Gorilla Doctor Jan Ramer has shared Gashangi’s last biopsy with oncologists Dr. Michael Kent (UC Davis) and Dr. Phil Bergman (Sloan Kettering), and pathologist Dr. Linda Lowenstine (UC Davis). All three have concurred that Gashangi has melanoma. This is the first known case in non-human primates, not just in mountain gorillas. Various treatment options have been discussed, including follow-up surgery and drug therapies. The four doctors have concluded that further surgery is not a viable option because too much tissue would have to be removed — and there would still be a high probability that cancerous cells would remain.
In considering drug therapies, Gashangi’s quality of life has to be balanced with treatment efficacy. No one wants to put her on a course of drugs that will make her feel terrible and offer only a slightly higher chance of remission. The other major concern is choosing a therapy that isn’t likely to upset the other members of the Nyakamwe group, either from the standpoint of seeing her suffer or a therapy that requires repeated interventions. The team has decided to treat Gashangi with a DNA vaccine. She will be given a course of four injections that contain human tyrosinase, a rate-limiting enzyme that controls the production of melanin (melanin is what determines the color of hair, skin, and the iris of the eye). Although there is a 98% sequence identity between human and gorilla tyrosinase, Gashangi’s T-cells should recognize the foreign tyrosinase injected into the tumor site and mount a localized attack against the protein on the melanoma cells. Presently, the tumor is hiding under Gashangi’s immunologic radar, which is why its growth is unchecked. This therapy is also desirable because it acts in a very localized manner, rather than causing a systemic immune response. Last, but certainly not least, this therapy exhibits only mild side-effects, such as temporary soreness at the injection site and possible localized invitiligo (loss of ski pigmentation).
Jan will head out this week to give Gashangi’s her first injection. We will make sure to pass along information and photos as soon as she returns.