Systemic Anti-Cancer Therapy Dose Modifications for Individuals With Duffy Null Phenotype

This study is comprised of a main study, an observational study, and optional survey studies. The main study is being done to see whether using Duffy null specific treatment dosing guidelines can reduce or delay dose modifications and avoid neutropenic fever (fever in the setting of low neutrophils) for people with Duffy null phenotype receiving treatment for multiple myeloma or triple negative breast cancer. The observational study is to collect dose modification and neutropenic fever information on patients who do not have the Duffy null phenotype and receive the same standard of care regimens to see if there are differences in dose modifications and neutropenic fever between the two groups. The survey studies seek to understand general health experiences and preferences and experiences specific to people with Duffy null phenotype. Study Drugs Include: * Daratumumab * lenalidomide * bortezomib * dexamethasone * carboplatin * paclitaxel * pembrolizumab * cyclophosphamide * doxorubicin