Invivyd Announces Selection of Potential Best-In-Class RSV Antibody Candidate VBY329; Targeting 2H 2026 IND Readiness
Invivyd (Nasdaq: IVVD) nominated VBY329, a monoclonal antibody candidate for prevention of Respiratory Syncytial Virus (RSV) in newborns, infants, and children, and plans to advance it toward IND readiness in 2H 2026. In vitro data show average antiviral potency 1.5-fold vs nirsevimab and 1.2-fold vs clesrovimab, plus up to ~500-fold enhanced neutralization against nirsevimab-resistant RSV F protein variants in pseudovirus assays. VBY329 includes half-life extension and biophysical properties expected to provide equivalent or greater in vivo half-life versus comparators. Invivyd said it will present in vitro data at a future medical congress and continues discovery work on ultra-long half-life RSV antibodies for elderly and immunocompromised populations.
Invivyd (Nasdaq: IVVD) ha nominato VBY329, una candidata a anticorpo monoclonale per la prevenzione del virus respiratorio sinciziale (RSV) nei neonati, bambini e bambini piccoli, e prevede di portarla verso IND readiness in 2H 2026. I dati in vitro mostrano una potenza antivirale media 1,5-fold rispetto a nirsevimab e 1,2-fold rispetto a clesrovimab, oltre a un fino a ~500-fold di neutralizzazione potenziata contro varianti della proteina F di RSV resistenti a nirsevimab in saggi su pseudovirus. VBY329 include estensione della emivita e proprietà biophysiche attese per fornire emivita in vivo equivalente o maggiore rispetto ai comparatori. Invivyd ha dichiarato che presenterà dati in vitro a un futuro congresso medico e continua la scoperta di anticorpi RSV ad emivita ultra-lunga per anziani e popolazioni immunocompromesse.
Invivyd (Nasdaq: IVVD) nominó VBY329, una candidata de anticuerpo monoclonal para la prevención del virus respiratorio sincitial (RSV) en recién nacidos, infantes y niños, y planea avanzar hacia IND readiness in 2H 2026. Los datos in vitro muestran una potencia antiviral media 1,5 veces mayor que la de nirsevimab y 1,2 veces mayor que la de clesrovimab, además de hasta ~500-fold mejor neutralización contra variantes de la proteína F de RSV resistentes a nirsevimab en ensayos con pseudovirus. VBY329 incluye extensión de la vida media y propiedades biofísicas que se esperan proporcionen una vida media in vivo equivalente o mayor frente a los comparadores. Invivyd afirmó que presentará datos in vitro en un próximo congreso médico y continúa la investigación de anticuerpos RSV de vida media ultralarga para personas mayores y poblaciones inmunocomprometidas.
Invivyd (Nasdaq: IVVD)는 신생아, 영아 및 어린이의 RSV 예방을 위한 단클론 항체 후보 VBY329를 지명했고, 2분기~하반기 2026년 내 IND 준비를 향해 나아갈 계획이다. 시험관(in vitro) 데이터는 nirsevimab 대비 평균 항바이러스 효능 1.5배와 clesrovimab 대비 1.2배를 보여주며, nirsevimab 저항 RSV F 단백질 변이에 대한 중화가 최대 ~500배 향상되는 가짜바이러스(pseudovirus) 분석 결과도 있다. VBY329는 반감기 연장 및 생물물리적 특성을 포함하여 비교 물질 대비 체내 반감기가 동등하거나 더 길 것이라고 예상된다. Invivyd는 향후 의학 학술대회에서 in vitro 데이터를 발표할 예정이며, 고령자 및 면역저하 인구를 위한 초장반감기의 RSV 항체 발견 연구를 계속 진행 중이다.
Invivyd (Nasdaq : IVVD) a nommé VBY329, une candidate d'anticorps monoclonaux pour la prévention du virus respiratoire syncytial (VRS) chez les nouveau-nés, nourrissons et enfants, et prévoit de l’amener vers une préparation IND au cours du 2e semestre 2026. Les données in vitro montrent une puissance antivirale moyenne 1,5 fois supérieure à celle de nirsevimab et 1,2 fois supérieure à celle de clesrovimab, ainsi qu’un déploiement allant jusqu’à environ 500 fois une neutralisation renforcée contre des variantes résistantes de la protéine F du VRS chez nirsevimab dans des essais sur pseudovirus. VBY329 comprend une extension de la demi-vie et des propriétés biophysiques qui devraient offrir une demi-vie in vivo équivalente ou supérieure à celle des comparateurs. Invivyd a déclaré qu’il présentera les données in vitro lors d’un futur congrès médical et poursuit les travaux de découverte sur des anticorps RSV à demi-vie ultra-longue pour les personnes âgées et les populations immunodéprimées.
