28% Weight Loss: Lilly's Retatrutide Just Redefined the Obesity Market – This Week in Biotech #101
Plus the covert campaign that took out Makary, and a 65% lung cancer trial win that could reshape Keytruda's future (May 15-21, 2026).
Welcome back to This Week in Biotech by Biotech Blueprint, edition 101, covering biotech and pharma news from May 15 to 21, 2026.
🎙️ Biotech Blueprint brings you weekly video updates on the latest biotech and pharma news, plus in-depth podcast interviews with industry leaders. You can find us on YouTube, Spotify, and Apple Podcasts. If you want to be featured on our podcast, get in touch.
🌐 For consulting inquiries, please email us or visit BiotechBlueprintConsulting.com.
👥 If you haven’t already, please connect with me or follow me on LinkedIn.
Treating a new realm of diseases
Beyond traditional limits: explore the drug delivery technology opening new doors in genomic medicine.
VIDEO SUMMARY
THIS WEEK’S KEY TAKEAWAYS 🔑
The number that defines this week is 28.3%. That is the average body weight lost on the 12 mg dose of Lilly’s retatrutide in TRIUMPH-1, the first successful Phase 3 readout for the GIP/GLP-1/glucagon triple agonist that has been the most watched obesity asset in the pipeline for two years. A second pivotal trial in patients with knee osteoarthritis hit 28.7% plus a 75.8% reduction in pain scores. We have officially entered the territory where a pill or injection produces weight loss comparable to bariatric surgery. The bear case on incretin pricing pressure may eventually arrive, but the front of the efficacy curve just moved again, and Novo Nordisk’s CagriSema and Pfizer’s Metsera assets now have to be measured against a 30% ceiling rather than a 25% one. The wrinkle worth holding onto is the discontinuation curve. 11.3% of patients on the 12 mg dose dropped out for adverse events versus 4.9% on placebo, which is why the 9 mg arm is probably the commercial sweet spot.
The other big story this week is about how pharma is choosing to build, not what it is building. The same Lilly that posted the retatrutide data also acquired Engage Bio for up to $202 million, its seventh M&A move of 2026, to pick up a non-viral DNA delivery platform. Bristol Myers Squibb signed a strategic agreement with Anthropic to deploy Claude across more than 30,000 employees in a workflow-embedded configuration that goes well beyond a chatbot. Incyte struck two AI deals the same week. The emerging pattern is that large pharma is buying discovery infrastructure now, and enterprise AI has crossed from “nice to have” into table stakes.
Two weeks after Marty Makary’s exit, the FDA story has moved from leadership churn into something more operational. Endpoints published an investigation into the coordinated campaign of biotech executives, lobbyists, and former FDA officials that pushed him out, with Biohaven CEO Vlad Coric as a central figure after his company’s pushback on a late-April complete response letter. On the same day, the acting head of NIAID reportedly stepped down, and NIH Director Jay Bhattacharya was grilled by Senate Appropriations on the 2027 budget. The leadership vacuum is widening, not narrowing. If you have a PDUFA date or a Type B meeting on the calendar this summer, you should probably plan for delays.
Outside obesity and US policy, the most strategically important readout came out of China. Merck partner Kelun-Biotech’s sac-TMT combined with Keytruda cut the risk of tumor progression or death by 65% versus Keytruda alone in first-line PD-L1-positive non-small cell lung cancer. This is the first Phase 3 trial of an antibody-drug conjugate combined with a checkpoint inhibitor to win in first line lung cancer. Keytruda loses patent exclusivity in 2028, and Merck’s strategic response is to convert it into a backbone for combination regimens. Nobody really cares anymore that the asset came from China. The next real test is whether the Western confirmatory study running in parallel reproduces the result.
BIOTECH/PHARMA NEWS 🧬
🔹 Lilly reported positive Phase 3 topline results for retatrutide, its triple-agonist obesity drug, in adults with obesity or overweight plus at least one weight-related comorbidity without diabetes. After 80 weeks, the 12 mg dose drove 28.3% weight loss, roughly 70 pounds on average, versus 2.2% on placebo. The 9 mg dose delivered about 24% and the 4 mg dose about 19%. Discontinuation rates due to adverse events were 4.1%, 6.9%, and 11.3% across the three doses versus 4.9% on placebo, with nausea, diarrhea, and vomiting as the dominant side effects. A second trial in patients with obesity and knee osteoarthritis hit 28.7% weight loss and a 75.8% reduction in WOMAC pain scores at the high dose. Seven additional retatrutide Phase 3 trials read out through 2026 across diabetes, sleep apnea, MASH, chronic low back pain, and cardiovascular outcomes. Lilly is no longer fighting on the same efficacy frontier as Novo’s CagriSema, which posted 22.7% in a comparable population last year. The likely commercial read is that retatrutide expands the obesity market rather than cannibalizing Zepbound, because the 12 mg discontinuation rate creates real-world dose ceiling effects. Lilly will not run pricing off the 12 mg label.
