Table 4 HU holding/de-escalation and stopping criteria

Absolute neutrophil count <1500/uL

Positive urine pregnancy test

Platelet count <95,000/uL

Any cytopenia that does not resolve after holding HU for 2 weeks

Hb <9 g/dL with absolute reticulocyte count <95,000/uL

Request of the subject or proxy (withdrawal of consent by the subject)

Investigator’s discretion

Subject is lost to follow-up