Drug Trials Snapshots: YARTEMLEA
HOW TO USE THIS SNAPSHOT
The information provided in Snapshots highlights who participated in the key clinical trials that supported the original FDA approval of this drug, and whether there were differences among sex, race, age, and ethnic groups. The "MORE INFO" bar shows more detailed, technical content for each section. The Snapshot is intended as one tool for consumers to use when discussing the risks and benefits of the drugs.
LIMITATIONS OF THIS SNAPSHOT
Do not rely on Snapshots to make decisions regarding medical care. Always speak to your healthcare provider about the benefits and risks of a drug.
Some of the information in this Snapshot is for presentation purposes and does not represent the approved conditions of use of this drug. Refer to the YARTEMLEA Prescribing Information for all the approved conditions of use of this drug (e.g., indication(s), population(s), dosing regimen(s), safety information).
Snapshots are limited to the information available at the time of the original approval of the drug and do not provide information on who participated in clinical trials that supported later approvals for additional uses of the drug (if applicable).
YARTEMLEA (narsoplimab)
(yar TEM lee uh)
Omeros Corporation
Approval date: December 23, 2025
DRUG TRIALS SNAPSHOT SUMMARY:
What is the drug for?
YARTEMLEA is a prescription drug that is a MASP-2 inhibitor indicated for the treatment of adult and pediatric patients 2 years of age and older with hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA).
How is this drug used?
YARTEMLEA is an injection that is taken once weekly.
Who participated in the clinical trials?
The FDA approved YARTEMLEA based on the Study TMA-001 (NCT02222545) that enrolled 28 adult patients and 19 adult and pediatric patients with TA-TMA enrolled in an expanded access program (EAP). Study TMA-001 was conducted at 27 sites in 12 countries including Belgium, Bulgaria, Hong Kong, Italy, Lithuania, Malaysia, New Zealand, Poland, Singapore, Taiwan, Thailand, and the United States. There were 9 patients from the United States.
How were the trials designed?
YARTEMLEA was evaluated in a single-arm, open-label study (Study TMA-001) that enrolled 28 adult patients who developed TA-TMA following hematopoietic stem-cell transplantation (HCT) and in 19 adult and pediatric patients with TA-TMA with evaluable patient-level response data enrolled in an EAP. The primary endpoint for both were thrombotic microangiopathy (TMA) response defined as improvement in both of two laboratory TMA markers (lactate dehydrogenase [LDH] and platelet counts) and either improvement in organ function or independence from transfusions.
How were the trials designed?
Study TMA-001 is a single-arm, open-label study in which 28 patients with TA-TMA received YARTEMLEA once weekly for a median of 8 weeks (range: 2 to 16). In total, 24 patients received YARTEMLEA 4 mg/kg intravenously once weekly and 4 patients received YARTEMLEA 370 mg intravenously once weekly. Key inclusion criteria were a diagnosis of TA-TMA that persisted at least two weeks following modification or discontinuation of treatment with calcineurin inhibitor (CNI) or at least 30 days after transplant with platelet count <150,000/µL, evidence of microangiopathic hemolysis (presence of schistocytes, serum LDH > upper limit of normal, or haptoglobin < lower limit of normal), and renal dysfunction. The primary efficacy endpoint was the proportion of TA-TMA patients who responded to YARTEMLEA treatment.
The single patient expanded access treatment plan (EAP; also known as a compassionate use plan) provides patients access to the investigational product YARTEMLEA. The purpose of the EAP is to provide access to patients with TA-TMA who are not able to participate in a study and who may benefit from treatment based on the medical judgment of their respective physicians. This is an uncontrolled, case-by-case patient EAP. Dosing for patients ≥50 kg is YARTEMLEA 370 mg initially twice weekly and for at least eight weeks. Dosing for patients ≤50 kg is 4 mg/kg initially twice weekly and for at least eight weeks. Change in dose frequency is determined by treatment response.
DEMOGRAPHICS SNAPSHOT
Figure 1 shows how many male and female patients were enrolled in the clinical trials used to evaluate the efficacy and side effects of YARTEMLEA.
Figure 1. Baseline Demographics by Sex (TMA-001, EAP Subgroup 1 (N=19))
Source: Adapted from FDA Review
Figure 2 shows how many patients by race were enrolled in the clinical trials used to evaluate the efficacy and side effects of YARTEMLEA.
Figure 2. Baseline Demographics by Race (TMA-001, EAP Subgroup 1 (N=19))
Source: Adapted from FDA Review
Figure 3 shows how many patients by age were enrolled in the clinical trials used to evaluate the efficacy and side effects of YARTEMLEA.
