To the Editor: The events of the phase 1 trial of TGN1412, asdetailed by Suntharalingam et al. (Sept. 7 issue),1 are a soberingreminder of the risks that research volunteers take when theyparticipate in trials, but the article did not contain any commentson the subjects' mental state as they emerged from this near-deathexperience. The volunteers did not just suffer insults to kidneyand pulmonary function; they were afflicted emotionally andperhaps intellectually as well. When an experimental drug hassuch serious adverse effects, it is worth reporting the psychologicaleffects, which inform the ethical impact of testing experimentalregimens and advance our understanding of the management ofpsychological harm. Without mention of the afflicted subjects'ability to return to their normal lives and their jobs or ofpsychological counseling offered to them, I view the articleby Suntharalingam et al. as incomplete.
Keri Gardner, M.D., M.P.H. UCLA School of Medicine Los Angeles, CA 90024 kerik{at}ucla.edu
References
Suntharalingam G, Perry MR, Ward S, et al. Cytokine storm in a phase 1 trial of the anti-CD28 monoclonal antibody TGN1412. N Engl J Med 2006;355:1018-1028. [Free Full Text]
To the Editor: We believe that the cytokine-release syndromestrongly resembles the toxic shock syndrome, which is inducedby a staphylococcal superantigen that activates T cells, throughtheir antigen receptor, to induce massive cytokine release.1However, mice with deletion of the CD28 gene are protected fromsuperantigen-induced, toxic shock syndrome–like disease.2In addition, peptides that block binding to CD28 also blocksuperantigen-dependent cytokine secretion by T cells.3 Together,these observations indicate that T cells activated by superantigenbinding to both CD28 and the antigen receptor mediate the toxicshock syndrome.
CD28-deficient mice are protected from lethal superantigen challengethrough the selective abrogation of the release of tumor necrosisfactor (TNF).2 Because TNF is also strongly induced by anti-CD28antibodies and TNF infusion can induce toxic shock syndrome–likedisease,4 short-term use of anti-TNF agents may benefit patientswith the toxic shock syndrome and related syndromes involving"cytokine storm."
David B. Corry, M.D. Dorothy E. Lewis, Ph.D. Baylor College of Medicine Houston, TX 77030 dcorry{at}bcm.tmc.edu
References
McCormick JK, Yarwood JM, Schlievert PM. Toxic shock syndrome and bacterial superantigens: an update. Annu Rev Microbiol 2001;55:77-104. [CrossRef][Web of Science][Medline]
Saha B, Harlan DM, Lee KP, June CH, Abe R. Protection against lethal toxic shock by targeted disruption of the CD28 gene. J Exp Med 1996;183:2675-2680. [Free Full Text]
Arad G, Levy R, Hillman D, Kaempfer R. Superantigen antagonist protects against lethal shock and defines a new domain for T-cell activation. Nat Med 2000;6:414-421. [CrossRef][Web of Science][Medline]
Remick DG, Kunkel RG, Larrick JW, Kunkel SL. Acute in vivo effects of human recombinant tumor necrosis factor. Lab Invest 1987;56:583-590. [Web of Science][Medline]
To the Editor: CD28 expression by human neutrophils has beendocumented, and its activation alone results in the secretionof interferon-.1 We now find that a subgroup of human neutrophilsexpresses the T-cell receptor (Figure 1). We have also shownthat costimulation of the T-cell receptor and CD28 triggersthe release of interleukin-8 in these cells.2 Therefore, neutrophilsmay represent a quantitatively important target of TGN1412 andmay link the pathogenesis of the cytokine-release syndrome tothe innate immune system.
Figure 1. Human Neutrophils Expressing the T-Cell Receptor.
Expression of the T-cell receptors and β (indicated in red) is shown in a normal human peripheral-blood neutrophil (Panel A) and in a lymphocyte from the same person, used as a control cell (Panel B). Cells were double-stained with a monoclonal antibody against the T-cell receptors and β (red) and the neutrophil marker CD15 (green); the nuclei were counterstained with 4',6-diamidine-2-phenylidole dihydrochloride (blue). Panel C shows the presence of the T-cell receptors and β on the surface of a peripheral-blood neutrophil on immunogold electron microscopy. Arrows indicate T-cell receptor heterodimers (pairs).
