Last Week Tonight in BioPharma |Week of May 18, 2026
Retatrutide wows, Sac-TMT continues to shine, Regeneron co-signs Parabilis, and much more!
Welcome back to Last Week Tonight in BioPharma (LWTB). What a week! Eli Lilly dropped bariatric-level Phase 3 obesity data for retatrutide that puts every competitor on notice, ASCO 2026 turned into a showcase for ADC data that reset the competitive calculus in multiple tumor types, and Regeneron placed a $2.3B bet on a new drug class that does not yet exist in any pharmacy.
Meanwhile, the institutional collapse of the U.S. regulatory and infectious disease infrastructure continued to accelerate in ways that should concern every biopharma executive with a PDUFA date in 2026 or 2027. All that and more below. Let’s get into it!
If you subscribe to Big Pharma Sharma (BPS) for LWTB and you like what you read, consider upgrading to paid to read my best work.
📡 PRESS RELEASE DECODER
What the press releases actually mean
Lilly’s Triple-G Retatrutide Posts Bariatric-Level Weight Loss in TRIUMPH-1
📅 May 21, 2026 | 🏢 Eli Lilly ( LLY 0.00%↑ ) | 💊 retatrutide (LY3437943) | 🏷 Phase 3 Topline Data (Positive)
Eli Lilly reported topline results from TRIUMPH-1, the pivotal Phase 3 obesity trial for retatrutide, a first-in-class triple GIP/GLP-1/glucagon agonist. At the 12 mg dose, patients in the all-comers population achieved 28.3% mean body weight loss at 80 weeks, extending to 30.3% at 104 weeks. Topline results were released via press release on May 21, 2026, with the full data package to be presented at the ADA 2026 Scientific Sessions. TRANSCEND-T2D-1, the companion trial in patients with type 2 diabetes, is reading out alongside TRIUMPH-1.
The headline efficacy number that will define the retatrutide commercial narrative is this: 45.3% of patients on the 12 mg dose achieved 30% or greater body weight loss, a threshold historically associated with bariatric surgery outcomes. Retatrutide’s mechanistic differentiation from ZEPBOUND (tirzepatide), which targets GIP and GLP-1 only, comes from the added glucagon receptor agonism, a component hypothesized to drive the incremental weight loss above what dual agonism alone can deliver. ZEPBOUND achieved approximately 22% mean weight loss in the SURMOUNT-1 trial.
🧠 BPS Take: When we covered Novo Nordisk’s ($NVO) WEGOVY HD data out of ECO in the May 17 edition, the 28% weight loss figure came from early responders only, a pre-selected subgroup that represents a fraction of treated patients. Retatrutide’s 28.3% comes from an all-comers population, which is a stronger claim from a regulatory and commercial positioning standpoint.
While 30% weight loss (@ 104 wks) and 28% (@80 wks) are the headliners, both of those numbers come from the 12mg (max) dose. What I was more impressed by was the 4mg (lowest) dose, hitting 19% (@80wks).
I am curious to see the full data to learn how quickly that level was achieved. Remember these are patients who avg. 250 lbs at baseline in the study. In the real world that’s roughly the 90th percentile in the US.
As we know, by some measures at least ~40% of the US population is obese and up to ~75% are overweight. For a lot of these folks, losing 20% of BW (~40lb for a 200lb person) will be more than enough to see their desired health and aesthetic benefits.
My guess is the 4mg dose will be the best-selling dose-level of retatrutide.
The bigger question for me is what this does to the tirzepatide franchise in the medium term. ZEPBOUND is currently Lilly’s obesity crown jewel, and retatrutide, if approved, will sit above it in efficacy. Lilly could opt to let reta completely cannibalize its ZEPBOUND business. And in fact Lilly is running a head-to-head study between the two products, called TRIUMPH-5.
But they could also opt to position ZEPBOUND for a slightly different customer groups (people looking to lose less weight less quickly, less tolerant of AEs, etc.) and price the two products differently, perhaps sandwiching Novo’s WEGOVY between them on price.
This would put huge squeeze on Novo’s business. You have a cheaper ZEPBOUND option with equivalent or greater efficacy and better safety on one end, and a powerhouse 30% weight loss premium product on the other.
