Olanzapine for young people with anorexia nervosa: a synopsis of the main results from the OPEN open-label feasibility study

Ece Sengun  Filiz; Dominic Stringer; Vanessa Kellermann; Rachel Olive; Olena Said; Hiba Mutwalli; Sevgi Bektas; Melahat Nur Akkese; Katie Ireland; Demelza Beishon-Murley; Joel W T Khor; Lee  Allman; Nicus Kotze; Ben Carter; Elizabeth Tyrrell-Bunge; Katie Rowlands; Johanna Keeler; Glynis Ivin; Mima Simic; Dilveer Sually; Jessica Bentley; Allan Young; Sloane Madden; Sarah Byford; Sabine Landau; Janet Treasure; Ulrike Schmidt; Dasha Nicholls; Vanessa Lawrence; Hubertus Himmerich

doi:10.3310/GJHH0812

Olanzapine for young people with anorexia nervosa: a synopsis of the main results from the OPEN open-label feasibility study

Ece Sengun Filiz
, Dominic Stringer
, Vanessa Kellermann
, Rachel Olive
, Olena Said
, Hiba Mutwalli
, Sevgi Bektas
, Melahat Nur Akkese
, Katie Ireland
, Demelza Beishon-Murley
, Joel W T Khor
, Lee Allman
, Nicus Kotze
, Ben Carter
, Elizabeth Tyrrell-Bunge
, Katie Rowlands
, Johanna Keeler
, Glynis Ivin
, Mima Simic
, Dilveer Sually

Jessica Bentley, Allan Young, Sloane Madden, Sarah Byford, Sabine Landau, Janet Treasure, Ulrike Schmidt, Dasha Nicholls, Vanessa Lawrence, Hubertus Himmerich

Imperial College London
King's College London
South London and Maudsley NHS Foundation Trust
SLaM South London and Maudsley NHS Foundation Trust
South West London and St George's Mental Health NHS Trust
Sussex Partnership NHS Foundation Trust
Dorset Healthcare University NHS Foundation Trust
University of Sydney

Research output: Contribution to journal › Article › peer-review

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Abstract

Background: In clinical practice, olanzapine is commonly used in young people with anorexia nervosa, although the underpinning evidence-base is limited. However, its efficacy, tolerability, acceptability and adherence rate, and the patients', carers' and clinicians' views of olanzapine treatment are unclear. This synopsis article summarises the methods and results of the OPEN feasibility study, overarching the findings and drawing comprehensive conclusions from a quantitative feasibility outcome paper and two qualitative research papers. Methods: The OPEN study assessed the feasibility of a future randomised controlled trial on olanzapine in young people with anorexia nervosa in an open-label, one-armed feasibility study. In this study, we aimed to include 55 patients with anorexia nervosa or atypical anorexia nervosa aged 12-24 who gained < 2 kg within at least 1 month of treatment as usual. Time points for assessments were at baseline, 8 weeks, 16 weeks, and 6 or 12 months. We estimated recruitment, adherence and attrition rates and mean changes in body weight, body mass index and eating disorder psychopathology. In addition, we explored the views on and experiences with olanzapine treatment within a clinical trial setting using qualitative interviews with young people with anorexia nervosa, their families and clinicians. Results: Fifty-two people were pre-screened, 35 were eligible and 20 participants were recruited and started olanzapine. Of these, 15 continued olanzapine for ≥ 16 weeks. Participants experienced, on average, a decrease in their eating disorder psychopathology, and body weight and body mass index increased during treatment with olanzapine as an adjunct to treatment as usual. Important themes derived from semi-structured qualitative interviews with young people and their parents were: moving away from the illness towards recovery, evaluating information on olanzapine, consent and trust in shared decision-making and the ambivalence around recovery. The main themes expressed by clinicians included: acknowledging the concerns of young people with anorexia nervosa and their families, prioritising person-centred care, the limited service capacity and strict study eligibility criteria. Limitations: The study failed to meet the recruitment target and showed low adherence rates for treatment with olanzapine. Possible reasons for the recruitment difficulties and the low adherence rate include the high clinical workload of eating disorder services during and after the COVID-19 pandemic, the heterogeneity of eating disorder service setup across the country, and the reluctance of patients to agree to take olanzapine under the relatively restricted conditions of a clinical study. Conclusions: A realistic time schedule for site-preparation, recruitment, treatment and follow-up, realistic recruitment targets and easy access to medical and laboratory examinations may improve the success of future feasibility studies and randomised controlled trials in this patient group. Future work: The difficulties in conducting the OPEN study will inform the planning for future pharmacological and non-pharmacological studies in anorexia nervosa. Therefore, we developed a checklist with action points for the planning of pharmacological trials in eating disorders. Furthermore, novel pharmacological options such as typical and atypical psychedelic drugs (e.g. psilocybin and ketamine) might be more acceptable for people with anorexia nervosa as they do not have the side effect of immediate weight gain. Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number NIHR130780.