Kerstin Puellmann, M.D. Alexander W. Beham, M.D. University of Regensburg 93053 Regensburg, Germany kerstin.puellmann{at}web.de
Wolfgang E. Kaminski, M.D. University of Heidelberg 68167 Mannheim, Germany
References
Venuprasad K, Banerjee PP, Chattopadhyay S, et al. Human neutrophil-expressed CD28 interacts with macrophage B7 to induce phosphatidylinositol 3-kinase-dependent IFN-gamma secretion and restriction of Leishmania growth. J Immunol 2002;169:920-928. [Free Full Text]
Puellmann K, Kaminski WE, Vogel M, et al. A variable immunoreceptor in a subpopulation of human neutrophils. Proc Natl Acad Sci U S A 2006;103:14441-14446. [Free Full Text]
To the Editor: The TGN1412-exposed patients described by Suntharalingamet al. had many of the clinical and laboratory features of themacrophage activation syndrome, also known as secondary hemophagocyticlymphohistiocytosis, a severe and sometimes fatal condition.1,2Unfortunately, important diagnostic criteria for the macrophageactivation syndrome,3,4 such as increased ferritin and solubleCD25 levels, enhanced activity of natural killer cells, andspecific histologic characteristics of bone marrow, were notreported in these patients. Also, hepatosplenomegaly and lymphadenopathy,which are classic features of the macrophage activation syndrome,were absent in the volunteers exposed to TGN1412, perhaps becauseof the very acute nature of the reaction. If characterized further,TGN1412 may provide insight into the mechanisms that lead tothe macrophage activation syndrome in other clinical settings,such as juvenile idiopathic arthritis or sepsis. This understandingmay also help in the handling of future situations similar tothe one described by Suntharalingam et al., in which evidencefrom clinical trials, including those involving patients withthe macrophage activation syndrome, could help guide the careof the affected patients.3
Facundo Garcia-Bournissen, M.D. Mariana Boragina, M.D. ShinyaIto, M.D. Hospital for Sick Children Toronto, ON M5G 1X8, Canada facundo.garciabournissen{at}sickkids.ca
References
Emmenegger U, Schaer DJ, Larroche C, Neftel KA. Haemophagocytic syndromes in adults: current concepts and challenges ahead. Swiss Med Wkly 2005;135:299-314. [Medline]
Sawhney S, Woo P, Murray KJ. Macrophage activation syndrome: a potentially fatal complication of rheumatic disorders. Arch Dis Child 2001;85:421-426. [Free Full Text]
Henter JI, Horne A, Arico M, et al. HLH-2004: diagnostic and therapeutic guidelines for hemophagocytic lymphohistiocytosis. Pediatr Blood Cancer (in press).
Ravelli A, Magni-Manzoni S, Pistorio A, et al. Preliminary diagnostic guidelines for macrophage activation syndrome complicating systemic juvenile idiopathic arthritis. J Pediatr 2005;146:598-604. [CrossRef][Web of Science][Medline]
To the Editor: Suntharalingam et al. report severe adverse eventsin the phase 1 study of TGN1412. Monoclonal antibodies, whichcannot be metabolized in the liver and cannot be eliminatedfrom the kidney, usually have long half-lives.1 Double filtrationplasmapheresis, which selectively removes high-molecular-weightsubstances, including immunoglobulins and immune complexes,has been proven to be effective for the clearance of circulatingmonoclonal antibodies,2 and some studies have shown the usefulnessof continuous hemofiltration or continuous hemodiafiltrationfor ameliorating cytokine storm.3,4 We would like the authorsto comment on whether these therapeutic measures might be beneficialfor the treatment of severe adverse events associated with monoclonalantibodies.
Morihito Takita, M.D. Tomoko Matsumura, M.D. Masahiro Kami, M.D. University of Tokyo Tokyo 108-8639, Japan
Yeh JH, Chen WH, Chiu HC, Bai CH. Clearance studies during subsequent sessions of double filtration plasmapheresis. Artif Organs 2006;30:111-114. [CrossRef][Web of Science][Medline]
Heering P, Morgera S, Schmitz FJ, et al. Cytokine removal and cardiovascular hemodynamics in septic patients with continuous venovenous hemofiltration. Intensive Care Med 1997;23:288-296. [CrossRef][Web of Science][Medline]
Iglesias J, Marik PE, Levine JS. Elevated serum levels of the type I and type II receptors for tumor necrosis factor-alpha as predictive factors for ARF in patients with septic shock. Am J Kidney Dis 2003;41:62-75. [CrossRef][Web of Science][Medline]
The authors reply: The psychological effect of serious adverseevents on healthy subjects involved in clinical trials is important;critical illness has its own known neuropsychological consequences.1,2Our institution does provide follow-up after discharge of patientswho stay in the intensive care unit for more than 3 days. However,our article was limited to the physiological and immunologicevents that occurred within 30 days after exposure; the omissioncited by Gardner does not make the report incomplete.