🔹 Lilly also closed its acquisition of Engage Bio for up to $202M, picking up a non-viral DNA delivery platform that combines engineered DNA payloads with lipid nanoparticles. The aim is to solve the persistent problems with gene therapy delivery: potency, tolerability, and the ability to redose, all of which have constrained the AAV-based approaches Sarepta and others have relied on. This is Lilly’s seventh acquisition of 2026 and continues a clear strategic pattern: the company is treating genetic medicine as a delivery problem rather than a payload problem.
🔹 Endpoints News published an investigation this week describing a multi-month coordinated effort by biotech executives, lobbyists, and former FDA officials that contributed to Marty Makary’s departure on May 12, with Biohaven CEO Vlad Coric featured prominently after Biohaven’s late-April complete response letter on a spinocerebellar ataxia program. The broader regulatory landscape is also fraying. The acting head of NIAID reportedly stepped down, and NIH Director Jay Bhattacharya faced bipartisan Senate scrutiny on the 2027 budget. The practical implications include real delay risk for PDUFA decisions, Type B meeting outcomes, and advisory committee scheduling for at least the rest of the quarter, with small-cap companies under $200 million in cash and active regulatory engagement the most exposed.
🔹 Kelun-Biotech released the OptiTROP-Lung05 Phase 3 abstract ahead of ASCO 2026, reporting a 65% reduction in the risk of tumor progression or death for sac-TMT combined with Keytruda versus Keytruda alone in previously untreated PD-L1-positive non-small cell lung cancer. Sac-TMT is a TROP2-directed antibody-drug conjugate carrying a topoisomerase I inhibitor payload, and Merck licensed ex-China rights from Kelun back in 2022. This is the first Phase 3 of any antibody-drug conjugate plus checkpoint inhibitor combination to hit in first line lung cancer. The competitive read matters as AstraZeneca and Daiichi Sankyo’s datopotamab deruxtecan has struggled to convert Phase 3 signals into a first line label, and Merck now has a credible path to turn Keytruda into a combination backbone heading into its 2028 patent expiration. The enrollment was China-only, and Western confirmatory trials are running in parallel, so the question of whether the regional efficacy translates is real. The 65% magnitude is large enough that even a substantial regional discount would still be commercially material.
🔹 BMS signed a strategic agreement with Anthropic to deploy Claude across more than 30k employees globally, with use cases spanning scientific literature summarization, clinical protocol drafting, internal data querying, and routine documentation. The deal also includes Claude Code for research and drug development functions. Combined with Incyte’s two AI deals the same week, it seems that enterprise AI is now baseline infrastructure for top-20 pharma rather than a differentiated capability.
🔹 Immunovant reported Week 16 results from its IMVT-1402 trial in difficult-to-treat rheumatoid arthritis, with ACR20, ACR50, and ACR70 response rates of 72.7%, 54.5%, and 35.8% in patients who had failed at least two prior advanced therapies, including both JAK and anti-TNF inhibitors. Response rates held in the subgroup that had failed both classes. Shares moved on the print. The proof-of-concept readout in cutaneous lupus is expected in the second half of 2026 and will be the next decisive print for the company’s autoimmune blockbuster thesis.
🔹 BioMarin’s Voxzogo hit the primary endpoint in a Phase 3 trial in hypochondroplasia, with annualized growth velocity 2.33 cm per year above placebo at Week 52, opening a second pediatric short-stature indication beyond the original achondroplasia label. Filings are planned for the second half of 2026. Two days earlier, BMN 401, an enzyme therapy acquired in the 2025 Inozyme buyout, missed its radiographic clinical endpoint in ENPP1 deficiency despite hitting on the biomarker co-primary, and will require FDA discussion on surrogate to clinical translation.
Have a great rest of your week and thanks for reading Biotech Blueprint!
The weight loss data is pronounced, but so too is the peripheral neuropathy and heart rate increases