Current News


Apr 2016
NEW PUBLICATION - Chimeric antigen receptor T cells secreting anti-PD-L1 antibodies more effectively regress renal cell carcinoma in a humanized mouse model

Advances in the treatment of metastatic clear cell renal cell carcinoma (ccRCC) have led to improved progression-free survival of many patients; however the therapies are toxic, rarely achieve durable long-term complete responses and are not curative. Herein we used a single bicistronic lentiviral vector to develop a new combination immunotherapy that consists of human anti-carbonic anhydrase IX (CAIX)-targeted chimeric antigen receptor (CAR) T cells engineered to secrete human anti-programmed death ligand 1 (PD-L1) antibodies at the tumor site. The local antibody delivery led to marked immune checkpoint blockade. Tumor growth diminished 5 times and tumor weight reduced 50-80% when compared with the anti-CAIX CAR T cells alone in a humanized mice model of ccRCC. The expression of PD-L1 and Ki67 in the tumors decreased and an increase in granzyme B levels was found in CAR T cells. The anti-PD-L1 IgG1 isotype, which is capable of mediating ADCC, was also able to recruit human NK cells to the tumor site in vivo. These armed second-generation CAR T cells empowered to secrete human anti-PD-L1 antibodies in the ccRCC milieu to combat T cell exhaustion is an innovation in this field that should provide renewed potential for CAR T cell immunotherapy of solid tumors where limited efficacy is currently seen. 

Suarez ER, Chang DK, Sun J, Sui J, Freeman GJ, Signoretti S, Zhu Q, Marasco WA. Chimeric antigen receptor T cells secreting anti-PD-L1 antibodies more effectively regress renal cell carcinoma in a humanized mouse model. Oncotarget. 2016 Apr 29. PMID: 27145284.

 

Mar 2016
NEW PUBLICATION - Humanized mouse G6 anti-idiotypic monoclonal antibody has therapeutic potential against IGHV1-69 germline gene-based B-CLL

In 10-20% of the cases of chronic lymphocytic leukemia of B-cell phenotype (B-CLL), the IGHV1-69 germline is utilized as VH gene of the B cell receptor (BCR). Mouse G6 (MuG6) is an anti-idiotypic monoclonal antibody discovered in a screen against rheumatoid factors (RFs) that binds with high affinity to an idiotope expressed on the 51p1 alleles of IGHV1-69 germline gene encoded antibodies (G6-id(+)). The finding that unmutated IGHV1-69 encoded BCRs are frequently expressed on B-CLL cells provides an opportunity for anti-idiotype monoclonal antibody immunotherapy. In this study, we first showed that MuG6 can deplete B cells encoding IGHV1-69 BCRs using a novel humanized GTL mouse model. Next, we humanized MuG6 and demonstrated that the humanized antibodies (HuG6s), especially HuG6.3, displayed ∼2-fold higher binding affinity for G6-id(+) antibody compared to the parental MuG6. Additional studies showed that HuG6.3 was able to kill G6-id(+) BCR expressing cells and patient B-CLL cells through antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). Finally, both MuG6 and HuG6.3 mediate in vivo depletion of B-CLL cells in NSG mice. These data suggest that HuG6.3 may provide a new precision medicine to selectively kill IGHV1-69-encoding G6-id(+) B-CLL cells.

Chang DK, Kurella VB, Biswas S, Avnir Y, Sui J, Wang X, Sun J, Wang Y, Panditrao M, Peterson E, Tallarico A, Fernandes S, Goodall M, Zhu Q, Brown JR, Jefferis R, Marasco WA. Humanized mouse G6 anti-idiotypic monoclonal antibody has therapeutic potential against IGHV1-69 germline gene-based B-CLL. MAbs. 2016 Mar 10:1-12. PMID: 26963739.


