Amylyx Priced an Upsized $500.2M Offering as the FDA Approved Ultragenyx and Regeneron Rare Disease Drugs: The Week’s Binary Ledger Tally (August 21, 2026)

Last updated: August 21, 2026

Amylyx priced an upsized $500.2 million stock offering at $35.50 per share within two days of its avexitide Phase 3 win, while the FDA approved Ultragenyx’s GENGLYCOS gene therapy and Regeneron’s Pasatru for rare diseases, capping a week of resolved biotech binaries.

This page covers the Amylyx offering terms and price path, both rare disease approvals in detail, Amgen’s exit from its TScan collaboration, Lilly’s Amplitude RNA vaccine deal, the Moderna repricing, the oral obesity scorecard, and the full seven column binary ledger for the week of August 17, 2026.

How did Amylyx price a $500.2 million offering two days after its Phase 3 win?

Amylyx Pharmaceuticals priced an upsized underwritten public offering of 14,090,000 shares at $35.50 per share on August 19, 2026, for gross proceeds of about $500.2 million, up from the $350.0 million proposed one day earlier. The deal is expected to close on or about August 21.

The sequence ran on a 72 hour clock. Amylyx (Nasdaq: AMLX) reported on August 18 that avexitide cut composite Level 2 and Level 3 hypoglycemic events 55 percent versus placebo in the Phase 3 LUCIDITY trial in post bariatric hypoglycemia (p=0.000003), announced a $350.0 million proposed offering that same evening, and priced the enlarged deal the following night. Underwriters hold a 30 day option for up to 2,113,500 additional shares at the offering price, roughly $75 million more if exercised in full. Leerink Partners, Morgan Stanley, Guggenheim Securities, and LifeSci Capital are joint bookrunners. Proceeds fund pre commercial activities for avexitide, including additional manufacturing capacity, plus research and development and working capital, ahead of a planned NDA submission by the end of 2026 under Breakthrough Therapy designation.

The price path is the detail that matters. Per market data, AMLX closed at $35.11 on August 18, the day the LUCIDITY data and the proposed offering were both announced, closed at $38.60 on August 19, the day the deal priced, and closed at $39.66 on August 20. The $35.50 print therefore sits above the close that preceded the offering announcement and about 8 percent below the pricing day close, and the stock finished the week trading above the offer price. For comparison, Silence Therapeutics sold $201.3 million at $13.50 per ADS within days of its divesiran Phase 2 data earlier this month.

What did the FDA approve for glycogen storage disease type Ia?

The FDA granted accelerated approval on August 19 to Ultragenyx’s GENGLYCOS (pariglasgene brecaparvovec-opnr, formerly DTX401), an AAV gene therapy for glycogen storage disease type Ia in patients eight years and older, the first approved treatment addressing the underlying cause of the disease and Ultragenyx’s first approved gene therapy.

Glycogen storage disease type Ia (GSDIa) leaves patients unable to release glucose from stored glycogen, forcing round the clock cornstarch dosing to avoid life threatening hypoglycemia. Ultragenyx Pharmaceutical (Nasdaq: RARE) estimates 1,500 to 2,500 diagnosed patients in the United States. GENGLYCOS is approved as an adjunct to nutritional management to reduce daily cornstarch intake, and the approval rests on the Phase 3 GlucoGene study: 46 participants enrolled, with the modified intent to treat population of 44 (20 on GENGLYCOS at 1.0×10^13 GC/kg, 24 on placebo) showing a statistically significant reduction in daily cornstarch requirements at week 48 (p<0.001). Because the approval is accelerated, continued approval may hinge on confirmatory evidence.

The approval carries weight beyond the indication. Ultragenyx received a rare pediatric disease priority review voucher, a monetizable asset in its own right, and it lands weeks after Sangamo’s bankruptcy auction put clearing prices on gene therapy assets sold under duress. Ultragenyx held its binary in portfolio through a regulatory process that included earlier setbacks and got paid with an approval. Its second gene therapy verdict comes quickly: the UX111 program for Sanfilippo syndrome type A, previously rejected on manufacturing grounds, has an FDA action date of September 19.

What does Pasatru’s approval mean for FOP patients?

The FDA approved Regeneron’s Pasatru (garetosmab-grts) on August 19 for adults with fibrodysplasia ossificans progressiva, making it the second approved FOP therapy and the first shown in a placebo controlled trial to reduce both new heterotopic ossification lesions and clinician assessed flare ups.

