An afterimage is an image that continues to appear in the eyes after a period of exposure to the original image. An afterimage may be a normal phenomenon (physiological afterimage) or may be pathological (palinopsia). Illusory palinopsia may be a pathological exaggeration of physiological afterimages. Afterimages occur because photochemical activity in the retina continues even when the eyes are no longer experiencing the original stimulus.The remainder of this article refers to physiological afterimages. A common physiological afterimage is the dim area that seems to float before ones eyes after briefly looking into a light source, such as a camera flash. Palinopsia  is a common symptom of visual snow. Negative afterimages
Negative afterimages are caused when the eyes photoreceptors, primarily known as rods and cones, adapt to overstimulation and lose sensitivity. Newer evidence suggests there is cortical contribution as well. Normally, the overstimulating image is moved to a fresh area of the retina with small eye movements known as microsaccades. However, if the image is large or the eye remains too steady, these small movements are not enough to keep the image constantly moving to fresh parts of the retina. The photoreceptors that are constantly exposed to the same stimulus will eventually exhaust their supply of photopigment, resulting in a decrease in signal to the brain. This phenomenon can be seen when moving from a bright environment to a dim one, like walking indoors on a bright snowy day.
The studies then compared the two groups for the proportion of participants with severe neutropenia (a very low count of white blood cells called neutrophils) and the duration of severe neutropenia in the first cycle of chemotherapy. In all three studies, participants who received trilaciclib had a lower chance of having severe neutropenia compared to participants who received a placebo. Among those who had severe neutropenia, participants who received trilaciclib, on average, had it for a shorter time than participants who received a placebo.The U.S. Food and Drug Administration (FDA) granted the application for trilaciclib priority review and breakthrough therapy designations. The FDA granted the approval of Cosela to G1 Therapeutics, Inc.

References
This article incorporates public domain material from the United States Department of Health and Human Services. External links
"Trilaciclib". Drug Information Portal. U.S. National Library of Medicine. Clinical trial number NCT03041311 for "Carboplatin, Etoposide, and Atezolizumab With or Without Trilaciclib (G1T28), a CDK 4/6 Inhibitor, in Extensive Stage Small Cell Lung Cancer (SCLC)" at ClinicalTrials.gov
Clinical trial number NCT02499770 for "Trilaciclib (G1T28), a CDK 4/6 Inhibitor, in Combination With Etoposide and Carboplatin in Extensive Stage Small Cell Lung Cancer (SCLC)" at ClinicalTrials.gov
Clinical trial number NCT02514447 for "Trilaciclib (G1T28), a CDK 4/6 Inhibitor, in Patients With Previously Treated Extensive Stage SCLC Receiving Topotecan Chemotherapy" at ClinicalTrials.gov