Original language	English
Pages (from-to)	1-17
Number of pages	17
Journal	Health Technology Assessment
Volume	30
Issue number	36
DOIs	https://doi.org/10.3310/GJHH0812
Publication status	Published - 31 May 2026

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10.3310/GJHH0812Licence: CC BY

Olanzapine for young people_VoRFinal published version, 1.36 MBLicence: CC BY

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Filiz, E. S., Stringer, D., Kellermann, V., Olive, R., Said, O., Mutwalli, H., Bektas, S., Akkese, M. N., Ireland, K., Beishon-Murley, D., Khor, J. W. T., Allman, L., Kotze, N., Carter, B., Tyrrell-Bunge, E., Rowlands, K., Keeler, J., Ivin, G., Simic, M., ... Himmerich, H. (2026). Olanzapine for young people with anorexia nervosa: a synopsis of the main results from the OPEN open-label feasibility study. Health Technology Assessment, 30(36), 1-17. https://doi.org/10.3310/GJHH0812

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title = "Olanzapine for young people with anorexia nervosa: a synopsis of the main results from the OPEN open-label feasibility study",

abstract = "Background: In clinical practice, olanzapine is commonly used in young people with anorexia nervosa, although the underpinning evidence-base is limited. However, its efficacy, tolerability, acceptability and adherence rate, and the patients', carers' and clinicians' views of olanzapine treatment are unclear. This synopsis article summarises the methods and results of the OPEN feasibility study, overarching the findings and drawing comprehensive conclusions from a quantitative feasibility outcome paper and two qualitative research papers. Methods: The OPEN study assessed the feasibility of a future randomised controlled trial on olanzapine in young people with anorexia nervosa in an open-label, one-armed feasibility study. In this study, we aimed to include 55 patients with anorexia nervosa or atypical anorexia nervosa aged 12-24 who gained < 2 kg within at least 1 month of treatment as usual. Time points for assessments were at baseline, 8 weeks, 16 weeks, and 6 or 12 months. We estimated recruitment, adherence and attrition rates and mean changes in body weight, body mass index and eating disorder psychopathology. In addition, we explored the views on and experiences with olanzapine treatment within a clinical trial setting using qualitative interviews with young people with anorexia nervosa, their families and clinicians. Results: Fifty-two people were pre-screened, 35 were eligible and 20 participants were recruited and started olanzapine. Of these, 15 continued olanzapine for ≥ 16 weeks. Participants experienced, on average, a decrease in their eating disorder psychopathology, and body weight and body mass index increased during treatment with olanzapine as an adjunct to treatment as usual. Important themes derived from semi-structured qualitative interviews with young people and their parents were: moving away from the illness towards recovery, evaluating information on olanzapine, consent and trust in shared decision-making and the ambivalence around recovery. The main themes expressed by clinicians included: acknowledging the concerns of young people with anorexia nervosa and their families, prioritising person-centred care, the limited service capacity and strict study eligibility criteria. Limitations: The study failed to meet the recruitment target and showed low adherence rates for treatment with olanzapine. Possible reasons for the recruitment difficulties and the low adherence rate include the high clinical workload of eating disorder services during and after the COVID-19 pandemic, the heterogeneity of eating disorder service setup across the country, and the reluctance of patients to agree to take olanzapine under the relatively restricted conditions of a clinical study. Conclusions: A realistic time schedule for site-preparation, recruitment, treatment and follow-up, realistic recruitment targets and easy access to medical and laboratory examinations may improve the success of future feasibility studies and randomised controlled trials in this patient group. Future work: The difficulties in conducting the OPEN study will inform the planning for future pharmacological and non-pharmacological studies in anorexia nervosa. Therefore, we developed a checklist with action points for the planning of pharmacological trials in eating disorders. Furthermore, novel pharmacological options such as typical and atypical psychedelic drugs (e.g. psilocybin and ketamine) might be more acceptable for people with anorexia nervosa as they do not have the side effect of immediate weight gain. Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number NIHR130780.",

