This is a prospective, single arm, phase II clinical trial of neoadjuvant Tebentafusp (KIMMTRAK®) in patients with locally advanced primary uveal melanoma. Patients must be HLA-A*02:01 with large, surgically unresectable (other than complete enucleation of the eye) primary uveal melanoma. The efficacy of this treatment will be assessed with the Simon's two stage design. The choice of design is guided by a desire to stop the trial early if the actual regression rate of primary uveal melanoma is 1% or lower.

This is an investigator-initiated, Phase II trial evaluating neoadjuvant treatment for locally advanced, unresectable primary uveal melanoma with Tebentafusp. Given the success of Tebentafusp in the metastatic setting, we are interested in utilizing Tebentafusp in the neoadjuvant setting. Limited clinical research data suggest that Tebentafusp might accumulate in primary uveal melanoma and result in regression of primary uveal melanoma. This clinical trial will explore this possibility for patients with large and unresectable primary uveal melanoma. Changes in primary UM after Tebentafusp treatment and eye toxicity related to treatment will be monitored with ophthalmologic ultrasound, Optical coherence tomography (OCT) and clinical examination. Primary eye tumor biopsy pre-Tebentafusp and post-Tebentafusp treatment will also be performed by fine-needle aspiration. Blood and aqueous humor circulating tumor-derived DNA will also be measured as a potential biomarker for response.

We will consider regression of the primary uveal melanoma by a 20% reduction in tumor volume a meaningful endpoint for this early phase clinical study. Reduction in volume by 20% could result in a proportion of patients who had planned enucleation prior to therapy to become suitable for plaque brachytherapy (exploratory endpoint).

The efficacy of this combination treatment will be assessed using the Simon's two stage design [Optimal Design]. The trial is carried out in two stages. In stage I, a total number of 8 patients will be accrued. If there are 0 responses (at least a 20% reduction in tumor volume) among these 8 patients, further enrollment of patients may be stopped. Otherwise, an additional 11 patients will be accrued in stage II, resulting in a total sample size of 19. If there are 2 or more responses among these 19 patients, we reject the null hypothesis and claim that the treatment is promising.

PRIMARY OBJECTIVE:

To assess the efficacy of neoadjuvant Tebentafusp in patients with large surgically unresectable (other than complete enucleation of the eye) primary uveal melanoma.

SECONDARY OBJECTIVES:

1. To assess the local (eye) and systemic toxicity with Tebentafusp treatment.
2. To investigate the usefulness of ctDNA as a biomarker for response.

EXPLORATORY OBJECTIVES:

1. To assess sight preservation.
2. To assess the change in radiation dose to the fovea.

OUTLINE:

Participants may be screened at Wills Eye Hospital before being consented and treated at Thomas Jefferson University. Patients receive tebentafusp intravenously (IV) over 15-20 minutes on days 1, 8, 15, and 22 of each cycle. Treatment repeats every 28 days for up to 2 cycles in the absence of disease progression or unacceptable toxicity. Within 28 days of their last dose of tebentafusp, patients undergo standard of care (SOC) primary eye treatment (plaque radiotherapy or eye enucleation), as decided by their treating physician. Patients also undergo ophthalmic ultrasound, optical coherence tomography (OCT), wide-angle fundus imaging, OCT angiography (OCTA), fluorescein angiography, orbit magnetic resonance imaging (MRI) or computerized tomography (CT) scan, and collection of blood samples throughout the trial, undergo biopsy and collection of aqueous humour samples at screening and on study, and undergo abdominal MRI and chest and pelvis CT at screening and during follow up.

After completion of primary eye treatment, patients are followed up at 3 months and then for survival for up to 5 years.

Inclusion Criteria:

Individuals must meet all of the following inclusion criteria in order to be eligible to participate in the study:

1. Male or female patient age ≥ 18 years of age at the time of informed consent.
2. Ability to provide and understand written informed consent prior to any study procedures.
3. Willingness to undergo tumor biopsies at baseline and post-Tebentafusp treatment.
4. Treatment naïve primary uveal melanoma with T3 or T4 category tumor size that are surgically unresectable (other than complete enucleation of eye).
5. No surgical indication to completely remove the tumor without enucleation.
6. Clinically or cytologically confirmed primary uveal melanoma.
7. Participants must be HLA-A*02:01 positive.
8. Predicted life expectancy of at least 12 weeks as estimated by investigator
9. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 at screening.
10. All other relevant medical conditions must be well-managed and stable, in the opinion of the investigator, for at least 28 days prior to first administration of study drug.
11. Absence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule.