Invivyd (Nasdaq: IVVD) hat VBY329 nominiert, eine Monoklon-Antikörper-Kandidatin zur Vorbeugung des respiratorischen Syncytial-Virus (RSV) bei Neugeborenen, Säuglingen und Kindern, und plant, sie in Richtung IND-Bereitschaft im 2. Halbjahr 2026 voranzubringen. In-vitro-Daten zeigen eine durchschnittliche antivirale Potenz 1,5-mal gegenüber nirsevimab und 1,2-mal gegenüber clesrovimab, sowie bis zu etwa 500-fach verbesserte Neutralisation gegen nirsevimab-resistente RSV-F-Protein-Varianten in Pseudovirus-Tests. VBY329 umfasst eine Halbwertszeitverlängerung und biophysikalische Eigenschaften, die voraussichtlich eine gleichwertige oder größere in-vivo-Halbwertszeit gegenüber Vergleichern ermöglichen. Invivyd sagte, dass es die in-vitro-Daten auf einem zukünftigen medizinischen Kongress präsentieren wird und die Entdeckung ultralanger RSV-Antikörper für ältere und immungeschwächte Bevölkerungsgruppen fortsetzt.
Invivyd (Nasdaq: IVVD) اختارت VBY329، وهو مرشح جسم مضاد أحادي النسيلة للوقاية من فيروس الجهاز التنفسي المخلوي (RSV) لدى حديثي الولادة والرضع والأطفال، وتخطط للدفع به نحو IND readiness in 2H 2026. تُظهر بيانات المختبر أن فعالية مضادّة للفيروسات المتوسطة 1.5‑ضعف مقارنة بنيسيرسيماب و1.2‑ضعف مقارنة بكلسروفيماب، بالإضافة إلى حتى حوالي 500‑ضعف تعزيز في التحييد ضد متغيرات لبروتين F لـ RSV المقاومة للنيرسيفيماب في اختبارات pseudovirus. يشمل VBY329 تمديد نصف العمر وخصائص فيزيائية حيوية من المتوقع أن توفر عمرًا حيويًا في الجسم مساوٍ أو أكبر من المقارنات. قالت Invivyd إنها ستعرض البيانات في المختبر في مؤتمر طبي مستقبلي وتواصل أعمال الاكتشاف على أضداد RSV ذات العمر النصفي فائق الطول للمسنين والسكان ذوي المناعة الضعيفة.
- Potency: 1.5-fold greater antiviral potency vs nirsevimab (average)
- Comparator potency: 1.2-fold greater antiviral potency vs clesrovimab (average)
- Resistance profile: up to ~500-fold enhanced neutralization vs nirsevimab-resistant variants in pseudovirus assays
- Development timeline: targeted IND readiness in 2H 2026
- Preclinical stage: VBY329 is nominated for preclinical development with no clinical data reported
- Evidence limited to in vitro: key claims (potency, resistance, half-life) are based on in vitro and pseudovirus assays only
Insights
Nomination of VBY329 is a positive preclinical milestone but remains early-stage with IND planning for
VBY329 is described as a monoclonal antibody candidate selected for pediatric RSV prophylaxis after in vitro screens showing higher average antiviral potency versus nirsevimab and clesrovimab, and an improved resistance profile in pseudovirus assays. The program uses half-life extension technology and biophysical characterization to target equivalent or longer in vivo persistence than existing comparators; these are typical preclinical levers to extend protection without vaccine-induced immunity.
Dependencies and risks include completion of IND-enabling studies, translation of in vitro potency and pseudovirus resistance into clinical efficacy, and demonstration of safety in neonates and infants; none of these are reported as complete. Key items to watch are progression through IND-enabling toxicology and CMC milestones and the stated goal of IND readiness in
The candidate targets a large pediatric RSV prophylaxis market cited at
The release highlights potential product advantages: higher average in vitro potency and a stronger resistance profile versus current standard-of-care antibodies, and potential for an expanded protective window via half-life extension. Those attributes could support positioning versus existing products if confirmed in humans, but reported claims are limited to in vitro and candidate-selection data.
