Its shares were trading 13 percent higher at 2,390 won in early afternoon trading after jumping as much as 29.79 percent to an intraday high of 2,745 won. The gain came despite a broad market selloff, with the benchmark KOSPI down more than 5 percent to around 6,477, triggering a sell-side sidecar.
The rally came after the U.S. Food and Drug Administration (FDA) approved Replimune's Tudriqev on Aug. 6, a new cancer treatment that uses viruses to attack tumors.
The drug is intended for certain patients with advanced melanoma, a serious form of skin cancer, whose disease continued to worsen despite immunotherapy, which helps the body's immune system fight cancer. It is used together with nivolumab, another medicine that helps the immune system attack cancer cells.
Tudriqev is an oncolytic virus therapy, which uses modified viruses to target cancer cells. The technology has been studied for years, but few drugs have reached the market, putting fresh attention on other developers working in the field.
Among them is Sillajen, which is developing the SJ-600 series, a group of experimental cancer drugs designed to avoid the body's natural defenses and remain active while traveling through the bloodstream. The firm says the therapy could reduce the amount of virus needed and potentially limit side effects.
It develops treatments that aim to attack tumor cells while helping the body's immune system fight the disease.
AJP Takeaways
• Sillajen shares jumped 13 percent to 2,390 won as of 1:44 p.m. on Aug. 19, 2026, after rising as much as 29.79 percent during the session.
• The rally followed the U.S. Food and Drug Administration's Aug. 6, 2026, approval of Replimune's Tudriqev, an oncolytic virus therapy for certain patients with advanced melanoma.
• Sillajen is developing the SJ-600 series, experimental cancer drugs designed to remain active in the bloodstream by avoiding the body's natural defenses.
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