"Thanks to everyone for your continued support," Klein tweeted after the news of Arnold's diagnosis was made public. "We appreciate everyone's generous well wishes and prayers. We will fight and we will win."
Arnold, 39, a neonatologist at Texas Children's Hospital, and Klein, 38, an entrepreneur and owner of Rocky and Maggie's, a pet accessories store in Houston, recently became parents to two children with dwarfism: son Will, 3, and daughter Zoey, 2.
"I always wanted to adopt another little person," Arnold told PEOPLE in an interview earlier this year. "I knew there was so much we know because of our own experiences."
The couple's struggles to become parents were difficult, and both say they have leaned on one another during difficult times.
Thanks to everyone for your continued support. We appreciate everyone's generous well wishes and prayers. We will fight and we will win!— Bill Klein (@ReallyBillKlein) December 6, 2013
"We have a different way of doing things than some couples," Klein told PEOPLE earlier this year. "Our approach is more along the lines of conservative optimism. And it is my priority for Jen to be safe."
Klein has been as determined as his wife to do everything possible for her in her cancer fight, Tweeting to fans that due to his wife's weakened state, "Prayers are welcome, hugs are not."
Arnold herself has put her unwavering resolve front and center, Tweeted that she is "in the process of beating this" and thanking fans for their "well wishes and support."
Thank you to all for your well wishes and support! #GetWellJen— Jennifer Arnold, MD (@JenArnoldMD) December 6, 2013