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BACKGROUND We have previously documented a paradoxical anti-tumor effect when castration-resistant prostate cancer patients were treated with intermittent, high-dose testosterone (i.e., Bipolar Androgen Therapy; BAT). Because, an adaptive increase in androgen receptor expression following chronic androgen deprivation therapy (ADT) may underlie this effect, we tested whether men with hormone-sensitive (HS) prostate cancer (PC) would also respond to BAT if given following a 6-month ADT lead-in. METHODS Asymptomatic HS PC patients with low metastatic burden or non-metastatic biochemically recurrent disease were enrolled. Following 6-month of ADT, those with a PSA

BACKGROUND There is an urgent need to develop new agents for treating metastatic prostate cancer to overcome multiple drug resistance to the current standard targeted cancer therapy. Emetine is a highly cytotoxic natural product protein synthesis inhibitor, which is toxic to all cell types. Its cytotoxicity can be blocked by derivatizing its N-2′ position. Thus emetine can be selectively delivered to cancer cells in the region of metastatic cancer as a prodrug that will be activated by an enzyme selectively overexpressed within the metastatic tumor microenvironment. In this work, we convert emetine to a prodrug activatable by the fibroblast activation protein (FAP), a serine protease overexpressed by the carcinoma associated fibroblasts. METHOD By using an iterative structure-activity relationship strategy, several peptidyl emetine prodrug analogs (1–11) were synthesized by chemical derivatization of emetine at its N-2′ position and tested for in-vitro activation by FAP. The lead prodrug 11 is made up of a DPPIV activatable prodrug precursor 10 (Ala-Pro-PABC-Emetine) coupled to FAP substrate (Ala-Ser-Gly-Pro-Ala-Gly-Pro). Activation assays of the prodrugs were performed in purified FAP, DPPIV, FBS, and human serum and were analyzed by LCMS. In vitro cytotoxicity assays of these prodrugs are carried out in prostate (LNCaP, PC3) and breast (MCF7 and MDA-MB-231) cancer cell lines. The prodrugs are also tested in normal immortalized human prostatic epithelial cell line (PrEC). RESULTS The lead FAP activated emetine prodrug 11 is activated to emetine in tandem by FAP and DPPIV in about 70% conversion within 24 hr. In prostate and breast cancer cell lines treated with prodrug 11, it is found to be equipotent with emetine in the presence of FAP and DPPIV. However, in the PrEC cell line grown in serum free media, prodrug 11 is more than 200-fold less cytotoxic than emetine in the absence of FAP and DPPIV. CONCLUSION This FAP activated prodrug of cytotoxic agent emetine further shows the crucial role of the N-2′ position of emetine in controlling its cytotoxicity. Significantly reduced toxicity observed in the PrEC cell line in the absence of FAP and DPPIV shows that prodrug 11 could be systemically delivered to regions of metastatic prostate cancer or other solid tumor for activation by cancer selective enzymes within the cancer microenvironment, such as FAP that is overexpressed by the carcinoma-associated fibroblasts. The two-step tandem enzymatic activation of prodrug 11 by FAP and DPPIV is a strategy for overcoming steric hindrance. Prostate 76:703–714, 2016. © 2016 Wiley Periodicals, Inc.

BACKGROUND As carcinoma progresses, the stroma undergoes a variety of phenotypic changes, including the presence of carcinoma-associated fibroblasts (CAFs) that express fibroblast activation protein (FAP). FAP is a post-prolyl endopeptidase whose expression in a healthy adult is largely restricted to the cancer-associated stroma. FAP-targeted prodrugs with a 100-fold greater therapeutic window over the parent compound were previously generated. METHODS Prodrugs and non-cleavable controls were incubated in the presence of FAP. Plasma and tumor half-lives (t1/2) of the full-length and active forms of the prodrugs were determined using LCMS. Biodistribution studies of prodrug activation were performed. Histopathological analysis of tissues from treated animals were compared to vehicle-treated controls. Toxicity and efficacy studies were performed in human breast (MDA-MB-231 and MCF-7) and prostate (LNCaP) cancer xenografts models. RESULTS These FAP-activated prodrugs have a significantly slower clearance from tumor tissue than the circulation (∼12 vs. ∼4.5 hr). Micromolar concentrations of active drug persist in the tumor. Active drug is detected in non-target tissues; however, histopathologic evaluation reveals no evidence of drug-induced toxicity. A FAP-activated prodrug (ERGETGP-S12ADT) inhibits tumor growth in multiple human breast and prostate cancer xenograft models. The anti-tumor effect is comparable to that observed with docetaxel, but results in significantly less toxicity. CONCLUSION FAP-activated prodrugs are a viable strategy for the management of prostate and other cancers. These prodrugs exhibit less toxicity than a commonly used chemotherapeutic agent. Further refinement of the FAP cleavage site for greater specificity may reduce prodrug activation in non-target tissues and enhance clinical benefit. Prostate 74: 1308–1319, 2014. © 2014 Wiley Periodicals, Inc.

BACKGROUND The Cancer and Leukemia Group B conducted a Phase II trial to evaluate the efficacy, toxicity, and pharmacokinetics of paclitaxel administered at a maximum dose density for patients with chemotherapy-naive, advanced-stage non–small cell lung carcinoma (NSCLC). METHODS Patients with Stage IIIB/IV or recurrent NSCLC, a performance status (PS) score of 0–1, and no history of chemotherapy exposure were eligible. Paclitaxel, 150 mg/m2, was administered over 3 hours during Weeks 1–6 of an 8-week cycle. Doses were modified for ANC < 1500/μL or for ≥ Grade 2 neuropathy on the day of therapy. Treatment continued until toxicity or disease progression. Pharmacokinetics were assessed at Weeks 1, 3, and 5 of Cycle 1. RESULTS Thirty-eight patients (median age, 64 years; range, 31–81 years) were treated. There were 21 males (PS = 0 for 17). Eleven patients had received previous radiation, 2 had brain metastases, 25 had adenocarcinoma, 23 had Stage IV disease, 6 had StageIIIB disease, and 9 had recurrent disease. Grade 3–4 granulocytopenia occurred in 39% of patients. There were no deaths due to toxicity. Grade 2 or 3 neuropathy occurred in 29% and 24% of patients, respectively. Ten (27%) patients had Grade 3 hyperglycemia (glucose concentration > 250 mg/dL). There were 16 partial responses (42%; 95% confidence interval [CI], 26–59%). The median survival period was 12.3 months (95% CI, 7.9–19.6%), and the 1-year and 2-year survival rates were 52% (95% CI, 39–71%) and 26% (95% CI, 15–45%), respectively. Paclitaxel pharmacokinetics were consistent with published values and clearance was not induced. Older age and hyperglycemia were associated with greater neurotoxicity. CONCLUSIONS Paclitaxel at 150 mg/m2 per week × 6 every 8 weeks can be administered safely in the cooperative group setting. These Phase II data are comparable to those associated with combination therapy. The weekly dose-dense schedule may be more active than conventional schedules. Cancer 2003;10:2480–6. © 2003 American Cancer Society. DOI 10.1002/cncr.11375