Genomic profiling of cell-free circulating tumor DNA in patients with colorectal cancer and its fidelity to the genomics of the tumor biopsy.

BACKGROUND: Liquid biopsy offers the ability to non-invasively analyze the genome of a tumor through circulating tumor DNA (ctDNA) to identify targetable and prognostic genomic alterations. Few studies have rigorously analyzed ctDNA results and determined the fidelity with which they recapitulate the genomics of a sequenced tissue sample obtained from the same tumor. The clinical utility study (CUS) for the FoundationACT™ ctDNA assay (Foundation Medicine, Cambridge, MA, USA; NCT02620527) is a multi-center prospective clinical study for multiple solid tumor types to compare genomic profiling of paired tissue and blood samples from the same patient. In this subset of the study, paired specimens from 96 patients with colorectal cancer (CRC) were analyzed with comprehensive genomic profiling (CGP) of the tumor tissue sample (FoundationOne®) and blood sample (FoundationACT™). METHODS: Both samples underwent CGP using the hybrid capture-based Illumina Hi-Seq technology. Maximum somatic allele frequency (MSAF) was used to estimate the fraction of ctDNA in the sample. The set of genes and targeted regions common to both tumor and liquid were compared for each subject. RESULTS: Among these patients, 61% were male; 74% had clinical stage IV disease, 19% had clinical stage III disease, and 7% had clinical stage II disease. Time between the tissue biopsy and liquid biopsy (range, 0-709 days) had a significant impact on the positive percent agreement (PPA) between the two assays. Eighty percent of cases had evidence of ctDNA in the blood (MSAF >0). For all cases with MSAF >0, 171 base substitutions and insertions/deletions (indels) were identified in the tumor, and 79% (PPA) of these identical alterations were also identified in matched ctDNA samples; PPA increased to 87% for cases <270 days between the tissue and liquid biopsy, 95% for <90 days, and 100% PPA for <30 days. All known and likely short variants in KRAS, NRAS, and BRAF were analyzed independently as testing of these genes is recommended by the National Comprehensive Cancer Network (NCCN) for patients with CRC and have therapeutic implications. For NCCN genes, PPA was 80% for all time points for short variants; PPA increased to 90% for cases <270 days between the tissue and liquid biopsy. There was high concordance for KRAS G12X between tissue and liquid: overall percent agreement (97%), PPA (93%), negative percent agreement (NPA) (100%), positive predictive value (PPV) (100%), and negative predictive value (NPV) (96%) for the <270 day cohort. CONCLUSIONS: In cases where tumor tissue profiling is not possible, these results provide compelling evidence that genomic profiling of ctDNA in late stage CRC shows a high concordance with tumor tissue sequencing results and can be used to identify most clinically relevant alterations capable of guiding therapy for these patients.

Downregulation of retinoblastoma protein is involved in the enhanced cytotoxicity of 4-hydroxytamoxifen plus mifepristone combination therapy versus antiestrogen monotherapy of human breast cancer.

In this study, human MCF-7 breast cancer cells, which express functional estrogen and progesterone receptors, were used to compare the efficacy of combined antiestrogen plus antiprogestin therapy to antiestrogen monotherapy. Cells were treated with the antiestrogen 4-hydroxytamoxifen (4-OHT) and/or the antiprogestin mifepristone (MIF) and effects on cell proliferation (cytostatic action), cell cycle phase, the phosphorylation state of the tumor suppressor retinoblastoma protein (Rb), and induction of active cell death (cytotoxic action) were determined. Combination hormonal therapy showed both increased cytostatic and cytotoxic activity as compared to either monotherapy. The increased cytostatic action was mediated by Rb activation; whereas, the cytotoxic (pro-apoptotic) action of combined hormonal therapy correlated to a significant reduction in Rb protein levels. To test the apparent role of Rb protein loss in the pro-apoptotic action of combined hormonal therapy, Rb was downregulated in MCF-7 cells using siRNA-targeting. The siRNA-mediated knockdown of Rb combined with 4-OHT therapy resulted in a pro-apoptotic action similar to that resulting from 4-OHT and MIF combination treatment, which included increased cell detachment from the monolayer, high-molecular-weight genomic DNA fragmentation, and cleavage of poly ADP-ribose polymerase (PARP) and lamin A. From these studies, we conclude that Rb protein downregulation is required for 4-OHT-treated, estrogen receptor positive (ER+) breast cancer cells to undergo active cell death. We discuss the potential of using an antiprogestin such as MIF plus antiestrogen treatment to more effectively downregulate Rb in ER+ breast cancer cells to increase the overall cytotoxic action of hormonal therapy.

