in preliminary studies on fl patients who were known or thought to be refractor to more conventional therapies these drugs, when combined with more conventional drugs, particularly rituximab, produced promising results. phosphoionsitide 3-kinase inhibitors produced overall response rates of 10–12.5 months in 42–59%; tisagenlecleuce cells produced an overall progression-free response rate of 70% after a follow-up of 28 months; phosphoinositide 3-kinase inhibitors produced overall response rates of ~40% and complete response rates of 1–20%; bruton's tyrosine kinase inhibitor produced overall and complete response rates of 38% and 18%, respectively; the bcl inhibitor produce overall and complete response rates of 33% and 14%, respectively; histone deacetylase inhibitors produce overall response rates of 35–71%; and checkpoint inhibitors produce overall response rates of 40–80% and complete response rates of 10–60%.