Sep 28, 2026 · 2h 26m
Bimagrumab exposes the hard economics of drug development
#409 ‒ Inside modern drug development: the science, economics, and regulatory hurdles behind bringing new medicines to patients | Lloyd Klickstein, M.D., Ph.D.
The episode shows why promising biology can still fail to deliver meaningful function, and how unexpected metabolic effects can revive a stalled medicine.
- 1Drug development begins with unmet clinical needs, then faces years of target selection, manufacturing, toxicology, regulation, and financing.
- 2Bimagrumab reliably increased muscle mass, but its limited functional gains redirected the program toward obesity and body-composition treatment.
- 3The next frontier may be preventive medicines targeting mTORC1 biology and cancer-protective pathways before disease becomes clinically apparent.
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Bimagrumab’s reliable muscle growth produced limited functional improvement, then its unexpected fat-loss and glucose effects redirected it into obesity treatment.
The brief
Lloyd Klickstein, a physician-scientist who moved from laboratory medicine into industry, explains why drug development starts with unmet patient needs rather than attractive biology alone.
The path from target to trial runs through molecule design, animal studies, GMP manufacturing, toxicology, funding, and IND review; each checkpoint can end a program long before approval.
Bimagrumab blocked activin type II receptors and produced striking muscle growth, but the phase-two results exposed a central problem: more muscle did not reliably mean more strength or function.
An unexpected reduction in fat mass and hemoglobin A1c gave the discarded asset a new direction, leading Versanis to test bimagrumab with semaglutide in the BELIEVE trial.
The combination delivered substantial fat loss, while strength gains remained smaller and variable; its unresolved biology, including an LDL increase, keeps the story open under Eli Lilly.
Klickstein closes by looking beyond treatment toward prevention, including selective mTORC1 inhibition and drugs designed to activate cancer-protective pathways before disease emerges.
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