An observational study in Hemophagocytic Lymphohistiocytosis (HLH), Macrophage Activation Syndrome (MAS) and Still Disease, sponsored by Swedish Orphan Biovitrum. Not yet recruiting at 18 sites in United States. Open to participants aged Up to 80 Years. Per ClinicalTrials.gov, last updated 2026-11-02.
Sponsored by Swedish Orphan Biovitrum · Observational
This study aims to evaluate safety information in patients with HLH/MAS in Still's disease exposed to Gamifant.
This is a prospective, low intervention, multicenter safety study to evaluate and characterize the long-term safety of Gamifant, an approved treatment for patients with HLH/MAS in known or suspected Still's disease. Pediatric and adult patients with HLH/MAS in known or suspected Still's disease, including sJIA, with inadequate response or intolerance to glucocorticoids, or with recurrent MAS, and who have either initiated Gamifant within the past 0 to 7 days or are prescribed to initiate Gamifant in accordance with the approved product label, are eligible for inclusion in the study.
111 studies on the registry are indexed under Lymphohistiocytosis, Hemophagocytic; 41 are open to participants now.
This study's planned enrollment of 70 is below the median of 114 across 34 observational studies indexed under Lymphohistiocytosis, Hemophagocytic.
Browse Lymphohistiocytosis, Hemophagocytic studies →Swedish Orphan Biovitrum is the lead sponsor of 82 studies on the registry; 6 are open to participants now.
Of its 17 completed or terminated interventional studies of FDA-regulated products, 15 (88%) have results posted.
Counted across the registry records on this site, refreshed daily.
Patients of participating sites who meet the protocol eligibility criteria.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
must be obtained from the patient or the patient's legally authorized representative.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients aged ≤80 years at index Gamifant administration who have received at least 1 dose of Gamifant 0-7 days prior to ICF date or is prescribed to initiate Gamifant for the treatment of HLH/MAS in Still's disease
Other: Local laboratory testing · Other: Local Lab Tests
Protocol-mandated assessments include specified laboratory testing at baseline and during the initial 12 months of follow-up (Week 1, Week 2, Month 1, Month 3, Month 6, Month 12): complete blood counts, differential leukocyte count, serum biochemistry/liver function tests, CMV PCR. CMV serology is only required (per protocol) to be conducted at baseline. No laboratory testing is required per protocol after the 12-month visit.
Protocol-mandated assessments include specified laboratory testing at baseline and during the initial 12 months of follow-up (Week 1, Week 2, Month 1, Month 3, Month 6, Month 12): complete blood counts, differential leukocyte count, serum biochemistry/liver function tests, CMV PCR. CMV serology is only required (per protocol) to be conducted at baseline. No laboratory testing is required per protocol after the 12-month visit.
Also known as: Complete blood counts (hematocrit, hemoglobin, platelet count, red blood cell count, white blood cell count), Differential leukocyte countf (lymphocytes, monocytes, neutrophils), Serum biochemistry/Liver function tests (aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, bilirubin [total, direct, and indirect]), Virus PCR: CMV PCR, CMV serology (IgM/IgG/Avidity), Virus PCR and serology tests: Epstein-Barr virus PCR & Adenovirus PCR
Outcome Measure: Incidence rate of treatment-emergent mycobacterium tuberculosis
Description: Occurrence of treatment-emergent mycobacterium tuberculosis and non-tuberculosis mycobacterium. A TEAE is defined as any AE that occurs from the administration of the index dose of Gamifant until the initial 12 months of follow-up, regardless of relationship to Gamifant. Unit of Measure: Number of events per 100-patient year
Time frame: Timeframe: up to 12 months
Outcome Measure: Incidence rate of treatment-emergent non-tuberculosis mycobacterium infections
Description: Occurrence of treatment-emergent mycobacterium tuberculosis and non-tuberculosis mycobacterium. A TEAE is defined as any AE that occurs from the administration of the index dose of Gamifant until the initial 12 months of follow-up, regardless of relationship to Gamifant. Unit of Measure: Unit of Measure: Number of events per 100-patient year
Time frame: Timeframe: up to 12 months
Outcome Measure: Incidence rate of treatment-emergent CMV reactivation and/or infection
Description: Occurrence of treatment-emergent CMV disease including reactivation and/or infection. A TEAE is defined as any AE that occurs from the administration of the index dose of Gamifant until the initial 12 months of follow-up, regardless of relationship to Gamifant. Unit of Measure: Number of events per 100-patient year
Time frame: Timeframe: up to 12 months
Outcome Measure: Incidence rate of serious treatment-emergent infections
Description: Occurrence of serious treatment-emergent infections (including CMV reactivation and/or infection, mycobacterium tuberculosis, and non tuberculosis mycobacterial infections). A TEAE is defined as any AE that occurs from the administration of the index dose of Gamifant until the initial 12 months of follow-up, regardless of relationship to Gamifant. Unit of Measure: Number of events per 100-patient year
Time frame: Timeframe: up to 12 months
Outcome Measure: Initial Gamifant dose at index
Description: To describe treatment patterns with Gamifant in patients with HLH/MAS treated with Gamifant Unit of Measure: mg/kg
Time frame: Timeframe: up to 12 months
Outcome Measure: Cumulative Gamifant dose over the index MAS episode
Description: To describe treatment patterns with Gamifant in patients with HLH/MAS treated with Gamifant Unit of Measure: mg/kg
Time frame: Timeframe: up to 12 months.