AstraZeneca Gets a FDA First-in-Class Win with BAXFENDY and a Regulatory Split Decision on Camizestrant in the Same Week
📅 May 18–22, 2026 | 🏢 AstraZeneca ( AZN 0.00%↑ ) | 💊 BAXFENDY (baxdrostat) + camizestrant | 🏷 FDA Approval + EU CHMP Opinion + Regulatory Divergence
The FDA granted approval on May 18, 2026 to BAXFENDY (baxdrostat), making it the first aldosterone synthase inhibitor ever approved globally for uncontrolled hypertension. The drug works by blocking CYP11B2, the enzyme responsible for aldosterone production, offering a mechanistically distinct option in a condition that affects roughly 100 million Americans. AstraZeneca acquired baxdrostat through its $1.8 billion buyout of CinCor Pharma in 2023, and this approval represents the first first-in-class NME payoff from that deal.
In the same week, the EU’s CHMP issued a positive opinion for camizestrant, AstraZeneca’s next-generation oral SERD, in HR+/HER2- early breast cancer based on SERENA-6 data. Recall, three weeks earlier, on April 30, 2026, the FDA’s ODAC voted 6-3 against camizestrant’s benefit-risk profile, leaving AstraZeneca staring at a NDA resubmission decision.
🧠 BPS Take: The CinCor acquisition logic looks very good right now. $1.8 billion for a first-in-class mechanism in a 100 million patient market is not chump change, but the math starts to feel reasonable the moment you see that approval. Aldosterone-driven hypertension has been a known and underserved segment for years, and BAXFENDY gives AstraZeneca a differentiated cardiovascular franchise asset that does not have a direct approved competitor. Although companies like Mineralys MLYS 0.00%↑ are looking to change that.
The camizestrant situation is the harder story to tell. The EU-US divergence signals that the SERENA-6 data package reads differently depending on the evidentiary standards being applied, and the FDA ODAC’s 6-3 vote against benefit-risk is a fairly clear signal about what a resubmission needs to fix. AZ’s path with camizestrant in the US is narrowing fast. VEPPANU launched into the oral SERD category with first-mover advantage. Every month AZN delays a resubmission is another month VEPPANU is building prescriber relationships and formulary positioning in the US without a competitor.
The bigger question for me is whether AZN believes a resubmission is winnable on revised data or whether the resources are better deployed elsewhere in the oncology portfolio. The EU approval buys some commercial optionality outside the US, but the American market is where the oral SERD war will actually be decided.
sac-TMT Posts Dual OS and PFS Win in TROP2
📅 May 21-22, 2026 | 🏢 Merck ( MRK 0.00%↑ ) + Kelun-Biotech ( $KLUN.SS ) | 💊 sacituzumab tirumotecan (MK-2870) / | 🏷 Phase 3 Readout
Merck and Kelun-Biotech dropped two headline Phase 3 readouts for sacituzumab tirumotecan (sac-TMT, MK-2870) at ASCO 2026 on May 21. In TroFuse-005, sac-TMT became the first TROP2-targeting ADC to demonstrate improvement in both overall survival and progression-free survival versus chemotherapy in patients with advanced or recurrent endometrial cancer. That OS signal is the landmark here. TROP2 ADCs have accumulated PFS data before, but a clean dual-endpoint win in a gynecologic solid tumor is a new bar for the class. Merck says these data will be presented at a future meeting.
The second readout, OptiTROP-Lung05, evaluated sac-TMT in first-line non-small cell lung cancer in Chinese patients and produced a PFS hazard ratio of 0.35 versus KEYTRUDA (pembrolizumab) alone, representing a 65% reduction in progression or death risk. Kelun reported that median progression-free survival (PFS) has not yet been reached in the sac-TMT patient group, compared to a PFS of 5.7 months for the anti–PD-1 mAb (p< 0.0001). Full data are set to be shared at ASCO in the coming days.
Merck is running a global P3 study, called TroFuse-007 in 1L PDL1-high NSCLC, which these ASCO data will have significant read-through to.
🧠 BPS Take: The Sac-TMT data continue to look stronger and stronger, posing a real threat to Gilead’s GILD 0.00%↑ TRODELVY, which has never been able to meet the sales expectations set by the $21B acquisition of Immunomedics.
Gilead’s GILD 0.00%↑ TRODELVY has not posted a clean OS win in a Phase 3 outside of breast cancer. AstraZeneca’s AZN 0.00%↑ DATROWAY is in a similar position. Between the two products, they’ve registered six failed P3 studie. Sac-TMT on the other hand, has had a spotless record, and these two new topline data readouts continue to brighten the shine coming off this molecule.
