BHV-1300
An investigational treatment for Graves' Disease.
The same compound appears under different names depending on the context. Here is how to identify BHV-1300 wherever you encounter it, plus the key facts at a glance.
- Generic name
- BHV-1300
- Development codes
- BHV-1300, BHV1300
- Drug class
- Extracellular protein degrader (MoDE)
- Manufacturer
- Biohaven
- How it's taken
- Given as a subcutaneous (under-the-skin) injection, currently once a week.
An investigational subcutaneous antibody degrader from Biohaven designed to rapidly and deeply lower total IgG — including the thyroid-stimulating autoantibodies that drive Graves' disease. Phase 1 data in healthy volunteers showed up to 84% maximum and 80% median IgG reduction at the 1,000 mg weekly dose, and an ongoing Phase 2a study in Graves' patients has reported complete suppression of TSH receptor antibodies and normalization of thyroid hormones in initial cohorts, and in May 2026 Biohaven reported that weekly 1,000 mg doses cut the disease-driving TSH receptor autoantibodies by more than 80% by week 12. A Phase 3 trial in about 300 adults with Graves' hyperthyroidism began in June 2026[2][3][1].
How BHV-1300 works
Graves' disease happens when the immune system makes an antibody that acts like a 'stuck-on' gas pedal for the thyroid gland. Normally the thyroid is told how much hormone to make by a brain signal called TSH. In Graves' disease, the body mistakenly makes an antibody (called a TSH-receptor antibody, or TRAb) that locks onto the same switch as TSH and keeps it turned on, so the thyroid keeps pumping out hormone no matter what.
That's what causes the rapid heartbeat, weight loss, tremor, heat intolerance, and eye problems people with Graves' feel[6]. BHV-1300 is designed to remove that bad antibody from the blood. It's built using Biohaven's MoDE (Molecular Degrader of Extracellular proteins) platform: one end of the molecule grabs onto IgG antibodies floating in the blood, and the other end sticks to a protein on the surface of liver cells called ASGPR.
The liver recognizes the attached IgG as 'take this out' and pulls the antibody inside, where it gets broken down. Because the bad TRAb antibody is made of IgG, lowering total IgG means lowering TRAb too — which takes pressure off the gas pedal and lets the thyroid go back to normal[2].
Mechanism: IgG-selective extracellular protein degrader (MoDE platform) that tags circulating IgG antibodies — including pathogenic thyroid-stimulating immunoglobulins — for rapid clearance by the liver
Side effects and safety
In the healthy-volunteer Phase 1 study, BHV-1300 was generally well tolerated across single and multiple doses up to 1,000 mg weekly. Most side effects were mild and included injection-site reactions, headache, and transient lab changes in fibrinogen and albumin that were not associated with bleeding or clinical problems.
Importantly, immunoglobulin levels returned toward baseline after dosing stopped, and no serious infections were reported[2]. Because the drug lowers all IgG — including the antibodies that help fight infection — longer trials are tracking infection risk carefully, especially with repeated dosing.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking BHV-1300
Given as a subcutaneous (under-the-skin) injection, currently once a week. In the Phase 1 multiple-ascending-dose study, weekly doses up to 1,000 mg produced about 80% median and 84% maximum reduction in total IgG[2]. Injections can be given in a clinic and, pending further study, may be self-administered at home in future trials.
Clinical trial results
The Phase 1 healthy-volunteer study (NCT05819879) tested single and multiple doses in more than 100 adults and showed dose-dependent, deep IgG reduction with a clean safety profile[2]. An ongoing Phase 2a open-label study in adults with Graves' disease (NCT06451874) has reported initial results showing complete suppression of TSH-receptor antibodies (TRAb) and normalization of free T3 and free T4 in the first patients treated, consistent with clinical remission of hyperthyroidism[3]. In May 2026, Biohaven reported that weekly 1,000 mg doses reduced pathogenic TSH receptor autoantibodies by more than 80% on average by week 12 in patients with Graves' hyperthyroidism. The pivotal Phase 3 study began in June 2026: a randomized, double-blind, placebo-controlled trial in about 300 adults testing whether thyroid hormones (T3, T4 and TSH) return to normal at 26 weeks without an antithyroid drug[1].
Development history
BHV-1300 is the lead program in Biohaven's MoDE (Molecular Degrader of Extracellular proteins) platform, licensed from Professor David Spiegel's group at Yale and built in parallel with the TRAP (Targeted Removal of Aberrant Proteins) subtype used for BHV-1400[5]. Biohaven nominated BHV-1300 as a broad IgG-lowering candidate because many autoimmune diseases — including Graves' disease, myasthenia gravis, and warm autoimmune hemolytic anemia — are driven by pathogenic IgG antibodies. The first healthy-volunteer study began in 2023; Graves' disease was selected as the first patient indication because TRAb levels correlate tightly with disease activity, giving an early, measurable readout of whether the degrader approach translates into clinical benefit[3].
Explore Graves' Disease trials
Common questions about BHV-1300
▸What is BHV-1300?
An investigational subcutaneous antibody degrader from Biohaven designed to rapidly and deeply lower total IgG — including the thyroid-stimulating autoantibodies that drive Graves' disease. Phase 1 data in healthy volunteers showed up to 84% maximum and 80% median IgG reduction at the 1,000 mg weekly dose, and an ongoing Phase 2a study in Graves' patients has reported complete suppression of TSH receptor antibodies and normalization of thyroid hormones in initial cohorts, and in May 2026 Biohaven reported that weekly 1,000 mg doses cut the disease-driving TSH receptor autoantibodies by more than 80% by week 12. A Phase 3 trial in about 300 adults with Graves' hyperthyroidism began in June 2026[2][3][1].