Monitor regulatory and clinical milestones, especially IND-enabling study completion and any forthcoming congress presentation of the in vitro dataset prior to IND filing. The timeline cited is IND readiness in
- VBY329 is designed for the prevention of Respiratory Syncytial Virus (RSV) infections in newborns, infants, and children, and results from Invivyd’s proprietary antibody discovery technology platform
- VBY329 meets Invivyd’s target profile of higher potency and improved barrier to resistance compared to standard of care RSV medicines, as assessed in vitro:
- Antiviral potency 1.5-fold greater on average than nirsevimab and 1.2-fold greater on average than clesrovimab against established authentic RSV strains representing circulating variants
- Resistance profile compared to nirsevimab reflects up to approximately 500-fold greater enhanced neutralization activity against RSV F protein variants resistant to nirsevimab in pseudovirus assays that reflect contemporary, circulating, nirsevimab-resistant variants associated with various RSV A & B strains
- Half-life extension technology and biophysical properties expected to confer equivalent or greater in vivo half-life compared to nirsevimab and clesrovimab, which, along with higher potency, may expand the protective window of VBY329 compared to standard of care
- Invivyd expects to advance VBY329 toward IND readiness in 2H 2026 for development in pediatric RSV prophylaxis, a blockbuster pharmaceutical market in 2024, expected to grow to
$3 -$4 billion in annual revenues globally by 2030 - Additional Invivyd discovery efforts focus on ultra-long half-life RSV antibodies with the aim of a candidate RSV vaccine-alternative for elderly and immunocompromised populations
NEW HAVEN, Conn., Nov. 24, 2025 (GLOBE NEWSWIRE) -- Invivyd, Inc. (Nasdaq: IVVD) today announced it has identified and nominated for preclinical development a potentially best-in-class monoclonal antibody candidate for the prevention of Respiratory Syncytial Virus (RSV) among neonates, infants, and children. Invivyd’s investigational antibody, VBY329, was generated by Invivyd’s proprietary antibody discovery technology, targeted at high value infectious diseases. RSV is a common respiratory illness and is the leading cause of hospitalization for infants in the United States.
“We are pleased that our technology platform has enabled us to identify such a promising candidate and are thrilled with the in vitro properties VBY329 demonstrates,” commented Robert Allen, Ph.D., Chief Scientific Officer of Invivyd. “Following a screen that required greater resistance to variation than can be seen with class-leader nirsevimab, we have also achieved a major step change in average product potency compared to nirsevimab and clesrovimab. These biophysical properties are understood to predict the extent of protection from lower respiratory tract infection following from RSV infection in babies, as well as expanding the duration of likely protection.”
VBY329 follows from a discovery strategy that required it to demonstrate differential binding activity against pre-fusion stabilized F proteins from RSV-A2 and RSV-B313726, as well as proteins encoding resistance determinants to nirsevimab, and to demonstrate improved neutralization potency within a pseudovirus panel representing this collection of variants. Invivyd anticipates that success along these lines demonstrates biophysical properties that may predict best-in-class clinical performance compared to standard of care.
“We are proud of our progress with VBY329,” noted Marc Elia, Chairman of the Invivyd Board of Directors. “RSV prophylaxis among babies and children under 24 months is a blockbuster, rapidly growing pharmaceutical market that frees our youngest, most vulnerable Americans, including newborns, from a high-burden pathogen, all without requiring the immune stimulation of a vaccine. Monoclonal antibodies have served vulnerable young children and their parents and care teams for almost 30 years, and can be considered a model for other infectious diseases where populations would benefit from robust protection beyond the capabilities of a vaccine.”
Invivyd expects to present in vitro VBY329 data at a future medical congress. Invivyd is moving VBY329 into IND-enabling processes with a goal of IND readiness in the second half of 2026.
Invivyd, via its proprietary technology platform, continues to investigate additional monoclonal antibodies for protection and treatment of important infectious diseases, such as measles, among vulnerable populations.
About VBY329
VBY329 is a novel, potential best-in-class monoclonal antibody (mAb) candidate being developed to prevent Respiratory Syncytial Virus (RSV) among neonates, infants, and children.