author = "Filiz, \{Ece Sengun\} and Dominic Stringer and Vanessa Kellermann and Rachel Olive and Olena Said and Hiba Mutwalli and Sevgi Bektas and Akkese, \{Melahat Nur\} and Katie Ireland and Demelza Beishon-Murley and Khor, \{Joel W T\} and Lee Allman and Nicus Kotze and Ben Carter and Elizabeth Tyrrell-Bunge and Katie Rowlands and Johanna Keeler and Glynis Ivin and Mima Simic and Dilveer Sually and Jessica Bentley and Allan Young and Sloane Madden and Sarah Byford and Sabine Landau and Janet Treasure and Ulrike Schmidt and Dasha Nicholls and Vanessa Lawrence and Hubertus Himmerich",

note = "Publisher Copyright: {\textcopyright} 2026 Filiz et al.",

year = "2026",

month = may,

day = "31",

doi = "10.3310/GJHH0812",

language = "English",

volume = "30",

pages = "1--17",

journal = "Health Technology Assessment",

issn = "1366-5278",

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Filiz, ES, Stringer, D, Kellermann, V, Olive, R , Said, O , Mutwalli, H , Bektas, S, Akkese, MN, Ireland, K, Beishon-Murley, D, Khor, JWT, Allman, L, Kotze, N, Carter, B, Tyrrell-Bunge, E, Rowlands, K , Keeler, J, Ivin, G, Simic, M, Sually, D, Bentley, J, Young, A, Madden, S, Byford, S , Landau, S , Treasure, J , Schmidt, U, Nicholls, D, Lawrence, V & Himmerich, H 2026, 'Olanzapine for young people with anorexia nervosa: a synopsis of the main results from the OPEN open-label feasibility study', Health Technology Assessment, vol. 30, no. 36, pp. 1-17. https://doi.org/10.3310/GJHH0812

TY - JOUR

T1 - Olanzapine for young people with anorexia nervosa

T2 - a synopsis of the main results from the OPEN open-label feasibility study

AU - Filiz, Ece Sengun

AU - Stringer, Dominic

AU - Kellermann, Vanessa

AU - Olive, Rachel

AU - Said, Olena

AU - Mutwalli, Hiba

AU - Bektas, Sevgi

AU - Akkese, Melahat Nur

AU - Ireland, Katie

AU - Beishon-Murley, Demelza

AU - Khor, Joel W T

AU - Allman, Lee

AU - Kotze, Nicus

AU - Carter, Ben

AU - Tyrrell-Bunge, Elizabeth

AU - Rowlands, Katie

AU - Keeler, Johanna

AU - Ivin, Glynis

AU - Simic, Mima

AU - Sually, Dilveer

AU - Bentley, Jessica

AU - Young, Allan

AU - Madden, Sloane

AU - Byford, Sarah

AU - Landau, Sabine

AU - Treasure, Janet

AU - Schmidt, Ulrike

AU - Nicholls, Dasha

AU - Lawrence, Vanessa

AU - Himmerich, Hubertus

PY - 2026/5/31

Y1 - 2026/5/31

N2 - Background: In clinical practice, olanzapine is commonly used in young people with anorexia nervosa, although the underpinning evidence-base is limited. However, its efficacy, tolerability, acceptability and adherence rate, and the patients', carers' and clinicians' views of olanzapine treatment are unclear. This synopsis article summarises the methods and results of the OPEN feasibility study, overarching the findings and drawing comprehensive conclusions from a quantitative feasibility outcome paper and two qualitative research papers. Methods: The OPEN study assessed the feasibility of a future randomised controlled trial on olanzapine in young people with anorexia nervosa in an open-label, one-armed feasibility study. In this study, we aimed to include 55 patients with anorexia nervosa or atypical anorexia nervosa aged 12-24 who gained < 2 kg within at least 1 month of treatment as usual. Time points for assessments were at baseline, 8 weeks, 16 weeks, and 6 or 12 months. We estimated recruitment, adherence and attrition rates and mean changes in body weight, body mass index and eating disorder psychopathology. In addition, we explored the views on and experiences with olanzapine treatment within a clinical trial setting using qualitative interviews with young people with anorexia nervosa, their families and clinicians. Results: Fifty-two people were pre-screened, 35 were eligible and 20 participants were recruited and started olanzapine. Of these, 15 continued olanzapine for ≥ 16 weeks. Participants experienced, on average, a decrease in their eating disorder psychopathology, and body weight and body mass index increased during treatment with olanzapine as an adjunct to treatment as usual. Important themes derived from semi-structured qualitative interviews with young people and their parents were: moving away from the illness towards recovery, evaluating information on olanzapine, consent and trust in shared decision-making and the ambivalence around recovery. The main themes expressed by clinicians included: acknowledging the concerns of young people with anorexia nervosa and their families, prioritising person-centred care, the limited service capacity and strict study eligibility criteria. Limitations: The study failed to meet the recruitment target and showed low adherence rates for treatment with olanzapine. Possible reasons for the recruitment difficulties and the low adherence rate include the high clinical workload of eating disorder services during and after the COVID-19 pandemic, the heterogeneity of eating disorder service setup across the country, and the reluctance of patients to agree to take olanzapine under the relatively restricted conditions of a clinical study. Conclusions: A realistic time schedule for site-preparation, recruitment, treatment and follow-up, realistic recruitment targets and easy access to medical and laboratory examinations may improve the success of future feasibility studies and randomised controlled trials in this patient group. Future work: The difficulties in conducting the OPEN study will inform the planning for future pharmacological and non-pharmacological studies in anorexia nervosa. Therefore, we developed a checklist with action points for the planning of pharmacological trials in eating disorders. Furthermore, novel pharmacological options such as typical and atypical psychedelic drugs (e.g. psilocybin and ketamine) might be more acceptable for people with anorexia nervosa as they do not have the side effect of immediate weight gain. Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number NIHR130780.

