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HEMERA in Stroke

About HEMERA-1

Registry
NCT04677777
Phase
1/2
Years
2021–2025
Treated
47 patients
Where
US stroke centers
ClinicalTrials.gov (opens in a new tab)SVIN 2024 paper (opens in a new tab)

HEMERA-1 was a three-part, multicenter Phase 1/2 study of PP-007 in patients with Acute Ischemic Stroke. Patients received PP-007 alongside standard of care with treatment starting within approximately 24 hours of symptom onset. The study's main goal was to assess safety and efficacy. HEMERA-1 met this primary objective: PP-007 was generally well tolerated, and the independent Data Safety Monitoring Board found no significant safety concerns.

About HEMERA-2

HEMERA-2 is a global, randomized, placebo-controlled, adaptive Phase 3 pivotal trial evaluating the efficacy and safety of PP-007 in patients with Acute Ischemic Stroke due to an anterior large vessel occlusion who undergo mechanical thrombectomy, with or without prior thrombolysis. Patients will receive up to two doses of PP-007 or placebo in addition to standard of care, with the first dose given within 24 hours of symptom onset. The primary endpoint is functional outcome at 90 days. PP-007 has received FDA Breakthrough Therapy and Fast Track designations.

Reopening the vessel is not the same as saving the brain

Stroke care has two treatments: clot-dissolving drugs (IV thrombolysis, since 1996) and clot removal (mechanical thrombectomy, since 2015). Even when clot removal works, many patients do not recover, due to the following:

  • Persistent hypoperfusion. Blood flow in the small vessels stays poor, in about 30% of patients.1
  • Reperfusion injury. Tissue is damaged when blood returns, in about 47% of patients.2

1Rivet, Stroke 2025 (opens in a new tab)2Zhou, Stroke 2023 (opens in a new tab)

Less than halfof A-LVO stroke patients reach functional independence at 90 days with standard of care (mRS 0–2).

  1. Minute 0

    A clot blocks an artery

    Blood stops reaching part of the brain, and cells there start to die within minutes.

  2. The first hours

    A core is lost, but the tissue around it can still be saved

    The penumbra exists around the core: starved of oxygen but able to improve recovery if perfusion is restored in time.

  3. Within 24 hours

    Clot removal can reopen the artery

    Thrombectomy clears the clot, and blood flows through the large vessel again.

  4. 24 to 72 hours

    The small vessels can stay blocked

    Constricted collaterals hold red blood cells back. In around 30% of patients, poor blood flow persists and the damage can keep spreading.

    Rivet, Stroke 2025 (opens in a new tab)

  5. With PP-007

    PP-007 is designed to preserve at-risk tissue

    The high oxygen affinity, in addition to its nano-scale size and anti-vasoconstrictive properties, helps PP-007 reach the penumbra and selectively release oxygen.

Despite advances that allow more patients to qualify for thrombectomy (SOC), outcomes have remained below 50%

ThrombectomyControl (Medical Management)Unmet needLiving independently at 90 days (mRS 0–2)

  1. 2015

    Stent retrievers, CT angiography

    Living independently at 90 days, thrombectomy against control: 46% vs 27%

    Large vessel stroke within 6 hours

  2. 2018

    Perfusion imaging

    Living independently at 90 days, thrombectomy against control: 45–49% vs 13–17%

    Window widened from 6 to 24 hours

  3. 2023

    Large-core strokes

    Living independently at 90 days, thrombectomy against control: 20–30% vs 7–12%

    Patients with a large core added

  4. 2025–26

    Low-profile devices for medium vessels (MeVOs)

    5 MeVO RCTs1 positive

    Limited MT Success in MeVOs

    Only 1 of 5 RCTs demonstrated significant improvement in functional outcomes

Goyal, Lancet 2016 (HERMES); Nogueira, NEJM 2018; Albers, NEJM 2018; Sarraj, NEJM 2023; Huo, NEJM 2023; Mocco, NEJM 2025; Jing, NEJM 2026; Saver, ESOC 2026; Clarençon, JAMA 2026; Hu, NEJM 2026.

Annual prevalence of stroke

720Kyearly Acute Ischemic Strokes in the USA and growing

Reopening the vessel is not always enough.Even after the occlusion is removed, the downstream vessels and tissue may still be left without oxygen.

HEMERA-1 is done. HEMERA-2 is next.

Pipeline
  1. 2024FDA Fast Track designationRegulatory
  2. 2025HEMERA-1 Phase 1/2 study completeClinical
  3. 2026FDA Breakthrough Therapy designationRegulatory
  4. 2027HEMERA-2, a randomized Phase 3 trialPlanned