Medics now want to find a suitable donor so he can undergo a stem cell transplant to prevent the leukaemia taking hold again.
The singer, who has supported U2 and Status Quo on tour, was first diagnosed with chronic lymphocytic leukaemia (CLL) more than 29 years ago aged 36.
Five days before he was due to fly to Chicago for a 50-date US tour in April, he found a lump in his neck.
The singer was referred from the North Wales Cancer Centre to The Christie for a drug trial with targeted therapy called acalabrutinib alongside standard chemotherapy.
Although acalabrutinib is already approved for CLL, it has not been tested in combination with chemotherapy for Richter’s Syndrome.