Outcome Measure: Duration of Gamifant treatment over the index MAS episode
Description: To describe treatment patterns with Gamifant in patients with HLH/MAS treated with Gamifant Unit of Measure: Days
Time frame: Timeframe: up to 12 months
Outcome Measure: Gamifant dosing frequency
Description: To describe treatment patterns with Gamifant in patients with HLH/MAS treated with Gamifant. Unit of Measure: Number of injections/week
Time frame: Timeframe: up to 12 months
Outcome Measure: Maximum single Gamifant dose received
Description: To describe treatment patterns with Gamifant in patients with HLH/MAS treated with Gamifant. Unit of Measure: mg/kg
Time frame: Timeframe: up to 12 months
Outcome Measure: Total cumulative Gamifant treatment duration and dose during follow-up.
Description: To describe treatment patterns with Gamifant in patients with HLH/MAS treated with Gamifant Unit of Measure: Months
Time frame: Timeframe: up to 12 months
Outcome Measure: Total cumulative Gamifant treatment dose during follow-up.
Description: To describe treatment patterns with Gamifant in patients with HLH/MAS treated with Gamifant Unit of measure: mg/kg
Time frame: Timeframe: Up to 12 months
Outcome Measure: Reason for gamifant treatment discontinuation
Description: To describe treatment patterns with Gamifant in patients with HLH/MAS treated with Gamifant. Unit of measure: Participants
Time frame: Timeframe: Up to 12 months
Outcome Measure: Time to MAS resolution
Description: Time-to-event analyses assessing the time from the index date to Investigator-assessed MAS resolution. Unit of measure: Days
Time frame: Timeframe: Up to 12 months
Outcome Measure: Number of participants with HLH/MAS-related hospitalizations
Description: To describe HLH/MAS-related HCRU during treatment with Gamifant. Unit of measure: Participants
Time frame: Timeframe: Up to 12 months
Outcome Measure: Duration of intensive care unit (ICU) care
Description: To describe HLH/MAS-related HCRU during treatment with Gamifant Unit of measure: Days
Time frame: Timeframe: Up to 12 months
Outcome Measure: Duration of hospitalization/length of stay (LoS)
Description: To describe HLH/MAS-related HCRU during treatment with Gamifant. Unit of measure: Days
Time frame: Timeframe: Up to 12 months
Outcome Measure: Number of participants with emergency department visits
Description: To describe HLH/MAS-related HCRU during treatment with Gamifant Unit of measure: Participants
Time frame: Timeframe: Up to 12 months
Outcome Measure: Number of participants with Prior HLH/MAS-related medications
Description: Prior medications are those medications that were started and stopped prior to Gamifant initiation. Unit of measure: Participants
Time frame: Timeframe: Up to 12 months
Outcome Measure: Number of participants with Concomitant HLH/MAS-related medications
Description: Concomitant medications are medications that were started prior to or at Gamifant initiation and are ongoing at Gamifant initiation. Unit of measure: Participants
Time frame: Timeframe: Up to 12 months
Outcome Measure: Number of participants with initiation of preemptive antiviral therapy
Description: Concomitant medications are medications that were started prior to or at Gamifant initiation and are ongoing at Gamifant initiation. Unit of measure: Participants
Time frame: Timeframe: Up to 12 months
Start is estimated for Dec 2026; primary completion for Dec 2030, 48 months later.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
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Lymphohistiocytosis, Hemophagocytic →