The trial measured how many subjects experienced complete or partial shrinkage (by a certain amount) of their tumors during treatment (overall response rate). For subjects harboring a PDGFRA exon 18 mutation, the overall response rate was 84%, with 7% having a complete response and 77% having a partial response. For the subgroup of subjects with PDGFRA D842V mutations, the overall response rate was 89%, with 8% having a complete response and 82% having a partial response. While the median duration of response was not reached, 61% of the responding subjects with exon 18 mutations had a response lasting six months or longer (31% of subjects with an ongoing response were followed for less than six months).The FDA approved avapritinib based on evidence from one clinical trial (NCT02508532) of 204 subjects with GIST. The trial was conducted at 17 sites in the United States, Europe and Asia.Avapritinib showed a median PFS of 4.2 months compared to 5.6 months for regorafenib. The difference in median PFS between the avapritinib and regorafenib groups was not statistically significant. The overall response rate was 17 percent for the avapritinib group and 7 percent for the regorafenib group. The VOYAGER trial evaluated the efficacy and safety of avapritinib (N=240) versus regorafenib (N=236) in patients with third- or fourth-line GIST.Avapritinib was approved for medical use in the European Union in September 2020.Ayvakit was granted approval for advanced systemic mastocytosis by the FDA on June 16th 2021. References
Further reading
Wu CP, Lusvarghi S, Wang JC,  et al. (July 2019).
Steatocystoma multiplex, is a benign, autosomal dominant congenital condition resulting in multiple cysts on a persons body. Steatocystoma simplex is the solitary counterpart to steatocystoma multiplex.In steatocystoma multiplex, the tendency to develop cysts is inherited in an autosomal dominant fashion, so one parent can be expected to also have steatocystoma multiplex. It may also occur sporadically. Both males and females may be affected. The onset at puberty is presumably due to hormonal stimulus of the pilosebaceous unit. They most often arise on the chest and may also occur on the abdomen, upper arms, armpits and face. In some cases cysts may develop all over the body. The cysts are mostly small (2–20 mm) but they may be several centimetres in diameter. They tend to be soft to firm semi-translucent bumps, and contain an oily, yellow liquid. Sometimes a small central punctum can be identified and they may contain one or more hairs (eruptive vellus hair cysts). They may become inflamed and heal with scarring, like acne nodules (see nodulocystic acne and hidradenitis suppurativa). On inflammation they can become incredibly painful and reach sizes between 4-6cm in diameter. The area around the cyst can become red and painful to the touch; making mobility, sitting, strenuous movement or everyday activities very difficult and painful. Steatocystomas are thought to come from an abnormal lining of the passageway to the oil glands (sebaceous duct). Localised, generalised, facial, acral, and suppurative types of steatocystoma multiplex have been described. Causes
It is associated with defects in Keratin 17.