A Study of FOR46 in Patients With Relapsed or Refractory Multiple Myeloma (RRMM)

Inclusion Criteria:

* Male or female ≥ 18 years of age
* Measurable MM that is relapsed or refractory to established therapies with known clinical benefit in RRMM or intolerant of those established MM therapies. Prior lines of therapy must include a proteasome inhibitor (PI), an immunomodulatory imide drug (IMiD) and a CD38-directed therapy in any order of combination.
* ECOG performance status of 0 or 1
* Adequate hematologic, renal and hepatic function
* Females of child-bearing potential must have a negative serum pregnancy test and use a medically acceptable form of contraception
* Male patients with with female partners of childbearing potential must agree to use 2 effective methods of contraception
* Patients must provide signed informed consent

Exclusion Criteria:

* Persistent clinically significant toxicities from previous anticancer therapy
* NCI CTCAE Grade ≥ 2 peripheral neuropathy from any etiology or has a genetic disorder that is associated with peripheral neuropathy even without current neuropathic manifestations
* Has received treatment with a stem cell transplant within 12 weeks before administration of patient's first dose of FOR46
* Has had radiation or systemic anticancer therapy within 14 days before first dose of FOR46
* Has received treatment with an investigational drug within 28 days before first dose of FOR46
* Has had a major surgical procedure within 28 days before administration of the patient's first FOR46 dose
* Is breastfeeding
* Clinically significant cardiovascular disease
* Uncontrolled, clinically significant pulmonary disease
* Uncontrolled intercurrent illness
* Has known positive status for HIV or either active/chronic hepatitis B/C
* Requires anticoagulation with warfarin or direct thrombin inhibitor; a washout of 7 days before the administration of a patient's first FOR46 dose is required for patients removed from these treatments
* Requires medications that are strong inhibitors or strong inducers of CYP3A4
* Has a history of episodic atrial fibrillation or flutter; patients with chronic atrial fibrillation are not excluded.
* Prior treatment with an ADC containing Monomethyl auristatin E (MMAE) or Monomethyl auristatin F (MMAF).