Reduced-intensity allogeneic hematopoietic stem cell transplantation in metastatic colorectal cancer as a novel adoptive cell therapy approach. The European group for blood and marrow transplantation experience

Abstract Reduced-intensity conditioning (RIC) regimens for allogeneic hematopoietic stem cell transplantation (HCT) allowed the existence of an allogeneic cell-mediated antitumor effect in metastatic colorectal cancer (mCRC) to be explored. We report on 39 patients with progressing mCRC treated with different RIC regimens in a multicenter clinical trial of the European Bone Marrow Transplantation Group. Disease status at transplant was progressive disease (PD) in 31 patients (80%), stable disease (SD) in 6 (15%), and partial response (PR) in 2 (5%). All patients engrafted (median donor T cell chimerism of 90% at day +60). Transplant-related morbidities were limited. Grades II-IV acute graft-versus-host disease (aGVHD) occurred in 14 patients (35%) and chronic GVHD (cGVHD) in 9 patients (23%). Transplant-related mortality occurred in 4 patients (10%). The best tumor responses were: 1 complete response (CR) (2%), 7 PR (18 %), and 10 SD (26%), giving an overall disease control in 18 of 39 patients (46%). Allogeneic HCT after RIC is feasible; the collected results compared favorably in terms of tumor response with those observed using conventional approaches beyond second-line therapies. The study of an allogeneic cell based therapy in less advanced patients is warranted

Immune reconstitution after allogeneic hematopoietic stem cell transplantation

After treatment with allogeneic hernatopoietic stem cell transplantation (HSCT) the patient suffers from a deficient immune system for at least 12 months or longer. During this period, the patient is susceptible to infections and if the state of immune deficiency is prolonged there is an increased risk of relapse of the underlying malignancy as well as development of secondary malignancies. The aim of this thesis was to study cellular and molecular mechanisms of the immune reconstitution after HSCT and investigate ways of promoting immune recovery. Previous studies from our group have demonstrated an oligoclonality of the B lymphocyte repertoire after HSCT. Studying the Ig heavy chain CDR3 repertoire in naive and memory B lymphocytes with CDR3 fragment size analysis, we could demonstrate a restricted diversity in memory B lymphocytes compared to naive B cells. At three months after HSCT, this restriction of the memory B cell pool is important to the overall restriction of the B lymphocyte repertoire. T cell function is low at this time point since the number of circulating T cells is decreased and treatment with immunosuppressive drugs inhibits T cell activation. However, T cell dysfunction alone does not explain restriction of the B cell repertoire after HSCT, our data also demonstrate an intrinsic B cell dysfunction. To determine the role of the conditioning regimen in the immune reconstitution after HSCT, we compared B and T cell recovery after HSCT in patients undergoing HSCT with reduced intensity conditioning or myeloablative conditioning. Comparing circulating levels of B, T and NK cells, no difference was detected between the groups. Analyzing the Ig H CDR3 repertoire with CDR3 fragment size analysis, we demonstrate a delayed recovery of the B cell repertoire, especially in patients undergoing HSCT with reduced intensity conditioning. On the other hand, TcRVbeta CDR3 repertoire recovery was faster in patients undergoing HSCT with reduced intensity conditioning than patients treated with myeloablative conditioning regimen. Thus, our data indicate that immune reconstitution is more dependent on other factors than the type of conditioning used before HSCT. There is a lot to gain if the period of immune deficiency after HSCT could be shortened or mitigated. Neuroendocrine hormones have been suggested as therapy to promote immune reconstitution after HSCT. We demonstrate altered levels of IGF-1R and TRalpha 1 receptor RNA expression in PBMCs after HSCT. The decreased IGF-1R RNA expression coincided with the expansion of T cells and activated T cells have previously been demonstrated to express low levels of IGF-1R. Therefore, we analyzed the expression of IGF-1R RNA in CD4 positive and CD8 positive T cells with real-time PCR technique. To investigate if GVHD was the T cell activating event, we correlated IGF-1R RNA expression with occurrence of GVHD. We demonstrate a decreased expression of IGF-1R RNA in CD4 and CD8 positive T lymphocytes up to twelve months after HSCT, that was not correlated to acute or chronic GVHD. Further studies are needed to clarify the role of IGF-1R in immune reconstitution after HSCT. In this thesis we have investigated mechanisms underlying the clinical problem of immune deficiency following HSCT, with advanced immunological and molecular biological methods. With this approach we intend to continue collecting knowledge about immune reconstitution in these severely ill patients and hopefully contribute to improved treatment and care

Mass Cytometry and Topological Data Analysis Reveal Immune Parameters Associated with Complications after Allogeneic Stem Cell Transplantation

Human immune systems are variable, and immune responses are often unpredictable. Systems-level analyses offer increased power to sort patients on the basis of coordinated changes across immune cells and proteins. Allogeneic stem cell transplantation is a well-established form of immunotherapy whereby a donor immune system induces a graft-versus-leukemia response. This fails when the donor immune system regenerates improperly, leaving the patient susceptible to infections and leukemia relapse. We present a systems-level analysis by mass cytometry and serum profiling in 26 patients sampled 1, 2, 3, 6, and 12 months after transplantation. Using a combination of machine learning and topological data analyses, we show that global immune signatures associated with clinical outcome can be revealed, even when patients are few and heterogeneous. This high-resolution systems immune monitoring approach holds the potential for improving the development and evaluation of immunotherapies in the future

Improved Survival after Allogeneic Hematopoietic Stem Cell Transplantation in Recent Years. A Single-Center Study

We analyzed the outcome of allogeneic hematopoietic stem cell transplantation (HSCT) over the past 2 decades. Between 1992 and 2009, 953 patients were treated with HSCT, mainly for a hematologic malignancy. They were divided according to 4 different time periods of treatment: 1992 to 1995, 1996 to 2000, 2001 to 2005, and 2006 to 2009. Over the years, many factors have changed considerably regarding patient age, diagnosis, disease stage, type of donor, stem cell source, genomic HLA typing, cell dose, type of conditioning, treatment of infections, use of granulocyte-colony stimulating factor (G-CSF), use of mesenchymal stem cells, use of cytotoxic T cells, and home care. When we compared the last period (2006-2009) with earlier periods, we found slower neutrophil engraftment, a higher incidence of acute graft-versus-host disease (aGVHD) of grades II-IV, and less chronic GVHD (cGHVD). The incidence of relapse was unchanged over the 4 periods (22%-25%). Overall survival (OS) and transplant-related mortality (TRM) improved significantly in the more recent periods, with the best results during the last period (2006-2009) and a 100-day TRM of 5.5%. This improvement was also apparent in a multivariate analysis. When correcting for differences between the 4 groups, the hazard ratio for mortality in the last period was 0.59 (95% confidence interval [CI]: 0.44-0.79; P < .001) and for TRM it was 0.63 (CI: 0.43-0.92; P = .02). This study shows that the combined efforts to improve outcome after HSCT have been very effective. Even though we now treat older patients with more advanced disease and use more alternative HLA nonidentical donors, OS and TRM have improved. The problem of relapse still has to be remedied. Thus, several different developments together have resulted in significantly lower TRM and improved survival after HSCT over the last few years