A Long-term Follow-up Study of Sotatercept for PAH Treatment (MK-7962-004/A011-12)

Inclusion Criteria:

• Have completed their current respective PAH sotatercept clinical study and itsrequirements, and must not have discontinued early

• Must be willing to adhere to the study visit schedule and understand and comply withall protocol requirements

• Must have the ability to understand and provide documented informed consent

• Females of childbearing potential must:

• Have a negative pregnancy test as verified by the investigator prior tostarting study drug administration; she must agree to ongoing pregnancy testingduring the course of the study and until 8 weeks after the last dose of thestudy drug

• If sexually active, have used, and agree to continue to use highly effectivecontraception in combination with a barrier method without interruption, for atleast 28 days prior to starting the investigational product, during the study (including dose interruptions), and for 16 weeks (112 days) afterdiscontinuation of study drug

• Refrain from breastfeeding a child or donating blood, eggs, or ovum for theduration of the study and for at least 16 weeks (112 days) after the last doseof study drug

• Male participants must:

• Agree to use a condom, defined as a male latex condom or non latex condom NOTmade out of natural (animal) membrane (e.g., polyurethane), during sexualcontact with a pregnant female or a female of childbearing potential whileparticipating in the study, during dose interruptions, and for at least 16weeks (112 days) following investigational product discontinuation, even if hehas undergone a successful vasectomy

• Refrain from donating blood or sperm for the duration of the study and for 16weeks (112 days) after the last dose of study drug

• Must agree not to participate in any other trials of investigational drugs/deviceswhile they are enrolled in the MK-7962-004 study

Exclusion Criteria:

• Did not participate in a sotatercept PAH parent trial

• Missed more than the equivalent of 4 consecutive doses between the end of parentstudy and the start of this study.

• Presence of an ongoing serious adverse event (SAE) that occurred during a PAHsotatercept clinical study that is assessed to be possibly or probably related tosotatercept

• Pregnant or breastfeeding females