Sacituzumab Govitecan Plus EV in Metastatic UC

This research study will assess what doses of Sacituzumab Govitecan and Enfortumab Vedotin can be safely combined in the treatment of metastatic urothelial carcinoma (mUC).

The names of the study drugs in this investigational combination are:

* Enfortumab Vedotin
* Sacituzumab Govitecan

This study is a single-center, open-label, nonrandomized phase I trial testing the safety and efficacy as well as defining the appropriate dose for future studies of Sacituzumab Govitecan and Enfortumab for people with metastatic urothelial carcinoma (mUC) progressing on platinum-based chemotherapy and PD1/L1 inhibitors

The U.S. Food and Drug Administration (FDA) has approved Enfortumab Vedotin for the treatment of metastatic urothelial carcinoma (mUC) (bladder cancer). The FDA has not approved Sacituzumab Govitecan for metastatic urothelial carcinoma (mUC) (bladder cancer) but it has been approved for other uses. The FDA has approved Sacituzumab Govitecan to treat a type of breast cancer at this time. Sacituzumab Govitecan has appeared promising in patients with bladder cancer that has spread and works by a different mechanism than Enfortumab Vedotin. Therefore, the researchers believe that combining these 2 drugs may control the cancer better than each drug does on its own.

This will be done through testing different combinations and checking for serious side effects; if there are no serious side effects a different dose combination will be explored. Once the best combination has been determined, the study will look to see how effective (how well the drug works) it is in slowing down the growth of metastatic urothelial carcinoma (mUC) progressing on platinum-based chemotherapy and PD1/L1 inhibitors and define the most appropriate level of the drugs to use for further studies.

The research study procedures include screening for eligibility, study treatment, and safety follow-up visits, in addition to general health status follow-up after study treatment.

Participants will receive study treatment for as long as they do not have serious side effects and their disease does not get worse. However, the duration may vary depending on how long the treatment works to control the cancer and how someone's body tolerates the side effects.

Immunomedics, a pharmaceutical company, is supporting this research study by providing funding for the research study, tests required for research purposes only, and the study drug Sacituzumab Govitecan.

It is expected that up to 24 people will take part in this research study.

Eligibility Criteria:
Inclusion Criteria:

* Participants must have histologically documented confirmed predominant urothelial carcinoma (i.e. of the bladder, renal pelvis, ureter or urethra). Patients with squamous differentiation or mixed cell types are eligible; small-cell carcinoma is not allowed.

Patients with locally advanced unresectable disease are eligible.

* Patient must have received prior treatment with a checkpoint inhibitor (CPI) in locally advanced or metastatic urothelial cancer setting. Patients who received CPI therapy in the neoadjuvant/adjuvant setting and had recurrent or progressive disease either during or within 3 months of therapy completion are eligible. A CPI is defined as a PD-1 or PD-L1 inhibitor.
* Patients must have received prior treatment with platinum containing therapy defined as within the adjuvant/neoadjuvant setting with recurrent or progressive disease within 12 months or receiving treatment with platinum in locally advanced or metastatic setting.
* Age ≥18 years. Because no dosing or adverse event data are currently available on the use of EV in combination with SG in participants \<18 years of age, children are excluded from this study, but will be eligible for future pediatric trials.
* ECOG performance status 0-1.
* Participants must have adequate organ and marrow function as defined below:

  * Leukocytes ≥3,000/mcL
  * Absolute neutrophil count ≥1,500/mcL
  * Platelets ≥100,000/mcL
  * Total bilirubin ≤ institutional upper limit of normal (ULN)
  * AST(SGOT)/ALT(SGPT) ≤2.5x institutional ULN OR