Fibrodysplasia ossificans progressiva turns muscle, tendon, and ligament into bone, progressively locking joints; Regeneron’s release puts the diagnosed population at roughly 900 people worldwide. Pasatru is a fully human monoclonal antibody that blocks Activin A, the ligand driving abnormal bone formation. In the 63 patient OPTIMA Phase 3 trial in adults, the 10 mg/kg monthly IV dose cut new heterotopic ossification lesions 90 percent versus placebo (2 lesions versus 19) over 56 weeks and clinician assessed flare ups 88 percent (9 versus 66). The lower 3 mg/kg dose matched on lesions (1 versus 19, a 94 percent reduction) but not on flare ups (15 percent reduction), and the label starts patients at 10 mg/kg with 3 mg/kg as a tolerability fallback. Ipsen’s Sohonos, approved in 2023, was the first FOP therapy; Pasatru gives adult patients a mechanism directed alternative and can be administered at home.

Set the two approvals side by side and the week’s regulatory pattern is hard to miss: a 44 patient gene therapy dataset and a 63 patient antibody dataset both cleared, the same week FDA warning letters went out to sterile manufacturing and API facilities. The agency’s demonstrated appetite for biology risk, and its near zero tolerance for factory risk, both showed up again within days.

Why did Amgen walk away from its TScan collaboration?

Amgen is terminating its Crohn’s disease target discovery collaboration with TScan Therapeutics effective November 10, 2026, citing a strategic review of its portfolio, according to Fierce Biotech. The May 2023 deal carried $30 million upfront and up to $500 million in milestones.

TScan (Nasdaq: TCRX) says the impact is minimal because its role was target discovery on the TargetScan platform while Amgen owned development, and it reports $100.2 million in cash as of June 30, funding operations into the second quarter of 2027, per company statements reported by Fierce Biotech. The context makes the entry notable: Fierce notes this follows Amgen’s January exit from the rocatinlimab collaboration with Kyowa Kirin, and it is the second partnered asset returned to sender in recent weeks after Johnson & Johnson handed prizloncabtagene autoleucel back to AbelZeta in July. Large companies are quietly returning mid stage and discovery stage binaries while writing small, heavily contingent checks for new ones.

What did Eli Lilly get in the Amplitude Therapeutics deal?

Eli Lilly signed a strategic collaboration with Boston based Amplitude Therapeutics on August 19 for exclusive rights to develop and commercialize trans amplifying RNA vaccine candidates against undisclosed infectious disease targets, with options on up to two additional targets. Financial terms were not disclosed.

Amplitude’s trans amplifying RNA (taRNA) platform separates the replicase and the antigen encoding RNA into two molecules, which the company says allows lower doses and simpler manufacturing than conventional mRNA or self amplifying designs. Founded in 2022 with backing from ARCH Venture Partners, Newpath Partners, and Alta Partners plus non dilutive funding from BARDA, CEPI, and the Gates Foundation, Amplitude keeps taRNA optimization and preclinical work; Lilly takes everything downstream. It is Lilly’s third platform option purchase in two weeks, after the OmniAb ion channel discovery deal (undisclosed upfront, up to $370 million in milestones) and the $50 million cash purchase of Sangamo’s delivery and zinc finger platforms out of bankruptcy.

How did the market reprice Moderna after the cancer vaccine win?

Per market data, Moderna stock rose 177 percent on August 19, from $62.96 to $174.38, after the intismeran autogene Phase 3 melanoma win, then gave back 23.5 percent on August 20 to close at $133.32. Merck rose 12.6 percent, then eased 2.1 percent.

The two day round trip is what happens when the asset holder declines to price a binary and the market prices it instead. Merck and Moderna disclosed no effect sizes from INTerpath-001, only that recurrence free survival and distant metastasis free survival both hit at a prespecified interim. Into that vacuum, per Fierce Biotech: Guggenheim projected adjuvant melanoma sales above $2 billion; William Blair modeled 2040 sales of $5.4 billion in melanoma under the 50/50 profit split, $10 billion in non small cell lung cancer, and $3.3 billion in renal cell carcinoma, while cautioning that the share moves reflect substantially more conviction than the disclosed data support. The bars have not moved: William Blair puts clear differentiation at a hazard ratio of 0.65 or better and disappointment above 0.75, in line with the Citi and Jefferies ranges reported before the readout. BioNTech and Arcturus both closed up more than 20 percent on August 19 on read through, per Fierce Biotech. The number arrives at a medical congress; until then, every dollar of the move is conviction, not data.

Who is winning the oral obesity race, Novo or Lilly?

Novo Nordisk’s Wegovy pill outsold Eli Lilly’s Foundayo roughly five to one in the second quarter, DKK 3.14 billion (about $490 million) versus $98 million, per the companies’ Q2 reports. Analysts quoted by BioSpace expect Lilly to close the gap by 2028 and lead thereafter.

