Visualizing Engrafted Human Cancer and Therapy Responses in Immunodeficient Zebrafish.

Xenograft cell transplantation into immunodeficient mice has become the gold standard for assessing pre-clinical efficacy of cancer drugs, yet direct visualization of single-cell phenotypes is difficult. Here, we report an optically-clear prkdc-/-, il2rga-/- zebrafish that lacks adaptive and natural killer immune cells, can engraft a wide array of human cancers at 37°C, and permits the dynamic visualization of single engrafted cells. For example, photoconversion cell-lineage tracing identified migratory and proliferative cell states in human rhabdomyosarcoma, a pediatric cancer of muscle. Additional experiments identified the preclinical efficacy of combination olaparib PARP inhibitor and temozolomide DNA-damaging agent as an effective therapy for rhabdomyosarcoma and visualized therapeutic responses using a four-color FUCCI cell-cycle fluorescent reporter. These experiments identified that combination treatment arrested rhabdomyosarcoma cells in the G2 cell cycle prior to induction of apoptosis. Finally, patient-derived xenografts could be engrafted into our model, opening new avenues for developing personalized therapeutic approaches in the future.

Metastatic Breast Cancer With ESR1 Mutation: Clinical Management Considerations From the Molecular and Precision Medicine (MAP) Tumor Board at Massachusetts General Hospital.

UNLABELLED: : The last decade in oncology has witnessed impressive response rates with targeted therapies, largely because of collaborative efforts at understanding tumor biology and careful patient selection based on molecular fingerprinting of the tumor. Consequently, there has been a push toward routine molecular genotyping of tumors, and large precision medicine-based clinical trials have been launched to match therapy to the molecular alteration seen in a tumor. However, selecting the "right drug" for an individual patient in clinic is a complex decision-making process, including analytical interpretation of the report, consideration of the importance of the molecular alteration in driving growth of the tumor, tumor heterogeneity, the availability of a matched targeted therapy, efficacy and toxicity considerations of the targeted therapy (compared with standard therapy), and reimbursement issues. In this article, we review the key considerations involved in clinical decision making while reviewing a molecular genotyping report. We present the case of a 67-year-old postmenopausal female with metastatic estrogen receptor-positive (ER+) breast cancer, whose tumor progressed on multiple endocrine therapies. Molecular genotyping of the metastatic lesion revealed the presence of an ESR1 mutation (encoding p.Tyr537Asn), which was absent in the primary tumor. The same ESR1 mutation was also detected in circulating tumor DNA (ctDNA) extracted from her blood. The general approach for interpretation of genotyping results, the clinical significance of the specific mutation in the particular cancer, potential strategies to target the pathway, and implications for clinical practice are reviewed in this article. KEY POINTS: ER+ breast tumors are known to undergo genomic evolution during treatment with the acquisition of new mutations that confer resistance to treatment.ESR1 mutations in the ligand-binding domain of ER can lead to a ligand-independent, constitutively active form of ER and mediate resistance to aromatase inhibitors.ESR1 mutations may be detected by genomic sequencing of tissue biopsies of the metastatic tumor or by sequencing the circulating tumor cells or tumor DNA (ctDNA).Sequencing results may lead to a therapeutic "match" with an existing FDA-approved drug or match with an experimental agent that fits the clinical setting.

Heterogeneous immunogenicity of SARS-CoV-2 vaccines in cancer patients receiving radiotherapy.

The immunogenicity of SARS-CoV-2 vaccines in cancer patients receiving radiotherapy is unknown. This prospective cohort study demonstrates that anti-SARS-CoV-2 spike antibody and neutralization titers are reduced in a subset of thoracic radiotherapy patients, possibly due to immunosuppressive conditions. Antibody testing may be useful to identify candidates for additional vaccine doses.

Clinical Grade "SNaPshot" Genetic Mutation Profiling in Multiple Myeloma.

Whole genome sequencing studies have identified several oncogenic mutations in multiple myeloma (MM). As MM progresses, it evolves genetically underscoring the need to have tools for rapid detection of targetable mutations to optimize individualized treatment. Massachusetts General Hospital (MGH) has developed a Clinical Laboratory Improvement Amendments (CLIA)-approved, high-throughput, genotyping platform to determine the mutation status of a panel of known oncogenes. Sequence analysis using SNaPshot on DNA extracted from bone marrow and extramedullary plasmacytomas is feasible and leads to the detection of potentially druggable mutations. Screening MM patients for somatic mutations in oncogenes may provide novel targets leading to additional therapies for this patient population.