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In The Spotlight: Sesen Bio


Shares of Sesen Bio Inc. (SESN) are up more than 37% over the past 3 days while the iShares Nasdaq Biotechnology Index (ETF)(IBB) has gained a mere 1.2% for the same period.

Sesen, formerly Eleven Biotherapeutics Inc., is a late-stage clinical company developing next-generation antibody-drug conjugate therapies for the treatment of cancer.

Antibody Drug Conjugates, or ADCs, are monoclonal antibodies (mAbs) linked to biologically active cytotoxic drugs, and therefore are thought to exhibit the specificity of therapeutic antibodies as well as the cancer-killing ability of cytotoxic drugs.

Sesen's lead product candidate is Vicinium, which is comprised of a recombinant fusion protein that targets epithelial cell adhesion molecule (EpCAM) antigens on the surface of tumor cells to deliver a potent protein payload, Pseudomonas Exotoxin A (ETA) to kill cancer cells.

Recently, i.e., on May 21, 2018, the Company reported encouraging three-month data from its ongoing VISTA study.

VISTA is a phase III trial evaluating Vicinium in a total of 133 patients with high-grade non-muscle invasive bladder cancer (NMIBC) that is either carcinoma in situ (CIS) or papillary with or without CIS, who have been previously treated with bacillus Calmette-Guérin (BCG), which is the current standard of care for NMIBC.

The primary endpoint of the trial is the complete response rate in patients with CIS with or without papillary disease.

The non-muscle invasive bladder cancer (NMIBC) that is carcinoma in situ (CIS) is cancer found on the inner lining of the bladder that has not spread into muscle or other tissue, with or without papillary disease. The papillary disease without CIS is cancer that has grown from the bladder lining out into the bladder, but has not spread into muscle or other tissue.

The recently reported results were from 111 patients with high-grade NMIBC that is either carcinoma in situ (CIS), or with papillary disease without CIS.

According to the trial results, Vicinium treatment resulted in a complete response rate of 42 percent at three months in carcinoma in situ (CIS) patients. Among patients with papillary disease without CIS, treatment with Vicinium demonstrated a 68 percent recurrence-free rate at three months.

However, despite the encouraging data, Sesen shares tumbled 23% that day as 4 treatment-related serious adverse events that were reported in the trial, including acute kidney injury or renal failure and cholestatic hepatitis, spooked the investors.

The Company expects to present 12-month data of the VISTA trial by mid-2019.

A phase I trial of Vicinium in combination with AstraZeneca's *Imfinzi in patients with high-grade non-muscle invasive bladder cancer is expected to begin early in the third quarter - with biomarker data expected towards the end of the quarter.

Imfinzi is an approved drug for the treatment of patients with metastatic urothelial carcinoma and for the treatment of patients with unresectable non-small cell lung cancer that has not progressed after chemoradiation.

*Key Numbers:

Accumulated deficit: $156.3 million
Revenue: Nil
Cash on hand: $19.7 million

(*As of March 31, 2018)

Recent event:

On May 30, 2018, the Company offered to sell 22.22 million shares of its common stock to the public at a price of $1.80 per share. The underwriters have a 30-day option to purchase up to an additional 3.33 million shares of common stock. The gross proceeds from the offering are expected to be roughly $40 million. The offering is expected to close on or about June 4, 2018.

Shares of Sesen have traded in a range of $1.53 to $3.44 over the last 1 year. The stock closed Thursday's (May 31st) trading at $2.27, up 26.11%.

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