The official information is that there is no cure. I could read about the odd case that went into remission, but that seems to be more the exception than the rule. Several of those cases needed bone marrow transplant due to transformation into myelofibrosis or AML. Others received treatment for another cancer and it resulted in lowering the allele burden of JAK2.
"Polycythemia Vera (PV) is a chronic disease: It's not curable, but it can usually be managed effectively for very long periods. The goal of therapy is to reduce the risk of thrombosis and to ease symptoms by lowering the number of extra blood cells. "
https://www.lls.org/myeloproliferative-neoplasm...

My GP said that some people go into remission without any effort.
I have also read that using interferon can help reduce the defects in the bone marrow. Hope I am paraphrasing this correctly.