Corry and Lewis suggest that the cytokine storm induced by TGN1412is similar to that resulting in the toxic shock syndrome, onthe basis of the activation of CD28 on T cells. Although T cellswere the intended targets of TGN1412, it is still unclear whetherT-cell activation induced the cytokine storm. The trigger mayhave been on another type of cell expressing CD28, as suggestedby Puellmann et al., or may have involved ligation of Fc receptors.Hence the macrophage activation syndrome was also considered.Since the neutrophil count was preserved and, as noted by Garcia-Bournissenet al., there was neither hepatosplenomegaly nor lymphadenopathy,we thought that the macrophage activation syndrome as a separateentity should be ruled out. Our article was a clinical reportof the unintended consequences of a phase 1 trial and subsequentemergency care. Laboratory investigations were limited to thosethat were of direct clinical benefit.
Anti-TNF therapy was considered. When transfer to our care tookplace 12 to 16 hours after TGN1412 infusion, we decided thatthe TNF peak was likely to have passed and that downstream eventshad already been triggered. As cytokine data became available,showing persistently high TNF levels, this decision was reviewed.In our minds, in the setting of severe lymphopenia and monocytopeniaof unknown duration, treatment with high-dose corticosteroidsand anti–interleukin-2 receptor antagonist antibody, andthe increased risk of secondary infections in the patients,the risk of anti-TNF therapy still outweighed its potentialbenefit. We would be yet more cautious with a cause associatedwith infection, such as the toxic shock syndrome.
We agree with Takita et al. Plasmapheresis was considered, butthe known pharmacokinetics of a low IgG4 antibody level suggestedthat the drug would be tissue-bound. We also agree that theremay be a role for continuous venovenous hemodiafiltration inblunting the cytokine storm associated with a severe systemicinflammatory response. Furthermore, high dialysate rates3 andhigh-cutoff filters4 have previously been suggested for usein treating sepsis. Our patients received continuous venovenoushemodiafiltration at an initial dialysate rate of 1 liter perhour, which was subsequently raised to 4 liters per hour, usingstandard membranes. In our opinion, aggressive multiorgan supportand early institution of high-volume diafiltration and treatmentwith high-dose corticosteroids, combined with the physiologicalresilience of these six young, healthy research volunteers,were key to their survival.
Andrew Castello-Cortes, F.R.C.A. Ganesh Suntharalingam, F.R.C.A. Northwick Park and St. Mark's Hospital London HA1 3UJ, United Kingdom ganesh.suntharalingam{at}nwlh.nhs.uk
Nicki Panoskaltsis, M.D., Ph.D. Imperial College London London HA1 3UJ, United Kingdom
References
Sukantarat KT, Burgess PW, Williamson RC, Brett SJ. Prolonged cognitive dysfunction in survivors of critical illness. Anaesthesia 2005;60:847-853. [CrossRef][Web of Science][Medline]
Jackson JC, Hart RP, Gordon SM, et al. Six-month neuropsychological outcome of medical intensive care unit patients. Crit Care Med 2003;31:1226-1234. [CrossRef][Web of Science][Medline]
Cole L, Bellomo R, Journois D, Davenport P, Baldwin I, Tipping P. High-volume haemofiltration in human septic shock. Intensive Care Med 2001;27:978-986. [CrossRef][Web of Science][Medline]
Morgera S, Klonower D, Rocktaschel J, et al. TNF-alpha elimination with high cut-off haemofilters: a feasible clinical modality for septic patients? Nephrol Dial Transplant 2003;18:1361-1369. [Free Full Text]
.1 We now find that a subgroup of human neutrophils expresses the T-cell receptor (Figure 1). We have also shown that costimulation of the T-cell receptor and CD28 triggers the release of interleukin-8 in these cells.2 Therefore, neutrophils may represent a quantitatively important target of TGN1412 and may link the pathogenesis of the cytokine-release syndrome to the innate immune system. 
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and β (indicated in red) is shown in a normal human peripheral-blood neutrophil (Panel A) and in a lymphocyte from the same person, used as a control cell (Panel B). Cells were double-stained with a monoclonal antibody against the T-cell receptors