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Gamma-Delta Immunotherapy

A Preamble

γδ T cells or “gammadelta” T cells are unique to primates and represent a minority white cell in our blood (0.5-5%); yet they play an essential role in sensing ‘danger’ by invading pathogens as they expand dramatically in many acute infections and may be a key fighter in cancer as well.  I want to discuss very exciting findings of how to harness these cells as an anticancer strategy but why does it belong in this blog?

Technically, gammadelta therapy is an immune therapy and is not “off-label” per se, because since these are a patient’s own cells, there is no issue of FDA approval or non-approval, and thus no issue of being on or off-label !   But, the key here are the drugs used to expand gammadelta T cells to use them to fight cancer are approved for other uses and these agents can be used off-label to direct the expansion of gammadelta T cells, hence the mention of this treatment here.

I am not easily excited, having been “in the business” if you will for decades and having seen so many mediocre agents and methods come and go in our “war against cancer” where true advance has been been disappointingly few.  But this time we may be on to something truly special.  The title of a recent review article by N Caccamo of Italy “Amiophosphonate-activated gammadelta T cells in immunotherapy of cancer: Doubt no more” ( Expert Opin Biol Ther 2008 Jul; 8:7, pp. 875-883) sums up the excitement.

Some Background

The background is not necesarily an easy one to understand if you do not have a science or medical background.  There are surprisingly few general introductory books on the topic, but the dated (1992) paperback “The Transformed Cell” by Steven Rosenberg is still a good primer for those who are interested but not necessarily want to earn college credit on the subject. And if you are not much interested at all in how this method works and all the immunology mumbo jumbo, but just want to know the practicalities of the treatment, you may as well skip to the last 2 sections to avoid a headful (and a headache!).

I have also put in BOLD some key concepts here in  order to highlight the key concepts for non-scientist or patients to help understand all this.

We as mammals have two innate immune defense systems:  an adaptive immune system unique to vertebrates in which lymphocytes participate with recognition of peptide antigens and which can be defined by memory of the target; and a more ancient innate immunity which is cell based (macrophages, monocytes, NK cells, NKT cells, dendritic cells) and which has no memory once demobilized.  The gammadelta cells can be thought of as unconventional T cells at the interface between and linking the two immune systems, and contribute to the elimiation of infections or cancers by direct and indirect killing as well as modulation and stimulation of other immune cells (eg macrophages and NK cells) and the secretion of cytokines, notably interferon gamma and TNF-alpha.

Gammadelta T cells were known since the time when I was graduating medical school, in the mid to late ’80s (See Lanier et al. The gamma T cell antigen receptor. J Clin Immunol 1987;7(6):429-40 and Pardoll et al., The unfolding story of T cell receptor gamma, FASEB J, 1987; 1(2):103-9.) and it became known  that gammadelta T cells can kill tumor cells.  However, over the years, these cells received much less attention than Natural Killer (NK) cells, NKT lymphocytes and the much more populous alphabeta T cells in regards to applications in cancer immunotherapy.

The use of killer cells against cancer has been a focus of research for nearly two decades. Since the original descriptions of in vitro lymphocyte-mediated cytotoxicity against cancer, there have been numerous quasi-sucessful attempts to exploit these for therapeutic use in the clinic.  I say “quasi-successful” because there are no mind blowing successes, regretfully.  Most modern research have focused on the role of either natural killer (NK) cells or cytotoxic CD8 + alphabeta T cells , and little attention has been paid to the role of gammadelta T cells due to a lack of understanding of how they work, as well as the practical problem of obtaining enough of them for bedside use.  Our clearer understanding of these cells and their role in infections, cancer and autoimmunity is only surfacing recently (The first world conference on gammadelta T cells only got under way in 2004).

Gammadelta cells share with alphabeta T cells certain functions such as cytokine production and potent cytotoxic (cell killing) activity but gammadelta cells recognize different sets of antigens, usually in a non-MHC-restricted fashion, and cancers are highly susceptible to gammadelta T-cell mediated lysis which led to the proposal that gammadelta T cells can be used for cancer immunotherapy (See Kabelitz D, Potential of human gammadelta T lymphocytes as immunotherapy for cancer, Int J Cancer 2004 Dec 10;112(5):727-32). Unlike conventional T lymphocytes which recognize peptide antigens,  this “alternative” T cell’s ability to recognize tumor cell ligands not seen by conventional alphabeta T cells is one property that makes them intriguing. The other unique property is the way they recognize antigens circumvents to ability to of cancer cells to eventually elide detection.

In Vitro Work

It has long been known that these cells can kill cancers.

