Repeat dosing of an antisense hypertension drug that Kardigan licensed from Ionis Pharmaceuticals did not lower patients’ blood pressure better than a single dose, according to Phase 2 data reported on Saturday.
The KARDINAL trial, presented at the American College of Cardiology meeting in New Orleans, had an unusual design. All the patients received a single 90 mg injection of the antisense oligonucleotide, called tonlamarsen, and were then randomized into two groups. One had four more monthly doses of the drug, and the others four placebo shots.
There was no significant difference between the groups in systolic blood pressure, as measured in a doctor’s office. This was due to “an unexpected, prolonged reduction in blood pressure in the single-dose arm,” Kardigan
said
.
An additional analysis of that co-primary endpoint found that both treatment groups had a blood pressure drop of about 6.7 mmHg at the five-month point, which the company called clinically meaningful. The patients in the study had treatment-resistant hypertension, and were already on between two and five blood pressure medications.
Kardigan’s CEO Tassos Gianakakos told
Endpoints News
that the results indicate that the single dose worked better than expected on the blood pressure measure, rather than the multi-dose cohort doing worse.
“What was honestly a bit of a surprise for us is the fact that a single dose had a prolonged effect on systolic blood pressure,” Gianakakos said. In the single-dose arm, the company had “very much expected the systolic blood pressure to return pretty darn near close to baseline.”
The finding is somewhat confusing, since on a mechanistic level, the drug does seem to work as intended.
In another co-primary endpoint, the repeat-dose regimen cut levels of the protein tonlamarsen targets, which is called angiotensinogen or AGT, to a significantly greater degree than the single dose. Those in the five-shot group saw their AGT levels fall 67%, whereas the single-dose cohort had a 23% reduction.
Tonlamarsen has a similar mechanism to Alnylam’s zilebesiran, an siRNA therapeutic that silences hepatic AGT expression. Zilebesiran
misfired
in a mid-stage trial last year. Alnylam is conducting a whopping 11,000-patient Phase 3
cardiovascular outcomes trial
with the drug.
Gianakakos said these two products act slightly differently. As an antisense oligonucleotide, tonlamarsen can modulate the levels of AGT more precisely than zilebesiran, he said.
In the write-up of the trial
published in
JACC
, the investigators wrote that “subsequent trials will need to compare tonlamarsen strictly with placebo and forego an active run-in period to definitively demonstrate the magnitude of [blood pressure] reduction.”
And that is what Kardigan intends to do, albeit in a slightly different population. The company is planning to kick off a Phase 2b trial named KARDINAL-ASH in patients who have been hospitalized for acute severe hypertension (ASH) later this year.
“These are folks who die from aortic rupture and aneurysm, from heart failure and renal disease. And they are in and out of the hospital,” Gianakakos said, adding that this will be the first drug trial specifically in this population.
The trial will enroll patients upon discharge and aim at “keeping them out of trouble” for the subsequent 90 days, Gianakakos said. Although what “out of trouble” means is yet to be defined, it could be getting their systolic blood pressure under 180 mmHg or 160 mmHg — “something like that.” This is higher than blood pressure guidelines suggest, but he pointed out that in these very sick patients, it is still a meaningful goal.
The trial will also aim to provide evidence that tonlamarsen can reduce surges in blood pressure, and patients will be constantly tracked with wearable monitors. This is prompted by a post-hoc analysis of the Phase 2 trial presented at ACC, which found that patients in the five-dose group had a 28% decrease in surges in systolic blood pressure above 150 mmHg relative to the one-dose cohort.
“If we keep people in the safe zone, we expect to see things like reductions in hospitalizations and improvements in mortality related to this end organ failure,” Gianakakos said. He could not specify when the trial will report, though he said the company feels “a sense of urgency,” and wants to get it done as quickly as possible.
If tonlamarsen makes it all the way to market, it will likely enter a very different environment to the one that exists now. An approval decision for AstraZeneca’s resistant hypertension pill baxdrostat is imminent, and its pivotal data were
very strong
. A similarly acting pill from
Mineralys Therapeutics
— both are aldosterone synthase inhibitors — could also gain approval towards the end of this year.
Gianakakos said this should not limit tonlamarsen’s market potential, since these drugs act on a separate biological pathway.
“They’re related, and I think they could be synergistic,” he said. But the aldosterone synthase inhibitors might not be able to prevent the surges seen in ASH patients.
Kardigan
emerged
in January 2025 with $300 million in funding. Two months later, Endpoints
reported
that it had licensed tonlamarsen from Ionis.