KARDINAL: Monthly Tonlamarsen May Not Enhance BP Lowering in Resistant Hypertension

Why It Matters

The findings suggest that deeper AGT suppression does not automatically translate into greater blood‑pressure control in resistant hypertension, tempering expectations for this new therapeutic class and guiding future trial designs.

Key Takeaways

• Monthly tonlamarsen cut AGT ~67% vs 23% single dose
• Both regimens lowered systolic BP ~6.7 mm Hg
• Serious adverse events higher with monthly dosing (5%)
• Trial lacked placebo‑only arm, limiting efficacy conclusions
• AGT suppression may aid adherence, not BP control

Pulse Analysis

Targeting hepatic angiotensinogen (AGT) represents a novel angle on renin‑angiotensin‑aldosterone system (RAAS) modulation. Tonlamarsen, a subcutaneous nucleic‑acid drug, aims to curb AGT production, theoretically reducing downstream angiotensin II without daily pills. This approach appeals to clinicians battling medication non‑adherence, a major driver of uncontrolled hypertension in the United States, where control rates hover below 50%. By delivering a monthly injection, the therapy could simplify regimens, but the biology of RAAS suggests that merely lowering AGT may not be sufficient when patients already use ACE inhibitors or ARBs.

The KARDINAL phase II trial enrolled 198 adults with systolic BP > 135 mm Hg despite two to five antihypertensives, most on ACE inhibitors or ARBs. After an initial single 90‑mg dose, participants received either four additional monthly injections or placebo. Results showed a striking 67% AGT reduction with monthly dosing versus 23% after one dose, yet office systolic pressure fell identically—about 6.7 mm Hg—in both arms. Safety signals were modest, though serious adverse events were more frequent in the monthly group (5% vs 2%). The lack of a true placebo‑only arm and the short 20‑week horizon limit confidence in the blood‑pressure signal.

Industry analysts view these data as a reality check for AGT‑targeted therapeutics. While the biochemical endpoint proved achievable, the clinical benefit remains uncertain, especially in patients already on RAAS blockers. Competitors such as Alnylam’s Zilebesiran and Mineralys’s Lorundrostat are pursuing similar pathways, but recent setbacks—including Baxdrostat’s mixed trial outcomes—highlight the challenge of translating molecular knock‑down into meaningful hemodynamic change. Future studies will need larger, placebo‑controlled cohorts and perhaps combination strategies to determine whether AGT suppression can finally deliver a differentiated, adherence‑friendly hypertension solution.