Gammadelta T cells are able to kill myeloma (Kunzmann et al. Blood, 2000; 96(2): 384-392, also Clin Exp Immunol, 2006;144(3):528-33) and lymphoma cells (Fisch et al. Europ J Immunol 1997;27:3368-3379)

Human Vgamma9Vdelta2+ gammadelta-T cells found able innately to recognize and kill certain human prostate tumor cell lines (DU-145 and PC-3 but not LNCaP) (Liu et al. J Urol, 2005;173(5):1552-6).

Gammadelta-T cells are able to innately recognize and kill human breast cancer cells in a gammadelta-TCR-dependent manner (Guo BL et al. Breast Cancer Res Treat 2005; 93(2):169-75.).

Freshly prepared gammadelta T cells consisting mainly of Vdelta2 gammadelta T cells showed increased cytotoxicity against bisphosphonate-treated pancreatic carcinoma cells (J Immunother 2007; 30(4):370-7)

Perhaps most exciting is the finding of efficient killing of cancer stem cells by gammadelta T cells (Todaro M, et al. J Immunol. 2009 Jun 1;182(11):7287-96).

In summary, most epithelial tumours (including melanomas, pancreatic adenocarcinomas, squamous cell carcinomas of the head and neck, and lung carcinoma – See Scan J Immunol, 2007;66(2-3):320-8) were susceptible to allogeneic gammadelta T-cell lysis and in the case of an established ovarian carcinoma, to autologous gammadelta T-cell killing

Animal Studies

Early on. Hayday found that mice lacking gammadelta cells were highly vulnerable to skin cancer when exposed to carcinogens.

A ‘St Jude’s regimen” utilizing human gammadelta T-cells from leukapheresis and adoptive transfer of the cells with an anti-GD2 antibody and the cytokine Fc-IL7 demonstrated enhance survival in a mouse model of human disseminated neuroblastoma (Clin Cancer Res 2005;11(23):8486-8491.

In models of mice bearing localized and disseminated prostate cancer treated i.v. with gammadelta T cells developed measurably less disease and superior survival compared with untreated mice (Liu Z, J Immunol, 2008;180(9):6044-53).

Intravesical administration of gammadelta T cells with zoledronic acid demonstrated antitumor activity against bladder cancer cells in the orthotopic murine model and resulted in prolonged survival (Yuasa T et al. Cancer Immunol Immunother 2009;58(4):493-5020

Recently published study ( Jul 2010) out of the U. of Alabama demonstrated efficacy of adoptively transferred gammadelta-T cells in both syngeneic (4T1) and xenogeneic (2Lmp) models of breast cancer, and the treatment was otherwise well-tolerated by treated animals. (Beck BH et al. Breast Ca Res Treat. 2010 Jul;122(1):135-44)

Stimulating and Expanding Gammadelta T Cells is Key.

Just knowing gammadelta T cells can kill cancer cells is not enough.  We and cancer patients all have these cells, but how to harness them to fight cancer in us or our patients? The limitations up until late ’90s has been the difficulties associated with identifying, harvesting, and expanding the cells. Thus the  key is in growing or expanding these cells either in the laboratory and externally applying the cells to the patient ( so-called adpotive therapy) or to stimulate and expand the gammadelta cells in our bodies somehow.  Both have been looked into:

Gammadelta cells is known to be stimulated by a number of non-peptide phosphorylated antigens, including a number of mycobacterial and bacterial derived molecules as when one encounters when one catches one of these infections (eg TB, E.Coli), as reported since the early ’90s.  Reports of gammadelta stimulation and expansion by small phosphorylated metabolites, amino-bisphosphonates (risedronate>alendronat>pamidronate) and synthetic phosphoantigens (defined as small, phosphorus-containing antigenic molecules) followed, openning up the opportunity of clinically applying this as a practical cancer treatment (reviewed by Fourniee and Bonneville in Res Immunol, 1996;147(5):338-47).

Pioneering work by the Italian team Casetti et al. elegantly demonstrated that co-stimulation simply with interleukin 2 plus non-peptide antigens or amino -bisphosphonates induced up to 100-fold increases in the numbers of peripheral blood Vgamma9Vdelta2 T cells in animals and together with a German team led by Wilhelm M et al. (see below, this laid the ground work for subsequent clinical endeavours in this field (Casetti R et al. Drug-Induced Expansion and Differentiation of V{gamma}9V{delta}2 T Cells In Vivo: The Role of Exogenous IL-2, J Immunol 2005;175(3):1593-8).

