PI3Kδ inhibition elicits anti-leukemic effects through Bim-dependent apoptosis.

PI3Kδ plays pivotal roles in the maintenance, proliferation and survival of malignant B-lymphocytes. Although not curative, PI3Kδ inhibitors (PI3Kδi) demonstrate impressive clinical efficacy and, alongside other signaling inhibitors, are revolutionizing the treatment of hematological malignancies. However, only limited in vivo data are available regarding their mechanism of action. With the rising number of novel treatments, the challenge is to identify combinations that deliver curative regimes. A deeper understanding of the molecular mechanism is required to guide these selections. Currently, immunomodulation, inhibition of B-cell receptor signaling, chemokine/cytokine signaling and apoptosis represent potential therapeutic mechanisms for PI3Kδi. Here we characterize the molecular mechanisms responsible for PI3Kδi-induced apoptosis in an in vivo model of chronic lymphocytic leukemia (CLL). In vitro, PI3Kδi-induced substantive apoptosis and disrupted microenvironment-derived signaling in murine (Eµ-Tcl1) and human (CLL) leukemia cells. Furthermore, PI3Kδi imparted significant therapeutic responses in Eµ-Tcl1-bearing animals and enhanced anti-CD20 monoclonal antibody therapy. Responses correlated with upregulation of the pro-apoptotic BH3-only protein Bim. Accordingly, Bim-/- Eµ-Tcl1 Tg leukemias demonstrated resistance to PI3Kδi-induced apoptosis were refractory to PI3Kδi in vivo and failed to display combination efficacy with anti-CD20 monoclonal antibody therapy. Therefore, Bim-dependent apoptosis represents a key in vivo therapeutic mechanism for PI3Kδi, both alone and in combination therapy regimes.

Trypanosoma cruzi screening in Texas blood donors, 2008-2012.

Chagas disease is an important emerging disease in Texas that results in cardiomyopathy in about 30% of those infected with the parasite Trypanosoma cruzi. Between the years 2008 and 2012, about 1/6500 blood donors were T. cruzi antibody-confirmed positive. We found older persons and minority populations, particularly Hispanic, at highest risk for screening positive for T. cruzi antibodies during routine blood donation. Zip code analysis determined that T. cruzi is associated with poverty. Chagas disease has a significant disease burden and is a cause of substantial economic losses in Texas.

Production of melanocyte-specific antibodies to human melanosomal proteins: expression patterns in normal human skin and in cutaneous pigmented lesions.

Multiple factors affect skin pigmentation, including those that regulate melanocyte and/or keratinocyte function. Such factors, particularly those that operate at the level of the melanosome, are relatively well characterized in mice, but the expression and function of structural and enzymatic proteins in melanocytes in human skin are not as well known. Some years ago, we generated peptide-specific antibodies to murine melanosomal proteins that proved to be instrumental in elucidating melanocyte development and differentiation in mice, but cross-reactivity of those antibodies with the corresponding human proteins often was weak or absent. In an effort to characterize the roles of melanosomal proteins in human skin pigmentation, and to understand the underlying mechanism(s) of abnormal skin pigmentation, we have now generated polyclonal antibodies against the human melanocyte-specific markers, tyrosinase, tyrosinase-related protein (TYRP1), Dopachrome tautomerase (DCT) and Pmel17 (SILV, also known as GP100). We used these antibodies to determine the distribution and function of melanosomal proteins in normal human skin (adult and newborn) and in various cutaneous pigmented lesions, such as intradermal nevi, lentigo simplex, solar lentigines and malignant melanomas. We also examined cytokeratin expression in these same samples to assess keratinocyte distribution and function. Immunohistochemical staining reveals distinct patterns of melanocyte distribution and function in normal skin and in various types of cutaneous pigmented lesions. Those differences in the expression patterns of melanocyte markers provide important clues to the roles of melanocytes in normal and in disrupted skin pigmentation.

Growth of tumor-derived activated T cells for the treatment of advanced cancer.