Figure 3. Baseline Demographics by Age (TMA-001, EAP Subgroup 1 (N=19))
Source: Adapted from FDA Review
Figure 4 shows how many patients by ethnicity were enrolled in the clinical trials used to evaluate the efficacy and side effects of YARTEMLEA.
Figure 4. Baseline Demographics by Ethnicity (TMA-001, EAP Subgroup 1 (N=19))
Source: Adapted from FDA Review
Who participated in the trials?
Table 1. Baseline Demographics by Age, Race, Sex, and Ethnicity, Study TMA-001 and EAP Subgroup
| Characteristic | TMA-001 | EAP Subgroup | Overall Adults | Overall | |
|---|---|---|---|---|---|
Adult | Pediatric1 | ||||
| Age, years | |||||
| Mean (SD) | 48 (13.3) | 55.5 (15.2) | 10.3 (4.5) | 50.3 (14.2) | 45.2 (19) |
| Median (min, max) | 48 (22, 68) | 62 (19, 71) | 10.5 (5, 15) | 51 (19, 71) | 48 (5, 71) |
| Age group, years, n (%) | |||||
| <17 | 0 | 0 | 6 (100) | 0 | 6 (12.8) |
| 17 to 65 | 25 (89.3) | 11 (84.6) | 0 | 36 (87.8) | 36 (76.6) |
| >65 | 3 (10.7) | 2 (15.4) | 0 | 5 (12.2) | 5 (10.6) |
| Sex, n (%) | |||||
| Female | 8 (28.6) | 8 (61.5) | 4 (66.7) | 16 (39) | 20 (42.6) |
| Male | 20 (71.4) | 5 (38.5) | 2 (33.3) | 25 (61) | 27 (57.4) |
| Race, n (%) | |||||
| Asian | 7 (25) | 0 | 0 | 7 (17.1) | 7 (14.9) |
| Black or African American | 2 (7.1) | 0 | 0 | 2 (4.9) | 2 (4.3) |
| Native Hawaiian or other Pacific Islander | 1 (3.6) | 0 | 0 | 1 (2.4) | 1 (2.1) |
| White | 17 (60.7) | 0 | 0 | 17 (41.5) | 17 (36.2) |
| Other | 1 (3.6) | 0 | 0 | 1 (2.4) | 1 (2.1) |
| Unknown | 0 | 13 (100) | 6 (100) | 13 (31.7) | 19 (40.4) |
| Ethnicity, n (%) | |||||
| Hispanic or Latino | 2 (7.1) | 0 | 0 | 2 (4.9) | 2 (4.3) |
| Not Hispanic or Latino | 26 (92.9) | 0 | 0 | 26 (63.4) | 26 (55.3) |
| Unknown | 0 | 13 (100) | 6 (100) | 13 (31.7) | 19 (40.4) |
Source: Adapted from FDA Review
1 Pediatric defined as <17 years of age
Abbreviations: EAP, expanded access program; SD, standard deviation
What are the benefits of this drug?
The benefit of YARTEMLEA was evaluated in a single-arm, open-label trial (Study TMA-001) of 28 patients with high-risk TA-TMA who received YARTEMLEA for 4 to 8 weeks, supported by detailed patient-level data for 19 high-risk patients treated under the YARTEMLEA EAP (EAP Subgroup). TMA response, defined as improvement in both of two laboratory TMA markers (LDH levels and platelet counts), and at least one of two clinical findings, specifically improvement in organ function and freedom from transfusion, was achieved in 17/28 (61%) patients in Study TMA-001 and 13/19 (68.4%) of the EAP Subgroup patients.
What are the benefits of this drug (results of trials used to assess efficacy)?
The efficacy of YARTEMLEA was assessed in a single-arm, open-label study (Study TMA-001) that enrolled 28 adult patients who developed TA-TMA following hematopoietic stem-cell transplantation (HCT) and 19 adult and pediatric patients with TA-TMA with evaluable patient-level response data enrolled in an EAP. In the Study TMA-001, 24 patients received YARTEMLEA 4 mg/kg intravenously once weekly and 4 patients received YARTEMLEA 370 mg intravenously once weekly. The median number of YARTEMLEA administrations received by the 28 patients in Study TMA-001 plus the 19 patients in the EAP was 8 (range: 2 to 34), and the median duration of therapy was 8 weeks (range: 2 to 16 weeks).
