The provided sources do not provide a specific discount amount for Yervoy. However, they do provide information on the pricing and availability of the drug. Yervoy is a biologic drug used for the treatment of advanced melanoma, and its active ingredient is ipilimumab. According to Drugs.com [2], the average retail price of a single 50mg vial of Yervoy is $10,000, and the cost of a full treatment course can exceed $120,000. However, the actual cost may vary depending on the patient's insurance coverage and the pharmacy they use. Drugpatentwatch.com [1] lists the expiration date for Yervoy's patent as October 26, 2022, which may lead to the availability of cheaper generic versions of the drug. A recent study published in JAMA Network Open [3] found that the high cost of cancer immunotherapy drugs, including Yervoy, can cause financial toxicity for patients and their families. The study suggests that policy interventions may be necessary to improve the affordability of these drugs. Overall, while the sources do not provide a specific discount amount for Yervoy, they highlight the high cost of the drug and the potential financial burden it may place on patients.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/YERVOY
[2] https://www.drugs.com/price-guide/yervoy
[3] https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2779418