 

Feb 2016
NEW PUBLICATION - IGHV1-69 polymorphism modulates anti-influenza antibody repertoires, correlates with IGHV utilization shifts and varies by ethnicity

IGHV polymorphism provides a rich source of humoral immune system diversity. One important example is the IGHV1-69 germline gene where the biased use of alleles that encode the critical CDR-H2 Phe54 (F-alleles) to make broadly neutralizing antibodies (HV1-69-sBnAb) to the influenza A hemagglutinin stem domain has been clearly established. However, whether IGHV1-69 polymorphism can also modulate B cell function and Ab repertoire expression through promoter and copy number (CN) variations has not been reported, nor has whether IGHV1-69 allelic distribution is impacted by ethnicity. Here we studied a cohort of NIH H5N1 vaccinees and demonstrate for the first time the influence of IGHV1-69 polymorphism on V-segment usage, somatic hypermutation and B cell expansion that elucidates the dominance of F-alleles in HV1-69-sBnAbs. We provide evidence that Phe54/Leu54 (F/L) polymorphism correlates with shifted repertoire usage of other IGHV germline genes. In addition, we analyzed ethnically diverse individuals within the 1000 genomes project and discovered marked variations in F- and L- genotypes and CN among the various ethnic groups that may impact HV1-69-sBnAb responses. These results have immediate implications for understanding HV1-69-sBnAb responses at the individual and population level and for the design and implementation of "universal" influenza vaccine.

Avnir Y, Watson CT, Glanville J, Peterson EC, Tallarico AS, Bennett AS, Qin K, Fu Y, Huang CY, Beigel JH, Breden F, Zhu Q, Marasco WA. IGHV1-69 polymorphism modulates anti-influenza antibody repertoires, correlates with IGHV utilization shifts and varies by ethnicity. Sci Rep. 2016 Feb 16;6:20842. PMID: 26880249.

 

Dec 2015
NEW PUBLICATION - Anti-CCR4 antibody enhances anti-tumor immunity by modulating tumor-infiltrating Tregs in an ovarian cancer xenograft humanized mouse model

Recent studies have demonstrated that regulatory T cells (Tregs) are recruited to tumor sites where they can suppress antitumor immunity. The chemokine receptor CCR4 is expressed at high levels on functional CD4+CD25+FoxP3+ Tregs and production of the CCR4 ligand CCL22 by tumor cells and tumor-associated macrophages is associated with Treg recruitment to the tumor site. Here, we tested IgG1 and IgG4 isotypes of human anti-CCR4 mAb2-3 for their in vitro activity and in vivo capacity in a NSG mouse model bearing CCL22-secreting ovarian cancer (OvCA) xenograft to modulate Tregs and restore antitumor activity. Both mAb2-3 isotypes blocked in vitro chemoattraction of Tregs to CCL22-secreting OvCA cells. However, they differed in their in vivo mode of action with IgG1 causing Treg depletion and IgG4 blocking migration to the tumors. Primary T cells that were primed with OvCA-pulsed dendritic cells (DCs) demonstrated INFγ secretion that could be enhanced through Treg depletion by mAb2-3. Humanized mice reconstructed with allogeneic tumor-primed T cells (TP-T) were used to evaluate the restoration of OvCA immunity by depletion or blockade of Tregs with mAb2-3. We observed that IgG1 was more potent than IgG4 in inhibiting tumor growth. Mechanism studies demonstrated that mAb2-3 treatment lead to inhibition of IL-2 binding to its receptor. Further studies showed that mAb2-3 induced CD25 shedding (sCD25) from Tregs which lead to a decrease in IL-2-dependent survival. Together, the results demonstrate that mAb2-3 is an agonist antibody that can restore anti-OvCA immunity through modulation of Treg activity. 

Chang DK, Peterson E, Sun J, Goudie C, Drapkin RI, Liu JF, Matulonis U, Zhu Q, Marasco WA. Anti-CCR4 monoclonal antibody enhances antitumor immunity by modulating tumor-infiltrating Tregs in an ovarian cancer xenograft humanized mouse model. Oncoimmunology. 2015 Dec 10;5(3):e1090075. eCollection 2016 Mar. PMID: 27141347  

 

Dec 2014
NEW PUBLICATION - Effects of human anti-spike protein receptor binding domain antibodies on SARS coronavirus neutralization escape and fitness

The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002 and Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 has resulted in severe human respiratory disease with high death rates. Their zoonotic origins highlight the likelihood of reemergence or further evolution into novel human coronavirus pathogens. Broadly neutralizing antibodies (nAbs) that prevent infection of related viruses represent an important immunostrategy for combating coronavirus infections; however, for this strategy to succeed, it is essential to uncover nAb-mediated escape pathways and to pioneer strategies that prevent escape. Here, we used SARS-CoV as a research model and examined the escape pathways of broad nAbs that target the receptor binding domain (RBD) of the virus. We found that neither single nAbs nor two nAbs in combination blocked escape. Our results suggest that targeting conserved regions with less plasticity and more structural constraint rather than the SARS-CoV RBD-like region(s) should have broader utility for antibody-based immunotherapy  

