The purpose of this first multi-dose study in cancer patients is to determine the maximum tolerated dose (MTD) or recommended phase II dose (RP2D), characterize the safety, tolerability and pharmacokinetics profile. Once the MTD has been established and/or a RP2D chosen, the study will enroll patients into the expansion portion of the study.

Inclusion Criteria:

1. Histologically confirmed diagnosis of prostate cancer, breast cancer, or uterine leiomyoma
2. Detectable metastases by bone scan, CT-scan, or MRI.
3. Presence of prolactin receptor in primary or metastatic tumor (Dose Escalation only)
4. Suitable venous access for blood sampling

Exclusion Criteria:

1. Prior treatment with any anti-prolactin receptor antibody
2. Major surgery within 28 days before study treatment
3. Patients who have received radiotherapy ≤ 2 weeks prior to starting study drug
4. Prior anaphylactic or other severe infusion reaction to antibody formulations

Other protocol-defined inclusion/exclusion criteria may apply