Patient-first drug development.
About nine in ten experimental medicines that enter clinical trials never reach the people they were designed to help. The most-cited analysis of the failure problem, published in Acta Pharmaceutica Sinica B, attributes 40% to 50% of those failures to a single root cause: lack of clinical efficacy. The drugs work in cells, in animals, sometimes even in healthy volunteers. Then they meet actual patients and fall apart.
For Leen Kawas, co-founder and managing general partner at Propel Bio Partners, that statistic is the strongest argument she knows for inverting the way drug development gets sequenced. The Los Angeles biotech investor co-founded Propel Bio Partners in 2022 to back companies that begin with patient questions and work their way back to the lab, rather than the other way around.
The traditional sequence in biopharma is familiar: a researcher identifies a molecular target, designs a candidate, tests it in animals, then runs through three phases of human trials before submitting to regulators. The patient enters the picture late, often as a recruitment statistic.
That model has been shifting since at least 2012, when the FDA began formalizing what it calls patient-focused drug development, or PFDD. The agency has since released a four-part guidance series describing how sponsors should collect and submit patient experience data for regulatory decisions. A 2024 policy brief in 'Frontiers in Medicine' argues PFDD is now an integral piece of the development paradigm, though its full potential remains underrealized.
Kawas frames the same idea less procedurally. Her view, drawn from a recent Enterprise Radio conversation, is that drug development as currently practiced contains too many redundancies and too few feedback loops with the people it's meant to serve. "There's a lot of redundancies in our industry," she told the show. "Ways of things that people are used to doing, things which most of the time is expensive and capital intensive." Her prescription is to treat those inefficiencies as openings for entrepreneurs willing to design programs that center patient outcomes from the first protocol forward.
The diligence framework Leen Kawas has described publicly runs along two parallel tracks. The first is the conventional one: science and business fundamentals. The second, less common in standard biotech investing, is whether a candidate company has built a credible path to reaching underserved populations rather than defaulting to the easiest commercial markets first.
The second track is where patient-experience signals enter the model. Kawas has been explicit that money on its own can't carry a biotech program from early science to durable impact. Propel Bio Partners pairs every investment with what she has called an ecosystem of strategic and operational support. The point of that ecosystem is to help portfolio companies move programs forward faster and with fewer late-stage failures.
What that posture means in the questions she asks of founders becomes clearer when you listen to her describe what she values. She has talked openly about the importance of building an advisory board early, with the right clinical voices in the room. She has emphasized identifying inefficiencies in drug development as a strategic opportunity rather than a tolerated friction. And she has consistently returned to the criterion that a therapy should be able to reach more than the easiest commercial cohort.
Drug-development efficiency, in her framing, is an underexploited investing edge. A startup that has interrogated which clinical workflows add value, and which exist out of habit, is a better-priced asset than one selling pure target novelty. The patient-first lens sharpens that judgment. It tells you which workflow steps actually serve the people the therapy is meant to reach.
Propel Bio Partners offers a working example of how that thesis translates into capital allocation. Two of its higher-profile portfolio bets, both on company boards Kawas serves, illustrate the pattern.
The first is Persephone Biosciences, a San Diego microbiome company whose My Baby Biome study is one of the largest investigations of infant gut health undertaken in the United States. Its initial findings, published in June 2025 in Communications Biology, a Nature portfolio journal, showed 76% of U.S. infants carry deficient levels of Bifidobacterium, a foundational gut microbe linked to immune development. A quarter of the babies had none at all. Persephone's product pipeline is being designed around what the patient population, in this case the very youngest patients, actually needs to thrive.
The second is Inherent Biosciences, where an epigenetic test for male infertility addresses a gap in reproductive medicine that historically left women bearing most of the diagnostic and treatment burden. Inherent's diagnostic begins with a clinical reality patients had been describing for decades, that "unexplained" infertility is often not unexplained at all, and works backward to the science.
Kawas tends to describe the operational logic in plain terms. Her stated goal at Propel Bio Partners is to support founders building companies that "improve human health on a broad scale," which in her construction means therapies designed to reach more people, not fewer. That orientation traces back to her decision-making at LeonaBio, the neuroscience-focused biotech she previously co-founded and led to a 2020 IPO that raised more than $400 million.
There's a financial argument layered into the philosophical one. The Tufts Center for the Study of Drug Development, whose periodic R&D cost analyses have become an industry benchmark, has estimated the full cost of bringing a single new prescription medicine to market in the billions of dollars when capitalized over development time. When 90% of candidates fail and the dominant failure mode is misalignment with what real patients experience, the math starts pointing in a particular direction.
That direction also overlaps with where regulators are pushing the industry. The FDA's June 2024 draft guidance on Diversity Action Plans requires sponsors of many late-stage trials to submit enrollment goals broken down by demographics including sex, age, race, and ethnicity. The agency's premise is straightforward: drugs studied in narrow populations don't always work as advertised in everyone else. A separate 2024 STAT News report on a Health and Human Services inspector general review found that NIH-funded trials still routinely enrolled fewer Black patients and other underrepresented groups than they had planned for.
For an investor like Leen Kawas, the inference is that startups designing for representative populations from day one have a structural advantage over those retrofitting diversity at the regulatory stage.
Leen Kawas tends to give scientist-founders the same handful of pieces of advice when they ask how to build durable biotech businesses. She tells them to know what they don't know and hire accordingly. She tells them to network for advice, not just capital. And she tells them that a fresh outlook is a competitive asset, especially in an industry as set in its conventions as this one.
Underneath that practical guidance is the deeper thesis: that the entrepreneurs most likely to clear the failure cliff are the ones who treat patient experience as the input to discovery rather than its endpoint. The future of drug development, in the framing Kawas keeps returning to, will be defined by companies that figured out earlier than their competitors how to listen to the people their science is supposed to help.
It's a quieter argument than the moonshot rhetoric that dominates much of the biotech press. It's also, given what the failure data shows, harder to dismiss.
