Stem cell transplantation programme at Singapore General Hospital

Natural Killer Cells for Therapy of Leukemia

Clinical application of natural killer (NK) cells against leukemia is an area of intense investigation. In human leukocyte antigen-mismatched allogeneic hematopoietic stem cell transplantations (HSCT), alloreactive NK cells exert powerful anti-leukemic activity in preventing relapse in the absence of graft-versus-host disease, particularly in acute myeloid leukemia patients. Adoptive transfer of donor NK cells post-HSCT or in non-transplant scenarios may be superior to the currently widely used unmanipulated donor lymphocyte infusion. This concept could be further improved through transfusion of activated NK cells. Significant progress has been made in good manufacturing practice (GMP)-compliant large-scale production of stimulated effectors. However, inherent limitations remain. These include differing yields and compositions of the end-product due to donor variability and inefficient means for cryopreservation. Moreover, the impact of the various novel activation strategies on NK cell biology and in vivo behavior are barely understood. In contrast, reproduction of the third-party NK-92 drug from a cryostored GMP-compliant master cell bank is straightforward and efficient. Safety for the application of this highly cytotoxic cell line was demonstrated in first clinical trials. This novel 'off-the-shelf' product could become a treatment option for a broad patient population. For specific tumor targeting chimeric-antigen-receptor-engineered NK-92 cells have been designed.

Emerging natural killer cell immunotherapies: large-scale ex vivo production of highly potent anticancer effectors

Natural killer (NK) cell therapies are emerging worldwide as promising anticancer treatments, exploiting the fast cytolytic action of NK effectors and their potentially broad applicability against a wide range of malignancies. Until recently, clinical protocols have mainly involved freshly isolated NK cells or short- term activated NK cells or lymphokine-activated killer (LAK) cells. However, overall effector numbers and their anticancer potencies remained restricted, which poses a limiting factor to clinical efficacy. Recent developments in the field aim to improve clinical trial designs by increasing effector to target cell ratios in vivo and by application of superior cytotoxic NK effectors. Large-scale production of clinical grade NK cells through long-term activation in ex vivo cultures are another novel means in achieving these goals. However, such procedures require compliance with the strict Good Manufacturing Practice (GMP) regulations to ensure quality and safety of the NK cell product. Although the overall number of new protocols still remains comparably low, some of the protocols are already translated into clinical use. Also striking is the diversity of the different protocols proposed. We highlight in this review the most recent developments in the NK cell field with a focus on long-term NK cell expansion. Critical issues relating to this novel and promising type of therapy are highlighted and discussed.

Cord blood banking in France: reorganising the national network

Paradoxically, France is one of the leading exporters of cord blood units worldwide, but ranks only 17th in terms of cord blood units per inhabitant, and imports 64% of cord blood grafts to meet national transplantation demands. With three operational banks in 2008, the French allogeneic cord blood network is now entering an important phase of development with the creation of seven new banks collecting from local clusters of maternities. Although the French network of public banks is demonstrating a strong commitment to reorganise and scale up its activities, the revision of France's bioethics law in 2010 has sparked a debate concerning the legalisation of commercial autologous banking. The paper discusses key elements for a comprehensive national plan that would strengthen the allogeneic banking network through which France could meet its national medical needs and guarantee equal access to healthcare.

Trends of hematopoietic stem cell transplantation in the third millennium

PURPOSE OF REVIEW

Hematopoietic stem cell transplantation (HSCT) has evolved into an accepted therapy for many congenital or acquired disorders of the hematopoietic system. It has seen major changes in indications and use of transplant techniques. HSCT is a high cost procedure and requires investments; information on trends is essential for patient counselling and healthcare planning.

RECENT FINDINGS

HSCT rates have increased worldwide. Increase is constant and predictable; the reasons therefore are manifold. Introduction of reduced intensity conditioning regimens has opened access to patients at older age and with comorbidities. Higher numbers of unrelated volunteer donors and cord blood products give access to HSCT for patients without family donors. For some well defined indications, HSCT has become the most cost efficient therapy in countries with limited resources. Use of HSCT is under discussion for nonhematopoietic indications, as is the use of nonhematopoietic stem cells for organ repair.

SUMMARY

HSCT is likely to continue to increase for currently established indications. Indications and technologies will vary between countries with limited or nonrestricted resources. The most cost effective approach might not be the same everywhere. Novel indications will emerge but time will be needed to confirm their benefit. Close observation of global trends will become an essential tool for healthcare agencies in order to provide the necessary infrastructure in time.