Exclusion Criteria:

An individual who meets any of the following criteria will be excluded from participation in this study:

1. Symptomatic uveal melanoma that requires immediate ophthalmological intervention such as enucleation.

2. Evidence of metastatic disease.

3. Previous treatment with Tebentafusp.

4. Patients with any out-of-range laboratory values defined as:

   • Serum creatinine > 1.5 x upper limit of normal (ULN) and/or creatinine clearance (calculated using Cockcroft-Gault Formula, or measured) < 50 mL/minute
   • Albumin < 3.0 g/dl
   • Total bilirubin >1.5 mg/dL (or 1.3 x ULN). Patients with hyperbilirubinemia clinically consistent with an inherited disorder of bilirubin metabolism (e.g., Gilbert syndrome) will be eligible at the discretion of the treating physician and/or the principal investigator.
   • Alanine aminotransferase > 1.5 x ULN
   • Aspartate aminotransferase > 1.5 x ULN
   • Absolute neutrophil count < 1.0 x 109 /L
   • Absolute lymphocyte count < 0.5 x 109 /L
   • Platelet count < 100 x 109 /L
   • Hemoglobin < 9.0 g/dL
   • Uncorrectable abnormal potassium, magnesium, corrected calcium or phosphate abnormality of National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE v5.0) > grade 1
   • Morning cortisol < lower limit of normal (unless the patient has asymptomatic adrenal insufficiency and is receiving stable replacement doses)

5. History of severe hypersensitivity reactions (e.g., anaphylaxis) to other biologic drugs or monoclonal antibodies.

6. Clinically significant cardiac disease or impaired cardiac function, including any of the following:

   • Left Ventricular Ejection Fraction <50%
   • Clinically significant and/or uncontrolled heart disease such as congestive heart failure (New York Heart Association grade ≥ 2), uncontrolled hypertension, or clinically significant arrhythmia uncontrolled with medical treatment
   • Acute myocardial infarction or unstable angina pectoris < 6 months to Screening

7. Active infection requiring systemic antibiotic therapy. Patients requiring systemic antibiotics for infection must have completed therapy at least 1 week prior to the first dose of study drug.

8. Participants with a history of human immunodeficiency virus (HIV) infection. NOTE: Testing is not required unless mandated by the local health authority. Participants with HIV infection may be eligible if ALL of the following are applicable:

   1. Receiving an approved, stable, effective combination antiretroviral therapy regimen for > 3 months prior to the planned first study intervention. NOTE: please review Section 5.7 and consider whether any actions should be taken to minimize potential drug-drug interactions,
   2. CD4 T cell count > 350 cells/µl,
   3. CD4 T cell nadir (lowest historical count) > 200 cells/µl, and
   4. Viral load confirmed as < 50 copies/mL during Screening.

9. Participants with a known history of chronic viral infections as indicated below.

   NOTE: Testing for hepatitis B virus (HBV) or hepatitis C virus (HCV) is not required unless mandated by the local health authority.

   1. Known HBV infection defined as hepatitis B surface antigen reactive. NOTE: Participants with HBV infection on stable anti-viral therapy for > 4 weeks prior to the planned first study intervention and viral load confirmed as undetectable during Screening may be eligible.
   2. Known active HCV infection defined as detectable HCV RNA (qualitative) infection. NOTE: History of HCV is not exclusionary if participants have received curative treatment and viral load is confirmed as undetectable during screening.

10. Malignant disease, other than that being treated in this study. Exceptions to this exclusion include the following: malignancies that were treated curatively and have not recurred within 2 years prior to study treatment; completely resected basal cell and squamous cell skin cancers; any malignancy considered to be indolent and that has never required therapy; and completely resected carcinoma in situ of any type.

11. Any medical condition that would, in the investigator's or Sponsor's judgement, prevent the patient's participation in the clinical study due to safety concerns, compliance with clinical study procedures or interpretation of study results.

12. Patients receiving systemic steroid therapy or any other immunosuppressive medication at any dose level. Local steroid therapies (e.g., otic, ophthalmic, intra-articular or inhaled medications) are acceptable.

13. Major surgery within 2 weeks of the first dose of study drug (minimally invasive procedures such as bronchoscopy, tumor biopsy, insertion of a central venous access device, and insertion of a feeding tube are not considered major surgery and are not exclusionary).

14. Radiotherapy within 2 weeks of the first dose of study drug.

15. Use of hematopoietic colony-stimulating growth factors (e.g., G-CSF, GMCSF, M-CSF) ≤ 2 weeks prior to start of study drug. An erythroid-stimulating agent is allowed as long as it was initiated at least 2 weeks prior to the first dose of study treatment and the patient is not red blood cell transfusion dependent.

16. Pregnant, likely to become pregnant, or lactating women (where pregnancy is defined as the state of a female after conception and until the termination of gestation).

17. Women of child-bearing potential who are sexually active with a non-sterilized male partner, defined as all women physiologically capable of becoming pregnant, unless they are using highly effective contraception during study treatment (defined in Section 8.4.7), and must agree to continue using such precautions for 6 months after the final dose of study drug; cessation of birth control after this point should be discussed with a responsible physician.

18. Male patients must be surgically sterile or use double barrier contraception methods from enrolment through treatment and for 6 months following administration of the last dose of study drug.