ATYR1940

TEAEs were defined as adverse events (AEs) with an onset following administration of the first dose of study drug. AEs were defined as any untoward medical occurrence in a participant administered study drug and that does not necessarily have a causal relationship with the study drug. Worsening of a pre-existing medical condition should have been considered an AE if there was either an increase in severity, frequency, or duration of the condition or an association with significantly worse outcomes. SAEs were defined as any AE that, in the view of either the Investigator or Sponsor, resulted in any of the following outcomes as fatal, life-threatening, required in-participant hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, a congenital anomaly/birth defect, an important medical event. A summary of all SAEs and Other AEs (nonserious) regardless of causality is located in 'Reported Adverse Events' Section.

Summarized titers are reported below.

Participants with Jo-1 Ab levels ≥1.5 U/mL were to be discontinued from dosing of the study drug.

Laboratory parameters included hematology (hematocrit, hemoglobin, red blood cell count, white blood cell count neutrophils, lymphocytes, monocytes, eosinophils, basophils, and platelet count); serum chemistries (blood urea nitrogen, creatinine, total bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, total protein, sodium, potassium, bicarbonate, calcium, chloride, magnesium, inorganic phosphate, creatine kinase, lactate dehydrogenase, C-reactive protein, troponin, myoglobin, insulin-like growth factor 1, and cholesterol \[nonfasting\]); and urinalysis (color, pH, specific gravity, protein, glucose, ketones, and blood). Clinically significant laboratory abnormalities were based upon Investigator's discretion. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

Pulmonary evaluations included pulmonary function tests and pulse oximetry. Clinically significant changes were to be reported as adverse events. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

ECG parameters that were evaluated included heart rate and PR, QR, and QT intervals. A clinically significant ECG abnormality was based upon the Investigator's discretion. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

The vital sign parameters that were evaluated included heart rate, systolic and diastolic blood pressure, and respiration rate as well as temperature. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

MMT (muscle strength) will be graded using a modified Medical Research Council scale. Scores were converted to 13-point scale (range from 0 \[on contraction palpable\] to 12 \[normal strength\]). An overall total score was calculated by summing all scores for a total possible score of 336. Decreased muscle strength was indicated by a decreased score. An overall total score was calculated as long as 24 of the 28 individual scores were non-missing.

Ocular parameters included vitreous, retina, macula, choroid, optic nerve, and optic nerve pallor. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

Body systems that were evaluated during the physical examination included general appearance, head, eyes, ears, nose, throat, cardiovascular system, respiratory system, gastrointestinal system (abdomen), lymphatic system, musculoskeletal system, skin, psychiatric, and neurologic. Neurologic examination included assessment of mental status, memory, cranial nerves, motor function, reflexes, and sensory testing. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

The vital sign parameters that were evaluated included blood pressure, pulse and respiration rates, and body temperature. Vital signs abnormalities that were considered by the Investigator to be clinically significant were reported as AEs if the finding represented a change from baseline. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

Laboratory parameters included hematology (hematocrit, hemoglobin, red blood cell count, white blood cell count with differential \[neutrophils, lymphocytes, monocytes, eosinophils, basophils\], and platelet count); serum chemistries (blood urea nitrogen, creatinine, total bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, total protein, sodium, potassium, bicarbonate, calcium, chloride, magnesium, inorganic phosphate, creatine kinase, lactate dehydrogenase, C-reactive protein, troponin, myoglobin, insulin-like growth factor 1, and cholesterol \[nonfasting\]); and urinalysis (color, pH, specific gravity, protein, glucose, ketones, and blood). Clinically significant laboratory abnormalities were based upon Investigator's discretion. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

TEAEs were defined as adverse events (AEs) with an onset following administration of the first dose of study drug. An AE was defined as any untoward medical occurrence in a participant or clinical investigation participant administered a pharmaceutical product and that does not necessarily have a causal relationship with study drug. Worsening of a pre-existing medical condition, (that is, diabetes, migraine headaches, gout) should have been considered an AE if there was either an increase in severity, frequency, or duration of the condition or an association with significantly worse outcomes. Classification of AEs was to be done by the Investigator according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE), version 4.03. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

Criterion for a positive Jo-1 Ab test result: \>10.0 units/milliliter (U/mL), a cut-point associated with anti-synthetase syndrome. Criterion for an equivocal Jo-1 Ab test result: 7.0 to 10.0 U/mL. Participants were required to have a negative Jo-1 Ab test result (defined as \<7 U/mL) for inclusion in the study as well as to continue dosing with study drug during the study.

Laboratory parameters included hematology (hematocrit, hemoglobin, platelet count, red blood cell count, white blood cell count, neutrophils, lymphocytes, monocytes, eosinophils, basophils); serum chemistries (blood urea nitrogen, creatinine, total bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase (GGT), alkaline phosphatase, sodium, total protein, bicarbonate, potassium, calcium, chloride, magnesium, inorganic phosphate, creatine phosphokinase \[will be fractionated if elevated\], lactic dehydrogenase, erythrocyte sedimentation rate, C-reactive protein, troponin, myoglobin, insulin-like growth factor 1, cholesterol \[non-fasting\]); Urinalysis (Color, pH, specific gravity, protein, glucose, ketones, blood). Clinically significant laboratory abnormalities were based upon Investigator's discretion. A summary of all Serious AEs and Other AEs (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

Body systems that were evaluated during the physical examination included general appearance, head, eyes, ears, nose, throat (HEENT), cardiovascular system, respiratory system, chest (breasts), gastrointestinal system (abdomen), lymphatic system, musculoskeletal system, skin, psychiatric, and neurologic. Neurologic examination included assessment of mental status, memory, cranial nerves, motor function, and reflexes, and sensory testing. The body systems with at least 1 physical abnormality is presented. One participant could be represented in more than 1 body system category. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

Pulmonary function testing included measurements of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.