For my Dermatology Times article I interviewed Dr. Theobald, the Chief Medical Officer at Collagenex (they make Periostat and Oracea).
They have found ways to take oral antibiotics and chemically modify them. With Periostat and Oracea, they had to stay to low doses. But with newer generation antibiotics they can remove the antibacterial actions and enhance the anti-inflammatory actions at high doses.
What they are finding in pre-clinical and clinical studies on skin cancer and inflammatory skin disorders is that the anti-inflammatory actions are now enhanced enough to normalize vascular dilation (which feeds skin cancer and our disorders) and skin inflammation. More specifically, in these disorders, nitric oxide (inducible) is greatly elevated, VEGF is greatly elevated, inflammatory cytokines are greatly elevated and neutrophils are found in the skin in outlandish numbers.
These new chemically modified anti-inflammatory antibiotics normalize nitric oxide which greatly reduces blood flow. It blocks VEGF production considerably (but not totally) which attenuates new blood vessel growth, normalizes cell adhesion molecules which helps stop the vicious inflammatory cycle, and stops the penetration of neutrophils through the blood vessel walls and chemotaxis up to the epidermis (e.g. blocks papule formation).
I could not gather much else, but it seems as if they are doing this with several classes of antibiotics and seeing which ones have the greatest effect and least side efffects. The only side effect noticed was increased sun sensitivity when not wearing sunblock, so I hope they figure that one out.