Sui J, Deming M, Rockx B, Liddington RC, Zhu QK, Baric RS, Marasco WA.  Effects of human anti-spike protein receptor binding domain antibodies on severe acute respiratory syndrome coronavirus neutralization escape and fitness.  J Virol. 2014 Dec;88(23):13769-80. doi: 10.1128/JVI.02232-14. Epub 2014 Sep 17.  PMID: 25231316
 

June 26, 2014
NEW PUBLICATION - Prolonged expression of an anti-HIV-1 gp120 minibody to the female rhesus macaque lower genital tract by AAV gene transfer

Abstract
Topical microbicides are a leading strategy for prevention of HIV mucosal infection to women; however, numerous pharmacokinetic limitations associated with coitally related dosing strategy have contributed to their limited success. Here we test the hypothesis that adeno-associated virus (AAV) mediated delivery of the b12 human anti-HIV-1 gp120 minibody gene to the lower genital tract of female rhesus macaques (Rh) can provide prolonged expression of b12 minibodies in the cervical-vaginal secretions. Gene transfer studies demonstrated that, of various green fluorescent protein (GFP)-expressing AAV serotypes, AAV-6 most efficiently transduced freshly immortalized and primary genital epithelial cells (PGECs) of female Rh in vitro. In addition, AAV-6-b12 minibody transduction of Rh PGECs led to inhibition of SHIV162p4 transmigration and virus infectivity in vitro. AAV-6-GFP could also successfully transduce vaginal epithelial cells of Rh when applied intravaginally, including p63+ epithelial stem cells. Moreover, intravaginal application of AAV-6-b12 to female Rh resulted in prolonged minibody detection in their vaginal secretions throughout the 79-day study period. These data provide proof of principle that AAV-6-mediated delivery of anti-HIV broadly neutralizing antibody (BnAb) genes to the lower genital tract of female Rh results in persistent minibody detection for several months. This strategy offers promise that an anti-HIV-1 genetic microbicide strategy may be possible in which topical application of AAV vector, with periodic reapplication as needed, may provide sustained local BnAb expression and protection.

Abdel-Motal UM,  Harbison C, Han T, Pudney J, Anderson DJ, Zhu Q, Westmoreland S, Marasco WA.   Prolonged expression of an anti-HIV-1 gp120 minibody to the female rhesus macaque lower genital tract by AAV gene transfer. Gene Therapy. June 26, 2014; doi: 10.1038/gt.2014.56. pdf.



May 27-29, 2014
Endemic and Emerging Viral Diseases of Priority MENA (Middle East North Africa) Workshop in Doha, Qatar

Dr. Marasco will be speaking at the MENA workshop at the Four Seasons Hotel in Doha, Qatar on Wednesday, May 28.  The workshops scientific focus will be on Flaviviruses (including Hepatitis C and Al-Khumra), Hepatitis E, HIV/AIDS and its co-morbidities, Coronaviruses (including Middle East Respiratory Syndrome), and other viral diseases important in the MENA region.  The title of Dr. Marasco's talk is "Identification of Human Neutralizing Antibodies against MERS-CoV and Their Role in Virus Adaptive Evolution".

 


May 1, 2014
NEW PUBLICATION - Molecular Signatures of Hemagglutinin Stem-Directed Heterosubtypic Human Neutralizing Antibodies Against Influenza A Viruses

The quest for universal influenza vaccine has gained wide interest with the discovery of human neutralizing antibodies that are able to variably cross neutralize and protect against different influenza strains, subtypes, groups and lineages. These antibodies, which bind to a highly conserved epitope in the hemagglutinin stem, are often encoded by rearranged IGHV1-69 germline genes that alone make contact with HA and prevent virus entry and emergence of escape mutants. Our study was undertaken to gain an understanding of what structural requirements enable a rearranged IGHV1-69 Ab to become a potent cross-neutralizing antibody. We found that in addition to a critical amino acid triad consisting of a pair of anchor residues in CDR-H2 and a properly positioned CDRH3 Tyr, distinctive V-segment substitutions that arise in positions that are distinct from phase I AID somatic hypermutation (SHM) hotspot motifs are often required. As few as two V-segment SHM can fulfill this role which appears to facilitate the optimal binding of CDR-H2 Phe54 and CHR-H3-Tyr into adjacent hydrophobic pockets in the HA stem. These studies provide new information on the SHM requirements for IGHV1-69-encoded B cells to produce HV1-69-sBnAbs and suggest that there may exist alternative routes to their elicitation by vaccination.

