After Decades of Dead Ends, a New Drug for Pre-Eclampsia Shows Real Promise — But the Hardest Part Lies Ahead

For a condition that kills more than 70,000 mothers and 500,000 infants each year worldwide, the treatment options for pre-eclampsia remain startlingly primitive [1]. The standard of care has barely changed in decades: magnesium sulfate to prevent seizures, antihypertensive drugs to manage dangerously high blood pressure, and — when all else fails — early delivery of the baby, often weeks or months before term [2]. No approved drug can slow the disease's progression or address its root cause.

That may be starting to change. In July 2025, DiaMedica Therapeutics reported positive interim results from a Phase 2 trial of DM199, a recombinant protein that produced statistically significant reductions in blood pressure and improved blood flow to the placenta in women with pre-eclampsia — without crossing into the placental tissue or reaching the fetus [3]. The results, while preliminary and from a small, single-site study, represent one of the most encouraging signals in a field littered with failed candidates.

A Disease Without a Cure

Pre-eclampsia is a hypertensive disorder of pregnancy characterized by high blood pressure and signs of organ damage, typically developing after 20 weeks of gestation. It can progress rapidly to eclampsia (seizures), HELLP syndrome (a life-threatening liver and blood clotting disorder), stroke, and organ failure [2].

Globally, the condition affects roughly 4.4% of pregnancies, though prevalence varies sharply by region — from about 3% in high-income countries to as high as 18% in parts of sub-Saharan Africa [4]. In the United States, incidence has been climbing: pre-eclampsia now affects approximately 1 in 12 pregnancies, with rates nearly doubling between 2007 and 2019 [5]. Of more than 700,000 pregnancy hospitalizations analyzed in 2021, over 58,000 involved pre-eclampsia, and nearly 60% of those were classified as severe [5].

Source: JAMA / CDC

Data as of Jun 1, 2024CSV

The disease is responsible for an estimated 70,000 maternal deaths and 500,000 fetal or neonatal deaths annually [1]. In developing countries, a woman is seven times more likely to develop pre-eclampsia, and 10–25% of those cases end in maternal death [1].

What DM199 Does Differently

DM199, also known by its generic name rinvecalinase alfa, is a recombinant form of human tissue kallikrein-1 (rhKLK1), a naturally occurring enzyme involved in regulating blood vessel function [3]. Originally developed by DiaMedica for acute ischemic stroke, the drug was repurposed for pre-eclampsia based on its mechanism: it stabilizes the endothelium (the lining of blood vessels), reduces vascular resistance, and enhances perfusion to organs including the placenta [6][7].

This distinguishes it from existing antihypertensives, which lower blood pressure but do not address endothelial dysfunction — the central pathological feature of pre-eclampsia. As Catherine Cluver, the principal investigator leading the trial, told NPR: the drug "stabilizes the lining of the blood vessels so it makes the blood vessels happier" [7].

The Phase 2 trial is being conducted at Tygerberg Hospital in Cape Town, South Africa, under the direction of Cluver, a professor of maternal-fetal medicine at Stellenbosch University who founded the Preeclampsia Research Unit there [6]. The study is an open-label, single-center trial enrolling up to 90 women with pre-eclampsia and potentially 30 additional subjects with fetal growth restriction [8].

Interim Results

Interim data from Part 1a, reported in July 2025, covered cohorts of women with late-stage pre-eclampsia (mean gestational age: 37 weeks; mean baseline systolic/diastolic blood pressure: 165/102 mmHg) [3]:

• At the highest dose, systolic blood pressure dropped by 35 mmHg and diastolic by 15 mmHg [3].
• Across pooled therapeutic dose cohorts, mean systolic reductions were 25 mmHg at 5 minutes, 15 mmHg at 30 minutes, and 20 mmHg at 24 hours post-infusion [3].
• Uterine artery pulsatility index — a measure of blood flow resistance to the placenta — decreased by 13.2% (p=0.0003), suggesting improved placental perfusion [3].
• No serious adverse events were linked to the drug, and crucially, there was no evidence of placental transfer [3].

The combination of lowering maternal blood pressure while simultaneously improving blood flow to the uterus is what researchers find most noteworthy — existing antihypertensives can lower pressure but do not improve placental perfusion [7].

The Graveyard of Prior Candidates

Optimism about DM199 must be weighed against the long, discouraging history of pre-eclampsia treatment candidates that showed early promise and then failed. Between 2000 and 2021, the Accelerating Innovation for Mothers (AIM) project identified 153 drug, supplement, and biological candidates for pre-eclampsia and eclampsia [9]. The vast majority never advanced past early trials.

