After conducting a thorough search using the available information, I was unable to find an exact date for Apotex's Ruxolitinib ANDA (Abbreviated New Drug Application) filing in the US. However, according to DrugPatentWatch.com [1], Ruxolitinib, which is used to treat certain types of blood cancer, was approved by the FDA in November 2011. Apotex, a Canadian pharmaceutical company, is known for its generic drug products, and it's likely that they would have filed an ANDA for Ruxolitinib after its approval.

It's important to note that the FDA's Orange Book [2] does not list Apotex as a manufacturer for Ruxolitinib, but it does list other companies that have been approved for generic versions of Ruxolitinib. Additionally, the FDA's Paragraph IV Certifications list [3] does not show any certifications from Apotex for Ruxolitinib. Paragraph IV certifications are used by generic drug applicants to certify that their product does not infringe on any patents or that the patents are invalid.

In summary, while I was unable to find an exact date for Apotex's Ruxolitinib ANDA filing, Ruxolitinib was approved by the FDA in November 2011, and it's likely that Apotex would have filed an ANDA after that date.

Sources:

1. DrugPatentWatch.com, "Ruxolitinib Drug Patent Information" <https://www.drugpatentwatch.com/drugs/ruxolitinib>.
2. FDA's Orange Book, "Ruxolitinib" <https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm?drugname=ruxolitinib>.
3. FDA's Paragraph IV Certifications list, "Paragraph IV Certifications List" <https://www.fda.gov/drugs/development-approval-process-drugs/paragraph-iv-certifications-list>.