte, 517 in NightLyte, and 506 in MoonLyte). Only one study, NightLyte, met the primary endpoint where the PANSS PSFS significantly differed from placebo at week 12, and only in the 10-mg arm: mean difference in score -1·37, 95% CI -2·27 to -0·47; p=0·0028. Improvements from baseline for the bitopertin 20-mg arm in Nightlyte were not significant compared with placebo: -3·77, 95% CI -4·40 to -3·14; p=0·3142. Results from the other two studies also did not differ from placebo (TwiLyte 0·58, 95% CI -0·34 to 1·50, p=0·22 for 10 mg and 0·43, -0·49 to 1·36, p=0·36 for 20 mg; MoonLyte 0·06, 95% CI -0·79 to 0·92, p=0·88 for 5 mg and 0·44, -0·41 to 1·28, p=0·31 for 10 mg). Placebo responses varied across studies and might have contributed to the differences in efficacy between studies. Four deaths occurred during the 12-week treatment period, three in NightLyte (upper gastrointestinal haemorrhage, alcohol poisoning and related head injury, and a completed suicide) and one in MoonLyte (myocardial infarction in a patient with pre-existing risk factors). Only the death by suicide was deemed related to the study drug. The incidence of serious adverse events was low across treatment groups in all three studies; psychiatric disorders were the most frequently reported serious adverse events and the most frequent cause of adverse events leading to discontinuation. INTERPRETATION: Only one of six active treatment arms across the three studies offered an advantage of adjunctive bitopertin over placebo for the treatment of suboptimally controlled symptoms of schizophrenia. The small improvement associated with bitopertin together with the varying placebo response suggests that adjunctive bitopertin treatment might offer only modest benefit to suboptimal responders to antipsychotics, if any. FUNDING: F Hoffmann-La Roche.

AQW051, a novel, potent and selective α7 nicotinic ACh receptor partial agonist: pharmacological characterization and phase I evaluation.

BACKGROUND AND PURPOSE: Activation of the α7 nicotinic ACh receptor (nACh receptor) is considered an attractive target for the treatment of cognitive impairment associated with neurological disorders. Here we describe the novel α7-nACh receptor agonist AQW051 as a promising drug candidate for this indication. EXPERIMENTAL APPROACH: AQW051 was functionally characterized in vitro and cognitive effects evaluated in rodent behavioural models. Pharmacokinetics and tolerability were evaluated in three phase I placebo-controlled studies in 180 healthy subjects. KEY RESULTS: In vitro, AQW051 bound with high affinity to α7-nACh receptors and stimulated calcium influx in cells recombinantly expressing the human α7-nACh receptor. In vivo, AQW051 demonstrated good oral bioavailability and rapid penetration into the rodent brain. AQW051 administered over a broad dose range facilitated learning/memory performance in the object recognition and social recognition test in mice and the water maze model in aged rats. Clinically, AQW051 was well tolerated in healthy young and elderly subjects, with an adverse event (AE) profile comparable with placebo. No serious AEs were reported and all AEs were either mild or moderate in severity at single oral doses up to 200 mg and multiple daily doses up to 75 mg. Once-daily oral administration of AQW051 resulted in continuous exposure and a two- to threefold accumulation compared with steady state was achieved by 1 week. CONCLUSIONS AND IMPLICATIONS: These data support further development of AQW051 as a cognitive-enhancing agent, as a therapeutic, for example, in Alzheimer's disease or schizophrenia.

Defining therapeutic benefit for people with schizophrenia: focus on negative symptoms.

Schizophrenia is a complex, heterogeneous, multidimensional disorder within which negative symptoms are a significant and disabling feature. Whilst there is no established treatment for these symptoms, some pharmacological and psychosocial interventions have shown promise and this is an active area of research. Despite the effort to identify effective interventions, as yet there is no broadly accepted definition of therapeutic success. This article reviews concepts of clinical relevance and reports on a consensus conference whose goal was to apply these concepts to the treatment of negative symptoms. A number of key issues were identified and discussed including: assessment of specific negative symptom domains; defining response and remission for negative symptoms; assessment of functional outcomes; measurement of outcomes within clinical trials; and the assessment of duration/persistence of a response. The group reached a definition of therapeutic success using an achieved threshold of function that persisted over time. Recommendations were agreed upon with respect to: assessment of negative symptom domains of apathy-avolition and deficit of expression symptoms; thresholds for response and remission of negative symptoms based on level of symptomatology; assessing multiple domains of function including social occupation, activities of daily living, and socialization; the need for clinical trial data to include rate of change over time and converging sources of evidence; use of clinician, patient and caregiver perspectives to assess success; and the need for establishing criteria for the persistence of therapeutic benefit. A consensus statement and associated research criteria are offered as an initial step towards developing broad agreement regarding outcomes of negative symptoms treatment.

Reliability, validity and ability to detect change of the PANSS negative symptom factor score in outpatients with schizophrenia on select antipsychotics and with prominent negative or disorganized thought symptoms.

The PANSS is a valid instrument assessing schizophrenia symptom severity. Analyses have identified a five-factor solution. The negative symptom factor (NSFS) is robust, having been replicated in multiple analyses. The score has superior content validity versus the negative subscale. Aspects of validity in patients with predominant negative symptoms have yet to be established. The present data are from a Phase IIb study of add-on bitopertin therapy in schizophrenia outpatients with prominent negative or disorganized thought symptoms treated with antipsychotics. Analyses were conducted to evaluate reliability, validity and sensitivity to change. Test-retest screening to baseline was high (ICC=0.93). This was maintained in-study, for patients with no change in CGI negative symptom severity (CGI-S-N). Internal consistency at baseline was adequate (α=0.71) and increased at later assessments. Pearson correlation at baseline showed a good association between NSFS and CGI-S-N (0.63), but not overall CGI-S (0.31). Association with PSP at baseline was moderate (-0.39) and for change at Week eight good (-0.65). NSFS responders (≥20% improvement) at Week eight showed a significant improvement in function. The analyses demonstrated reliability, validity and ability to detect change of the NSFS, in schizophrenia patients with prominent negative or disorganized thought symptoms.

Carboxy-terminated oligo(ethylene glycol)-alkane phosphate: synthesis and self-assembly on titanium oxide surfaces.

The surface immobilization of oligo- and poly(ethylene glycol) on solids is a widely used approach to prevent the nonspecific adsorption of proteins, bacteria, and cells. A novel tri(ethylene glycol) derivative, phosphoric acid-mono(22-carboxy-12,15,18,21-tetraoxadocosyl) ester, was synthesized with the aim to produce self-assembled monolayers (SAMs) on metal/metal oxide surfaces. This compound contains two reactive, terminal moieties: the phosphoric acid group as anchor to the surface, and the carboxylic group as linker for further attachment of molecules such as peptides and proteins to be present at the surface. The adsorption on titanium-dioxide-coated substrates was studied quantitatively and the resulting SAMs were characterized by angle-dependent X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry. XPS data showed that the monomolecular layer is attached with the phosphate group to the substrate, but not fully ordered. The dry adlayer thickness was determined to be 13.4 A, which is less than expected for a densely packed monolayer. Surface concentration calculated from ellipsometry data resulted in a grafting density of 2.03 molecules/nm2.