Merck may have cracked the code on TROP2 ADCs. They have an aggressive P3 program built behind Sac-TMT, because they feel they have a best-in-class product that is up against floundering competitors. Going where TRODELVY and DATROWAY could not, in lung cancer, both 1L as well as EGFR-mutant, appears to be the initial play, followed by expansion into breast cancers and other gynecologic tumors.
The threat doesn’t stop at TROP2 ADCs either. The NSCLC 1L data set to be presented at ASCO, should stop the PD1xVEGF companies who have in-licensed Chinese bispecifics in their tracks as well. When you compare the Sac-TMT readout to Summit and Akeso’s China-only data of ivonescimab, the Sac-TMT looks quite a bit better across both safety and efficacy. The same translatability concerns of China-only data to a global population apply, but just on a China-to-China basis, it is hard to ignore how strong OptiTROP-Lung05 looks relative to PD-1xVEGF.
🌐 CONNECTING THE DOTS
When the outside world meets biopharma
GLP-1s Cut Metastatic Progression Up to 50% Across Four Obesity-Related Cancers — But the Comparator Choice Is Already Under Fire Ahead of ASCO
📅 May 21, 2026 | 🏥 Cleveland Clinic / Taussig Cancer Institute | 💊 GLP-1 RAs vs. DPP-4 inhibitors | 📄 ASCO 2026 Abstract 3143 (pre-meeting press briefing)
Ahead of next week’s ASCO Annual Meeting, Cleveland Clinic investigators led by Dr. Mark Orland released real-world data suggesting GLP-1 receptor agonists may meaningfully reduce metastatic progression across several obesity-related cancers. The story made its way into the lay press.
Using the TriNetX network, the team ran a propensity-matched retrospective analysis of 12,112 Stage I–III patients who initiated either a GLP-1 (semaglutide, tirzepatide, liraglutide, dulaglutide) or a DPP-4 inhibitor after diagnosis, matching on BMI, glycemic factors, smoking, comorbidities, oncologic treatments, and concurrent medications. Statistically significant reductions in progression to Stage IV were observed in four of seven tumor types: NSCLC (10% vs. 22%), breast (10% vs. 20%), colorectal (13% vs. 22%), and hepatocellular carcinoma (19% vs. 28%). Prostate, pancreatic, and renal cell trended favorably but missed significance. A separate TCGA analysis found high tumor GLP-1R expression was associated with a 33% lower risk of death across the seven types, and 45% lower in breast specifically.
🧠 BPS Take: I’ll withhold judgment until I see the full ASCO data. However, there are some obvious caveat here with this being an observational study. The comparator is already contested. Dr. Jiang Bian (Indiana University), whose group published a related Medicare-claims analysis in Obesity in 2025, has noted that when GLP-1s are benchmarked against SGLT2 inhibitors rather than DPP-4s, the cancer benefit disappears.
Smarter minds than me can argue about the specifics, but the broader point here is that the benefits of GLP-1s may continue to accrue into unexpected areas like cancer. This study isn’t definitive by any means, but could sever as sufficient signal for academic groups to study GLP-1s as cancer prevention agents. A natural next step would be testing GLP-1s in patients in the adjuvant setting, perhaps in earlier stage tumors, to see if GLP-1s extend relapse free survival.
For now, there isn’t much for Lilly or Novo to act on, but these data may the first step towards a potential new indication for GLP-1s.
💰 FOLLOW THE MONEY
Deals, dollars, and what they signal
Regeneron Bets $125M Upfront and Up to $2.3B on Parabilis’s Helicon Peptides to Crack Undruggable Targets, Then Parabilis Files a Massive IPO
📅 May 18-19, 2026 | 🏢 Regeneron Pharmaceuticals ( REGN 0.00%↑ ) + Parabilis Medicines (pre-IPO) | 💊 Helicon Peptide Platform / Antibody-Helicon Conjugates (AHCs) | 🏷 Strategic Collaboration + IPO S-1 Filing
On May 18, Regeneron ( REGN 0.00%↑ ) announced a strategic collaboration with Parabilis Medicines built around Parabilis’s proprietary Helicon platform, which produces stabilized cell-penetrant alpha-helical peptides designed to reach intracellular and historically undruggable protein targets. The financial terms were anything but subtle: $50M in upfront cash plus a $75M equity investment, totaling $125M before a single milestone is triggered, with up to $2.3B in additional milestone payments attached. The collaboration is structured to combine Regeneron’s antibody engineering capabilities with Parabilis’s Helicon peptides to produce a new drug class called Antibody-Helicon Conjugates, or AHCs. Parabilis’s own lead program targets desmoid tumors, a rare and notoriously difficult-to-treat soft tissue cancer.
