Vyvgart Wins Broadest gMG Label; Merck Closes $6.7B Terns Deal

Four multi-billion-dollar acquisitions. An FDA approval two days ahead of schedule that hands argenx a label no competitor can touch. And a Wall Street Journal report that the commissioner running the agency may not be running it much longer.

Add Gilead's billion-dollar PrEP revision, a Phase 2 win in one of derm's toughest conditions, and a Phase 3 sweep in chronic thyroid eye disease — and you've got one of the most consequential weeks of 2026 so far. Let's get into it.

Welcome to The Pharma Closeout Weekend Edition for Sunday, May 10, 2026. I'm Alex Mercer.

And I'm Maya Patel. A lot happened this week that deserves a second look.

We've been tracking argenx's PDUFA date all week, and the FDA didn't make us wait. Two days ahead of the May 10th deadline, efgartigimod received the label expansion covering all adult gMG serotypes — AChR-Ab positive, MuSK-Ab positive, LRP4-Ab positive, and triple seronegative. Per argenx's press release, Vyvgart and Vyvgart Hytrulo are now the first and only approved treatments for all serotypes of adult gMG. That delivers the broadest MG label of any therapy on the market.

The backing data comes from ADAPT SERON — a hundred nineteen patients, randomized, double-blind, placebo-controlled — and notably, it's the largest study to date in gMG patients who lack detectable AChR antibodies, enrolling across three seronegative subtypes: MuSK-positive, LRP4-positive, and triple seronegative. Primary endpoint was MG-ADL score change from baseline to Week 4. Efgartigimod IV delivered a 3.35-point improvement versus 1.90 for placebo — treatment difference of 1.46, p-value 0.0068 per the filing. No new safety signals.

What makes this commercially significant: roughly twenty percent of gMG patients lack detectable AChR antibodies. About ten percent are triple seronegative — diagnosed clinically, managed empirically, with no approved FcRn therapy available to them until Thursday. Not J&J's Imaavy, not UCB's Rystiggo, not Zilbrysq. argenx just secured a structural label advantage that competitors can't match without running their own seronegative trials.

The question is whether the evidence base fully supports the label breadth. A 1.46-point MG-ADL difference in 119 patients — that's a more modest treatment effect than what ADAPT showed in the seropositive population. Payers evaluating this expansion are going to notice that gap.

They will. But their leverage is limited when argenx is the only evidence-based FcRn option in the room. Patients who've cycled through off-label immunosuppressants with no approved targeted alternative — that's not a market where anyone can point to a cheaper comparable. The pricing dynamics favor the first mover precisely because there is no second mover.

Especially for MuSK-positive patients, who respond poorly to pyridostigmine and conventional immunosuppression — a subgroup where the treatment algorithm genuinely changes with this approval. The competitive clock starts now: how long does argenx run unopposed before a rival invests in generating seronegative data of their own?

While argenx was locking down label territory, the rest of the industry was writing checks. Four biotech acquisitions closed or announced in May alone, putting 2026 M&A on a faster pace than every year since at least 2018 according to BioPharma Dive's tracker. The week's anchor: Merck completed its cash acquisition of Terns Pharmaceuticals on May 5th — $53 per share, roughly 86% of outstanding shares tendered by the May 4th expiration. Total deal value widely reported at approximately $6.7 billion. The asset is TERN-701, an oral allosteric BCR-ABL1 inhibitor carrying Breakthrough Therapy Designation for chronic-phase CML after two-plus prior TKIs. Let's bring in Marcus Webb on the structure.

And Terns was just one of four. Angelini agreed to acquire Catalyst for $4 billion — rare neuro. Bayer's buying Perfuse for up to $2.45 billion in glaucoma, its first drug company acquisition in years and potentially its largest since AskBio in 2020. Roche moved on PathAI in digital pathology for potentially over a billion. Four deals. Roughly $14 billion in aggregate. One week.

What's telling is the spread. CML, rare neuro, glaucoma, digital pathology — nobody's chasing a single hot modality. They're filling specific portfolio gaps across unrelated therapeutic areas and development stages. That kind of diversified appetite usually signals companies building for durability, not riding a wave.

The public markets are reinforcing that confidence. Odyssey Therapeutics priced an upsized $279 million IPO on its second attempt — they'd withdrawn their initial filing back in 2025. Sold 15.5 million shares at $18, above the midpoint, with an underwriter option for another 2.3 million shares. Nine of eleven biotech IPOs this year have raised at least $250 million — the strongest performance since the prior few years. Immunology-focused biotechs alone have banked $879 million in IPO proceeds in 2026 versus just $174 million for the immune drugmakers that debuted across all of 2025. And on the private side, CellCentric pulled in a $220 million Series D led by Venrock for an oral multiple myeloma drug heading toward Phase 3. When capital flows this freely into both public and private biotech, it reshapes the M&A calculus — founders have a credible alternative to a trade sale, and acquirers have to bid against the market, not just each other.

All that capital eventually needs clinical results behind it. And the data this week ran the full spectrum. Starting with a bright spot: Avalo Therapeutics reported positive Phase 2 LOTUS results for abdakibart, an IL-1-beta antibody, in moderate-to-severe hidradenitis suppurativa. Two hundred fifty-three patients randomized. HiSCR75 at Week 16 — 42.2% at the 150-milligram dose, 42.9% at 300 milligrams, versus 25.6% placebo. Both doses statistically significant, favorable safety profile.