The first full quarter of head to head oral GLP-1 competition went decisively to Novo Nordisk: Wegovy pill sales of DKK 3,141 million in Q2 per Novo’s half year report, against $98 million for Foundayo (orforglipron) in its first quarter on the market. BioSpace’s August 19 analysis assembles the reasons and the counterargument. GlobalData’s Sara Reci notes the efficacy dynamic has reversed at the top of the oral market, with oral semaglutide’s 16.6 percent weight loss versus Foundayo’s 11.2 percent, but projects Lilly catches up by 2028 and widens its lead through 2032 behind retatrutide. Truist’s Srikripa Devarakonda points to Lilly’s small molecule cost structure as the decisive advantage in price sensitive international markets, where Foundayo’s manufacturing economics work at prices an injectable peptide cannot reach. The scorecard: round one to Novo on brand and efficacy; the multi year race still tilts to Lilly on cost, capacity, and the next generation pipeline.

What is the seven column binary ledger and what did it show this week?

The binary ledger is our running tally of what companies do with high risk binary events, regulatory decisions and pivotal readouts, in the days surrounding resolution. Seven behaviors recurred all week: deferral, litigation, equity sales into strength, royalty sales, creation vehicles, contingent deals, and returned assets.

Two entries sit outside the table as deliberate counterexamples. AstraZeneca resolved three binaries in its own portfolio on Monday, one loss and two wins, and its stock barely moved. Merck and Moderna resolved the biggest binary of the week inside two large balance sheets and disclosed no number, and the market swung Moderna up 177 percent and back down 23.5 percent in two sessions. Companies that can hold their own binaries transfer the volatility to their shareholders’ screens instead of their capital structures.

What else happened this week?

The rest of the week’s ledger relevant and vertical news, in brief.

• FDA warning letters kept the manufacturing screws tight. Eugia Pharma Specialties, an Aurobindo unit in Hyderabad, was cited after a February inspection for inadequate aseptic barriers and operators repeatedly entering critical clean zones, with two sister sites already carrying unacceptable CGMP status; Tianjin Kilo Pharmaceutical in China was cited for distributing APIs it described as still in development, per Fierce Pharma.
• Biokin and BMS got a fourth China win for iza-bren. The Phase 3 Panku-Lung01 trial of izalontamab brengitecan, the EGFRxHER3 bispecific ADC BMS licensed for $800 million upfront in a deal worth up to $8.4 billion per Fierce Pharma, met its PFS primary endpoint versus chemotherapy in EGFR mutant NSCLC after TKI failure, with a positive OS trend and no numbers disclosed; the global Izabright-Lung01 readout is expected in 2028.
• Vitestro received FDA clearance for an autonomous robotic blood draw device, per MedTech Dive, and the FDA opened a public comment period on generative AI regulation in medical products, both extending the agency’s active month in device and AI policy.
• SK Pharmteco opened two API plants in Ireland, per Fierce Pharma, a small but real data point for the CDMO capacity recovery thesis.
• SK Biopharmaceuticals settled its Xcopri patent litigation with MSN, per Fierce Pharma; terms were not detailed.
• No Overton hearing date yet. The Senate HELP Committee has published no confirmation hearing date for FDA commissioner nominee Dr. Heidi Overton as of August 20. Every fourth quarter decision still belongs to the acting structure.

The week in five days

Frequently asked questions

How much did Amylyx raise in its August 2026 stock offering?

Amylyx priced 14,090,000 shares at $35.50 on August 19, 2026, for gross proceeds of about $500.2 million, upsized from the $350.0 million proposed a day earlier, with a 30 day underwriters option for up to 2,113,500 more shares.

Why did Amylyx raise money right after positive Phase 3 data?

The company is funding pre commercial activities for avexitide, including manufacturing capacity, ahead of an NDA planned by the end of 2026. Equity sold immediately after a clean pivotal win is typically the cheapest a small company will ever issue.

What is GENGLYCOS and what does it treat?

GENGLYCOS (pariglasgene brecaparvovec-opnr, formerly DTX401) is Ultragenyx’s AAV gene therapy for glycogen storage disease type Ia, approved under accelerated approval for patients eight and older to reduce daily cornstarch requirements alongside nutritional management.

Is GENGLYCOS a cure for GSDIa?

No. It is approved to reduce cornstarch intake as an adjunct to nutritional management, based on a statistically significant week 48 reduction in the Phase 3 GlucoGene study, and the accelerated approval may require confirmatory evidence for continued approval.

How many people have glycogen storage disease type Ia?

Ultragenyx estimates 1,500 to 2,500 diagnosed patients in the United States.

What is Pasatru and how well did it work?

Pasatru (garetosmab-grts) is Regeneron’s anti Activin A antibody for adults with fibrodysplasia ossificans progressiva. In the 63 patient OPTIMA trial, the 10 mg/kg dose reduced new heterotopic ossification lesions 90 percent and clinician assessed flare ups 88 percent versus placebo over 56 weeks.

