Lurbinectedin is a chemotherapy drug used to treat certain types of cancer. According to the sources provided, hair loss is a possible side effect of lurbinectedin treatment. However, the frequency of hair loss is not explicitly stated in the sources.

The first source, Drug Patent Watch [1], provides information on the patent status and exclusivity of pharmaceutical drugs, including lurbinectedin. However, it does not provide information on the side effects of the drug.

The second source, Mayo Clinic [2], is a reputable medical institution that provides information on various drugs, including lurbinectedin. According to Mayo Clinic, hair loss is a possible side effect of lurbinectedin treatment. However, the frequency of hair loss is not specified.

The third source, a research article published in the journal Cancers [3], discusses the efficacy and safety of lurbinectedin in treating certain types of cancer. The article mentions hair loss as a potential side effect of the drug, but does not provide information on the frequency of hair loss.

In conclusion, hair loss is a possible side effect of lurbinectedin treatment, according to the sources provided. However, the frequency of hair loss is not explicitly stated in these sources. Patients who are prescribed lurbinectedin should discuss the potential side effects with their healthcare provider.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LURBINECTEDIN
[2] https://www.mayoclinic.org/drugs-supplements/lurbinectedin-intravenous-route/side-effects/drg-20490804?p=1
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8900004/