title: Polymorphisms in FcgammaRIIIA (CD16) receptor expression are associated with clinical response to rituximab in Waldenström's macroglobulinemia.
abstract: OBJECTIVE
  Rituximab is an important therapeutic for Waldenstrom's macroglobulinemia (WM). Polymorphisms in FcgammaRIIIA (CD16) receptor expression modulate human immunoglobulin G1 binding and antibody-dependent cell-mediated cytotoxicity, and may therefore influence responses to rituximab.
  
  
  METHODS
  Sequence analysis of the entire coding region of FcgammaRIIIA was undertaken in 58 patients with WM whose outcomes after rituximab were known.
  
  
  RESULTS
  Variations in five codons of FcgammaRIIIA were identified. Two were commonly observed (FcgammaRIIIA-48 and FcgammaRIIIA-158) and predicted for amino acid polymorphisms at FcgammaRIIIA-48: leucine/leucine (L/L), leucine/arginine (L/R), and leucine/histidine (L/H). Polymorphisms at FcgammaRIIIA-158 were phenylalanine/phenylalanine (F/F), phenylalanine/valine (F/V), and valine/valine (V/V). A clear linkage between these polymorphisms was detected and all patients with FcgammaRIIIA-158F/F were always FcgammaRIIIA-48L/L, and patients with either FcgammaRIIIA-L/R or -L/H always expressed at least one valine at FcgammaRIIIA-158 (P < or = .001). The response trend was higher for patients with FcgammaRIIIA-48L/H (38.5%) versus -48L/R (25.0%) and LL (22.0%), and was significantly higher for patients with FcgammaRIIIA-158V/V (40.0%) and -V/F (35%) versus -158F/F (9.0%; P = .030). Responses for patients with FcgammaRIIIA-48L/L were higher when at least one valine was present at FcgammaRIIIA-158 (P = .057), thereby supporting a primary role for FcgammaRIIIA-158 polymorphisms in predicting rituximab responses. With a median follow-up of 13 months, no significant differences in the median time to progression and progression-free survival were observed when patients were grouped according to their FcgammaRIIIA-48 and -158 polymorphisms.
  
  
  CONCLUSIONS
  The results of these studies therefore support a predictive role for FcgammaRIIIA-158 polymorphisms and responses to rituximab in WM.
authors.affiliation: Bing Program for Waldenström's Macroglobulinemia, Dana-Farber Cancer Institute, LG102, 44 Binney St, Boston, MA 02115, USA. steven_treon@dfci.harvard.edu
authors.forename: Steven P
authors.initials: SP
authors.lastname: Treon
authors.forename: Mark
authors.initials: M
authors.lastname: Hansen
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Branagan
authors.forename: Sigitas
authors.initials: S
authors.lastname: Verselis
authors.forename: Christos
authors.initials: C
authors.lastname: Emmanouilides
authors.forename: Eva
authors.initials: E
authors.lastname: Kimby
authors.forename: Stanley R
authors.initials: SR
authors.lastname: Frankel
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Touroutoglou
authors.forename: Barry
authors.initials: B
authors.lastname: Turnbull
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Anderson
authors.forename: David G
authors.initials: DG
authors.lastname: Maloney
authors.forename: Edward A
authors.initials: EA
authors.lastname: Fox
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000494:pharmacology / Q000627:therapeutic use*; D058846:Antibodies, Monoclonal, Murine-Derived; D015703:Antigens, CD / Q000235:genetics*; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D003062:Codon; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D058851:GPI-Linked Proteins; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D017452:Receptors, IgG / Q000235:genetics*; D000069283:Rituximab; D016896:Treatment Outcome; D008258:Waldenstrom Macroglobulinemia / Q000188:drug therapy* / Q000235:genetics*
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D015703:Antigens, CD; D000970:Antineoplastic Agents; D003062:Codon; C428200:FCGR3B protein, human; D058851:GPI-Linked Proteins; D017452:Receptors, IgG; D000069283:Rituximab