We have been involved in many cancer vaccine trial

We have been involved in many cancer vaccine trials, primarily for brain tumors (targeting EGFR-III or other tumor specific antigen). The key with cancer vaccines is to find an antigen specific only to the tumor, such that the immune system is revved up by the vaccine to kill only those cells, and leave the healthy ones alone.

They aren't saying the lactalbumin protein causes cancer, just that the cancer cells over-express that protein, but normal cells don't (outside of late pregnancy and during lactation). So, this is a nice specific cancer antigen that can be targeted with a vaccine.

There are many cancer vaccine trials ongoing by many companies (see Inovio for instance for their HPV cervical cancer and RRP vaccines and hTERT- WT1 - PSMA GBM therapeutic).

Unfortunately cancer vaccines for solid tumors have not found great success thus far. Hopefully this one has better luck in treating mTNBC or even preventing recurrence.

A recent overview of cancer vaccines:

https://www.nature.com/articles/s41568-021-00346-0

One of the latest trends is combining a cancer vaccine (to produce the T-effector cells to kill the tumors) with an immunomodulatory drug (typically anti-PD1 "checkpoint inhibitor" ) to remove the immunosuppressants that keep the killer T-cells away. The tumor microenvironment and general state of the immune system (amazingly related to gut microbiome) are very important. It's possible that leronlimab could be synergistic with some of these cancer vaccines, by keeping the T-Regs away from the tumor and allowing the newly revved up T-cells to kill the cancer.