Pembrolizumab TX-naive Distant Mets Melanoma and Use of AMT (PET) at Baseline as Imaging Biomarker

Objectives:

Primary Objective

Explore association between intensity of C11-AMT PET at baseline, as measured by mean
standardized uptake value (SUVmax at each lesion), total tumor metabolic volume, measurement
of intra-tumoral and inter-lesional heterogeneity), with objective response rate (ORR) at 12
weeks as defined via RECIST 1.1 to pembrolizumab in patients with Programmed Death (PD)-1
inhibitor-naïve unresectable stage III or distant metastatic (AJCC stage IV) melanoma.

Secondary Objectives

Estimate ORR (CR + PR) by RECIST 1.1 at 12 weeks to pembrolizumab in patients with PD-1
inhibitor-naïve unresectable stage III or distant metastatic metastatic melanoma (AJCC stage
III/IV).

Estimate progression-free survival (PFS) in patients with unresectable stage III or distant
metastatic melanoma treated with pembrolizumab as front-line therapy.

Explore associations in SUVmax and other PET parameters (e.g. total tumor metabolic volume,
measurement of intra-tumoral and inter-lesional heterogeneity) between C11-AMT PET and
fluorodeoxyglucose (FDG)-PET at baseline.

Explore associations between SUVmax, and other PET parameters (e.g. total tumor metabolic
volume, measurement of intra-tumoral and inter-lesional heterogeneity) identified at baseline
C11-AMT PET imaging with expression of components of the Indoleamine-pyrrole 2,3-dioxygenase
(IDO) pathway detected by immunohistochemistry (IHC) or immunofluorescence (LAT1, IDO, TPH1),
lymphocyte subtypes (CD4, cluster of differentiation 8 (CD8), FoxP3, MDSC), PD-1/PD-L1, and
other immune checkpoint pathways (LAG3, glucocorticoid-induced tumor necrosis factor receptor
(GITR), TIM3) in freshly acquired tumor specimens prior to treatment with pembrolizumab.

Assess metabolic changes at week 12 (or earlier, if patient progresses) following treatment
with pembrolizumab using baseline and week 12 FDG PET.

Outline:

Screening:

Physical exam, medical history, and laboratory tests, as per standard of care. Brain MRI and
Whole body FDG PET/CT scan with IV contrast will be performed at least 24 hours before
C11-AMT PET scanning. Although, the FDG PET/CT scan with IV contrast is preferred the
following baseline measurements may be used if they have occurred within the below specified
windows:

1. Whole body FDG PET/CT scan without IV contrast, will be accepted for study purposes
(i.e. correlation between baseline FDG PET scan and baseline C11-AMT scan) if it has
occurred within 28 days before the C11-AMT PET scan. In this case, the patient will only
be required to have a baseline CT scan of the chest, abdomen, and pelvis (also neck, if
applicable) with IV contrast within 28 days of starting pembrolizumab.

2. CT scan with IV contrast will be accepted for study purposes (i.e. baseline tumor
assessment) if it has occurred within 28 days of starting pembrolizumab. In this case,
the patient will only be required to have a baseline PET scan without CT coregistration
28 days prior to C11-AMT. This is to correlate baseline FDG PET with baseline C11-AMT
PET parameters.

If eligibility criteria are met, patients will proceed to Study Related Scans and Biopsy:

C11-AMT PET will be performed at least 24 hours before pembrolizumab treatment and at least
24 hours after FDG PET/CT scan. A research biopsy will be performed before pembrolizumab
treatment.

After screening and study related scans and biopsy, treatment will consist of the following:

Pembrolizumab 200mg IV flat dose will be administered over 30 minutes on Day 1; Pembrolizumab
dosing will be repeated every 3 weeks until progression or subject withdrawal for other
reasons.

At the end of treatment:

Whole body FDG PET/CT scan with IV contrast.

Projected Accrual:

Up to 25 subjects who have not received prior therapy for their recent diagnosis of distant
metastatic melanoma.

Inclusion Criteria:

1. Sign written informed consent and HIPAA authorization for release of personal health
information. Note: HIPAA authorization may be included in the informed consent or
obtained separately.

2. Subject must be 18 years of age or more on the day of signing informed consent.

3. Have histologic or cytologic biopsy-proven diagnosis of unresectable stage III or
distant metastatic melanoma, irrespective of histologic type (i.e. cutaneous, unknown
primary, mucosal, or ocular). Patients with resectable bulky stage IIIB or stage IIIC
melanoma (for example at least 2.5-cm in shortest diameter for lymph nodes infiltrated
by tumor and at least 2-cm in longest diameter for non-lymph nodes infiltrated by
tumor) can also be entered into the study at the discretion of the Principal
Investigator.

