Study of TAK-672 in Participants With Acquired Hemophilia A

The main aims of the study are to learn if TAK-672 can control bleeds in participants with acquired hemophilia A and if the participants have side effects from TAK-672. Acquired hemophilia A is when people's immune system attacks specific proteins, known as clotting factors, in their bodies. This is different from hemophilia A, which is a condition people are born with.

At the first visit, the study doctor will check who can take part. For those who can take part, participants will visit the clinic or hospital when they get their next bleed. They will receive TAK-672 slowly through a vein. This is called an infusion. They might need extra infusions of TAK-672 to control the bleed. After their bleed is controlled, participants will regularly visit the clinic for a check-up and to treat any further bleeds. This will happen until all participants have received their last dose of TAK-672 to control their 1st bleed. After this, all participants will visit the clinic 90 days later for a final check-up.


Eligibility Criteria:
Inclusion Criteria:

1. Male or female Japanese participants of \>=18 years of age.
2. Participants who (or their legally authorized representatives) have provided his/her written informed consent form prior to any study-related procedures and study product administration.
3. Participants with a diagnosis of AHA based on clinical evaluation and supportive local laboratory testing as shown below:

   * Presentation with spontaneous bleeding without anatomical cause and without prior known bleeding disorder.
   * Prolonged activated partial thromboplastin time (aPTT) without explanation.
   * Abnormal aPTT cross mixing test consistent with FVIII inhibitors
   * Confirmation of a low FVIII:C.
   * Positive FVIII inhibitor (\>=0.6 BU) as measured either in the local or central laboratory
4. Participants with a severe bleeding episode which the investigator finds necessary to treat and whose severe bleeding episode meets at least 1 of the following criteria:

   * Bleeds that pose a threat to a vital organ that could threaten life (e.g. intracranial bleed, or any site that could obstruct the airway).
   * Bleeds that pose a threat to a vital organ where life is not threatened but the organ function could be impaired (e.g., intraspinal bleed threatening the spinal cord and/or nerve conduction; a continual bleed into the kidney or bladder that could result in an obstructive uropathy, testicular bleed, bleed in and around the eye).
   * Bleeds requiring a blood transfusion to maintain the Hgb level at above-life or organ threatening levels (e.g. post-surgical, gastro-intestinal, retro-peritoneal, and thigh bleeds).
   * Intramuscular bleeds where muscle viability and/or neurovascular integrity is significantly compromised or at risk of being compromised.
   * Intra-articular bleeds impacting a major joint associated with severe pain, swelling and severe loss of joint mobility (reduced \>70%) or where a bleed could result in joint destruction (e.g. in and around the femoral head).
5. Participants who are taking anti-thrombotics (including anti-platelet agents and anticoagulantswith confirmatory laboratory testing documenting specific FVIII inhibitor titer and with 3 half-lives of the agent have elapsed since the last dose.
6. Participants with expected life expectancies of at least 90 days prior to the onset of the hemorrhagic episode.
7. Participants of reproductive age who have agreed to use acceptable methods of contraception and if female, undergo pregnancy testing as part of the screening process.
8. Participant who are able to willing and able to comply with the requirements of the protocol.

Exclusion Criteria:

1. Participants with an established reason for bleeding that is not correctable even with hemostatic therapy.
2. Participants presenting a bleeding episode that is assessed likely to resolve on its own, even if left untreated.
3. Participants with a known major sensitivity (anaphylactoid reactions) to therapeutic products of porcine or hamster origin; examples include therapeutics of porcine origin (e.g. previously marketed porcine FVIII, Hyate: C) and recombinant therapeutics prepared from hamster cells (e.g. Humira, Advate, and Enbrel).
4. Participants with the use of hemophilia medication: prior to the administration of TAK-672 under one of the following conditions: (1) use of "recombinant activated factor VII (rFVI)Ia " within 3 hours prior to TAK-672 administration (2) use of " activated prothrombin complex concentrate (aPCC)" within 6 hours prior to TAK-672 administration or (3) use of " plasma-derived FX/FVIIa complex concentrate (pd-FX/FVIIa) " within 8 hours prior to TAK-672 administration.
5. Participants with an anticipated need for treatment or device during the study that may interfere with the evaluation of the safety or efficacy of TAK-672, or whose safety or efficacy may be affected by TAK-672.
6. Participants who are currently pregnant or breastfeeding, or planning to become pregnant or father a child during the study
7. Participants who have participated in another clinical study and has been exposed to an investigational product or device within 30 days prior to the study enrollment.
8. Participants who are scheduled to participate in another non-observational (interventional) clinical study involving an investigational product or device during the course of the study.
9. Participants who are unable to or unwilling to comply with the study design, protocol requirements, and/or the follow-up procedures.
10. Participants whose majority of age are under legal protection.
11. Participants who are an immediate family member, study site employee, or are in a dependent relationship with a study site employee who is involved in the conduct of this study (e.g. spouse, parent, child, sibling) or may consent under duress.
12. Participants who are judged by the investigator as being ineligible for any other reason.