In 1994, we reported on a series of patients treated with T-cell therapy (Study #1). This paper (Study #2) is an update of our experience through 1999 in the production of tumor-derived activated cells (TDAC), also called tumor-infiltrating lymphocytes (TIL), from tumor biopsies. TDAC were successfully grown in medium containing Interleukin-2 from 75% of the 366 tumor biopsies tested. There was no significant difference in success (growth to 1 x 10(9) cells) comparing primary and metastatic tumors. Many of the tumors were shipped to the laboratory by overnight delivery from distant sites. Success rate did decrease with the length of time for tumor transport in excess of 24 hours. Certain additional cytokines were tested when cultures did not grow. Interleukin-4 was beneficial in the development of 1 of 4 TDAC cultures which did not grow with IL-2 alone. In order to produce TDAC to treat patients, cells were grown in gas permeable plastic bags or in artificial capillary bioreactor cultures. Approximately 1 x 10(9) were seeded from an initially successful "feasibility study" to bulk produce cells for treatment. Harvest was carried out after about 3 weeks. Sixty-three patients were treated at least once with a minimum of 1 x 10(10) TDAC given by intravenous infusion. On the average, the number of cells per treatment was 3 x 10(10) with a viability of 87%. TDAC cultures contained T cells with variable ratios of CD4 to CD8 cells. Secreted granulocyte-monocyte colony stimulating factor, interferon gamma and tumor necrosis factor alpha were measured in TDAC conditioned medium. Only 34 patients received the full course of 4 TDAC treatments. The cells were well tolerated with mild fever and dyspnea. Partial responses were observed in 8 patients, including the dramatic regression of scalp nodules in a patient with renal cancer. These results showed that therapeutic amounts of TDAC can be produced in cell culture in a reasonable and cost-effective manner. The cells were well tolerated and responses were seen in renal and melanoma patients resistant to IL-2 with bulky, advanced cancer.

Phase I study of CBT-1 and Taxol in patients with Taxol resistant cancers.

CBT-1, a natural product, was studied as an MDR modulator with Taxol (135 mg/m2) in an escalating dose Phase I clinical trial. CBT-1 was administered orally at doses from 300 mg/m2 to 500 mg/m2 daily x 7. The MTD was determined to be 500 mg/m2 with moderate nausea and occasional emesis. Side effects were mainly attributable to Taxol rather than the study drug. A total of 18 patients were registered on study with only one patient determined to be intolerant of CBT-1 due to nausea and emesis. In this Phase I study four patients (3 breast, 1 NSCLC) remained stable for greater than two cycles of treatment. No complete or partial responses were seen in this Taxol resistant population of patients with advanced cancer.

Chemo-biotherapy with 5-fluorouracil, leucovorin, and alpha interferon in metastatic carcinoma of the colon--a Cancer Biotherapy Research Group [CBRG] phase II study.

BACKGROUND: Biochemical modulation of 5-Fluorouracil activity with Leucovorin has been well documented in colorectal cancer. Several studies have shown increased efficacy of 5-fluorouracil in combination with alpha interferon. We therefore initiated a phase II trial of dual modulation of 5-fluorouracil with leucovorin and alpha interferon to evaluate outcomes in patients with metastatic carcinoma of the colon. METHODS: Patients with metastatic colon carcinoma with expected survival > 4 months and performance status of ECOG < or = 2 were treated weekly with Leucovorin 400 mg i.v. followed by 5-FU 600 mg/m2 i.v. bolus. Alpha interferon 3-9 million units was administered subcutaneously every Monday, Wednesday and Friday. Patients were analyzed for toxicity, tumor response and survival. RESULTS: Sixteen patients with a median age of 66 years were treated. Three patients were not evaluable for response but were evaluable for toxicity. Grades 3 and 4 toxicities were neutropenia, diarrhea, mucositis, nausea and vomiting, fatigue, fever, asthenia and elevated hepatic enzymes. One patient died from complications associated with diverticulitis and neutropenia. Objective response rate was 23% (95% confidence interval 4-46%) and median survival was 11.5 months (95% confidence interval 6.3-19 months). Thirty-eight percent of the patients were alive at one year and 19% at two years. CONCLUSION: The combination of 5-fluorouracil, leucovorin and alpha interferon as administered in this phase II study did not result in enhanced response rate or survival. However this regimen was associated with considerable toxicity.

A phase I and pharmacokinetic study of CBT-1 as a multidrug resistance modulator in the treatment of patients with advanced cancer.