4. Have measurable disease based on RECIST v1.1. for solid tumors

5. Be willing to undergo fresh tumor tissue biopsy of an accessible tumor lesion prior to
pembrolizumab. A mandatory fresh biopsy will be collected following C11-AMT PET
imaging. Subjects for whom fresh samples cannot be provided (e.g. inaccessible or
subject safety concern) or do not agree to this fresh tumor research biopsy of
accessible tumor will be deemed ineligible for study participation. Exception to the
mandatory tumor tissue collection are patients with metastatic lung lesions as the
only site of metastatic disease. Fresh biopsy collection from these subjects will be
optional, due to high risk of pneumothorax.

6. Be willing to allow for investigators to collect archival tumor tissues from surgical
procedures that may have been performed before or after enrollment into this trial for
research purposes (in-house cases and/or outside cases). These samples will be
obtained by study staff as long as subject continues on follow-up. Blocks of tissue
will be requested, and if blocks are not able to be obtained, 5micron slides (10-15)
will be sufficient.

7. Be willing to be injected with 11C-methyl-L-tryptophan (C11-AMT)

8. Have a performance status of 0 - 2 on the Eastern Cooperative Oncology Group (ECOG)
Performance Scale.

9. Has not received prior therapy with cytotoxic T lymphocyte antigen (CTLA)-4,
PD-1/PD-L1 inhibitors, other co-stimulatory or co-inhibitory immune checkpoint
antibody therapies (e.g. LAG3, TIM3, cluster of differentiation (CD) 137, Killer
immunoglobulin-like receptor (KIR3DL), cluster of differentiation (CD) 70, and CD27)
for distant metastatic melanoma. Patients who have received mitogen-activated protein
kinase (MAPK) inhibitors are allowed on condition that they have recovered from
adverse events to at most Grade 1 by CTCAE v4.03 and at least 15 days have elapsed
between last dose of MAPK inhibitors and C11-AMT imaging. Patients who have previously
received CTLA-4 inhibitors in the adjuvant setting are allowed to participate as long
as they discontinued CTLA-4 treatment at least 30 days ago and meet criteria outlined
in inclusion #14. Patients who have previously received adjuvant PD-1 inhibitors are
excluded.

10. Demonstrate adequate organ function as defined in below; all screening labs to be
obtained within 14 days prior to C11-AMT PET scan:

Hematological:

Hemoglobin (Hgb) - ≥ 9 g/dL or ≥ 5.6 mmol/L without transfusion or erythropoietin
(EPO) dependency (within 7 days of Hgb) Absolute Neutrophil Count (ANC) - ≥ 1,500/mm3
Platelets - ≥ 100,000/mm3

Renal:

Serum Creatinine OR Measured or calculated creatinine clearance (GFR can also be used
in place of creatinine or CrCl) - ≤1.5 x ULN OR ≥ 60 mL/min using the Cockcroft-Gault
formula for subject with creatinine levels > 1.5 X institutional upper limits of
normal (ULN)

Hepatic:

Serum Total Bilirubin - ≤ 1.5 X ULN Aspartate aminotransferase (AST) - ≤ 2.5 X ULN OR
< 5 X ULN for subjects with liver metastases Alanine aminotransferase (ALT) - ≤ 2.5 X
ULN OR < 5 X ULN for subjects with liver metastases Albumin - ≥ 2.5 mg/dL

Coagulation:

International Normalized Ratio (INR) or Prothrombin Time (PT) - ≤1.5 X ULN, unless
subject is receiving anticoagulant therapy as long as PT or PTT is within therapeutic
range of intended use of anticoagulants Activated Partial Thromboplastin Time (aPTT) -
≤1.5 X ULN, unless subject is receiving anticoagulant therapy as long as PT or PTT is
within therapeutic range of intended use of anticoagulants

11. Female subjects of childbearing potential should have a negative urine or serum
pregnancy within 14 days prior to C11-AMT PET scan. If the urine test is positive or
cannot be confirmed as negative, a serum pregnancy test will be required.

12. Female subjects of childbearing potential must be willing to use adequate methods of
contraception as outlined - Contraception for the course of the study through 120 days
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 > 1
year.

Note: Abstinence is acceptable if this is the usual lifestyle and preferred
contraception for the subject.

Male subjects should agree to use an adequate method of contraception as outlined -
Contraception starting with the first dose of study therapy through 120 days after the
last dose of study therapy.

Note: Abstinence is acceptable if this is the usual lifestyle and preferred
contraception for the subject.

13. Patients who have received prior adjuvant high dose interferon are allowed to
participate as long as the last injection was given at least 30 days prior to the
C11-AMT PET scan and they have fully recovered from side effects (i.e., Grade ≤1 or
permanent side effects that require hormone replacement therapy).

14. Patients on adjuvant ipilimumab are allowed to participate at least 30 days from drug
discontinuation as long as they have at most Grade 1 adverse events (or grade 2 if
they have to received hormone replacement therapy for their otherwise grade 1
ipilimumab-induced autoimmune endocrinopathies).

