The Bradeney Bunch band has so far raised almost £3,000 as part of a fundraising drive to help the 21-month-old who has the rare condition mucopolysaccharide MPS Type 1 Hurler.
This means his body cannot convert sugar into necessary protein and he will need stem cell treatment.
This Saturday the band will be playing at the Danery pub, in Kidderminster Road, Quatford, WV15 6QJ in aid of the effort. The music will include the new song Step By Step which was written as a tribute to Gunner and his family.
The band members are Steve Street on drums, John Hodgetts on keyboard, Andrew Tither on bass, Mark Cronin on lead guitar, Les Jones on rhythm guitar and Emma Jarratt on vocals.
They will be performing at the Danery from midday until about 2.30pm.
Les, who also owns Bradeney House Care Home, in Worfield said: "It would be great to see as many people as possible at the Danery on Saturday to support the cause. Proceeds from sales of the CD, a concert in the park and a raffle and support from other businesses we've raised more than £2,500 so far.
"The song is quite poignant and is about Gunner and his family's experiences. The song has had some good reviews so far."
Copies of Step By Step are available from Spotify, Amazon or iTunes or by contacting 01746 717920.
All proceeds will go to The Gunner Lewis-Vale Trust.