Effect of GSK3640254 on the Pharmacokinetics of a Combination Oral Contraceptive

Inclusion Criteria

• Subject must be 18 to 50 years of age inclusive, at the time of signing the informed consent.
• Subjects who are healthy as determined by the investigator or medically qualified designee based on a medical evaluation including medical history, physical examination, laboratory tests, and cardiac monitoring (history and ECG).
• Body weight >=45.0 kilograms (kg) (99 pounds [lbs]) and body mass index (BMI) within the range 18.5 to 31.0 kilograms per meter square (kg/m^2) (inclusive).
• Contraceptive use should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.
• Female subjects will be included.
• Subject must not be pregnant or breastfeeding.
• Subject is a woman of childbearing potential (WOCBP) with intact ovarian function, as determined by medical history. Subjects must use Portia for the duration of the run-in and treatment periods.
• WOCBP must have been on an acceptable form of contraceptive for at least 28 days prior to start of study intervention. Acceptable forms of contraception prior to study intervention include the following: Intrauterine device or intrauterine system; Combined estrogen and progestogen oral contraceptive; Contraceptive vaginal ring; Percutaneous contraceptive patches (if used, the patch must be removed during study participation); Bilateral tubal occlusion; Male partner sterilization with documentation of azoospermia prior to the female subject's entry into the study, and this male is the sole partner for that subject. The documentation on male sterility can come from the site personnel's review of subject's medical records, medical examination and/or semen analysis, or medical history interview provided by her or her partner.; Sexual abstinence.
• Subjects who have been on a stable regimen of an oral contraceptive for at least 3 consecutive months must be without evidence of breakthrough bleeding or spotting.
• Subjects who have been taking oral contraceptives should continue their current regimen until check-in to the clinic for the run-in period. Subjects not currently taking an oral contraceptive are eligible, provided all other eligibility criteria are met.
• Subjects may proceed to the treatment period provided the toxicity profile during the run-in period with Portia is acceptable in the opinion of the investigator.
• Subjects must agree to use an additional method of contraception from the following list of contraceptive methods for the run-in period, treatment period, and for 28 days after the last dose of study intervention: Non hormonal Intrauterine device; Bilateral tubal occlusion; Male partner sterilization with documentation of azoospermia prior to the female subject's entry into the study, and this male is the sole partner for that subject. The documentation on male sterility can come from the site personnel's review of subject's medical records, medical examination and/or semen analysis, or medical history interview provided by her or her partner.; Sexual abstinence. For the 28 days after study exit, women may resume oral contraceptives but double barrier methods (a combination of male condom with either cervical cap, diaphragm, or sponge with spermicide) must be used in addition.
• Women of childbearing potential must have a negative highly sensitive serum pregnancy test on Day -4 and Day -1.
• Additional requirements for pregnancy testing during and after study intervention as outlined in protocol.
• Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form and protocol.

Exclusion Criteria

• History of jaundice associated with taking oral contraceptives or with pregnancy.
• History of clinically significant irregular bleeding while taking oral contraceptives.
• History of past deep venous thrombosis, pulmonary embolism, stroke, transient ischemic attack, phlebitis, or migraine headaches with prolonged au