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

Inclusion Criteria: * Diagnosis of: * Cohort 1: MM, based on IMWG criteria12, and currently requires treatment * Cohort 2: Stage II or III TNBC, with definition per protocol Section 3.2.1 AND * Plan for treatment, per their treating physician, or currently receiving their first cycle (see 3.3.3 for definition) of: * Cohort 1: Dara-RVd for MM * Cohort 2: A Keynote 522-based regimen of carboplatin, paclitaxel, and pembrolizumab given as the first phase of neoadjuvant treatment for TNBC.\*\*\* * Participants are eligible even if the duration of carboplatin and paclitaxel goes beyond 4 cycles, or if the use of pembrolizumab, doxorubicin, and cyclophosphamide is not planned or is not certain, as long as neoadjuvant treatment starts with carboplatin-paclitaxel-pembrolizumab. This cohort will be referred to as "Keynote 522" for the remainder of the protocol. AND * Confirmed Duffy null phenotype * Previous testing is acceptable if performed by a CLIA-approved test AND * Age \>=18 years old Exclusion Criteria: * Inability to understand and the willingness to sign a written informed consent document * ANC\