Exhibit 99.3

U.S. Patents Owned or Licensed by MedImmune, Inc.*

|Product/ Project |  | US Patent
No. |  | Subject Matter                                                                                            |  | Expiration Date
|---------------- |  | ------------- |  | --------------------------------------------------------------------------------------------------------- |  | ---------------
|E. coli          |  | 4,795,803     |  | Adhesin antigens                                                                                          |  | 1/3/2006       
|                 |  | 5,804,198     |  | Adhesin vaccines                                                                                          |  | 9/8/2015       
|                 |  | 6,291,649     |  | Anti-adhesin antibodies                                                                                   |  | 3/2/2005       
|                 |  | 6,500,434     |  | Chaperone and Adhesin Proteins: Vaccines, Diagnostic and Methods for Treating Infections                  |  | 4/23/2019      
|Vitaxin          |  | 5,753,230     |  | Use of antibodies anti- avb3 antibodies to inhibit angiogenesis in tumors and inflamed tissue             |  | 5/19/2015      
|MEDI-507         |  | 5,730,979     |  | Anti-CD2 antibodies and their use in treating T-cell mediated immune responses                            |  | 3/24/2015      
|                 |  | 5,951,983     |  | Anti-CD2 antibodies and their use in treating T-cell mediated immune responses                            |  | 9/14/2016      
|                 |  | 5,817,311     |  | Use of anti-CD2 antibodies in treating T-cell mediated immune responses                                   |  | 10/6/2015      
|HPV              |  | 6,228,368     |  | Capsomeres containing HPV L1 protein and their use in preventing and treating HPV infection               |  | 10/6/2017      
|                 |  | 6,066,324     |  | HPV VLPs containing L1 protein with deletions                                                             |  | 10/9/2015      
|                 |  | 6,261,765     |  | Disassembly/reassembly of Papillomavirus Virus Like Particles                                             |  | 9/5/2017       
|                 |  | 6,165,471     |  | HPV capsomeres with reduced assembly capacity                                                             |  | 7/2/2018       
|                 |  | 6,153,201     |  | Oral Immunization with Papillomavirus Virus Like Particles                                                |  | 3/9/2013       
|                 |  | 6,361,778     |  | Papillomavirus Like Particles, Fusion Proteins as well as Processes for Their Production                  |  | 9/16/2019      
|                 |  | 6,416,945     |  | Disassembly/reassembly of Papillomavirus Virus Like Particles                                             |  | 9/5/2017       
|RSV              |  | 5,824,307     |  | Synagis® & other anti-RSV antibodies and their use in treating or preventing RSV infection                |  | 10/20/2015     
|                 |  | 5,582,827     |  | Immunoglobulin from plasma for treatment of RSV                                                           |  | 12/10/2013     
|                 |  | 4,800,078     |  | Treatment of respiratory disease caused by RSV using human gamma globulin                                 |  | 1/24/2006      
|                 |  | 5,412,077     |  | Effective Antibody Titers Against Respiratory Viruses                                                     |  | 8/4/2020       
|Strep            |  | 5,928,900     |  | Pad1 protein                                                                                              |  | 7/27/2016      
|                 |  | 5,981,229     |  | DNA encoding Exp1 and PlpA proteins                                                                       |  | 11/9/2016      
|                 |  | 5,834,278     |  | DNA encoding pneumococcal MsrA                                                                            |  | 5/1/2016       
|                 |  | 6,245,335     |  | Streptococcal choline binding proteins                                                                    |  | 5/1/2017       
|                 |  | 5,736,367     |  | Vectors and Prokaryotes which Autocatalytically Delete Resistance                                         |  | 4/7/2018       
|                 |  | 5,798,243     |  | Bacterial Peptide Methionine Sulfoxide Reductase an Adhesion Associated Protein, and Antibiotic Therapies |  | 5/1/2016       
|                 |  | 6,420,135     |  | Streptococcus pneumoniae polynucleotides and sequences                                                    |  | 10/03/17       
|                 |  | 6,503,511     |  | Derivatives of Choline Binding Proteins for Vaccines                                                      |  | 4/6/2019       
|IL-9             |  | 5,157,112     |  | Antibodies which specifically bind mammalian T cell growth factor P40                                     |  | 10/20/2009     
|                 |  | 6,037,149     |  | DNA and RNA molecules that encode Met-IL-9 and their use for recombinant production                       |  | 8/23/2016      
|                 |  | 5,580,753     |  | DNA molecules encoding IL-9 and their use for recombinant production                                      |  | 12/3/2013      
|                 |  | 5,734,037     |  | Nucleic acid molecules that hybridize to DNA encoding IL-9                                                |  | 5/23/2009      
|                 |  | 5,414,071     |  | Human IL-9 protein                                                                                        |  | 5/9/2012       
|                 |  | 5,164,317     |  | Method for enhancing proliferation of mast cells using IL-9                                               |  | 3/23/2010      
|                 |  | 5,132,109     |  | Method for enhancing IgG production using IL-9 and IL-4                                                   |  | 10/5/2010      
|                 |  | 5,246,701     |  | Method to inhibit IgE production using anti-IL-9 antibodies or other IL-9 inhibitors                      |  | 10/5/2010      