About Invivyd
Invivyd, Inc. (Nasdaq: IVVD) is a biopharmaceutical company devoted to delivering protection from serious viral infectious diseases, beginning with SARS-CoV-2. Invivyd deploys a proprietary integrated technology platform unique in the industry designed to assess, monitor, develop, and adapt to create best in class antibodies. In March 2024, Invivyd received emergency use authorization (EUA) from the U.S. FDA for a monoclonal antibody (mAb) in its pipeline of innovative antibody candidates. Visit https://invivyd.com/ to learn more.
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Cautionary Note Regarding Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “anticipates,” “believes,” “could,” “expects,” “estimates,” “intends,” “potential,” “predicts,” “projects,” “targets” and “future” or similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. Forward-looking statements include statements concerning, among other things, the company’s RSV discovery program, and the potential of VBY329 as a novel, potential best-in-class mAb candidate being developed to prevent RSV among neonates, infants, and children; the company’s anticipated development timeline for VBY329 and goal of IND readiness in the second half of 2026; Invivyd’s expectation that certain properties of VBY329 assessed in vitro may predict best-in-class clinical performance compared to standard of care medicines; the potential for the half-life extension technology and biophysical properties of VBY329 to confer equivalent or greater in vivo half-life compared to nirsevimab and clesrovimab; expectations about the market size and opportunity for pediatric RSV prophylaxis; the potential of Invivyd’s additional discovery efforts focused on ultra-long half-life RSV antibodies to result in identifying a candidate RSV vaccine-alternative for elderly and immunocompromised populations; Invivyd’s expectation to present in vitro VBY329 data at a future medical congress; the potential of Invivyd’s technology platform to investigate additional monoclonal antibodies for protection and treatment of important infectious diseases, such as measles, among vulnerable populations; the company’s devotion to delivering protection from serious viral infectious diseases; and other statements that are not historical fact. The company may not actually achieve the plans, intentions or expectations disclosed in the company’s forward-looking statements and you should not place undue reliance on the company’s forward-looking statements. These forward-looking statements involve risks and uncertainties that could cause the company’s actual results to differ materially from the results described in or implied by the forward-looking statements, including, without limitation: the timing, progress and results of the company’s discovery and preclinical development activities, including with respect to VBY329; whether the company’s discovery efforts will result in identifying a candidate RSV vaccine-alternative for elderly and immunocompromised populations or a monoclonal antibody candidate for protection or treatment of measles, and the timing thereof; whether or not any preclinical candidate identified by the company is determined to be suitable for clinical development; the risk that results of nonclinical studies or clinical trials may not be predictive of future results, and interim data are subject to further analysis; the predictability of clinical success of the company’s product candidates based on neutralizing activity in nonclinical studies and the assessment of other in vitro properties; potential variability in neutralizing activity of product candidates tested in different assays, such as pseudovirus assays and authentic assays; the company’s reliance on third parties with respect to virus assay creation and product candidate testing; uncertainties related to the regulatory authorization or approval process, and available development and regulatory pathways for authorization or approval of the company’s product candidates; changes in the regulatory environment; whether VBY329 has an equivalent or greater in vivo half-life compared to nirsevimab and clesrovimab; changes in expected or existing competition; the complexities of manufacturing monoclonal antibodies; macroeconomic and political uncertainties; the company’s ability to continue as a going concern; and whether the company has adequate funding to meet future operating expenses and capital expenditure requirements. Other factors that may cause the company’s actual results to differ materially from those expressed or implied in the forward-looking statements in this press release are described under the heading “Risk Factors” in the company’s Annual Report on Form 10-K for the year ended December 31, 2024, and its Quarterly Report on Form 10-Q for the quarter ended September 30, 2025, each filed with the Securities and Exchange Commission (SEC), and in the company’s other filings with the SEC, and in its future reports to be filed with the SEC and available at www.sec.gov. Forward-looking statements contained in this press release are made as of this date, and Invivyd undertakes no duty to update such information whether as a result of new information, future events or otherwise, except as required under applicable law.
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FAQ
What is Invivyd announcing about VBY329 and the timeline for IND readiness for IVVD?
How does VBY329's potency compare to nirsevimab and clesrovimab in Invivyd data for IVVD?
What resistance advantage does VBY329 show versus nirsevimab-resistant RSV variants for IVVD?
Will Invivyd present VBY329 data publicly for IVVD and where?
Does Invivyd claim VBY329 has a longer half-life than current RSV antibodies for IVVD?
What market opportunity does Invivyd cite for pediatric RSV prophylaxis related to IVVD?
