An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. An SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment-emergent events were between first dose of study drug and up to 28 days after last dose that were absent before treatment or that worsened relative to pre-treatment state.

Criteria for laboratory test abnormality: Hematology (hemoglobin, hematocrit, red blood corpuscles \[RBC\] count: less than \[\<\]0.8\*lower limit of normal \[LLN\], platelets: \<0.5\*LLN/greater than \[\>\]1.75\*upper limit of normal \[ULN\], leukocytes: \<0.6\*LLN or \>1.5\*ULN, lymphocytes, total neutrophils: \<0.8\*LLN or \>1.2\*ULN, basophils, eosinophil: \<0.8\*LLN, monocytes: \>1.2\*ULN); Liver Function (aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase: \>0.3\*ULN, total protein, albumin: \<0.8\*LLN or \>1.2\*ULN); total bilirubin, direct bilirubin, indirect bilirubin: \>1.5\*ULN; Renal Function (blood urea nitrogen, creatinine: \>1.3\*ULN, uric acid: \>1.2\*ULN); Electrolytes (sodium: \<0.95\*LLN or \>1.05\*ULN, potassium, chloride, calcium, bicarbonate: \<0.9\*LLN or \>1.1\*ULN; creatine kinase: \>2.0\*ULN; glucose fasting: \<0.6\*LLN or \>1.5\*ULN, urine white blood corpuscles \[WBC\] and RBC: greater than or equal to (\>=) 20/High Power Field \[HPF\]).

Criteria for clinically significant vital signs abnormalities included supine/sitting pulse rate of \<40 beats per minute (bpm) or \>120 bpm, supine systolic blood pressure (SBP) of \<90 millimeter of mercury (mmHg), \>=30 mmHg maximum increase and decrease from baseline in same posture, supine diastolic blood pressure (DBP) of \<50 mmHg; \>=20 mmHg maximum increase and decrease from baseline in same posture.

Clinically significant ECG findings included PR interval \>=300 milliseconds (msec) or \>=25 percent (%) increase from baseline (if baseline PR interval \>200 msec) or \>=50% increase (if baseline PR interval less than or equal to \[\<=\] 200 msec); QRS interval \>=140 msec or \>=50% increase from baseline; QT interval \>=500 msec, corrected QT interval based on Fridericia's formula (QTcF) 450 to \<480 msec, 480 to \<500 msec, \>=500 msec or \>=30 msec but \<60 msec increase from baseline or \>=60 msec increase from baseline.

Physical examination included general examination and examination of head, ears, eyes, nose, mouth, throat, neck, abdomen, skin, heart, lungs, lymph nodes, and gastrointestinal and musculoskeletal and neurological system.

Results are reported in micro international units per milliliter (mcIU/mL).

Anti-PF-05231023 antibodies and neutralizing antibodies were analyzed only for participants who received PF-05231023 as per planned analysis. One sample at Day 1 was inadvertently tested for neutralizing antibody even though the corresponding anti-PF-05231023 antibody was negative.

Anti-PF-05231023 antibodies and neutralizing antibodies were analyzed only for participants who received PF-05231023 as per planned analysis. One sample at Day 39 was inadvertently tested for neutralizing antibody even though the corresponding anti-PF-05231023 antibody was negative.