I could not find any studies specifically on lurbinectedin and breast milk. The drug is a synthetic analog of a marine-derived compound and is indicated for the treatment of metastatic small cell lung cancer (SCLC) in adult patients who have progressed after prior platinum-containing therapy [1]. The FDA has approved Lurbinectedin under the brand name Zepzelca for this indication [2].

According to the prescribing information of Zepzelca, it is not known whether the drug is excreted in human milk or not, and there are no data on the effects of the drug on breastfed infants or milk production [3]. Therefore, the manufacturer advises patients not to breastfeed during treatment with Zepzelca and for at least one week after the last dose [3].

In conclusion, there are no studies available on lurbinectedin and breast milk. The prescribing information of Zepzelca advises against breastfeeding during treatment with the drug due to the lack of data on its effects on breastfed infants and milk production [3].

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LURBINECTEDIN
[2] https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/213702s000lbl.pdf
[3] https://pp.jazzpharma.com/pi/zepzelca.ca.PM-en.pdf