Django-rest-framework update user from another user

I need to change users from another user.

But when I call serializer.save () it is not saved in the database and does not display an error.

My user model:

class User(AbstractBaseUser, PermissionsMixin):
   class Meta:
      db_table='empresa_user'

   email = models.EmailField(
   verbose_name='email address',
   max_length=255,
   unique=True,
   )
   first_name      = models.CharField(verbose_name='User first name', max_length=30, blank=False)
   last_name       = models.CharField(verbose_name='User last name', max_length=30, blank=False)
   is_active       = models.BooleanField(default=True)
   is_staff        = models.BooleanField(default=False)
   dt_criacao = models.DateTimeField(null=True, default=timezone.now)

   perfil  = models.CharField(verbose_name='Perfil do usuário', max_length=1, blank=False, null=False, default='B')
   empresa = models.ForeignKey(Empresa, related_name='empresa', on_delete=models.DO_NOTHING, null=False, blank=False, verbose_name='Empresa')

   objects = UserManager()

   USERNAME_FIELD = 'email'
   REQUIRED_FIELDS = ('first_name', 'last_name')

   def get_full_name(self):
      return self.first_name +' '+ self.last_name

   def get_short_name(self):
      return self.first_name

   def __str__(self):
      return self.email

My serializer:

UserModel = get_user_model()

class UpdateUserPerfilSerializer(serializers.ModelSerializer):
   class Meta:
      model = UserModel
      fields = ('perfil', )

   def validate_perfil(self, value):
      if value not in ('A', 'G', 'B', ):
         raise serializers.ValidationError("Perfil inválido")
      return value

My view:

@api_view(['PUT'])
@permission_classes((permissions.IsAuthenticated,))
def put_user(request, pk):
   empresa = get_empresa(request.user)

   try:
      user = get_user_model().objects.get(empresa=empresa, pk=pk)
   except get_user_model().DoesNotExist:
      raise Http404

   serializer = UpdateUserPerfilSerializer(user, data=request.data)

   if serializer.is_valid():
      serializer.save()
      return Response(serializer.data)
   return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

I'm making the call this way:

curl -X PUT ' link ' -H 'Authorization: JWT MY_TOKEN' -d '{"Profile" : "B"} '

And this is my answer, and there is no error:

{"profile": "A"}