Exclusion Criteria:

1. Is currently participating and receiving study therapy for his/her advanced melanoma
or has participated in a study of an investigational agent and received study therapy
in the advanced melanoma setting.

2. Has received prior treatment with PD-1/PD-L1 pathway inhibitors in the adjuvant
setting.

3. Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any
other form of immunosuppressive therapy within 7 days prior to C11-AMT PET Scan

4. Has a known history of active tuberculosis (Bacillus Tuberculosis)

5. Hypersensitivity to pembrolizumab or any of its excipients described

6. Has had prior monoclonal antibody (mAb) targeting immune checkpoint proteins, for
distant metastatic melanoma and have progressed or have developed intolerable side
effect.

7. Adjuvant anticancer treatments are allowed at least 30 days has elapsed between the
infusion/injection and C11-AMT PET scan as part of this study.

8. Prior radiation therapy for metastatic melanoma is allowed as long as the patient
bears measurable actively growing disease outside the previously irradiated field.
Note: If subject received major surgery, they must have recovered adequately from the
toxicity (i.e., all symptoms ≤ grade 1) and/or complications from the intervention
prior to starting therapy.

9. History of prior malignancy, with the exception of the following:

- Non-melanoma skin cancers, non-invasive bladder cancer, and carcinoma in situ of
the cervix,

- Prior history of prostate provided patient not under active systemic treatment
other than hormonal therapy and with documented undetectable prostate-specific
antigen (PSA) (<0.2ng/mL),

- Chronic lymphocytic leukemia (CLL)/ small lymphocytic lymphoma (SLL) provided
patient has isolated lymphocytosis (Rai stage 0), and does not require systemic
treatment [for "B" symptoms, Richter's transformation, lymphocyte doubling time
(<6 months), lymphadenopathy or hepatosplenomegaly],

- Lymphoma or any type or hairy-cell leukemia provided patient is not on active
systemic treatment and is in complete remission, as evidenced by PET/CT scans and
bone marrow biopsies for at least 3 months,

- Papillary thyroid cancer. Since this malignancy very infrequently metastasizes
distantly, patients with concurrent metastatic melanoma can be enrolled even if
patients may: A) have just completed thyroidectomy within the last 2 years, B)
have not received adjuvant radioactive iodine therapy, C) were only recently
diagnosed with asymptomatic papillary thyroid cancer and their surgery is
pending.

- History of malignancy provided patient has completed therapy and is free of
disease for ≥ 2 years. If patient had other malignancy within the last 2 years
from which he may have been completely cured by surgery alone, he may considered
to be enrolled on condition that the risk of development of distant metastatic
disease based on AJCC staging system is less than 30%.

10. Has known active parenchymal central nervous system (CNS) metastases that are
symptomatic, and/or more than one lesions, and/or their largest diameter is > 5-mm
and/or require antiepileptic drugs or corticosteroids. Patients with carcinomatous
meningitis are also excluded. Exceptions are: subjects with previously treated brain
metastases provided they are stable (without evidence of progression by imaging) for
at least 2 weeks prior to C11-AMT and any neurologic symptoms have returned to
baseline, have no evidence of new or enlarging brain metastases, and are not using
ongoing steroids for at least 7 days prior to C11-AMT. Patients with active (i.e. not
treated with stereotactive radiosurgery), single, asymptomatic, up to 5-mm in largest
diameter brain metastases (measured either by brain MRI with IV contrast or head CT
with IV contrast measured within 2 weeks prior to C11-AMT) are allowed.

11. Has active autoimmune disease that has required systemic treatment in the past 2 years
(i.e. with use of disease-modifying agents, corticosteroids or immunosuppressive
drugs). Replacement therapy (e.g., thyroxine, insulin, or physiologic corticosteroid
replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a
form of systemic treatment.

12. Has known history of (non-infectious) pneumonitis that required steroids, or any
evidence of current pneumonitis.

13. Has an active infection requiring systemic therapy.

14. Has a history or current evidence of any condition, therapy, or laboratory abnormality
that might confound the results of the trial, interfere with the subject's
participation for the full duration of the trial, or is not in the best interest of
the subject to participate, in the opinion of the treating investigator.

15. Has known psychiatric or substance abuse disorders that would interfere with
cooperation with the requirements of the trial.

16. Is pregnant or breastfeeding, or expecting to conceive or father children within the
projected duration of the trial, starting with the pre-screening or screening visit
through 120 days after the last dose of trial treatment.

17. Has a known history of Human Immunodeficiency Virus (HIV) (HIV 1/2 antibodies).

18. Has known active Hepatitis B (e.g., HBsAg reactive) or Hepatitis C virus (HCV) (e.g.,
HCV RNA [qualitative] is detected).

19. Has received a live vaccine within 14 days of C11-AMT PET scan. Note: Seasonal
influenza vaccines for injection are generally inactivated flu vaccines and are
allowed; however intranasal influenza vaccines (e.g., Flu-Mist®) are live attenuated
vaccines, and are not allowed.