The primary efficacy assessment of YARTEMLEA was based on TMA response defined as improvement in both of two laboratory TMA markers (LDH and platelet counts) and either improvement in organ function or independence from transfusions. The same response criteria were applied to both the Study TMA-001 and EAP patients. In Study TMA-001 and the EAP, TA-TMA response was achieved in 17/28 (60.7%) and 13/19 (68.4%) patients, respectively (Table 2).
Table 2. Efficacy Results, Study TMA-001 and EAP Subgroup, Efficacy Population
| Parameter | TMA-001 | EAP Subgroup, N=19 | |
|---|---|---|---|
Adult | Pediatric | ||
| TMA response, n/Ns (%) | 17/28 (61) | 9/13 (69) | 4/6 (67) |
| 95% CI (Clopper–Pearson) | 40.6, 78.5 | 38.6, 90.9 | 22.3, 95.7 |
| Improvement in TMA markers, n/Ns (%) | 17/28 (61) | 9/13 (69) | 4/6 (67) |
| Platelet count | 14/23 (61) | 9/13 (69) | 4/6 (67) |
| LDH | 21/28 (75) | 11/13 (85) | 5/6 (83) |
| Improvement in organ function, n/Ns (%) | 20/27 (74) | 11/13 (85) | 5/6 (83) |
| Freedom from transfusion, n/Ns (%) | 12/25 (48) | 9/13 (69) | 3/5 (60) |
Source: Adapted from FDA Review
Abbreviations: CI, confidence interval; EAP, expanded access program; LDH, lactate dehydrogenase; N, number of patients in treatment arm; n, number of patients meeting criteria; Ns, total number of patients for each specific subgroup and were assigned to that specific arm; TMA, thrombotic microangiopathy
Were there any differences in how well the drug worked in clinical trials among sex, race, and age?
- Sex: The number of female patients was small; therefore, differences in how YARTEMLEA worked among sexes could not be determined.
- Race: The number of patients of races other than White was small; therefore, differences in how YARTEMLEA worked among races could not be determined.
- Age: The number of patients in age groups other than 17 to 65 was small; therefore, differences in how YARTEMLEA worked among age groups could not be determined.
Were there any differences in how well the drug worked in clinical trials among sex, race, and age groups?
Since the number of female patients was small, subgroup analysis by sex could not be determined. Because the number of patients 17 to 65 years of age was small, differences in how YARTEMLEA worked among age groups could not be determined. The number of patients who were Black or African American and Asian or Pacific Islander were small, and therefore the differences in how YARTEMLEA among races could not be compared. The number of Hispanic or Latino patients was also small, and the differences in how YARTEMLEA worked among ethnicities could not be compared.
Table 3. Efficacy Results by Subgroup, Study TMA-001
| Subgroup | # Responders n/N | Proportion (95% CI) |
|---|---|---|
| Overall | 17/28 | 60.7 (40.6, 78.5) |
| Sex | ||
| Male | 13/20 | 65 (40.8, 84.6) |
| Female | 4/8 | 50 (15.7, 84.3) |
| Age, years | ||
| <17 | 0/0 | NA |
| 17 to 65 | 15/25 | 60 (38.7, 78.9) |
| >65 | 2/3 | 66.7 (9.4, 99.2) |
| Race | ||
| White | 10/17 | 58.8 (32.9, 81.6) |
| Black or African American | 1/2 | 50 (1.3, 98.7) |
| Asian or Pacific Islander | 5/8 | 62.5 (24.5, 91.5) |
| Other | 1/1 | 100 (2.5, 100) |
| Unknown | 0/0 | NA |
| Ethnicity | ||
| Hispanic or Latino | 2/2 | 100 (15.8, 100) |
| Not Hispanic or Latino | 15/26 | 57.7 (36.9, 76.6) |
| Unknown | 0/0 | NA |
Source: FDA analysis
Abbreviations: CI, confidence interval; n, number of responders in the subgroup; N, number of subjects in the subgroup; NA, not applicable
Table 4. Efficacy Results by Subgroup, EAP Subgroup, Adult Population
| Subgroup | # Responders n/N | Proportion (95% CI) |
|---|---|---|
| Overall | 9/13 | 69.2 (38.6, 90.9) |
| Sex | ||
| Male | 4/5 | 80 (28.4, 99.5) |
| Female | 5/8 | 62.5 (24.5, 91.5) |
| Age, years | ||
| <17 | 0/0 | NA |
| 17 to 65 | 7/11 | 63.6 (30.8, 89.1) |