---

|          |  | 5,962,269 |  | Processes and hybridomas for producing anti-IL-9 receptor antibodies                                                                                                                                                                                                                            |  | 10/5/2016 
|--------- |  | --------- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |  | ----------
|          |  | 6,261,559 |  | Treating asthmatic symptoms using anti-IL-9 antibodies                                                                                                                                                                                                                                          |  | 8/23/2016 
|          |  | 5,789,237 |  | Nucleic acid molecules that hybridize to DNAs encoding human and murine IL-9 receptors                                                                                                                                                                                                          |  | 8/4/2015  
|          |  | 5,750,377 |  | Methods for production of mammalian T cell growth factor P40                                                                                                                                                                                                                                    |  | 5/12/2015 
|          |  | 5,116,951 |  | IL-9 receptor protein                                                                                                                                                                                                                                                                           |  | 9/19/2010 
|          |  | 5,587,302 |  | Nucleic acid molecules encoding mammalian T cell growth factor P40                                                                                                                                                                                                                              |  | 12/24/2013
|          |  | 5,208,218 |  | Mammalian T cell growth factor P40 protein                                                                                                                                                                                                                                                      |  | 5/4/2010  
|          |  | 5,180,678 |  | Methods of detecting IL-9                                                                                                                                                                                                                                                                       |  | 9/19/2010 
|Ethyol    |  | 5,424,471 |  | Process for preparing crystalline forms                                                                                                                                                                                                                                                         |  | 7/13/2012 
|          |  | 5,591,731 |  | Dosage forms of crystalline amifostine                                                                                                                                                                                                                                                          |  | 7/31/2012 
|          |  | 5,824,664 |  | Agents and methods for inhibiting HIV viral and protein expression using compounds that belong to a family which contains amifostine                                                                                                                                                            |  | 10/20/2015
|          |  | 5,846,958 |  | Methods of stimulating hematopoietic progenitor cells using a compound that belong to a family which contains amifostine                                                                                                                                                                        |  | 12/8/2015 
|          |  | 5,906,984 |  | Methods of stimulating hematopoietic progenitor cells using specific compounds, which include amifostine                                                                                                                                                                                        |  | 2/17/2015 
|          |  | 5,994,409 |  | Methods of treating toxicities associated with chemotherapy, a method of treating a nephrodisorder, and a method of treating xerostomia, all of which use a compound that belongs to a family which contains
amifostine                                                                         |  | 12/9/2017 
|          |  | 6,051,563 |  | Subcutaneous administration, method of protecting against toxicities associated with ionizing radiation                                                                                                                                                                                         |  | 2/12/2017 
|          |  | 6,127,351 |  | Methods of treating or protecting against toxicities associated with chemotherapy using a specific dosing regime, a method of stimulating bone marrow growth, and a method of treating myelodysplastic syndrome, all of which
use a compound that belongs to a family which contains amifostine |  | 2/12/2017 
|          |  | 6,218,377 |  | Methods of treating or protecting against toxicities associated with specific chemotherapy agents, and a method of protecting normal tissue in cancer patients, both of which use a compound that belongs to a family which
contains amifostine                                                 |  | 2/12/2017 
|          |  | 6,239,119 |  | Methods of treating damaged or infected mucosal tissue using a compounds that belongs to a family which contains amifostine                                                                                                                                                                     |  | 4/26/2019 
|          |  | 6,384,259 |  | Stable Amorphous Amifostine Composition and Methods for the Preparation and Use of the Same                                                                                                                                                                                                     |  | 11/16/2018
|          |  | 6,407,278 |  | Stable Amorphous Amifostine Composition and Methods for the Preparation and Use of the Same                                                                                                                                                                                                     |  | 11/16/2018
|          |  | 6,489,312 |  | Novel Pharmaceutical Formulations Comprising Aminoalkyl Phosphorothioates                                                                                                                                                                                                                       |  | 6/15/2019 
|NeuTrexin |  | 5,716,960 |  | Cystalline glucuronate hydrate salt                                                                                                                                                                                                                                                             |  | 2/10/2015 
|          |  | 6,017,921 |  | Crystalline glucuronate salt                                                                                                                                                                                                                                                                    |  | 1/13/2015 
|          |  | 6,017,922 |  | Thermally stable crystalline non-salts                                                                                                                                                                                                                                                          |  | 5/18/2018 
|          |  | 6,258,821 |  | Trimetrexate ascorbate and compositions comprising trimetrexate and ascorbic acid                                                                                                                                                                                                               |  | 4/26/2019 
|          |  | 6,258,952 |  | Methods of producing monohydrate                                                                                                                                                                                                                                                                |  | 5/18/2018 
|          |  | 4,376,858 |  | 2,4-Diamino-5-methyl-6-[(3,4,5-
trimethoxyanilino)methyl]quinazoline salts                                                                                                                                                                                                                      |  | 10/31/2004
|          |  | 4,694,007 |  | Use of Trimetrexate as Antiparasitic Agent                                                                                                                                                                                                                                                      |  | 9/15/2006 
|          |  | 4,677,219 |  | Substituted Benzonitriles                                                                                                                                                                                                                                                                       |  | 7/17/2006 