Avalo paired that readout with a $375 million raise, banking the runway for Phase 3 planning. The strategic read here: HS has been built almost entirely around anti-TNF and IL-17 inhibition. An IL-1-beta approach gives abdakibart a differentiated mechanism story — and those response rates position it competitively at this stage of development.

Two more pivotal wins. Celcuity's Phase 3 VIKTORIA-1 hit its primary endpoint — gedatolisib in PIK3CA-mutant breast cancer with clinically meaningful PFS improvement. Detailed data heads to a late-breaking oral at ASCO this month. And Viridian posted Phase 3 REVEAL-2 data for elegrobart in chronic thyroid eye disease. Proptosis responder rates — that's reduction in eye bulging, which is typically what drives patients toward surgical intervention — came in at 50% and 54% for the every-four-week and every-eight-week doses, respectively, versus 15% placebo. Both at p less than 0.0001. Viridian says elegrobart is the only subcutaneous program with positive Phase 3 data in both active and chronic TED, with a BLA tracking for Q1 2027.

Not everything broke to the upside. Entrada lost more than half its market value after Phase 1/2 Duchenne data came in below expectations. BioNTech announced plans to close multiple manufacturing sites and implement significant workforce reductions — the post-COVID overcapacity correction still unwinding three years on. And the story with the longest tail: the Wall Street Journal reported Friday that President Trump has approved a plan to fire FDA Commissioner Marty Makary, described as ending a notably turbulent tenure. No formal execution confirmed as of this weekend.

We've been saying it all week — leadership changes don't pause the review clock, but they absolutely shift priorities and resource allocation inside the building. Enhertu's PDUFA is eight days out. Several more decisions are queued into the summer. No successor has been named. Every sponsor with an active application is now factoring in a transition with an empty chair.

And one story that sits at the intersection of commercial execution and strategic ambition. Gilead raised its full-year Yeztugo forecast from $800 million to $1 billion, calling the long-acting PrEP launch unprecedented. The numbers back it up: Q1 product sales ex-Veklury hit $6.8 billion, up 8% year-over-year. Biktarvy drove $3.4 billion of that, up 7%. The broader HIV franchise grew 10%. Overall 2026 guidance went up by $400 million.

Impressive top line. But Gilead also flagged $11.5 billion in acquisition-linked charges dragging on profits — that's Arcellx, Ouro, and Tubulis all compounding at once. They're building aggressively across cell therapy, oncology, and inflammation simultaneously. Whether that investment portfolio starts producing returns before Biktarvy's lifecycle matures is the defining question for Gilead's second half.

Maya, what slipped through the cracks this week?

Under the radar — and this one got completely buried by the bigger headlines — Eisai disclosed Thursday that the FDA extended the review period for Leqembi Iqlik, the subcutaneous starting dose in Alzheimer's, by three months. The PDUFA date moves from May 24th to August 24th.

We had that May 24th date circled as a near-term catalyst going back weeks. A three-month extension signals the FDA identified information gaps during review — they needed additional data from Eisai. For a drug that's already struggled with infusion logistics and sluggish uptake, this delays the most patient-friendly dosing option by a full quarter.

For community neurologists who were counting on subcutaneous initiation to simplify their prescribing workflow, that's three more months of the status quo. And in a market where Kisunla has been gaining share partly on dosing convenience, every month Leqembi's complexity persists is a month the competitive gap gets harder to close.

Looking at the week ahead. The marquee date is May 18th — Enhertu's sBLA PDUFA for neoadjuvant HER2-positive early breast cancer, backed by the DESTINY-Breast11 data. That trial showed a pathologic complete response rate of 67.3% versus 56.3% for the standard arm, p-value 0.003. Approval would push Enhertu into earlier-stage disease — a major commercial expansion for Daiichi Sankyo and AstraZeneca.

Before that, the AUA meeting opens May 15th in Washington. The Friday plenary features EnGene's updated pivotal data for detalimogene in BCG-unresponsive non-muscle invasive bladder cancer. The interim look showed a 54% complete response rate, but a twelve-month duration-of-response estimate of just 25% raised real durability questions. The full dataset at AUA needs to close that gap.

ASCO abstracts drop May 21st, with Celcuity's gedatolisib VIKTORIA-1 data slated for a late-breaking oral at the meeting later in the month. Daiichi Sankyo reports earnings tomorrow — we'll be listening for specifics on the $610 million ADC manufacturing charge they disclosed this week. And Odyssey's IPO is expected to close tomorrow as well, adding another data point to an exceptional year for biotech listings.

Between Enhertu's decision, the AUA presentations, ASCO abstract releases, unresolved FDA leadership, and mifepristone access still in limbo, the next two weeks carry enough catalysts to reshape several therapeutic conversations at once.

That wraps our weekend closeout. argenx rewrote the MG competitive map. Merck bet $6.7 billion on CML. Avalo cracked open a new angle in HS. Viridian swept active and chronic TED. Gilead pushed PrEP toward a billion-dollar year. And the question of who runs the FDA just got a whole lot louder. This industry packs more into five days than most sectors manage in a quarter, and honestly, we wouldn't have it any other way. If this briefing keeps you sharp, follow us on Spotify, drop a rating, and subscribe — we're back tomorrow with your Monday setup.

Go enjoy your Sunday evening. Big week ahead, and we'll be right here for every bit of it. See you tomorrow.