Amy M. Lin

Potentiating Endogenous Antitumor Immunity to Prostate Cancer through Combination Immunotherapy with CTLA4 Blockade and GM-CSF

CTL-associated antigen 4 (CTLA4) is a costimulatory molecule expressed on activated T cells that delivers an inhibitory signal to these T cells. CTLA4 blockade with antibody treatment has been shown to augment antitumor immunity in animal models and is being developed as a treatment for cancer patients. As has been seen in preclinical models, combining CTLA4 blockade and granulocyte macrophage colony-stimulating factor (GM-CSF)-based immunotherapies can enhance the antitumor efficacy of this approach. We therefore examined whether CTLA4 blockade could be combined with GM-CSF administration. We treated 24 patients with metastatic, castration-resistant prostate cancer in a phase I trial where sequential cohorts were treated with increasing doses of ipilimumab, a fully human anti-CTLA4 antibody. Study subjects also received s.c. injections of GM-CSF at a fixed dose. Of the six patients treated at the highest dose level, three had confirmed PSA declines of >50%, including one patient that had a partial response in visceral metastases. Expansion of activated, circulating CD25(+) CD69(+) CD8(+) T cells occurred more frequently at higher doses of treatment and was greater in magnitude than was seen in patients who received the same doses of either ipilimumab or GM-CSF alone. By screening sera with protein arrays, we showed that our treatment can induce antibody responses to NY-ESO-1. These results show that this combination immunotherapy can induce the expansion not only of activated effector CD8 T cells in vivo but also of T cells that are specific for known tumor-associated antigens from the endogenous immune repertoire.

Targeting RNA Polymerase I with an Oral Small Molecule CX-5461 Inhibits Ribosomal RNA Synthesis and Solid Tumor Growth

Deregulated ribosomal RNA synthesis is associated with uncontrolled cancer cell proliferation. RNA polymerase (Pol) I, the multiprotein complex that synthesizes rRNA, is activated widely in cancer. Thus, selective inhibitors of Pol I may offer a general therapeutic strategy to block cancer cell proliferation. Coupling medicinal chemistry efforts to tandem cell- and molecular-based screening led to the design of CX-5461, a potent small-molecule inhibitor of rRNA synthesis in cancer cells. CX-5461 selectively inhibits Pol I-driven transcription relative to Pol II-driven transcription, DNA replication, and protein translation. Molecular studies demonstrate that CX-5461 inhibits the initiation stage of rRNA synthesis and induces both senescence and autophagy, but not apoptosis, through a p53-independent process in solid tumor cell lines. CX-5461 is orally bioavailable and demonstrates in vivo antitumor activity against human solid tumors in murine xenograft models. Our findings position CX-5461 for investigational clinical trials as a potent, selective, and orally administered agent for cancer treatment.

A phase II trial of imatinib mesylate in patients with biochemical relapse of prostate cancer after definitive local therapy

To determine the biological effects of imatinib mesylate (STI‐571, Gleevec®; Novartis Pharmaceuticals, Inc., East Hanover, NJ, USA), as measured by prostate‐specific antigen (PSA) kinetics in men with biochemical relapse of prostate cancer after definitive local therapy.

A phase 1 study of everolimus and sorafenib for metastatic clear cell renal cell carcinoma

The current study was conducted to assess the maximum tolerated dose (MTD), safety, pharmacokinetics, and preliminary antitumor effect of everolimus, a mammalian target of rapamycin inhibitor, in combination with sorafenib, a tyrosine kinase inhibitor, in patients with metastatic clear cell renal cell carcinoma.

Preexisting Levels of CD4 T Cells Expressing PD-1 Are Related to Overall Survival in Prostate Cancer Patients Treated with Ipilimumab