Mifepristone induces growth arrest, caspase activation, and apoptosis of estrogen receptor-expressing, antiestrogen-resistant breast cancer cells.

PURPOSE: A major clinical problem in the treatment of breast cancer is the inherent and acquired resistance to antiestrogen therapy. In this study, we sought to determine whether antiprogestin treatment, used as a monotherapy or in combination with antiestrogen therapy, induced growth arrest and active cell death in antiestrogen-resistant breast cancer cells. EXPERIMENTAL DESIGN: MCF-7 sublines were established from independent clonal isolations performed in the absence of drug selection and tested for their response to the antiestrogens 4-hydroxytamoxifen (4-OHT) and ICI 182,780 (fulvestrant), and the antiprogestin mifepristone (MIF). The cytostatic (growth arrest) effects of the hormones were assessed with proliferation assays, cell counting, flow cytometry, and a determination of the phosphorylation status of the retinoblastoma protein. The cytotoxic (apoptotic) effects were analyzed by assessing increases in caspase activity and cleavage of poly(ADP-ribose) polymerase. RESULTS: All of the clonally derived MCF-7 sublines expressed estrogen receptor and progesterone receptor but showed a wide range of antiestrogen sensitivity, including resistance to physiological levels of 4-OHT. Importantly, all of the clones were sensitive to the antiprogestin MIF, whether used as a monotherapy or in combination with 4-OHT. MIF induced retinoblastoma activation, G(1) arrest, and apoptosis preceded by caspase activation. CONCLUSIONS: We demonstrate that: (a) estrogen receptor(+)progesterone receptor(+), 4-OHT-resistant clonal variants can be isolated from an MCF-7 cell line in the absence of antiestrogen selection; and (b) MIF and MIF plus 4-OHT combination therapy induces growth arrest and active cell death of the antiestrogen-resistant breast cancer cells. These preclinical findings show potential for a combined hormonal regimen of an antiestrogen and an antiprogestin to combat the emergence of antiestrogen-resistant breast cancer cells and, ultimately, improve the therapeutic index of antiestrogen therapy.

A phase II study of weekly paclitaxel and carboplatin in previously untreated patients with advanced non-small-cell lung cancer.

PURPOSE: Both paclitaxel (P) and carboplatin (C) have a significant activity in non-small cell lung cancer (NSCLC). Weekly administration of P is active, is dose intense, and has a favorable toxicity profile. To evaluate the efficacy and toxicity of weekly P and C in advanced-stage NSCLC, we initiated this phase II study in patients with advanced NSCLC (III B with pleural effusion and stage IV). PATIENTS AND METHODS: Eligible patients were treated with paclitaxel 100 mg/m2 intravenously (iv) over 1 h followed by carboplatin AUC 2 iv over 30 min. This treatment was administered weekly for 3 of every 4 wk until disease progression or intolerable toxicities. RESULTS: Of the 30 patients enrolled in the study, one patient did not meet the eligibility criteria. Of the remaining 29 patients, 6 did not complete at least two cycles of treatment and hence were not assessable for response. The overall response rate was 43.5% (10/23) (all partial responses). An additional 43.5% had stable disease. The median time to progression was 162 d and the median duration of response was 169 d. Overall survival at 1 yr on intent-to-treat analyses was 44% and median survival was 10.8 mo. We observed the following grade 3/4 toxicities: hypersensitivity to paclitaxel (13%), hypersensitivity to carboplatin (3%), neutropenia (31%), thrombocytopenia (7%); 31% experienced grade 1 neuropathy and 17% experienced grade 2 neuropathy. CONCLUSIONS: We conclude that weekly paclitaxel and carboplatin is active and very well tolerated in patients with advanced NSCLC.

Induction of antiproliferation and apoptosis in estrogen receptor negative MDA-231 human breast cancer cells by mifepristone and 4-hydroxytamoxifen combination therapy: a role for TGFbeta1.