---

|                              |  | 5,160,727 |  | Tumor Cell Sensitization Method                                                        |  | 3/21/2010 
|----------------------------- |  | --------- |  | -------------------------------------------------------------------------------------- |  | ----------
|PALA                          |  | 5,491,135 |  | Methods of treating a viral infections (e.g.,hepatitis B and C and secondary to HIV 1) |  | 2/13/2013 
|Platinum                      |  | 4,895,935 |  | Platinum Pharmaceuticals                                                               |  | 1/23/2007 
|CMV                           |  | 6,291,236 |  | Human CMV sequences and attenuated viruses                                             |  | 3/31/2015 
|                              |  | 5,925,751 |  | Human CMV sequences and attenuated viruses                                             |  | 3/31/2015 
|                              |  | 5,721,354 |  | Human CMV sequences and attenuated viruses                                             |  | 3/31/2015 
|                              |  | 6,040,170 |  | Human CMV sequences and attenuated viruses                                             |  | 3/31/2015 
|EBV                           |  | 4,707,358 |  | Epstein-Barr virus gp350 subunit protein vaccine                                       |  | 11/17/2004
|                              |  | 6,054,130 |  | Non-splicing variants of EBV gp350 protein and gene                                    |  | 4/18/2014 
|                              |  | 5,824,508 |  | Non-splicing variants of EBV gp350 protein and gene                                    |  | 4/18/2014 
|                              |  | 6,458,364 |  | Non-Splicing Variants of GP350/220                                                     |  | 04/24/2020
|Influenza                     |  | 5,690,937 |  | Temperature sensitive mutants of influenza                                             |  | 6/5/2015  
|                              |  | 6,090,391 |  | Recombinant tryptophan mutants of influenza PB2 gene                                   |  | 2/23/2016 
|                              |  | 6,322,967 |  | Recombinant tryptophan mutants of influenza PB2 gene                                   |  | 2/23/2016 
|HSV                           |  | 4,554,159 |  | Vaccine against HSV-1 and HSV-2                                                        |  | 11/19/2002
|                              |  | 4,769,331 |  | Recombinant herpes simplex cloning methods and materials                               |  | 9/6/2005  
|                              |  | 4,859,587 |  | Recombinant herpes simplex vectors and vaccines                                        |  | 8/22/2006 
|                              |  | 5,288,641 |  | Herpes simplex as a vector                                                             |  | 2/22/2011 
|                              |  | 5,328,688 |  | Recombinant herpes simplex with 34.5 gene knockout                                     |  | 6/12/2011 
|                              |  | 5,599,691 |  | Herpes simplex as a vector                                                             |  | 2/4/2014  
|                              |  | 5,641,651 |  | Synthetic HSV promoters and uses                                                       |  | 6/24/2014 
|                              |  | 5,714,153 |  | Recombinant herpes simplex vaccines and vectors                                        |  | 12/23/2012
|                              |  | 5,846,707 |  | Herpes simplex as a vector                                                             |  | 6/4/2004  
|                              |  | 5,922,328 |  | Gamma 34.5 mutants of herpes simplex viruses                                           |  | 9/11/2016 
|                              |  | 6,071,692 |  | Herpes simplex as a gene expression vector and vaccine                                 |  | 6/4/2004  
|                              |  | 6,120,773 |  | Gamma 34.5 gene modification of herpes simplex viruses                                 |  | 9/19/2017 
|                              |  | 6,172,047 |  | Herpes viruses modified for use as cancer treatment                                    |  | 1/9/2018  
|Negative Stranded RNA Viruses |  | 5,166,057 |  | Recombinant negative strand RNA viruses                                                |  | 11/24/2009
|                              |  | 5,578,473 |  | Recombinant negative strand RNA viruses                                                |  | 11/24/2009
|                              |  | 5,786,199 |  | Recombinant negative strand RNA viruses and vaccines                                   |  | 7/28/2015 
|                              |  | 5,820,871 |  | Recombinant negative strand RNA viruses  bicistronic                                  |  | 10/13/2015
|                              |  | 5,854,037 |  | Recombinant negative strand RNA viruses                                                |  | 12/29/2015
|                              |  | 6,001,634 |  | Recombinant negative strand RNA viruses                                                |  | 8/28/2009 
|                              |  | 6,022,726 |  | Attenuated negative strand RNA viruses and methods                                     |  | 2/8/2017  
|                              |  | 6,316,243 |  | Recombinant attenuated double strand RNA viruses                                       |  | 11/13/2018
|                              |  | 5,840,520 |  | Recombinant RSV viruses                                                                |  | 11/24/2015
|VZV                           |  | 6,087,170 |  | VZV gene and mutant VZV viruses                                                        |  | 4/28/2014 

---

QuickLinks