Retrospective analysis of blood from cancer patients receiving the combination of anti–CTLA-4 plus GM-CSF revealed no relation between survival and changes in immune cell subsets with treatment. However, short-term survivors had high preexisting PD-1+ CD4 T-cell counts. Cytotoxic T-lymphocyte–associated antigen-4 (CTLA-4) blockade can induce tumor regression and improved survival in cancer patients. This treatment can enhance adaptive immune responses without an exogenous vaccine, but the immunologic biomarkers associated with improved clinical outcome in cancer patients are not fully established. A phase Ib trial in patients with metastatic, castration-resistant prostate cancer was performed combining ipilimumab with sargramostim (GM-CSF). In addition to evaluating ipilimumab dose, patients were followed clinically for response and overall survival, and for immunomodulation of circulating T cells. PSA declines of ≥50% and radiographic responses were observed at doses of ≥3 mg/kg/dose. Timing of clinical responses could be either immediate or delayed. Durable responses were also observed off treatment. A subset of patients experienced long-term survival with or without objective clinical responses. The relationship between T-cell phenotype in peripheral blood and overall survival was examined retrospectively. We found that the treatment induced an increase in the levels of CD4+ effector T (Teff) cells, regulatory T cells, PD-1+ CD4 Teff cells, and PD-1+ CD8 T cells. However, these increased levels were not associated with overall survival. Instead, low pretreatment baseline levels of PD-1+ CD4 Teff cells were found to correlate with longer overall survival. Furthermore, baseline levels of PD-1+ CD4 Teff cells from patients with shorter overall survival were higher than from cancer-free male control subjects. These results suggest that preexisting expression of immunologic checkpoint marker PD-1 on CD4 Teff cells may help identify patients that may benefit from ipilimumab treatment. Cancer Immunol Res; 3(9); 1008–16. ©2015 AACR.

A pilot dose‐escalation study of the effects of nordihydroguareacetic acid on hormone and prostate specific antigen levels in patients with relapsed prostate cancer

To assess the tolerability of the effects of nordihydroguareacetic acid (NDGA) and its effect on prostate‐specific antigen (PSA) kinetics in patients with relapsed prostate cancer, as among the many biological effects of NDGA is the inhibition of the insulin‐like growth factor 1 receptor (IGF‐1R) tyrosine kinase.

Prostate cancer update: 2006.

Purpose of review This review highlights the most important developments in the diagnosis, prevention, and treatment of prostate cancer published in the medical literature over the past year. Recent findings Recent research has revealed a relatively high rate of prostate specific antigen screening in elderly men regardless of comorbidity status. Other findings include data that finasteride may increase the sensitivity of prostate specific antigen to detect prostate cancer. In terms of use of androgen deprivation therapy as part of primary therapy, a randomized trial has demonstrated that immediate therapy for locally advanced prostate cancer improves overall survival. There is growing literature, however, confirming the risks associated with this treatment, including an increased incidence of cardiovascular events and diabetes. New randomized trial data of adjuvant radiotherapy for high-risk disease have not demonstrated a survival benefit over observation. For patients who experience disease relapse following local therapy, definitions of biochemical failure following prostatectomy and radiation therapy are proposed. In more advanced disease, immunotherapy has preliminarily demonstrated survival benefit in a randomized trial. Summary Data reported over the last year have significant implications for those involved in the management of prostate cancer, ranging from primary care physicians to medical oncologists, urologists, and radiation oncologists.

Effect of the somatostatin analog octreotide acetate on circulating insulin-like growth factor-1 and related peptides in patients with non-metastatic castration-resistant prostate cancer: Results of a phase II study

BACKGROUND Insulin-like growth factor (IGF) mediated signaling has been implicated in the growth of many tumor types including prostate cancer, and it is hypothesized that lowering circulating IGF levels in men with castration resistant prostate cancer (CRPC) will slow tumor growth. In this study, the efficacy of depot octreotide acetate was prospectively evaluated in patients with CRPC. METHODS Eligible patients had progressive non-metastatic CRPC. Octreotide acetate 30 mg was administered intramuscularly every 28 days. Changes in PSA, IGF-1, IGF-2, IGF binding protein-1 (IGFBP-1), and IGFBP-3 were evaluated over time. RESULTS Accrual was stopped early after a pre-planned interim analysis showed no prostate specific antigen (PSA) declines after 3 cycles of treatment among the first 13 patients enrolled. Median baseline PSA and IGF-1 measurements were 36.2 ng/ml and 162.6 ng/ml, respectively, and median time on treatment was 13 weeks. Radiographic progression occurred in 7 patients, PSA-only progression occurred in 5 patients, and 1 patient was taken off the study due to a grade 3 drug interaction. After 3 cycles of treatment IGF-1 significantly declined with a median -34.5% (P = 0.01) and IGFBP-1 significantly increased with a median 76.3% (P = 0.046). IGF-2 and IGFBP-3 were not significantly changed from baseline. CONCLUSIONS Octreotide acetate significantly lowers IGF-1 and raises IGFBP-1 levels in patients with non-metastatic CRPC, but does not result in sustained declines in PSA. While treatment with single-agent octreotide may not be warranted, its inclusion in combination regimens directly targeting the IGF-1 receptor on tumor cells may be of interest.