| >65 | 2/2 | 100 (15.8, 100) |
| Race | ||
| White | 0/0 | NA |
| Black or African American | 0/0 | NA |
| Asian or Pacific Islander | 0/0 | NA |
| Other | 0/0 | NA |
| Unknown | 9/13 | 69.2 (38.6, 90.9) |
| Ethnicity | ||
| Hispanic or Latino | 0/0 | NA |
| Not Hispanic or Latino | 0/0 | NA |
| Unknown | 9/13 | 69.2 (38.6, 90.9) |
Source: FDA analysis
Abbreviations: CI, confidence interval; EAP, expanded access program; n, number of responders in the subgroup; N, number of subjects in the subgroup; NA, not applicable
Table 5. Efficacy Results by Subgroup, EAP Subgroup, Pediatric Population
| Subgroup | # Responders n/N | Proportion (95% CI) |
|---|---|---|
| Overall | 4/6 | 66.7 (22.3, 95.7) |
| Sex | ||
| Male | 1/2 | 50 (1.3, 98.7) |
| Female | 3/4 | 75 (19.4, 99.4) |
| Age, years | ||
| <17 | 4/6 | 66.7 (22.3, 95.7) |
| 17 to 65 | 0/0 | NA |
| >65 | 0/0 | NA |
| Race | ||
| White | 0/0 | NA |
| Black or African American | 0/0 | NA |
| Asian or Pacific Islander | 0/0 | NA |
| Other | 0/0 | NA |
| Unknown | 4/6 | 66.7 (22.3, 95.7) |
| Ethnicity | ||
| Hispanic or Latino | 0/0 | NA |
| Not Hispanic or Latino | 0/0 | NA |
| Unknown | 4/6 | 66.7 (22.3, 95.7) |
Source: FDA analysis
Abbreviations: CI, confidence interval; EAP, expanded access program; n, number of responders in the subgroup; N, number of subjects in the subgroup; NA, not applicable
What are the possible side effects?
Serious adverse reactions were reported in 61% of patients receiving YARTEMLEA. Serious adverse reactions in >5% of patients who received YARTEMLEA included acute kidney injury, confusional state, acute respiratory failure, neutropenic sepsis, septic shock, pulmonary edema, and vomiting. Fatal adverse reactions occurred in 7% of patients, including neutropenic sepsis and septic shock.
Adverse reactions leading to dosage interruptions occurred in 7% of patients who received YARTEMLEA and included Escherichia sepsis, pyrexia, pulmonary alveolar hemorrhage, and acute myocardial infarction.
The most common adverse reactions (≥20%) were viral infections, sepsis, hemorrhage, diarrhea, vomiting, nausea, neutropenia, pyrexia, fatigue, and hypokalemia.
What are the possible side effects (results of trials used to assess safety)?
Table 6. Safety Results, Adverse Reactions (≥15%) in Patients Receiving YARTEMLEA, Study TMA-001, Safety Population
| Adverse Reaction | All Grades N=28 n (%) | Grade ≥3 N=28 n (%) |
|---|---|---|
| Hemorrhage* | 12 (43) | 2 (7) |
| Diarrhea | 10 (36) | 2 (7) |
| Infection, viral* | 10 (36) | 2 (7) |
| Neutropenia* | 10 (36) | 10 (36) |
| Pyrexia | 10 (36) | 1 (4) |
| Vomiting | 9 (32) | 2 (7) |
| Fatigue* | 8 (29) | 1 (4) |
| Hypokalemia* | 7 (25) | 3 (11) |
| Nausea | 7 (25) | 1 (4) |
| Sepsis* | 7 (25) | 6 (21) |
| Pneumonia* | 5 (18) | 4 (14) |
| Hypotension* | 5 (18) | 3 (11) |
| Abdominal pain* | 5 (18) | 1 (4) |
| Anemia* | 5 (18) | 3 (11) |
| Back pain | 5 (18) | 0 (0) |
Source: YARTEMLEA Prescribing Information
* Grouped terms
GLOSSARY
CLINICAL TRIAL: Voluntary research studies conducted in people and designed to answer specific questions about the safety or effectiveness of drugs, vaccines, other therapies, or new ways of using existing treatments.
COMPARATOR: A previously available treatment or placebo used in clinical trials that is compared to the actual drug being tested.
EFFICACY: How well the drug achieves the desired response when it is taken as described in a controlled clinical setting, such as during a clinical trial.
PLACEBO: An inactive substance or "sugar pill" that looks the same as, and is given the same way as, an active drug or treatment being tested. The effects of the active drug or treatment are compared to the effects of the placebo.
SUBGROUP: A subset of the population studied in a clinical trial. Demographic subsets include sex, race, and age groups.