Associations of Multiparametric Breast MRI Features, Tumor-Infiltrating Lymphocytes, and Immune Gene Signature Scores Following a Single Dose of Trastuzumab in HER2-Positive Early-Stage Breast Cancer.

Dynamic biomarkers that permit the real-time monitoring of the tumor microenvironment response to therapy are an unmet need in breast cancer. Breast magnetic resonance imaging (MRI) has demonstrated value as a predictor of pathologic complete response and may reflect immune cell changes in the tumor microenvironment. The purpose of this pilot study was to investigate the value of breast MRI features as early markers of treatment-induced immune response. Fourteen patients with early HER2+ breast cancer were enrolled in a window-of-opportunity study where a single dose of trastuzumab was administered and both tissue and MRIs were obtained at the pre- and post-treatment stages. Functional diffusion-weighted and dynamic contrast-enhanced MRI tumor measures were compared with tumor-infiltrating lymphocytes (TILs) and RNA immune signature scores. Both the pre-treatment apparent diffusion coefficient (ADC) and the change in peak percent enhancement (DPE) were associated with increased tumor-infiltrating lymphocytes with trastuzumab therapy (r = -0.67 and -0.69, p < 0.01 and p < 0.01, respectively). Low pre-treatment ADC and a greater decrease in PE in response to treatment were also associated with immune-activated tumor microenvironments as defined by RNA immune signatures. Breast MRI features hold promise as biomarkers of early immune response to treatment in HER2+ breast cancer.

Extraordinary clinical response to ibrutinib in low-grade ovarian cancer guided by organoid drug testing.

Low-grade serous ovarian cancer (LGSOC) typically responds poorly to standard platinum-based chemotherapy and new therapeutic approaches are needed. We describe a remarkable response to targeted therapy in a patient with platinum-resistant, advanced LGSOC who had failed standard-of-care chemotherapy and two surgeries. The patient was in rapid decline and entering hospice care on home intravenous (i.v.) opioid analgesics and a malignant bowel obstruction requiring a G-tube. Genomic analysis of the patient's tumor did not indicate obvious therapeutic options. In contrast, a CLIA-certified drug sensitivity assay of an organoid culture derived from the patient's tumor identified several therapeutic choices, including Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, as well as the EGFR inhibitors afatinib and erlotinib. Following off-label administration of daily ibrutinib as monotherapy, the patient had an exceptional clinical turnaround over the following 65 weeks with normalization of CA-125 levels, resolution of the malignant bowel obstruction, halting of pain medications, and improvement of performance status from ECOG 3 to ECOG 1. After 65 weeks of stable disease, the patient's CA-125 levels began to rise, at which point the patient discontinued ibrutinib and began taking afatinib as monotherapy. The patient's CA-125 levels remained stable for an additional 38 weeks but due to anemia and rising CA-125 levels, the patient switched to erlotinib and is currently being monitored. This case highlights the clinical utility of ex vivo drug testing of patient-derived tumor organoids as a new functional precision medicine approach to identify effective personalized therapies for patients who have failed standard-of-care treatments.

Targeting BET Proteins BRD2 and BRD3 in Combination with PI3K-AKT Inhibition as a Therapeutic Strategy for Ovarian Clear Cell Carcinoma.

Ovarian clear cell carcinoma (OCCC) is a rare, chemo-resistant subtype of ovarian cancer. To identify novel therapeutic targets and combination therapies for OCCC, we subjected a set of patient-derived ovarian cancer cell lines to arrayed high-throughput siRNA and drug screening. The results indicated OCCC cells are vulnerable to knockdown of epigenetic gene targets such as bromodomain and extra-terminal domain (BET) proteins BRD2 and BRD3. Subsequent RNA interference assays, as well as BET inhibitor treatments, validated these BET proteins as potential therapeutic targets. Because development of resistance to single targeted agents is common, we next performed sensitizer drug screens to identify potential combination therapies with the BET inhibitor CPI0610. Several PI3K or AKT inhibitors were among the top drug combinations identified and subsequent work showed CPI0610 synergized with alpelisib or MK2206 by inducing p53-independent apoptosis. We further verified synergy between CPI0610 and PI3K-AKT pathway inhibitors alpelisib, MK2206, or ipatasertib in tumor organoids obtained directly from patients with OCCC. These findings indicate further preclinical evaluation of BET inhibitors, alone or in combination with PI3K-AKT inhibitors for OCCC, is warranted.