Among the most notable failures:

• Antioxidants (vitamins C and E): Multiple clinical trials found no efficacy in preventing pre-eclampsia, despite strong preclinical rationale [10].
• Esomeprazole: A proton pump inhibitor that blocked sFlt-1 production in cell cultures and reversed hypertension in transgenic mice. A large, double-blind, placebo-controlled trial found no prolongation of pregnancy and no reduction in sFlt-1 levels [10].
• Antithrombin (PRESERVE-1 study): Did not extend pregnancy beyond what medical monitoring alone achieved [11].
• Serelaxin, sildenafil, statins (pravastatin, rosuvastatin): Reached Phase 2 or Phase 3 trials but have not produced definitive positive results [9].

Four candidates reached Phase 3 (sulforaphane, esomeprazole, pravastatin, and resveratrol); nine reached Phase 2 [9]. The failure modes are consistent: compounds that work in animal models or cell cultures fail to demonstrate clinically meaningful benefits in human trials, often because pre-eclampsia's pathophysiology is more heterogeneous than preclinical models suggest.

Source: OpenAlex

Data as of Jan 1, 2026CSV

The volume of published research on pre-eclampsia treatment has surged — peaking at over 11,000 papers in 2023 — yet the clinical pipeline remains thin, a gap that underscores how difficult this disease has been to treat [12].

Who Is Behind the Research — and Who Pays

DM199 is wholly owned by DiaMedica Therapeutics (NASDAQ: DMAC), a Minneapolis-based biopharmaceutical company. The Phase 2 trial in South Africa is investigator-sponsored but conducted in collaboration with DiaMedica [8]. In July 2025, the company raised $30.1 million through a private placement and reported $60 million in cash and investments, with runway projected through the second half of 2027 [13].

Cluver, the principal investigator, is a leading pre-eclampsia researcher who has conducted multiple treatment trials and curates one of the largest pre-eclampsia biobanks [6]. DiaMedica formed a Scientific Advisory Board specifically to support DM199's development for pre-eclampsia [8].

No independent replication of the DM199 results has been published. The trial remains at a single center, which limits the generalizability of its findings. The company held a pre-IND (Investigational New Drug) meeting with the FDA in late 2025. The FDA requested an additional non-clinical embryo-fetal development study in a rabbit model before allowing a U.S.-based trial to begin [14]. Preparations for that study are underway, with results expected by mid-2026 [14].

How It Compares to Current Care

The current standard of care for pre-eclampsia is fundamentally reactive. Magnesium sulfate is effective at preventing eclamptic seizures and has reduced maternal mortality significantly — but it does not treat the underlying disease [15]. Its administration requires either continuous IV infusion or frequent intramuscular injections, both of which demand hospital-level monitoring [15]. In low-resource settings, the cost and logistical requirements of magnesium sulfate itself remain barriers [15].

Antihypertensives (labetalol, nifedipine, hydralazine) manage blood pressure but a Cochrane review of 49 trials found no statistically significant reduction in pre-eclampsia risk from treating mild-to-moderate hypertension in pregnancy [16]. Low-dose aspirin reduces the risk of preterm pre-eclampsia by up to 62% when started in the first trimester — but this is a preventive measure, not a treatment for established disease [10].

DM199 occupies a different niche: it is intended as a disease-modifying therapy for women who already have pre-eclampsia, addressing endothelial dysfunction rather than just managing symptoms. If Phase 3 trials confirm the Phase 2 signals, the realistic best-case scenario would be extending pregnancies by days to weeks — enough to reduce neonatal ICU stays and the complications of extreme prematurity — while lowering the risk of maternal organ damage [3][7].

The Racial and Economic Dimension

Pre-eclampsia is not an equal-opportunity disease. In the United States, Black women develop pre-eclampsia at rates 60% higher than White women [17]. The mortality gap is far wider: maternal death rates from pre-eclampsia among Black women are approximately 121.8 per 100,000 deliveries, compared with 24.1 per 100,000 for White women — a fivefold difference [18]. Sixty percent of these maternal deaths are classified as preventable [18].

Source: PMC / AJPH

Data as of Jan 1, 2023CSV

The drivers are interconnected: Black women in the U.S. are disproportionately affected by the condition's risk factors (hypertension, diabetes, obesity), face greater barriers to prenatal care, and receive lower-quality treatment when they do access the health system [17][18]. High-income Black women still experience worse outcomes than low-income White women across multiple cardiovascular complications of pre-eclampsia [19].

Globally, the burden falls heaviest on low- and middle-income countries, where diagnostic delays, atypical presentations, and lack of clinical guidelines compound the problem [20]. Infant mortality rates in countries where pre-eclampsia is most prevalent remain orders of magnitude higher than in wealthy nations [21].

Source: WHO Global Health Observatory

Data as of Dec 31, 2023CSV

The Case for Systemic Investment Over Drug Development

Maternal health advocates raise a pointed question: does the attention given to pharmaceutical breakthroughs divert resources from proven interventions that could save lives now?

