Obinutuzumab is a new monoclonal antibody, that may be set to replace Rituximab. While it is very new it has actually been in clinical studies for several years. But it takes many years to evaluate whether something works. This is especially true for indolent lymphomas where the survival is very long, so it takes very long to find out if a treatment is "better".
The results of the GALLIUM study (1) appear to show that it gets higher response rates with more durable remissions. Based on those findings the European Union has now (in 2017) recommended Obinutuzumab be used as the frontline treatment for follicular lymphoma.
Currently in the USA it is approved only for previously treated follicular lymphoma. That is likely to change in the next few years.