diff --git a/graphene/utils/str_converters.py b/graphene/utils/str_converters.py
index 3b06ee05..ae8ceffe 100644
--- a/graphene/utils/str_converters.py
+++ b/graphene/utils/str_converters.py
@@ -18,4 +18,4 @@ def to_snake_case(name):
 
 
 def to_const(string):
-    return re.sub('[\W|^(?=\d)]+', '_', string).upper()
+    return re.sub('[\W|^]+', '_', string).upper()