Exciting Human Observations and Clinical Data

In the past few years, clinical data has been pouring in fast and furious suggesting practicability and efficacy of this unique therapy.

In 2005, Bennouna et al. presented a phase I trial of 18 BrHPP (Phosphostim) and low dose IL-2 treated patients with solid tumors in a poster session at ASCO (JCO, 2005; 2005 ASCO Annual Meeting Proc 23(16S), Pt II of II:2536).

By 2007, Godder KT et al. from the US reported intriguing 5 year follow-up results showing three-fold overall survival advantage in acute leukemics with increased gammadelta cells following partially mismatched allogeneic stem cell transplantation, and postulated a graft versus leukemia effect (Bone Marrow Transplant 2007;39(12):751-7).

One of the earlier trials using gammadelta therapy was carried out by a German team from Wuerzberg utilizing low-dose interleukin 2 (IL-2) in combination with pamidronate in patients with relapsed/refractory low-grade non-Hodgkin lymphoma (NHL) or multiple myeloma (MM). They observed significant in vivo activation/proliferation of gammadelta T cells in 5 out of 9 patients (55%) who had positive in vitro response to pamidronate / IL-2 stimulation and objective responses (PR) were achieved in 3 patients (33%) . And thus the team demonstrated for the first time that this therapy was feasible (Wilhelm M. et al, Gammadelta T cells for immune therapy of patients with lymphoid malignancies, Blood, 2003;102(1):200-6).

Recently, a Japanese team from Tokyo attempted adoptive immunotherapy using in vitro-activated autologous gammadelta T cells against advanced renal cell cancer had found that it was well tolerated and induced anti-tumor effects (kobayashi H. et al, Cancer Immunol Immunother. 2007 Apr;56(4):469-76) . A French team using gammadelta T cells expanded in vivo with BrHPP (IPH1101, Phosphostim) and interleukin 2 (IL-2) at administered by infusion to metastatic renal cell cancer patients resulted in stable disease in 6 patients out of 10 (Bennouna J. et al. Cancer Immunol Immunother 2008;57(11):1599-609).

Almost simultaneously, the Italian team led by Dieli F of Palermo initiated a phase I clinical trial in metastatic hormone-refractory prostate cancer to examine the feasibility of using zoledronate in combination with low-dose interleukin 2 (IL-2) to stimulate gammadelta cells against the cancer and registered 3 partial remissions and five stable diseases out of nine patients (Dieli et al. Cancer Res.2007;67(15):7450-7) .

The same team above from Palermo also reported positive results in a small trial in May of 2010 of using zoledronic acid with low dose IL-2 in 10 “therapeutically terminal, advanced metastatic” breast cancer patients. Treatment was well tolerated and there was a statistically significant correlation of clinical outcome with peripheral Vgamma9Vdelta2 T cell numbers, with three patients who sustained robust peripheral Vgamma9Vdelta2 cell populations after treatment responding with declining cancer markers and partial remission or stable disease (Meraviglia S, et al. Clin Exp Immunol. 2010 May 10 Epub ahead of print), while a Japanese team almost simultaneously reported in Feb of 2010 thr complete remission of a patient with lung metastasis from renal cell carcinoma after six cycles of autologous in vitro-activated gammadelta T-cells followed by low-dose interleukin-2 and zoledronic acid intravenous infusion. Complete remission was achieved which has been maintained for 2 years without any additional treatment (Kobayashi H, et al. Anticancer Res 2010 Feb;30(2):575-9)

At the moment, there has been trials including a study of the use of gammadetla therapy in recurrent non-small cell lung cancer at the U. of Tokyo in Japan and an active phase I trial “Immunotherapy of Hepatocellular Carcinoma With Gamma Delta T Cells” which involves the direct intrahepatic injection of gammadelta cells going on in Rennes, France under the direction of Dr. Jean-Luc Raoul.  Researcher Lamb LS Jr. and team at the U. of Alabama have also been exploring explores graft engineering techniques in the development for the therapeutic use of gammadelta T cells against glioblastoma multiforme (Immunol Res. 2009;45(1):85-95)

