When I met her in her kitchen in Surrey, glitterball dangling from the ceiling, she told me flare ups in her hands left her struggling to lift a cup of tea and she would need to take drugs 45 minutes before getting out of bed in the morning, otherwise it would be too painful.
The disease became much more aggressive in the past decade, which has been "pretty horrendous" and Katie needed long spells in hospital. Her lupus was damaging her heart, lungs and kidneys, leaving her on the cusp of needing dialysis.
"Lupus at its worst was in bed, unable to move, going downhill rapidly, possibly dying…now I'm living," she told me.
But speaking to Katie, a year-and-a-half after her experimental treatment, she has the energy and zest for life of a woman reborn.
"It's amazing. I'm living like a normal person, I'm literally saying yes to anything. I sort of forgot that you could feel this good," she said.
The difference is an experimental treatment Katie had to reset her immune system at University College London Hospitals.
It works by engineering a civil war within the immune system – to get one part to destroy the part causing disease.
Out of the first six patients treated, five are still in remission. One has improved symptoms, but had a lupus flare after 11 months.
The team, presenting data at the EULAR European Congress of Rheumatology, said their patients were still well after more than 18 months.
However, it is still uncertain how long the treatment will last before the lupus returns and how successful it will be when trialled in more patients.
Dr Maria Leandro, a consultant rheumatologist at UCLH, told BBC News: "If we were to have patients in remission for three-to-five years consistently, that would be a major gain in lupus, it may be longer than that, but we'll have to wait and see.
"This is clearly a significant step forward towards a possible cure, so it is very exciting."
This approach – known as CAR-T or chimeric antigen receptor T-cells – is already an approved treatment in blood cancers including some leukaemias and lymphomas.
This is some of the earliest data suggesting the approach can also be used in autoimmune disease.
Many of these diseases work in a similar way to lupus. It means there is the potential for CAR-T therapy to be used more widely to target errant B cells.