AB - Background: In clinical practice, olanzapine is commonly used in young people with anorexia nervosa, although the underpinning evidence-base is limited. However, its efficacy, tolerability, acceptability and adherence rate, and the patients', carers' and clinicians' views of olanzapine treatment are unclear. This synopsis article summarises the methods and results of the OPEN feasibility study, overarching the findings and drawing comprehensive conclusions from a quantitative feasibility outcome paper and two qualitative research papers. Methods: The OPEN study assessed the feasibility of a future randomised controlled trial on olanzapine in young people with anorexia nervosa in an open-label, one-armed feasibility study. In this study, we aimed to include 55 patients with anorexia nervosa or atypical anorexia nervosa aged 12-24 who gained < 2 kg within at least 1 month of treatment as usual. Time points for assessments were at baseline, 8 weeks, 16 weeks, and 6 or 12 months. We estimated recruitment, adherence and attrition rates and mean changes in body weight, body mass index and eating disorder psychopathology. In addition, we explored the views on and experiences with olanzapine treatment within a clinical trial setting using qualitative interviews with young people with anorexia nervosa, their families and clinicians. Results: Fifty-two people were pre-screened, 35 were eligible and 20 participants were recruited and started olanzapine. Of these, 15 continued olanzapine for ≥ 16 weeks. Participants experienced, on average, a decrease in their eating disorder psychopathology, and body weight and body mass index increased during treatment with olanzapine as an adjunct to treatment as usual. Important themes derived from semi-structured qualitative interviews with young people and their parents were: moving away from the illness towards recovery, evaluating information on olanzapine, consent and trust in shared decision-making and the ambivalence around recovery. The main themes expressed by clinicians included: acknowledging the concerns of young people with anorexia nervosa and their families, prioritising person-centred care, the limited service capacity and strict study eligibility criteria. Limitations: The study failed to meet the recruitment target and showed low adherence rates for treatment with olanzapine. Possible reasons for the recruitment difficulties and the low adherence rate include the high clinical workload of eating disorder services during and after the COVID-19 pandemic, the heterogeneity of eating disorder service setup across the country, and the reluctance of patients to agree to take olanzapine under the relatively restricted conditions of a clinical study. Conclusions: A realistic time schedule for site-preparation, recruitment, treatment and follow-up, realistic recruitment targets and easy access to medical and laboratory examinations may improve the success of future feasibility studies and randomised controlled trials in this patient group. Future work: The difficulties in conducting the OPEN study will inform the planning for future pharmacological and non-pharmacological studies in anorexia nervosa. Therefore, we developed a checklist with action points for the planning of pharmacological trials in eating disorders. Furthermore, novel pharmacological options such as typical and atypical psychedelic drugs (e.g. psilocybin and ketamine) might be more acceptable for people with anorexia nervosa as they do not have the side effect of immediate weight gain. Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number NIHR130780.

UR - https://www.scopus.com/pages/publications/105038484896

U2 - 10.3310/GJHH0812

DO - 10.3310/GJHH0812

M3 - Article

SN - 1366-5278

VL - 30

SP - 1

EP - 17

JO - Health Technology Assessment

JF - Health Technology Assessment

IS - 36

ER -

Olanzapine for young people with anorexia nervosa: a synopsis of the main results from the OPEN open-label feasibility study

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