Mifepristone (MIF) is an antiprogestin with potent anti-glucocorticoid and anti-androgen activity. MIF also appears to have anti-tumor activity independent of its ability to bind to nuclear receptors. In this study, we tested the ability of MIF to inhibit the growth of ER and PR negative breast cancer cells. In addition, because high-dose anti-estrogen treatment has been shown to inhibit ER and PR negative breast cancer cells, we compared the anti-proliferative activity of MIF to that of the anti-estrogen 4-hydroxytamoxifen (TAM) or combination hormonal therapy (MIF + TAM). MIF and TAM therapy induced a significant time- and dose-dependent growth inhibition and, ultimately, induced cell death in MDA-231 cells as evidenced by increased DNA fragmentation, cytochrome c release from the mitochondria, and the activation of caspase-3. The anti-proliferative activity of TAM plus MIF combination treatment was at least additive as compared to either monotherapy. The earliest indicator of TAM and MIF cytostatic and cytotoxic action on MDA-231 cells was a significant (p<0.05) induction of TGFbeta1 secretion into the growth medium within 4 h of treatment. Secreted TGFbeta1 levels at 24 and 48 h were significantly higher in the TAM plus MIF treatment group as compared to cells treated with TAM or MIF alone. TGFbeta1 neutralizing antibody or addition of mannose-6-phosphate (M6P), a reagent also used to inhibit TGFbeta1, significantly attenuated the TAM and/or MIF-induced cell growth inhibition and cell death. In summary, our results indicate that MIF used in combination with TAM can effectively kill estrogen-insensitive human breast cancer cells. Our study further implies that agents that effectively increase TGFbeta1 levels in ER negative breast cancer cells may be one treatment approach for hormone-independent breast cancers.

Rituximab provides durable remission in a patient with refractory aggressive diffuse B-cell lymphoma failing salvage chemotherapy.

The outcome of patients with aggressive refractory diffuse large B-cell lymphoma (DLCL) is generally poor. A 43-year-old female with DLCL, who relapsed after first line chemotherapy (CHOP--cyclophosphamide, doxorubicin, vincristine, and prednisone) and progressed despite salvage chemotherapy (EPOCH-etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin), was treated effectively with 8 cycles of Rituximab. She is without evidence of disease with a follow-up of 32 months. We report this case to bring to attention the possibility of sustained durable remission with single agent Rituximab in refractory DLCL.

Treatment of a patient with end-stage renal disease with Rituximab: pharmacokinetic evaluation suggests Rituximab is not eliminated by hemodialysis.

The purpose of this study was to determine if therapeutic levels of Rituximab could be achieved in a patient with renal failure being dialyzed and if Rituximab is removed by hemodialysis. A 54-year-old man with low-grade lymphoma and renal failure on hemodialysis received 8 weekly treatments of Rituximab at 375 mg/M(2). Serum Rituximab levels were obtained before and after each treatment, before and after dialysis following each treatment, as well as in the dialysate fluid. The serum levels of Rituximab increased gradually with each treatment and were comparable to levels in patients with normal renal function. The postdialysis levels were higher than the predialysis levels as a consequence of hemo-concentration after dialysis. Rituximab was not detected in the dialysate fluid. The patient developed life-threatening hyperkalemia after the fourth treatment, which we believe occurred secondary to tumor lysis. Therapeutic levels of Rituximab may be maintained in patients undergoing dialysis. Rituximab is not eliminated by hemodialysis.

Infectious complications in patients receiving mobilization chemotherapy for autologous peripheral blood stem cell collection.

The purpose of this retrospective study was to evaluate infectious complications in patients receiving mobilization chemotherapy for stem cell collection prior to autologous peripheral blood stem cell transplantation. An additional goal was to evaluate risk factors associated with the development of infectious complications. At the Medical College of Georgia BMT center, 54 patients were administered mobilization chemotherapy for the purpose of collecting stem cells between June, 1997, and May, 2002. All patients received Filgrastim in addition to chemotherapy, and 50 of 54 patients received prophylactic acyclovir, fluconazole, and ciprofloxacin until neutrophil recovery. The median duration to neutrophil recovery was 11 days. Fourteen of 54 (26%) patients developed fever/infections during the mobilization phase. One patient developed both a catheter-related infection and Clostridium difficile colitis, increasing the total number of infectious episodes to 15. Twelve patients had a documented site of infection whereas 2 patients had neutropenic fever with no identifiable source. Eight of the 15 (55%) infections were Gram-positive catheter infections. All the patients were treated successfully with antibiotics. No systemic fungal infections were identified and none of the patients died from complications related to mobilization chemotherapy. Logistic regression was applied for univariate and multivariate analysis and showed that age, sex, diagnosis, neutrophil recovery, disease status, use of salvage chemotherapy, and mobilization regimen used did not affect the infection rate. In our series of 54 patients, 14 patients developed fever/infections during mobilization. Although there is a substantial risk of infectious complications among patients who receive mobilization chemotherapy, it is not clear that prophylactic antibiotics decrease infectious complications. Because the vast majority of infections are Gram-positive catheter infections, it appears reasonable to employ Gram-positive prophylaxis. Controlled studies should be conducted to define the optimum mobilization regimens as well as the optimum combination of prophylactic antibiotics.