Role of Adoptive T- Cell Therapy in Post Hematopoietic Stem Cells Transplant Viral Infections-: A Systemic Review
Authors: Imtiaz Hassaan , Farooqi Muhammad Saad , Faizan Unaiza , Rehman Saad Ur , Arshad Muhammed Hamza , Baloch Ali Shahbaz , Hashmi Syed Shahnawaz , Jamal Abdullah , Ali Taimoor Jaffar , Khan Ali Younas , Ahmed Zahoor , Dar Abdul Jabbar , Mirza Muhammad Ali , Khurshid Qasim , Anwer Faiz 
Published: November 2020

Introduction
Allogenic hematopoietic stem cell transplantation (Allo-HSCT) used for the treatment of multiple hematological malignancies requires immunosuppression, that can lead to the reactivation of viruses like EBV, CMV, adenovirus (AdV). These viruses pose a life-threatening risk to an individual like Graft vs Host Disease (GVHD) and other virus-specific complications. Adoptive T cell therapy (ATC) is an approach to treat refractory post-Allo-HSCT transplant viral infections. The aim of this study is to assess the efficacy of various ATCs being developed against various viruses.
Methods
A systematic search on PubMed, Embase, Clinicaltrials.gov, and Web of Science was performed for adoptive immunotherapy in viral infections after stem cell transplantation from inception to May 28, 2020. Out of 604 studies, 13 phase I and II clinical trials were selected for the systematic review.
Results
A total of 13 studies were included of which two studies included data on the pediatric population (n=13). A total of 335 patients (pts) were enrolled in 13 studies of which 264 were evaluable.
CMV
Perruccio et al. (2005) in a randomized controlled trial (RCT) assessed the efficacy of ATC against both Aspergillus and CMV after alloSCT. Median follow up (f/u) was six months. For Aspergillus (n=23), 90% and 54% achieved clearance, while for CMV (n=68) 92% and 9% didn't develop CMV reactivation in treatment and control group respectively. Overall Survival (OS) and progression-free survival (PFS) rate at two years were 92% and 80% respectively.
Smith et al. (2018) (n=21) in a phase I trial studied the transfusion of virus-specific T cells (VST) (n=13) against CMV infection after undergoing alloSCT. After a median f/u of 28 weeks, overall response rate (ORR) was 85%.
Bao et al. (2012) (n=10) conducted a study with VST transfusion against CMV infection (n=7). ORR was 85% of which 3 pts who were on immunosuppressive had shown reactivation.
Miej et al. (2012) in phase I/II study (n=6) assessed the response of VST against refractory CMV with CR of 100%
Neuenhahn et al. (2017) studied a phase I/II prospective trial (n=17) (CMV Seropositive graft donor (D+) 9/17 and CMV Seronegative graft donor (D-) 8/17) with CR of 62% in D+ group. In D- group only 37% developed T cells after Third-Party Donor transfer and only these achieved CR, while pts with no T cell detection in D- group (63%), only one achieved CR.
Micklethwaite et al. (2008) did a phase I clinical trial (n=12) of CMV specific T cells given prophylactically. Only four pts showed CMV reactivation.
Adenovirus
Feucht et al. (2019) performed a phase I/II clinical trial (n=30) of VST against refractory AdV infection. 47% showed CR, 13% with negative blood AdV cleared virus from other sites, 10% showed PR. OS at six months was 71%.
Winnie et al. (2018) (n=8) conducted phase I/II RCT among pediatric pts. Median f/u was six months. All patients have shown a decrease in AdV viral load.
Qasim et al. (2013) conducted a prospective trial (n=5) among pediatric pts with CR of 60% until six weeks f/u. 20% died due to AdV viremia.
Multi-virus CTLs
Gerdemann et al. (2013) (n=36) did a clinical trial by infusing multi-virus cytotoxic T lymphocytes (CTLs) (n=10), reactive against CMV, EBV, and AdV. CR in 80% of the pts.
Muranski et al. (2017) performed a phase I trial (n=9) and infused multi-virus CTLs prophylactically. No AdV, BK, or EBV related disease was observed in any pts while 11% pts had asymptomatic AdV viremia. Only those pts who received steroid therapy had CMV reactivation (44%).
Ma et al. (2015) performed a phase I/II RCT with an intervention group (n=19, evaluable=10) and control group (n=33) with an infusion of multi-virus CTLs against CMV, EBV, AdV, and VZV after alloSCT, prophylactically. Pts in the intervention group had no reactivation of EBV, AdV, or VZV. 6 (60%) pts with CMV had reactivation; four before T cell therapy and two in the context of steroid therapy. OS at one year was 89% and 81% in the intervention and control group respectively.
Third-Party Donor T-cells
Tzannou et al. (2017) (n=37) in a phase II study demonstrated ORR of 92% (95% CI, 78.1% to 98.3%) in various viruses with ORR for BK virus 100%, CMV 94%, Adv 71%, EBV 100% and HHV-6 67%.
Conclusion
Adoptive T cell therapy for viral infections has shown efficacy in Post- allo-SCT pts who achieved complete clearance of infection in many cases, showed only minimal adverse events, and no major risk for GVHD related to this therapy was noted.

Disclosures
Anwer: Incyte, Seattle Genetics, Acetylon Pharmaceuticals, AbbVie Pharma, Astellas Pharma, Celegene, Millennium Pharmaceuticals.: Honoraria, Research Funding, Speakers Bureau.