A Study to Evaluate Safety/Tolerability of Immunotherapy Combinations in Participants With Triple-Negative Breast Cancer and Gynecologic Malignancies

Dose escalation of AB928 in combination with pegylated liposomal doxorubicin (PLD) at
standard doses will be assessed in participants with advanced metastatic triple-negative
breast cancer or ovarian cancer. In this dose escalation combination study participants will
receive oral administration of AB928 as well as iv infusion of PLD.

Dose expansion of AB928 in combination with PLD at standard doses will be assessed in
participants with advanced metastatic triple-negative breast cancer or ovarian cancer. The
dose of AB928 used will be determined based on the findings from the dose-escalation phase.

Overall duration of treatment will depend on how well the treatment is tolerated. Treatment
may continue until unacceptable toxicity or progressive disease or other reasons specified in
the protocol.

Inclusion:

1. Female participants ≥ 18 years of age at the time of screening;

2. Must have at least 1 measurable lesion per RECIST v1.1;

3. Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1;

4. Confirm that an archival tissue sample is available and ≤ 6 months old; if not, a new
biopsy of a tumor lesion must be obtained, or fresh biopsy at screening;

5. Adequate organ and marrow function;

6. Breast Cancer: Participants must have histologically confirmed ER-negative,
PgR-negative, and HER2-negative breast cancer (per ASCO/CAP guidelines) that is
metastatic, advanced or recurrent with progression for which no alternative or
curative therapy exists; OR Ovarian Cancer:Participants must have histologically
confirmed ovarian cancer (per ASCO/CAP guidelines) that is metastatic, advanced or
recurrent with progression for which no alternative or curative therapy exists;

Exclusion:

1. Use of any live vaccines against infectious diseases within 4 weeks (28 days) of
initiation of investigational product.

2. Underlying medical conditions that, in the Investigator's or Sponsor's opinion, will
make the administration of investigational product hazardous

3. Has known psychiatric or substance abuse disorders that would interfere with
cooperation with the requirements of the trial.

4. Is pregnant or breastfeeding or expecting to conceive or father children within the
projected duration of the study, starting with the pre-screening or screening visit
through 30 days after the last dose of AB928 in combination with PLD.

5. Any active autoimmune disease or a documented history of autoimmune disease or
syndrome that required systemic treatment in past 2 years

6. Prior malignancy active within the previous 2 years except for locally curable cancers
that have been apparently cured, such as basal or squamous cell skin cancer,
superficial bladder cancer or carcinoma in situ of the cervix, breast, or prostate
cancer.

7. Prior chemotherapy, targeted small-molecule therapy, or radiation therapy within 4
weeks prior to Day 1 or has not recovered (ie, ≥ Grade 1 or baseline) from AEs due to
a previously administered agent

8. Participants who are eligible for potentially curative available therapies or
interventions.

9. Use of other investigational drugs within 28 days of investigational product
administration