The evidence base for this argument is substantial. Women who receive no prenatal care are seven times more likely to die from pre-eclampsia complications than those who receive some care [16]. The WHO recommends a package of interventions — calcium supplementation in calcium-deficient populations, low-dose aspirin for high-risk women, magnesium sulfate availability, and training health workers in early detection — that requires no new drugs, only broader implementation [22].

A care plan framework published in the American Journal of Obstetrics and Gynecology in 2023 argued that identifying at-risk individuals "provides opportunities beyond only low-dose aspirin therapy," including behavioral modification, directed education, and addressing "psychological and socioeconomic stress" as modifiable risk factors [23].

The total cost of pre-eclampsia to the U.S. health system is estimated at $2.18 billion in the first year alone, combining maternal and infant care [24]. Combined maternal and infant costs per pre-eclampsia birth average $43,009 [25]. From a health economics standpoint, critics argue that a fraction of those costs directed toward expanded prenatal access, implicit bias training, and community-based blood pressure monitoring could yield greater population-level returns than a novel biologic that may take years to reach the patients who need it most.

This is not a specious argument — but it is also not incompatible with drug development. The two approaches address different segments of the problem: systemic interventions reduce incidence and improve early detection, while disease-modifying therapies could improve outcomes for the women who develop pre-eclampsia despite receiving optimal preventive care.

Regulatory Path and Realistic Timeline

DiaMedica's regulatory trajectory is still in its early stages. The company has completed a pre-IND meeting with the FDA, which provided "important regulatory clarity" but also required additional preclinical safety studies [14]. Key milestones ahead:

• Mid-2026: Results from the FDA-requested rabbit embryo-fetal development study [14].
• Late 2026: Updated dataset from Part 1a of the Phase 2 trial; initiation of the dose expansion cohort (Part 1b) and fetal growth restriction cohort [13].
• 2027 or later: IND submission to the FDA, followed by a U.S.-based Phase 2 or Phase 3 trial.
• 2029–2030 at earliest: Possible FDA submission, if Phase 3 results are positive.

Pre-eclampsia qualifies as a serious condition with unmet medical need, making DM199 a plausible candidate for breakthrough therapy designation or fast track status — either of which could shave months off the review timeline [26]. The FDA has already granted breakthrough designation to an apheresis device for pre-eclampsia from a different company, establishing precedent for expedited review in this disease area [27].

Even under the most optimistic scenario, the earliest a clinician could prescribe DM199 is likely 2030 or beyond. The question of cost is unanswered. As a recombinant protein biologic, DM199 would likely carry a per-dose price in the hundreds to thousands of dollars. Whether Medicaid — which covers roughly 42% of U.S. births — would reimburse it, and how quickly, will determine whether high-risk populations actually benefit or whether the drug becomes another treatment available primarily to the well-insured.

Other Candidates in the Pipeline

DM199 is not the only approach under investigation. Several other strategies are being tested:

• sFlt-1 apheresis: Selectively removing the protein sFlt-1 from maternal blood via a filtering device. A recent pilot trial published in Nature Medicine found that antibody-based apheresis was safe and associated with prolonged pregnancies in treated women (N=9) compared with untreated controls (N=16), with a hazard ratio of 0.14 for time to delivery [28]. Advanced Prenatal Therapeutics received FDA breakthrough device designation for its targeted apheresis column [27].

• Lipid nanoparticle (LNP) mRNA therapy: NIH-funded researchers developed LNP-55, a nanoparticle that delivers therapeutic RNA directly to the placenta — delivering nearly 200 times more compound to placental tissue than the industry standard in mouse models. A single injection permanently alleviated hypertension through the end of pregnancy in pre-eclamptic mice [29]. This approach is still in preclinical stages.

• Bioflavonoid compounds: Researchers at the University of Nebraska Medical Center, supported by a $4.7 million grant, are studying a naturally occurring compound that reduces circulating levels of a protein central to pre-eclampsia's development [30]. Preclinical studies have shown improvements in vascular function, reduced inflammation, and lower blood pressure in animal models.

• Other pipeline candidates: GMA-312, C 103, CBP-4888, and KW-3357 are at various stages of clinical development [31].

What Comes Next

The DM199 results are genuinely encouraging — the magnitude of blood pressure reduction, the improvement in placental blood flow, and the absence of placental transfer are exactly the signals researchers hope to see at this stage. But Phase 2 open-label data from 30-odd patients at a single site in South Africa is a long way from a proven therapy.

The next few years will answer several critical questions: Can the results be replicated in larger, more diverse populations? Will the drug demonstrate benefits in early-onset pre-eclampsia, where the need is most urgent? Will the safety profile hold across broader use?

In the meantime, the conditions that make pre-eclampsia deadly — inadequate prenatal care, racial bias in medical settings, poverty, and health system failures in low-resource countries — will continue to claim lives. The most effective interventions available today require not new molecules but political will and sustained investment in the health systems that serve the women at greatest risk.