How is Pasatru different from Ipsen’s Sohonos?

Sohonos (palovarotene), approved in 2023, is an oral retinoid used around flare ups and chronically in eligible patients. Pasatru is a monthly IV antibody blocking Activin A, approved for adults, and is the first FOP therapy to show reductions in both new lesions and flare ups in a placebo controlled trial.

Why is Amgen ending its TScan partnership?

Amgen cited a strategic review of its portfolio and research priorities, per Fierce Biotech. The 2023 deal paid TScan $30 million upfront with up to $500 million in milestones for Crohn’s disease target discovery; the termination is effective November 10, 2026.

What are the terms of the Lilly and Amplitude Therapeutics collaboration?

Financial terms were not disclosed. Lilly receives exclusive target specific rights to develop and commercialize trans amplifying RNA vaccines for undisclosed infectious disease targets, with options on up to two more; Amplitude runs taRNA optimization and preclinical work.

Why did Moderna stock fall on August 20, 2026?

After rising 177 percent on August 19 on the intismeran autogene Phase 3 win, Moderna gave back 23.5 percent on August 20, per market data, as analysts including William Blair cautioned that the move implied more conviction than the numberless topline supports.

When will the actual intismeran autogene hazard ratio be disclosed?

Merck and Moderna say detailed INTerpath-001 data will be presented at an upcoming international medical meeting. Analysts’ pre set bars put clear differentiation at a hazard ratio of 0.65 or better, with numbers above roughly 0.75 seen as disappointing.

Who sold more oral obesity medicine in Q2 2026, Novo Nordisk or Eli Lilly?

Novo Nordisk. Wegovy pill sales were DKK 3,141 million (about $490 million) in Q2 per Novo’s half year report, versus $98 million for Lilly’s Foundayo in its first quarter on the market. Analysts quoted by BioSpace expect Lilly to catch up by around 2028.

What happens with Capricor’s August 22 PDUFA date?

As of August 20 the FDA has published no new goal date, so the Saturday, August 22 action date formally stands. Capricor has said the agency indicated it will extend the date upon receipt of a BLA amendment; watch for any FDA written notice on Friday.

What is a rare pediatric disease priority review voucher?

A voucher granted with certain rare pediatric disease approvals that entitles the holder to a faster FDA review of a future application, and that can be sold to another company. Ultragenyx received one with the GENGLYCOS approval.

What FDA decisions are next on the calendar?

Ultragenyx’s UX111 for Sanfilippo syndrome type A on September 19, Grail’s Galleri advisory panel September 23, Scholar Rock’s apitegromab September 30, rusfertide in Q3, Summit’s ivonescimab November 14, and Vertex’s povetacicept November 30, all decided under the FDA’s acting leadership while the Overton nomination awaits a hearing.

Sources

Primary sources (August 18 to 20, 2026): Amylyx Pharmaceuticals pricing release (Business Wire, August 19) and preliminary prospectus supplement (SEC Form 424B5, August 18); Ultragenyx press release on the FDA approval of GENGLYCOS (August 19); Regeneron press release on the FDA approval of Pasatru (August 19) and the FDA’s announcement of a second FOP treatment; Amplitude Therapeutics and Eli Lilly joint release (PR Newswire, August 19); Amgen and TScan May 2023 collaboration releases and SEC exhibit (original deal terms); Novo Nordisk H1 2026 financial report (Wegovy pill sales); Eli Lilly Q2 2026 results (Foundayo sales); Moderna and Merck INTerpath-001 topline release (August 19).

Trade press and market reports: Fierce Biotech (August 19 to 20: TScan termination, intismeran analyst projections and stock moves); Fierce Pharma (August 18 to 19: Biokin Panku-Lung01, FDA warning letters, SK Pharmteco, SK/MSN settlement); BioSpace (August 19 to 20: oral obesity analysis, Ultragenyx and Regeneron coverage); BioPharma Dive (August 20: Ultragenyx approval); MedTech Dive (August 19 to 20: Vitestro clearance, FDA generative AI comment period); exchange close data for AMLX, MRNA, MRK, CAPR, and TCRX via market data providers.

Related coverage

• Merck and Moderna’s mRNA cancer vaccine met both Phase 3 endpoints in melanoma, and Amylyx followed its win with a $350M offering
• The Overton nomination, Amylyx’s 55% hypoglycemia win, and BioMarin’s $275M Alesta deal
• PTC and Lilly just bought Sangamo for parts: what the $163.55M bankruptcy auction says about gene therapy in 2026
• Retatrutide vs CagriSema: why 2026 is the year of the triple agonist