My Take

Although we have known about gammadelta cells, but the ability to use fairly straightforward medicines such as the amino-bisphosphonates and interleukin-2 off-label to dramatically expand these cells in a patient without serious side-effects opens the way to a practical immunotherapy.  The fact that there is laboratory data showing efficacy against leukemia/myeloma and also human experience which is positive for some solid tumor (prostate, breast, lung and kidney) cancer types gives hope that this treatment can be broadly deployed against an array of cancers, both hematologic and solid tumors.  Research finding that the therapy can efficiently kill cancer stem cells is also exciting.  Most importantly, that this therapy calls for a protocol that is much more simple (30 minute treatment every month) than the parenteral Vitamin C protocol with much more science behind it than IPT (Insulin Potentiation Therapy) and other “alternative” cancer regimens makes this a very attractive options for patients seeking an alternative to conventional chemotherapy or radiotherapy.  Although NK cells are much more popularly known but there is no practical way to expand NK cells in the patient but this gammadelta therapy is eminently praticable.  My colleague Dr. Thomas Nesselhut at the Institut of Tumortherapie in Duderstadt, Germany is starting to apply this as a part of the Dendritic Cell therapy protocol that we have been collaborating on for the past 5 years and it appears quite promising.  We are currently gearing up to offer this as a viable alternative therapy while working out some of the legal and logistics hurdles to deployment.  All very exciting indeed.  Your comments welcome !

Future Directions

-> Clinical trials covering other cancers beyond prostate, kidney, myeloma. and NHL.

-> Development of more potent gammadelta stimulants or expansion protocols.

-> Exploring naturally-derived gammadelta agonists for dietary preventative therapeutic regimens.

-> Exploring the preventative possibilities of gammadelta therapy

Categories: Uncategorized
  1. pan
    May 26, 2009 at 2:12 pm

    This all looks very promising. Have you seen the paper ‘Active hexose correlated compound enhances tumor surveillance through regulating both innate and adaptive immune responses,’ by Gao Y, Zhang D, Sun B, Fujii H, Kosuna K, Yin Z. (Cancer Immunol Immunother. 2006 Oct;55(10):1258-66.).

    The abstract reads: “Active hexose correlated compound (AHCC) is a mixture of polysaccharides, amino acids, lipids and minerals derived from cocultured mycelia of several species of Basidiomycete mushrooms. AHCC has been implicated to modulate immune functions and plays a protective role against infection. However, the potential role of AHCC in tumor immune surveillance is unknown. In this study, C57BL/6 mice were orally administered AHCC or water, followed by tumor cell inoculation. We showed that compared to pure water-treated mice, AHCC treatment significantly delayed tumor development after inoculation of either melanoma cell line B16F0 or lymphoma cell line EL4. Treatment with AHCC enhanced both Ag-specific activation and proliferation of CD4(+) and CD8(+) T cells, increased the number of tumor Ag-specific CD8(+) T cells, and more importantly, increased the frequency of tumor Ag-specific IFN-gamma producing CD8(+) T cells. Interestingly, AHCC treatment also showed increased cell number of NK and gammadelta T cells, indicating the role of AHCC in activating these innate-like lymphocytes. In summary, our results demonstrate that AHCC can enhance tumor immune surveillance through regulating both innate and adaptive immune responses.”

    Note the mention of increased number of gammadelta T cells…

  2. September 30, 2009 at 7:34 pm

    As many of my patients are interested in dietary and supplement for cancer, here is a short list of such items that may help enhance gammadelta cell function:

    Vitamin E (humans with colorectal cancer)
    Tea (humans)
    CLA (animals)
    N6:N3 fatty acid ration (animal)
    Fruit/Vegetable juice (healthy humans)

    For details, see Percival, Bukowski and Milner, “Bioactive Food Components tht Enhance gammadelta T Cell function May Play a Role in Cancer Prevention” J. Nutri 138: pp 1-4, ’08

    R Chang

  3. jp
    September 8, 2013 at 1:41 pm

    “Importantly, the patients with a high proportion of gammadelta T cells showed poorer survival rates in comparison to those with a low proportion of gammadelta T cells in breast cancer.” -cancerres.aacrjournals.org/cgi/content/meeting_abstract/72/8_MeetingAbstracts/3544

    Are they referring to the same Gamma Delta T Cells as your article above ?

    Thanks for any clarification.


    • September 9, 2013 at 1:48 am

      Yes, these are the same gammadelta cells we are referring to here.
      The abstract from the St Louis researchers observed higher number of gammadelta T cells in more advanced cases, and correlated the presence of higher number of such cells to poorer outcome. This is like saying that more policeman are noticed to present in more serious crime scenes, and of course the more serious or advanced or aggressive cases have a poorer outcome. The presence of the cells does not imply a cause/effect that the cell have to do with the more advanced situation or poorer outcome though, what I mean is that police presence only confirms the seriousness of the crime but may not be construed to imply poorer outcome of the crime. Anyway, there is a large body of research in this area, including research looking at presence of other cells etc, its worth it to see the abstract in that context.

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