Epigenetic Therapy with Panobinostat Combined with Bicalutamide Rechallenge in Castration-Resistant Prostate Cancer.

PURPOSE: This study assesses the action of panobinostat, a histone deacetylase inhibitor (HDACI), in restoring sensitivity to bicalutamide in a castration-resistant prostate cancer (CRPC) model and the efficacy and safety of the panobinostat/bicalutamide combination in CRPC patients resistant to second-line antiandrogen therapy (2ndLAARx). PATIENTS AND METHODS: The CWR22PC xenograft and isogenic cell line were tested for drug interactions on tumor cell growth and on the androgen receptor (AR), AR-splice variant7, and AR targets. A phase I trial had a 3 × 3 panobinostat dose-escalation design. The phase II study randomized 55 patients to panobinostat 40 mg (A arm) or 20 mg (B arm) triweekly ×2 weeks with bicalutamide 50 mg/day in 3-week cycles. The primary endpoint was to determine the percentage of radiographic progression-free (rPF) patients at 36 weeks versus historic high-dose bicalutamide. RESULTS: In the model, panobinostat/bicalutamide demonstrated synergistic antitumor effect while reducing AR activity. The dose-limiting toxicity was not reached. The probability of remaining rPF exceeded protocol-specified 35% in the A arm and 47.5% and 38.5% in the B arm. The probabilities of remaining rPF were 47.5% in the A arm and 38.5% in the B arm, exceeding the protocol-specified threshold of 35%. A arm/B arm: adverse events (AE), 62%/19%; treatment stopped for AEs, 27.5%/11.5%; dose reduction required, 41%/4%; principal A-arm grade ≥3 AEs, thrombocytopenia (31%) and fatigue (14%). CONCLUSIONS: The 40 mg panobinostat/bicalutamide regimen increased rPF survival in CRPC patients resistant to 2ndLAARx. Panobinostat toxicity was tolerable with dose reductions. Epigenetic HDACI therapy reduces AR-mediated resistance to bicalutamide in CRPC models with clinical benefit in patients. The combination merits validation using a second-generation antiandrogen.

KLF6 loss of function in human prostate cancer progression is implicated in resistance to androgen deprivation.

Inactivation of the transcription factor/tumor suppressor Krüppel-like factor 6 (KLF6) has been described in prostate cancer (PC). This study investigated the prevalence and significance of KLF6 exon 2 mutations and splice variants (SVs) in different stages of human PC progression. By using laser-capture microdissection and recombinant clone isolation of DNA sequences to enhance sensitivity, base changes were found in 20 (24.7%) of 81 PC tissues versus 1 (4%) of 25 normal prostate tissues (P = 0.02). Of 26 base changes, 54% produced nonsynonymous mutations. Only three mutations had driver characteristics (PCs, 4%; NPs, 0%). By using microdissection of fresh-frozen tissues and recombinant isolation of RNA sequences, SVs were found in 39 (75%) of 52 PCs and in 10 (45%) of 22 NPs (P = 0.01). Sixteen different SVs, including 13 unique SVs, were identified that used cryptic splicing sites and encoded nonfunctional KLF6 proteins. PCs that had survived hormone (androgen)-deprivation therapy (n = 21) had a significantly higher (P < 0.05) incidence, number, and expression level of nonfunctional SVs than either NPs (n = 22) or hormone-naïve PCs (n = 25). Forced expression of nonfunctional SVs conferred a survival advantage of androgen-dependent LNCaP cells under castration-simulated culture conditions. Together, these data suggest that decreased availability of functional KLF6 contributes to clinical PC progression. This decrease arises infrequently by somatic mutation and more commonly by the acquisition of SVs that provide a survival advantage under castrate conditions, enabling resistance to hormone therapy.

mTOR signaling pathway and mTOR inhibitors in cancer therapy.

Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase. It is ubiquitously expressed in cells and is a therapeutic target for the cancer treatment arsenal. Despite the great responses obtained in tumors addicted to specific mutations or overactivation of key members of the mTOR pathway (HiF1α in RCC, cyclin D1 in MCL, or TSC in SEGA), mTOR inhibitors as single agents have modest activity. Dual PI3K/mTOR kinase inhibitors have been developed with the idea of overcoming resistance to the mTOR inhibition through preventing the activation of PI3K/Akt as a result of release negative feedback loops.

Immunotherapy in the treatment of advanced prostate cancer.

Prostate cancer is a complex disease, and treatment selection is informed by numerous variables depending on the stage of disease. Moreover, patient expectations and the impact of treatment-related adverse events may influence treatment choices. Available treatment options over the course of the disease have included surgery, radiation therapy, hormonal therapy, immunotherapy, and chemotherapy. This complexity requires an understanding of a wide range of treatment options and the support of a multidisciplinary team that involves urologists, radiation oncologists, diagnostic radiologists, pathologists, and medical oncologists. Collaboration among these physicians allows for a comprehensive treatment strategy that addresses the individual needs of the patient throughout the course of his disease. Prior to 2004, treatment options for metastatic castrate-resistant prostate cancer (CRPC) were limited to therapies for palliation of pain and reduction of skeletal-related events. Over the past 7 years, four therapeutic options-three within the last 2 years-that provide a survival benefit in this setting have been approved. These therapies have diverse mechanisms, perhaps reflecting the complex nature of advanced prostate cancer. Among them is sipuleucel-T, the first autologous immunotherapy approved for any cancer. This review will discuss the rapidly changing treatment environment for metastatic CRPC and the increased exploration of immunotherapeutic approaches to advanced prostate cancer.