CBT-1, a natural product, was studied in an escalating dose Phase I clinical trial with doxorubicin at 60 mg/m2. CBT-1 was administered by mouth at doses from 200 mg/m2 to 600 mg/m2. The drug was given for 7 days and doxorubicin administered intravenously on day 6. The MTD was determined to be 500 mg/m2 although some patients did tolerate 600 mg/m2 with moderate nausea and occasional vomiting. Side effects were otherwise mild in the 23 patients treated. Pharmacokinetic determinations in an additional 11 patients demonstrated that CBT-1 did not significantly alter the pharmacokinetics of doxorubicin. In this Phase I study, 25 of 34 patients were evaluable for response and 5 patients demonstrated tumor shrinkage.

A revolution in the treatment of non-Hodgkin's lymphoma.

The use of monoclonal antibodies (MoAbs) for immunotherapy and radioimmunotherapy has ushered in a new era in the treatment of non-Hodgkin's lymphoma.

The Cancer Biotherapy Research Group [CBRG], formerly the National Biotherapy Study Group [NBSG]: a 10-year perspective.

The Cancer Biotherapy Research Group [CBRG], formerly known as the National Biotherapy Study Group [NBSG], celebrated its 10th anniversary in 1997. CBRG is a not-for-profit cancer clinical trials group of community oncologists whose activities for the most part have been funded by their associated community hospitals. From its inception the Group has focused on clinical investigations of biological agents in the treatment of patients with advanced cancer. This article reviews the history of the Group, its structure, accomplishments, and its current objectives and challenges.

Long-term survival after continuous infusion interleukin-2.

PURPOSE: Between 1987-1990, 612 patients received high-dose continuous intravenous interleukin-2 (IL-2) in phase II clinical trials of the National Biotherapy Study Group (NBSG). The purpose of this analysis was to determine the long-term survival rates associated with such therapy and the correlation, if any, between objective tumor response, and survival. METHODS: Patients who are known to have survived at least 3 years or more were identified. Actual and actuarial survival rates were determined for various malignancies and by tumor response. RESULTS: At least 37 (6.0%) survived > or = 3 years from the initiation of IL-2 therapy, and it is possible the 3-year survival rate is as high as 20%. This included 14/168 (8%) of patients with renal cell carcinoma, 10/175 (6%) melanoma, 2/51 (4%) lung cancer, 0/61 colorectal, 0/36 breast, 1/17 sarcoma, 1/14 pancreas, 1/19 ovary, 3/11 lymphoma, 2 adenocystic carcinomas, 2 carcinoid, and one Hodgkin's disease. Four hundred ninety-one of 612 (80%) are known to have died, 121 were still alive at the time of the last follow-up. Median survival was 7.9 months. Among 547 evaluable patients, there were eight complete responses (CR) and 42 partial responses (PR), for an objective response rate of 9%. An additional 32 patients had mixed or minimal responses (MR) for a total response rate of 15%. The 3-year survival rates were 25% for PR, 17% for PR, 16% for MR, 8% for stable disease (SD), and 2% for patients with progressive disease (PD). Responders made up a higher proportion of patients who survived > or = 3 years than of patients who survived < or = 3 years (14/37 = 38% vs 68/500 = 14%; p < .0001, X2). A higher proportion of responders survived > or = 3 years than non-responders (14/82 = 17% vs 23/230 = 4%, p < .0001, X2). Patients with CR, PR, or MR had a > or = 3-year survival rate (14/82 = 17%) than patients who had SD (20/249 = 8%; p = .02, x2, who in turn had a > or = 3-year survival rate that was greater than patients who had PD (3/206 = 2%; p = .001, X2). For individual trials in which 10 or more patients were enrolled, the percentage of patients surviving > or = 3 years ranged between 4% and 8%. CONCLUSION: We conclude that in the setting of IL-2 therapy for metastatic cancer, the probability of surviving > or = 3 years was approximately 12 times greater for responders, and five times greater for patients with SD; as compared to patients who had PD. Furthermore, despite diagnoses of metastatic cancer, often in settings in which disease had been refractory to standard therapy there was an actual 3-year survival rate of at least 6% to 8% for patients with metastatic melanoma and renal cell carcinoma.