Adoptive cellular therapy after hematopoietic stem cell transplantation

Effective cellular therapy using CD19 chimeric antigen receptor T-cells for the treatment of advanced B-cell malignancies raises the question of whether the administration of adoptive cellular therapy (ACT) posttransplant could reduce relapse and improve survival. Moreover, several early phase clinical studies have shown the potential beneficial effects of administration of tumor-associated antigen-specific T-cells and natural killer cells posttransplant for high-risk patients, aiming to decrease relapse and possibly improve survival. In this article, we present an in-depth review of ACT after transplantation, which has the potential to significantly improve the efficacy of this procedure and revolutionize this field.

How I treat high-risk acute myeloid leukemia using preemptive adoptive cellular immunotherapy

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a potentially curative treatment for patients with high-risk acute leukemias, but unfortunately disease recurrence remains the major cause of death in these patients. Infusion of donor lymphocytes (DLI) has the potential to restore graft-versus-leukemia immunologic surveillance; however, efficacy varies across different hematologic entities. Although relapsed chronic myeloid leukemia, transplanted in chronic phase, has proven remarkably susceptible to DLI, response rates are more modest for relapsed acute myeloid leukemia and acute lymphoblastic leukemia. To prevent impending relapse, a number of groups have explored administering DLI preemptively on detection of measurable residual disease (MRD) or mixed chimerism. Evidence for the effectiveness of this strategy, although encouraging, comes from only a few, mostly single-center retrospective, nonrandomized studies. This article seeks to (1) discuss the available evidence supporting this approach while highlighting some of the inherent challenges of MRD-triggered treatment decisions post-transplant, (2) portray other forms of postremission cellular therapies, including the role of next-generation target-specific immunotherapies, and (3) provide a practical framework to support clinicians in their decision-making process when considering preemptive cellular therapy for this difficult-to-treat patient population.

The second international meeting on allogeneic transplantation in solid tumors

In October 2005, the second international meeting on allogeneic transplantation in solid tumors was convened in Stresa (Italy). The aim of this second meeting was to share clinical experiences of allografting in solid tumors, to discuss preclinical data on the mechanisms of graft-versus-tumor (GVT) effect, and to review methods for more efficacious transplant approaches. On the first day, the most recent results in cancer immunotherapy were reviewed; head-to head comparisons of clinical results achieved by standard therapy and by allografting in renal, breast, and ovarian cancer were presented. On the second day, GVT mechanisms and preclinical models were examined; anecdotal reports of a GVT effect in sarcoma, pancreatic cancer, prostate cancer, colorectal cancer and lung cancer were presented; new strategies for optimizing transplant outcome were discussed, including patient selection, tumor debulking, auto-allo approaches, selective T-cell depletion, targeting with monoclonal antibodies, use of killer cell immunoglobulin-like receptor-ligand mismatched natural killer cells. In conclusion, allografting in solid tumors is feasible with limited toxicities and transplant-related mortality; a GVT effect has been documented in many different solid tumors; targeting of the immune response to the tumor by new strategies and identification of the target antigen(s) of the GVT effect are promising areas of research.