Sequential Use of the Androgen Synthesis Inhibitors Ketoconazole and Abiraterone Acetate in Castration-Resistant Prostate Cancer and the Predictive Value of Circulating Androgens

Purpose: Patients previously treated with ketoconazole were excluded from phase III trials of abiraterone acetate due to potential overlapping mechanism of action. The purpose of this study was to determine the clinical utility of abiraterone and its impact on circulating androgens following ketoconazole. Experimental Design: Chemotherapy-naïve patients with progressive metastatic castration-resistant prostate cancer (mCRPC) and prior ketoconazole therapy ≥28 days received abiraterone acetate 1,000 mg daily and prednisone 5 mg twice daily. The primary endpoint was the proportion of patients with PSA response, defined as ≥30% PSA decline at 12 weeks. H0 = 0.30 versus H1 = 0.50 (α = 0.05, power = 0.83). Circulating androgen levels were measured using liquid chromatography tandem mass spectrometry. Results: Thirty-nine patients were included in the final analysis. Twenty (51%; 95% confidence interval, 36%–66%) patients had ≥30% PSA decline; the null hypothesis was rejected. Sixteen (41%) had ≥50% PSA decline. Median PFS (progression-free survival) was 16 weeks; median radiographic PFS (rPFS) was 36 weeks. Samples for measurement of baseline androgens were available in 37 patients. The PSA response proportion was 59% in 29 patients with DHEA ≥ limit of quantitation (LOQ), compared with 13% in 8 patients with DHEA < LOQ (P = 0.042). Median PFS was 6 and 16 weeks in DHEA < LOQ and DHEA ≥ LOQ patients, respectively (P = 0.017); median rPFS was 14 and 36 weeks in DHEA < LOQ and DHEA ≥ LOQ patients, respectively (P < 0.001). Conclusions: Abiraterone demonstrates modest clinical efficacy in mCRPC patients previously treated with ketoconazole. Patients with DHEA ≥ LOQ were more likely to demonstrate PSA responses and longer PFS. Analysis of circulating androgens merits further investigation as a biomarker for response to androgen synthesis inhibitor therapy. Clin Cancer Res; 20(24); 6269–76. ©2014 AACR.

Tumor fistulization associated with targeted therapy: computed tomographic findings and clinical consequences.

Purpose: To describe the computed tomographic (CT) appearances and clinical consequences of tumor fistulization as a complication of targeted therapy for cancer. Methods: The committee on human research approved this Health Insurance Portability and Accountability Act-compliant study and waived written informed consent. Based on the records of the senior author and our multidisciplinary Tumor Boards, we retrospectively identified 4 patients (1 man and 3 women with a mean age of 55.25 years; range, 47 to 64 years) who developed tumor fistulization while being treated with targeted therapy consisting of sunitinib (n = 2); bevacizumab (n = 1); and XL184, an investigational c-Met inhibitor (n = 1). All available clinical, imaging, and histopathological records were reviewed, with particular emphasis on treatment administered, CT findings, and clinical course. Results: All 4 patients developed fistulae from large metastatic deposits in the abdomen (mean size before treatment, 10.55 cm; range, 7.4-13.4 cm) to the gastrointestinal tract, and one patient also developed fistulae from a lung metastasis of undetermined size to the bronchial tree. All fistulae manifested as the appearance of air within a pre-existing tumor mass. At the time of fistula detection, disease at other sites in the 4 patients showed signs of regression (n = 1), progression (n = 2), or stability (n = 1). Currently, one patient is alive without evidence of disease, and the 3 other patients are deceased. Conclusions: Targeted therapy can be associated with tumor fistulization to the gastrointestinal tract or tracheobronchial tree; familiarity with the CT findings should facilitate the diagnosis of this complication, which seems to be of variable and patient-specific prognostic significance.