Purpose: To evaluate 3 ¶-deoxy-3 ¶-[18 F]fluorothymidine-positron emission tomography (FLT-PET) for early monitoring response of high-grade non-Hodgkin's lymphoma to treatment with cyclophosphamide-adriamycin-vincristine-prednisone chemotherapy with or without rituximab immunotherapy (R-CHOP/CHOP). Experimental Design: Twenty-two patients with histologically proven high-grade nonHodgkin's lymphoma scheduled to undergo first line treatment with R-CHOP/CHOP were included. All patients received baseline imaging before therapy with FLT-PET. For noninvasive assessment of treatment response, FLT-PET was repeated at following time points: group 1 (n = 6), 1and 6 weeks after R-CHOP/CHOP; group 2 (n = 16), 2 days after rituximab and 2 days after CHOP application. Emission images were acquired 45 min after injection of 300 to 370 MBq of FLT. FLT uptake was quantified by region-of-interest technique on a lesion basis. Maximum standardized uptake values (SUV) for FLT were calculated using circular region of interest (diameter, 1.5 cm). Results: In all patients, morphologically proven lesions showed initially high FLT uptake (mean SUV, 8.1 F 3.9). In group 1, mean FLT SUV decreased 7 days after R-CHOP/CHOP by 77% (P < 0.001), the reduction in FLT SUV from baseline was 85% after 40 days (P = 0.003). In group 2, FLTuptake in patients without dexamethasone pretreatment revealed no significant reduction after rituximab (P = 0.3) but significantly decreased 2 days after CHOP to 32% compared with the baseline value (P = 0.004). Conclusions: Administration of R-CHOP/CHOP is associated with an early decrease in lymphoma FLT uptake. Interestingly, there was no reduction of FLT uptake after rituximab alone, indicating no early antiproliferative effect of immunotherapy. FLT-PET seems to be promising for early evaluation of drug effects in lymphoma.The standard therapy for high-grade non-Hodgkin's lymphoma is cyclophosphamide-adriamycin-vincristine-prednisone (CHOP) or CHOP-like regimens. The introduction of the chimeric monoclonal anti-CD20 antibody rituximab to standard chemotherapy has been shown to significantly improve both event-free as well as overall survival (1, 2). In contrast to its role in combination therapies, rituximab itself does not reveal a major cytotoxic effect as a single agent on high-grade non-Hodgkin's lymphoma (3).To evaluate antitumor efficacy and possible mechanisms of action in vivo, therapy monitoring plays a major role for evaluation of new therapeutic approaches. For the last decades, helical computed tomography (CT) has represented the gold standard for staging and restaging of non-Hodgkin's lymphoma. However, definition of response criteria based on conventional radiographic characteristics remains difficult because patients treated with chemotherapy often present with residual masses of uncertain significance. Especially differentiation between fibrotic tissue and viable tumor by CT is only of limited accuracy (4 -10).Positron emission tomography using the glucose analogue 2-[18 F]fluoro-2-deox...

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CD30 is a member of the tumor necrosis factor receptor superfamily, which can transduce signals for proliferation, death, or nuclear factor kappa B (NF-κB) activation. Investigation of CD30 signaling pathways using a yeast two-hybrid interaction system trapped a cDNA encoding the tumor necrosis factor receptor-associated factor (TRAF)-2 TRAF homology domain. TRAF-1 and TRAF-3 also interacted with CD30, and >90% of in vitro -translated TRAF-1 or -2, or 50% of TRAF-3, bound to the CD30 cytoplasmic domain. TRAF-1, -2, and -3 bound mostly, but not exclusively, to the carboxyl-terminal 36 residues of CD30. The binding was strongly inhibited by a CD30 oligopeptide centered around a PXQXT (where X is any amino acid) motif shared with CD40 and the Epstein–Barr virus transforming protein LMP1, indicating that this motif in CD30 is an important determinant of TRAF-1, -2 or -3 interaction. At least 15% of TRAF-1, -2, or -3 associated with CD30 when coexpressed in 293 cells. The association was not affected by CD30 cross-linking. However, cross-linking of CD30 activated NF-κB. NF-κB activation was dependent on the carboxyl-terminal 36 amino acids of CD30 that mediate TRAF association. TRAF-2 has been previously shown to have a unique role in TRAF-mediated NF-κB activation, and NF-κB activation following CD30 cross-linking was blocked by a dominant negative TRAF-2 mutant. These data indicate that CD30 cross-linking-induced NF-κB activation is predominantly TRAF-2-mediated.