Avnir Y, Tallarico AS, Zhu Q, Bennett AS, Connelly G, Sheehan J, Sui J, Fahmy A, Huang C-Y, Cadwell G, Bankston LA, McGuire AT, Stamatatos L, Wagner G, Liddington RC, Marasco WA.  Molecular Signatures of Hemagglutinin Stem-Directed Heterosubtypic Human Neutralizing Antibodies Against  Influenza A Viruses PLOS Pathogens. May 1, 2014, Vol 10, Issue 5 DOI:10.1371 pdf


April 28, 2014

NEW PUBLICATION - Identification of human neutralizing antibodies against MERS-CoV and their role in virus adaptive evolution

The recently emerged Middle East Respiratory Syndrome coronavirus (MERS-CoV) causes severe respiratory disease with ∼43% mortality. There is no licensed vaccine or antiviral for MERS. Here we identified seven human neutralizing Abs (nAbs) against MERS-CoV. These nAbs bind to three epitope groups in the viral Spike protein–receptor interface, blocking virus attachment. Five residues in the viral receptor-binding domain critical for neutralization escape were identified. Further study indicated that four of five mutations not only confer neutralization resistance but also impair receptor binding and viral fitness. This panel of nAbs offers the possibility of developing human mAb-based immunotherapy.

Tang XC, Agnihothram SS, Jiao Y, Stanhope J, Graham RL, Peterson EC, Avnir Y, Tallarico AS, Sheehan J, Zhu Q, Baric RS, Marasco WA.  Identification of human neutralizing antibodies against MERS-CoV and their role in virus adaptive evolution. PNAS April 28, 2014  PMID: 24778221

In the Media (featuring Dr. Marasco):
Why a MERS Vaccine Won't Be Easy, National Geographic, 5/23/14
Dana-Farber researcher blocks MERS virus in experiment, Boston Globe, 5/20/14
Scientists Searching for Antibodies Against Deadly Respiratory Disease, Boston Magazine 5/14/2014
How Cancer Researchers Are WOrking to Help FIght MERS Virus, DFCI Insight Blog, 5/15/2014
Boston institute developing effective treatments for MERS, NECN (New England Cable News) 5/14/2014
The MERS Virus-Dr. Wayne Marasco
, WRKO AM680 Boston, 5/13/2014
Second US Case of Mers confirmed: What You Need To Know, Forbes magazine, 5/13/2014
Second U.S. case of deadly MERS virus found in Orlando, USA Today, 5/13/2014
Logan travelers warnered about MERS virus, Boston Globe, 5/12/2014
First U.S. case of deadly MERS virus confirmed, USA Today article reprinted in the Israeli English Newspaper, 5/3/2014
Antibody Discovery may help combat deadly emerging disease
, DFCI Inside the Institute, 5/12/14
Scientists identify antibodies against deadly emerging respiratory disease, Dana-Farber Cancer Institute Spotlight, 4/28/14
MERS virus weakened by mutations, researchers found, Nature Middle East, 5/6/14
First Mers Case Reported in US, Still Not A Concern, US Finance Post, 5/6/2014
MERS outbreak picks up pace in Middle East, ScienceNews 5/5/14
First US case of deadly MERS virus confirmed: CDC
, Reuters, 5/2/14
Two MERS antibody studies may help quest for treatment.  Center for Infectious Disease Research and Policy News, 4/28/14
Scientists Identify Antibodies against Deadly Emerging MERS, Global Biodefense News on Pathogens & Preparedness, 4/9/14
Antibodies against deadly emerging disease MERS discovered, Science Daily, 4/28/14
MERS Cases & Research in the News this Week, ImmunoSEQ, 4/30/14