    ≤5x ULN with liver metastases and serum albumin \> 3 g/dL
  * Glomerular filtration rate (GFR) ≥30 mL/min/1.73 m2 (by Cockcroft Gault formula)
* Human immunodeficiency virus (HIV)-infected participants on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial.
* For participants with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated.
* Participants with a history of hepatitis C virus (HCV) infection must have been treated and cured. For participants with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load.
* Participants with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, should have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification. To be eligible for this trial, participants should be class 2B or better.
* Have measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) as per response evaluation criteria in solid tumors version 1.1 (RECIST 1.1 criteria). Tumor lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions
* Female subjects of childbearing potential must have a negative urine or serum pregnancy test within 72 hours prior to receiving the first dose of study medication. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required
* Female subjects of childbearing potential must be willing to use 2 methods of birth control or be surgically sterile or abstain from heterosexual activity for the course of the study through 6 months after the last dose of study medication. Subjects of childbearing potential are those who have not been surgically sterilized or have not been free from menses for \>2 years
* The effects of SG and EV on the developing human fetus are unknown. Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 4 months after completion of SG administration.
* Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

Subjects meeting any of the following exclusion criteria at Screening/Day 1 of treatment will not be enrolled in the study.

* Women who are pregnant or lactating. Pregnant women are excluded from this study because SG and EV have potential for teratogenic or abortifacient effects. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with EV or SG, breastfeeding should be discontinued if the mother is treated on protocol.
* Have had a prior anti-cancer biologic agent within 4 weeks prior to Cycle 1 Day 1 (C1D1) or have had prior chemotherapy, targeted small molecule therapy, or radiation therapy within 2 weeks prior to C1D1. Subjects participating in observational studies are eligible.
* Presence of any toxicities attributed to prior anti-cancer therapy that are not resolved to Grade 1 or baseline that could impose serious risk for complications before administration of study drug agent

  * Note: If subjects received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.
* Have previously received topoisomerase 1 inhibitors, SG or EV
* Have an active second malignancy. Subjects with a history of malignancy that have been completely treated, with no evidence of active cancer for 3 years prior to start of therapy on trial (Cycle 1 Day 1 \[C1D1\]), or subjects with surgically-cured tumors with low risk of recurrence are allowed to enroll.
* Have known active central nervous system (CNS) metastases and/or carcinomatous meningitis. Subjects with previously treated brain metastases may participate provided they have stable CNS disease for at least 4 weeks prior to the first dose of study drug and all neurologic symptoms have returned to baseline, have no evidence of new or enlarging brain metastases, and are taking ≤20 mg/day of prednisone or its equivalent.

All subjects with carcinomatous meningitis are excluded regardless of clinical stability.

* Have active cardiac disease, defined as:

  * Myocardial infarction or unstable angina pectoris within 6 months prior to C1D1
  * History of serious ventricular arrhythmia (i.e., ventricular tachycardia or ventricular fibrillation), high-grade atrioventricular block, or other cardiac arrhythmias requiring anti-arrhythmic medications (except for atrial fibrillation that is well controlled with antiarrhythmic medication); history of QT interval prolongation
  * New York Heart Association (NYHA) Class III or greater congestive heart failure or left ventricular ejection fraction of \< 40%
* Have active chronic inflammatory bowel disease (ulcerative colitis, Crohn's disease) or gastrointestinal (GI) perforation within 6 months of C1D1
* Have active serious infection requiring antibiotics (Contact medical monitor for clarification)
* Have other concurrent medical or psychiatric conditions that, in the Investigator's opinion, may be likely to confound study interpretation or prevent completion of study procedures and follow-up examinations.
* High dose systemic corticosteroids (≥20 mg of prednisone or its equivalent) are not allowed within 2 weeks prior to C1D1.
* Participants who are receiving any other investigational agents.
* History of allergic reactions attributed to compounds of similar chemical or biologic composition to EV or SG or any excipient contained in the drug formulations (including 2-(N-morpholino) ethane sulfonic acid (MES), histidine, treahalose dihydrate polysorbate 80 and polysorbate 20).
* Participants with uncontrolled intercurrent illness.
* Participants with psychiatric illness/social situations that would limit compliance with study requirements.
* Patients with uncontrolled diabetes. Uncontrolled diabetes is defined as hemoglobin A1C \>8% or 7-8% with associated diabetes symptoms that are otherwise not explained
* Uncontrolled tumor related bone pain or impending spinal cord compression.