This study is primarily designed to determine if tumor specific immunity can be generated in patients with highly suspicious pigmented lesions in response to intralesional IL-2, and whether that immunity can confer resistance to melanoma metastasis. Patients will be identified by qualified dermatologists and interviews will be held at the surgery clinic (4th floor Dickson Center) QEII HSC, NSHA.

The standard wait time from consultation to surgical biopsy is up to 4 weeks. Investigators will ensure that patients are seen immediately upon notification from participating dermatologist and all research components of the study are completed within the normally anticipated wait time. Through utilization of this standard wait time, intralesional IL-2 can potentially affect an immune response, that otherwise could not be achieved after the biopsy is completed. Given that the study is conducted within the normal wait time, it doesn't deviate from the normal standard of care. Following the study protocol, patients will receive intralesional injections on Day 1(Week 1 Visit) and Day 8 (Week 2 Visit), and excisional biopsies will be performed on Day 15 (Week 3 Visit), well within the accepted wait time from consultation to biopsy. The intralesional injections and collection of biospecimens beyond the biopsy deviate from but does not delay the normal standard of care. Two additional visits are required in addition to the initial consultation.

This study is a randomized, controlled, double-blind study. Patients with highly suspicious pigmented lesions will be randomly assigned by an algorithm to one of two groups: 1) treatment group patients will be treated intralesionally with IL-2 (Proleukin (Aldesleukin), Novartis Pharmaceuticals Canada Inc.) at a dose of 500,000 International Units (IU) in 0.1ml of sterilized saline (0.9%, m/v) for 2 treatment cycles 1 week apart (Day 1 and Day 7); 2) control group patients will be treated intralesionally with sterilized saline (0.9%, m/v) of the same volume (0.1ml). Randomization will be generated by a Random Block algorithm for each patient, and instruction preparation for each patient will be sent to pharmacy. IL-2 (Proleukin) will be obtained from Novartis by the pharmacy, paid for by Dr. Carman Giacomantonio's research services account. The pharmacy will be given instruction to prepare either IL-2 treatment or injectable control (saline). The pharmacy will assign a codified ID which will be provided along with the syringe with the patient name labeled as "Interleukin-2/Placebo" (thus blinding study to clinician and patient). As a pilot study, the principle of the design is to test the feasibility of proceeding to a larger and more expensive trial following the methodology and protocol proposed. As such there will be a minimum of 20 (10 treatment, 10 placebo) participants (up to a maximum of 60). It is estimated that statistical significance will be reached with 20 patients, however if it is not reached after 20 patients, an additional 10 (5 treatment, 5 control) patients will be enrolled. If significance is still not reached after 30 patients, an additional 10 patients will be enrolled and so on up to a maximum of 60 patients. If after 60 patients, significance is not achieved then further recruitment under the current protocol would not be logical and therefore the methodology would need to be revised or study discontinued.

On Day 1 (first treatment) and 15 (excisional biopsy), all patients will have blood (4 vials) and urine (25-50 ml) samples taken. Local reactions to injections will be monitored for non- specific signs such as bleeding, arythema, infection, or irritation. Investigators do not anticipate specific changes in the pigmented lesion related to the injection in this short time period, however all changes will be noted.

On Day 15, following the second intralesional injection an excisional biopsy will be performed following standard surgical techniques, as follows: ellipse of skin encompassing the pigmented lesion extending into the subcutaneous fat will be performed to achieve a grossly clear but narrow margin of excision. This small defect will be closed primarily with interrupted sutures. The biopsied specimen will be subsequently evaluated using standard histological techniques to confirm diagnoses, assess margin status (clear or involved) and depth of lesion invasion. The depth of lesion invasion will dictate the extent of subsequent surgical excisions and margin selection according to standard National Comprehensive Cancer Network (NCCN) guidelines. Pre-biopsy intralesional injections of 0.1ml into the lesion will not alter dimensions or architecture of the lesion or impact the extent the subsequent biopsy required. Lesions that are felt to be too large for closure without tissue manipulation or creation of flaps, will be biopsied using a punch biopsy sampling technique whereby 4mm diameter discs of tissue from representative areas of the lesion will be taken to confirm the diagnosis and the depth of invasion. The depth of invasion will dictate the extent and complexity of subsequent surgery required to remove the lesion and achieve clear margins according to NCCN guidelines. The biopsied specimen will be processed as follows: using a 22G needle a fine needle aspiration biopsy will be performed (the needle will be passed through the center of the lesion two times) for RNA analysis. The remainder of the tissue will be sent to pathology for standard histological assessment. The pathologist will also report the extent of observed tumor infiltrating lymphocytes (TILs) associated with treatment compared to control injections. Blood and urine will be assessed using metabalomic and proteomic methods to assess systemic immune response to treatment.

All blood, urine, and lesion biopsy samples will be labeled with a codified number (will not contain any patient identifying information) and will be immediately transported to Dr. Carman Giacomantonio laboratory at Dalhousie University for storage. Fine needle aspiration of excised samples will be assessed for tumor genetic and epigeneitic profile. Blood and urine will be assessed for proteomic and metabolomic profiles, respectively.

All study participants will receive assessments every 4 months for 2 years and biannual assessments for years 3 to 5 after the initial intervention to assess disease progression, or the development of new melanoma, to compare between both treatment and control groups. There is no standardize test or measurable biomarker to assess established or lasting immunity. This aspect of the study is identical to the patient assessment conducted as per standard of care for melanoma patients. Again, any publications of study results will be completed devoid of any information that could be used to identify patients included in the study.