▸How does BHV-1300 work?
Graves' disease happens when the immune system makes an antibody that acts like a 'stuck-on' gas pedal for the thyroid gland. Normally the thyroid is told how much hormone to make by a brain signal called TSH. In Graves' disease, the body mistakenly makes an antibody (called a TSH-receptor antibody, or TRAb) that locks onto the same switch as TSH and keeps it turned on, so the thyroid keeps pumping out hormone no matter what.
That's what causes the rapid heartbeat, weight loss, tremor, heat intolerance, and eye problems people with Graves' feel[6]. BHV-1300 is designed to remove that bad antibody from the blood. It's built using Biohaven's MoDE (Molecular Degrader of Extracellular proteins) platform: one end of the molecule grabs onto IgG antibodies floating in the blood, and the other end sticks to a protein on the surface of liver cells called ASGPR.
The liver recognizes the attached IgG as 'take this out' and pulls the antibody inside, where it gets broken down. Because the bad TRAb antibody is made of IgG, lowering total IgG means lowering TRAb too — which takes pressure off the gas pedal and lets the thyroid go back to normal[2].
▸What are the side effects of BHV-1300?
In the healthy-volunteer Phase 1 study, BHV-1300 was generally well tolerated across single and multiple doses up to 1,000 mg weekly. Most side effects were mild and included injection-site reactions, headache, and transient lab changes in fibrinogen and albumin that were not associated with bleeding or clinical problems.
Importantly, immunoglobulin levels returned toward baseline after dosing stopped, and no serious infections were reported[2]. Because the drug lowers all IgG — including the antibodies that help fight infection — longer trials are tracking infection risk carefully, especially with repeated dosing.
▸How is BHV-1300 taken?
Given as a subcutaneous (under-the-skin) injection, currently once a week. In the Phase 1 multiple-ascending-dose study, weekly doses up to 1,000 mg produced about 80% median and 84% maximum reduction in total IgG[2]. Injections can be given in a clinic and, pending further study, may be self-administered at home in future trials.
▸Is BHV-1300 FDA approved?
BHV-1300 is currently in phase 3 clinical trials for Graves' Disease. It has not yet received FDA approval.
▸How is BHV-1300 different from FcRn inhibitors like efgartigimod?
Both lower total IgG, but they work in different places. FcRn inhibitors block the recycling of IgG inside cells, which indirectly shortens how long antibodies last in the blood. BHV-1300 works in the bloodstream itself: it physically tags IgG antibodies and drags them to the liver for disposal through a receptor called ASGPR. In Phase 1, BHV-1300 achieved up to ~84% maximum IgG reduction with weekly subcutaneous dosing, with early Graves' data showing complete TRAb suppression and normalized thyroid hormones[2][3].
▸Could BHV-1300 eventually replace radioactive iodine or thyroid surgery for Graves' disease?
That's the question the Phase 2b/3 program will answer. Radioactive iodine and thyroidectomy cure hyperthyroidism by destroying the thyroid, but trade it for lifelong hypothyroidism and hormone replacement. If BHV-1300 can remove the TRAb antibodies long enough for the immune system to reset, patients might keep their own thyroid and regain normal function — something no current therapy reliably offers[7][3].
▸How do I enroll in a BHV-1300 Graves' disease trial?
Active trials are listed on ClinicalTrials.gov under the NCT numbers for the Phase 2a Graves' study (NCT06451874) and any subsequent Phase 2b/3 studies. Ask your endocrinologist whether you meet typical criteria (biochemical hyperthyroidism, positive TRAb, not already receiving radioactive iodine or surgery) and check for sites near you.
▸Is BHV-1300 available through expanded access?
Not at this time. BHV-1300 is investigational and only available through enrolled clinical trials. Biohaven has not opened a general expanded-access program for Graves' disease.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- Biohaven via SEC Form 8-K · 2026-08-10. Biohaven Reports Second Quarter 2026 Financial Results and Recent Business Developments. https://www.sec.gov/Archives/edgar/data/1935979/000193597926000067/a2026q2bhvnearningsprex991.htm
- Biohaven (Investor Relations) · 2024. Biohaven Announces Positive Phase 1 Clinical Data Demonstrating Best-in-Class Potential for BHV-1300, an Extracellular IgG Degrader. https://ir.biohaven.com/news-releases/news-release-details/biohaven-reports-positive-degrader-data-achieving-80-sustained
- Biohaven (Investor Relations) · 2025. Biohaven Announces Initial Phase 2a Clinical Data for BHV-1300 in Graves' Disease Showing Complete Suppression of TSH Receptor Antibodies. https://ir.biohaven.com/news-releases/news-release-details/biohaven-highlights-portfolio-progress-positive-early-patient
- Biohaven · 2025. Biohaven Pipeline — BHV-1300 Graves' Disease Program. https://www.biohaven.com/pipeline/
- Yale Office of Cooperative Research · 2022. Biohaven Licenses Yale's MoDE Extracellular Protein Degradation Platform. https://ir.biohaven.com/news-releases/news-release-details/biohaven-advances-development-mode-platform-technology-licensed
- Graves' Disease & Thyroid Foundation. Understanding Graves' Disease and TSH Receptor Antibodies. https://www.gdatf.org/about/about-graves-disease/
- American Thyroid Association / Thyroid · 2016. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism. https://pubmed.ncbi.nlm.nih.gov/27521067/