Sexually active fertile subjects, and their partners, must agree to use medically accepted double-barrier methods of contraception (e.g., barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the study and at least 6 weeks after termination of study therapy Sexually active fertile subjects (male and female) must agree to use medically accepted methods of contraception during the course of the study and for 30 days after the last dose of study treatment Sexually active fertile subjects, and their partners, must agree to use medically accepted double-barrier methods of contraception (e.g., barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the study and at least 6 months after termination of study therapy Male and female subjects must agree to medically accepted methods of contraception Sexually active fertile subjects, and their partners, must agree to use medically accepted double-barrier methods of contraception (e.g., barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the study and at least 6 weeks after termination of study therapy Sexually active fertile subjects (male and female), and their partners, must agree to use medically accepted methods of contraception (eg, barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the course of the study and for 4 months after the last dose of study drug(s) Sexually active fertile subjects(male and female)must agree to use medically accepted methods of contraception during the course of the study and for 4 months after the last dose of study treatment. Sexually active participants and their partners must agree to use medically accepted methods of contraception Sexually active fertile subjects, and their partners, must agree to use medically accepted double-barrier methods of contraception (e.g., barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the study and at least 6 weeks after termination of study therapy If a sexually active male or a sexually active female of child-bearing potential, agrees to use dual (two concurrent) forms of medically accepted contraception from the time of consent until 6 months after the last dose of either ONT-10 or T-DM1, whichever is longer. Sexually active fertile patients (male and female), and their partners, must agree to use medically accepted methods of contraception during the course of the study and for 3 months after the last dose of the study drug Female subjects who are lactating, pregnant or both male and female subjects with reproductive potential who refuse to practice medically accepted methods for contraception over the period from study consent to 90 days following the last dose of study treatment Sexually active fertile subjects, and their partners, must agree to use medically accepted methods of contraception (e.g., barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the course of the study and for 4 months after the last dose of study drug(s) Sexually active fertile subjects, and their partners, must agree to use medically accepted methods of contraception (e.g., barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the course of the study and for 3 months after the dose of study drug(s) for Cohorts 1, 2, and 4, and for 3 months after the surgery for Cohort 3 Sexually active fertile subjects and their partners must agree to use medically accepted methods of contraception. Sexually active participants must use medically acceptable methods of contraception during the course of this study Sexually active subject (male and female) must use medically acceptable methods of contraception during the course of the study Sexually active patients and their partners agree to use an accepted method of contraception during the course of the study