Induction of bicalutamide sensitivity in prostate cancer cells by an epigenetic Puralpha-mediated decrease in androgen receptor levels.

BACKGROUND: Increased androgen receptor (AR) levels support resistance to apoptosis and hormone therapy in advanced prostate cancer (PC). We recently linked the overexpression of AR in androgen-independent LNCaP cells (AI-cells) and tissues from castration-resistant patients to decreased nuclear levels of Pur-alpha (Puralpha) and loss from a protein complex bound to repressor sequences (ARS) in the 5'-UTR of AR. Strategies to regain control of increased AR transcription may overcome resistance of AI-cells and improve treatment outcomes. METHODS: MTT, real-time PCR, Western blot, ChIP, flow cytometry, and caspase 3/7 activation measured the effect on growth and targets of LBH589/bicalutamide treatment of AI-cells and androgen-dependent LNCaP cells (AD). RESULTS: Within 16 hr of treatment of AI-cells with low concentrations of the histone deacetylase inhibitor LBH589, a shift of cytoplasmic Puralpha restored the nuclear levels and the binding of Puralpha to the ARS. This was followed by a decline in AR-mRNA and protein reaching levels of parental AD-cells. The fraction of AI-cells in G1 increased and the cells in S phase decreased similar to AD-cells, and there was a modest caspase activation. Most notably, treatment of bicalutamide-resistant AI-cells with 10 nM LBH589 combined with 12.5 microM bicalutamide synergistically inhibited cell growth and induced a fivefold higher level of caspase 3/7 activation than observed in AD-cells. CONCLUSIONS: Low-dose LBH589 restores Puralpha binding to ARS and down-regulates AR transcription. Biologically, LBH589 reverses the resistance of AI-cells to bicalutamide and to apoptosis. The combination may restore the hormonal response of castration-resistant PC patients.

Vascular endothelial growth factor (VEGF) serum levels are associated with survival in early stages of lung cancer patients.

AIM: Evaluate the serum vascular endothelial growth factor (VEGF) levels in the prognosis of lung cancer patients. METHODS: Fifty-four serum samples were analyzed for VEGF concentrations (79.3% nonsmall cell lung cancer (NSCLC) and 20.7% small cell lung cancer). RESULTS: Patients with serum VEGF-A levels higher than the mean of the patients studied (434.93 pg/mL) presented a shorter median survival time than those with lower levels (p =.04), as in patients with NSCLC tumors (p =.04) and in those with stages I-II (p <.05), and high serum VEGF-A levels. CONCLUSION: Elevated VEGF serum levels have a negative prognostic impact on survival in NSCLC and early stages of lung cancer patients.

Prognostic significance of the expression of vascular endothelial growth factors A, B, C, and D and their receptors R1, R2, and R3 in patients with nonsmall cell lung cancer.

BACKGROUND: Lung cancer is the leading cause of cancer death in the world. The objective of this study was to investigate the expression of vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) in patients with nonsmall cell lung cancer (NSCLC) and its correlation with the prognosis for patients with lung cancer. METHODS: The expression status of VEGFs and VEGFRs was examined in 48 nonconsecutive specimens of primary lung cancer by immunohistochemistry. Correlations between the expression of VEGFs and VEGFRs and clinicopathologic parameters were analyzed. RESULTS: Nineteen of 48 samples (39.6%) were moderately/highly immunoreactive for VEGF-A, 6 samples (12.5%) were reactive for VEGF-B, 14 samples (29.2%) were reactive for VEGF-C, 11 samples (22.9%) were reactive for VEGF-D, 20 samples (41.7%) were reactive for VEGFR1, 26 samples (54.2%) were reactive for VEGFR2, 20 samples (41.7%) were reactive for VEGFR3, and 19 samples (39.6%) were reactive for nuclear expression of VEGFR3. Patients with moderate/high VEGF-C, VEGFR1, and VEGFR2 expression had worse survival, whereas patients with moderate/high VEGF-D and nuclear VEGFR3 expression had better survival. After adjusting according to tumor stage, VEGF-B and VEGF-D expression had a significant correlation with worse survival in patients with stage I and II disease. Patients with stage III and IV disease who had VEGFR1 and VEGFR2 expression had worse survival, whereas the expression of VEGF-D was correlated significantly with better survival. Finally, stage, VEGF-D expression, and VEGFR1 expression were significantly independent prognostic predictors. CONCLUSIONS: The results of the current study indicated that the over-expression of VEGFs and VEGFRs plays an important role in the survival of patients with NSCLC. The inclusion of angiogenic factors in the standard pathologic study of lung cancer may improve the clinical evaluation of patients with NSCLC.