Then, one day later on May 19, Parabilis filed an IPO S-1. The company had already raised approximately $800M in total private capital, including a $305M Series F in January 2026, making it one of the most heavily capitalized pre-IPO biotechs in recent memory. IPOScoop estimates the offering could rank as 2026’s largest biotech IPO.
🧠 BPS Take: Anytime Regeneron does a deal you have to take notice. This is because they don’t do a whole lot of them, and typically rely on internal innovation fare more than external. There is clearly something they see in Parabalis that they can’t do themselves. Fusing antibody-targeting with peptide payloads to create a brand new class of medicines could be a major step forward in the druggability of targets.
The deal structure is notable too, with Regeneron taking on $75M of equity in Parabalis. Filing an S-1 the morning after a $75M investment from one of the leading Big BioPharma players is also a very deliberate move, and any institutional investor picking up that prospectus is reading it with very different eyes than they would have 48 hours earlier. Regeneron’s name carries a lot of weight and the reputation of being a science-first company. Investors look at this an see less risk in this brand new class of medicines knowing that Regeneron has co-signed this platform and taken equity in the company.
Retro Biosciences Closes at $1.8B Pre-Money on Altman-Backed Longevity Thesis — Alzheimer’s Autophagy Readout in August Is the Real Catalyst
📅 May 22, 2026 | 🏥 Retro Biosciences (pre-IPO) | 💊 RTR242 (oral autophagy activator) + cell therapy + iPSC + AI protein engineering platforms | 📄 Financing Announcement — Initial Close Led by 4P Capital
Retro Biosciences, the Sam Altman-backed longevity company, announced the initial close of its latest financing round at a $1.8 billion pre-money valuation, led by 4P Capital. The round lands the company firmly in the upper tier of private longevity biotechs at a time when institutional capital has grown notably selective about the category.
Retro’s stated mission, adding 10 healthy years to human lifespan, is being pursued across four parallel platforms: a small-molecule autophagy program (lead asset RTR242), autologous iPSC-derived hematopoietic stem cell therapy via a partnership with the Murdoch Children’s Research Institute, in-house cGMP cell therapy manufacturing, and AI-enabled protein engineering.
RTR242, a first-in-class oral therapeutic designed to restart cellular autophagy, moved from indication selection to first-in-human dosing in 15 months and is now enrolling Alzheimer’s patients in Phase 1, with CEO Joe Betts-LaCroix telling STAT’s Breakthrough Summit West that no dose-limiting toxicities have been observed and that initial data is expected around August 2026.
🧠 BPS Take: A $1.8B valuation is massive, especially for a cmopany that has no clinical data to speak of yet. But this is part for the course for longevity companies with major tech CEO backing. The fact that Retro did not disclose the actual amount they raised or additional investors beyond their lead investors is also may indicate a sizable chunk of the investment coming from private individuals who may not want ot be named.
At the STAT News summit in San Francisco, Retro’s CEO noted that they are awaiting a clinical readout for RTR242. He mentioned that the drug looks safe and that they are continuing to escalate the dose to get to the maximum and see if any toxicity pops up. It’s good that there is no initial safety signal, but I would have some pause that they haven’t seen any tox yet and need to continue raising dose. As we know in the drug development world, the reason you arent’ seeing any AEs could be because your drug isn’t doing anything. We will need to see some sort of biological signal of protein aggregate clearance too in the full update.
Longevity companies remain a weird outlier in BioPharma. They all have massive valuations for little more than cool science at this point. I am hopeful we start to see real clinical signal coming from one or more of these shops, to graduate them to being actual drug developers and not just science projects for tech billionaires.
Worth flagging that RTR242’s autophagy mechanism is meaningfully differentiated from the amyloid-targeting antibody class (Leqembi, Kisunla) that currently defines Alzheimer’s therapeutics. Alzheimer’s is in major need of new MOAs beyond amyloid beta and tau targeting:
If the August data update shows some biological signal, that would be a nice first (small) step for Retro and the broader Alzheimer’s field.
Back next week with more BioPharma strategy takes! Share this with a friend or colleague if you found it helpful. Safe travels to ASCO if you are headed Chicago!