A Phase 3 Win and a 130% Takeover Premium Lit Up Rare Blood-Disease Stocks on Monday

NEW YORK, Oct. 20, 2026 /PRNewswire/ -- Market Updates News Commentary - Two unrelated announcements on Monday put one of biotech's smaller corners in the spotlight. A company developing a treatment for a rare light-sensitivity disorder reported that its pivotal Phase 3 trial met every primary and secondary endpoint, and its shares rose 38.86%. The same day, a developer of an RNA-based therapy for a rare blood disorder agreed to be acquired at a 130% premium, and its shares more than doubled. Several other companies working on rare blood and iron-metabolism disorders also moved higher, according to Stock Analysis data. Active Companies from around the markets with current developments this week include: Disc Medicine, Inc. (NASDAQ: IRON), Silence Therapeutics plc (NASDAQ: SLN), Protagonist Therapeutics, Inc. (NASDAQ: PTGX), Agios Pharmaceuticals, Inc. (NASDAQ: AGIO), Keros Therapeutics, Inc. (NASDAQ: KROS).

The common thread is the biology of red blood cells and iron. Two of these programs work through hepcidin, the hormone that controls how the body absorbs and releases iron, and others target the pathways that make heme and red blood cells. That biology sits behind conditions such as polycythemia vera, where the body overproduces red blood cells and many patients rely on repeated blood draws, and erythropoietic protoporphyria, where a buildup of protoporphyrin makes sunlight painful.

The field has been moving for months. In August, the FDA approved the first hepcidin mimetic for polycythemia vera, and two other companies in this group have FDA decisions or resubmissions on the calendar within the next year. Monday added a large acquisition and a Phase 3 readout to that list, with each company now facing its own next step.

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In other industry developments and happenings in the market this week include:

Disc Medicine, Inc. (NASDAQ: IRON)

Disc Medicine announced on October 19 that its pivotal Phase 3 APOLLO trial of bitopertin in adults and adolescents with erythropoietic protoporphyria met all primary and secondary endpoints. The randomized, double-blind trial enrolled 183 patients who received 60 mg of oral bitopertin or placebo once daily for six months. Bitopertin reduced whole-blood metal-free protoporphyrin IX by 41.4% versus placebo (p<0.0001) and increased average monthly total time in light without pain in month six by 12.2 hours versus placebo (p=0.0010).

The company described bitopertin as generally well tolerated, with dizziness the most common treatment-emergent adverse event and no events above Grade 3. Disc plans to resubmit its New Drug Application by the end of 2026 and anticipates an FDA decision by mid-2027. In February, the FDA had issued a Complete Response Letter on the earlier accelerated-approval application and, according to the company, indicated that APOLLO results could serve as evidence to support traditional approval. The shares rose 38.86% on Monday to $78.93.

Silence Therapeutics plc (NASDAQ: SLN)

Silence Therapeutics agreed on October 19 to be acquired by Merck KGaA, Darmstadt, Germany, for $20.00 in cash per American Depositary Share, a 130% premium to its October 16 closing price and an 82% premium to its 30-day volume-weighted average price of $10.99. The deal carries an equity value of about $1.3 billion and an enterprise value of $1.1 billion, will be carried out through a U.K. scheme of arrangement, and is expected to close in the first quarter of 2027, subject to shareholder, court and regulatory approvals.

The deal centers on divesiran, an siRNA therapy for polycythemia vera that holds FDA Fast Track and Orphan Drug designations. In the Phase 2 SANRECO trial reported in August, 88% of patients on divesiran responded versus 19% on placebo (p<0.0001). The ADSs rose 125.58% on Monday to $19.58.

Protagonist Therapeutics, Inc. (NASDAQ: PTGX)

Protagonist's rusfertide, a hepcidin mimetic peptide, was approved by the FDA in August as MIMRYLO for the treatment of erythrocytosis in adults with polycythemia vera, the same disease divesiran targets. In the Phase 3 VERIFY trial, 76.9% of patients on MIMRYLO plus standard of care responded in Weeks 20 to 32, versus 32.9% on placebo plus standard of care. Takeda commercializes MIMRYLO, and the approval triggered $275 million in payments to Protagonist.

Protagonist is eligible for up to $875 million in additional milestones and tiered royalties of 14% to 29%, and reported cash, cash equivalents and marketable securities of $849.5 million as of June 30, 2026. The shares rose 4.42% on Monday to $134.44.

Agios Pharmaceuticals, Inc. (NASDAQ: AGIO)

Agios has the sector's next scheduled regulatory event. The FDA granted Priority Review to its supplemental application for mitapivat in sickle cell disease under the accelerated approval pathway, with a PDUFA date of November 1, 2026. In the Phase 3 RISE UP trial, 40.6% of patients on mitapivat achieved a hemoglobin response versus 2.9% on placebo, while the trial's sickle cell pain crisis endpoint did not reach statistical significance.

Mitapivat is already marketed for thalassemia as AQVESME in the U.S., where Agios reported second-quarter U.S. net revenue of $40.9 million, and the company will report third-quarter results on November 5. The shares rose 11.43% on Monday to $34.90.

Keros Therapeutics, Inc. (NASDAQ: KROS)

Keros said on September 29 that it expects a $20 million development milestone from partner Takeda following dosing of the first patient in the ELRiSE MF Phase 3 trial of elritercept in myelofibrosis patients with anemia, after an earlier $20 million milestone tied to the first patient dosed in the ELRiSE MDS Phase 3 trial. Keros expects to distribute 25% of the net cash proceeds from each milestone to stockholders.

The company reported cash and cash equivalents of $257.6 million as of June 30, 2026, which it expects to fund operations into the first half of 2028. The shares rose 3.75% on Monday to $11.06.

Biotech stocks can move 40% or more on a single readout. Learn to read the charts behind moves like these with the free Stock Preachers guide, plus The Roadmap market reports, at stockpreachers.com.

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