Poplar Therapeutics, a Boston-based clinical-stage immunology company, has raised $45M in Series A extension funding led by Janus Henderson Investors. The company develops PHB-050, a next-generation anti-IgE antibody engineered to rapidly deplete IgE levels for patients with food allergy, atopic dermatitis, and other IgE-mediated diseases. The capital will advance Phase 1 trials of PHB-050, targeting high-IgE patients ineligible for current therapies like Xolair.
Food Allergy Funding Heats Post-RAPT
The extension brings total Series A to $95M, following a $50M initial round in January 2026 led by SR One. It arrives amid big pharma interest, with GSK acquiring RAPT Therapeutics for $2.2B in January 2026. Competitors like IgGenix raised $75M for allergen-specific antibodies, while Excellergy secured $70M for IgE cell blockers. Poplar's pan-IgE depletion approach fills gaps left by indication-specific rivals.
7M High-IgE Patients Excluded
IgE-mediated atopic diseases affect 20-30% of the global population, with food allergy alone impacting millions. Current anti-IgE therapy Xolair excludes patients with IgE levels above 700 IU/mL, leaving 3M U.S. patients untreated. These high-IgE individuals face severe risks from anaphylaxis, costing the U.S. healthcare system billions annually in emergency care.
Triple-Action Design Depletes IgE
PHB-050 features a humanized camelid VHH IgG1 Fc-fusion with SELF mutations for enhanced effector function. It blocks soluble IgE, promotes immune clearance of IgE-producing cells, and inhibits new production — driving total IgE toward zero faster than Xolair. Unlike IgGenix's peanut-specific antibodies or Excellergy's cell-bound IgE focus, Poplar targets broad atopic conditions.
As Tony Yao, Founder and CSO, explained:
"Preclinical data suggest PHB-050 can not only bind and block soluble IgE but can also rapidly drive total IgE toward zero."
This mechanism addresses Xolair's slow onset and high-IgE limitations.
Investors Back Clinical Push
Janus Henderson led the extension, joined by new investor RA Capital Management, with participation from SR One, Vida Ventures, and ArrowMark Partners. SR One's immunology track record includes Pandion Therapeutics' acquisition by Merck and Morphic Therapeutic's NASDAQ listing. The mix of VCs and asset managers signals conviction in Poplar scaling to Phase 2 amid a validated market.
Allergy Market Scales to $11B
The food allergy treatment market stands at $6.87B in 2024, projected to reach $11.33B by 2030 at 8.3% CAGR. Broader allergy therapeutics hit $41B with 6.6% CAGR. Xolair's 2024 FDA approval for food allergy spurred investment, yet gaps persist for high-IgE cases. Mabylon raised $37M in 2023 for peanut allergy antibodies.
Exits Fuel Leadership Credibility
Founder Tony Yao holds a Stanford MD PhD in immunology and developed PHB-050 at prior venture Phylaxis Bioscience. CEO Chip Baird led 2seventy bio through its $286M acquisition by Bristol Myers Squibb in 2025. CFO Vicki Eatwell managed finance during that exit, bringing proven scaling expertise to Poplar's Phase 1 program.
Phase 1 Data Expected 2H 2026
Funds extend runway through Phase 1 readout in second-half 2026, focusing on safety, pharmacokinetics, and pharmacodynamics in food allergy. Poplar plans multiple atopic indications, leveraging preclinical potency in high-IgE models.