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Background Vitamin D3 (VitD) deficiency is linked to increased incidence and worse survival in bladder cancer (BCa). In addition to cystectomy, patients are treated with cisplatin-based chemotherapy, however 30%-50% of patients do not benefit from this treatment. The effects of VitD deficiency on response to chemotherapy remain unknown. Methods To test effects of VitD supplementation on the response to cisplatin we analyzed patient serum VitD levels and correlated that with survival. In vivo, VitD deficient mice were treated with cisplatin, with or without pretreatment with the active VitD metabolite, 1,25 dihydroxyvitamin D3 (1,25D3 ). Lastly, using BCa cell lines, T24 and RT-112, the mechanism of action of 1,25D3 and cisplatin combination treatment was determined by apoptosis assays, as well as western blot and RT-PCR. Results In this study, we determined that low serum 25 hydroxyvitamin D3 (25D3 ) levels was significantly associated with worse response to cisplatin. Pretreating deficient mice with 1,25D3 , reduced tumor volume compared to cisplatin monotherapy. In vitro, 1,25D3 pretreatment increased the apoptotic response to cisplatin. 1,25D3 pretreatment increased expression of TAp73 and its pro-apoptotic targets, in a VDR dependent manner. VDR and its transcriptional targets were induced after 1,25D3 treatment and further increased after the combination of 1,25D3 and cisplatin in a TAp73 dependent manner. Conclusions Our data suggest that VitD deficiency could be a biomarker for poor response to cisplatin, and pretreating with VitD can increase the apoptotic response to cisplatin through VDR and TAp73 signaling crosstalk.

The anticancer activity of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3 or calcitriol) has been widely reported in preclinical models. However, systematic investigation into the chemopreventive potential of calcitriol against the spectrum of oral carcinogenesis has not been performed. To address this gap in knowledge, we conducted a preclinical prevention trial of calcitriol in the 4-nitroquinoline-1-oxide (4NQO) oral carcinogenesis model. C57BL/6 mice were exposed to the carcinogen 4NQO in drinking water for 16 weeks and randomized to control (4NQO only) or calcitriol arms. Calcitriol (0.1 μg i.p, Monday, Wednesday, and Friday) was administered for (i) 16 weeks concurrently with 4NQO exposure, (ii) 10 weeks post completion of 4NQO exposure, and, (iii) a period of 26 weeks concurrent with and following 4NQO exposure. Longitudinal magnetic resonance imaging (MRI) was performed to monitor disease progression until end point (week 26). Correlative histopathology of tongue sections was performed to determine incidence and multiplicity of oral dysplastic lesions and squamous cell carcinomas (SCC). Vitamin D metabolites and calcium were measured in the serum using liquid chromatography-mass spectrometry (LC–MS/MS) and colorimetric assay, respectively. Renal CYP24A1 (24-hydroxylase) and CYP27B1 (1α-hydroxylase) expression was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Immunostaining of tongue sections for vitamin D receptor (VDR), CYP24A1, and Ki67 was also performed. Non-invasive MRI enabled longitudinal assessment of lesions in the oral cavity. Calcitriol administered concurrently with 4NQO for 16 weeks significantly (P

EGFR tyrosine kinase inhibitors (EGFR TKIs) are the standard of care treatment for patients with EGFR-mutant lung adenocarcinoma (LUAD). Although initially effective, EGFR TKIs are not curative. Disease inevitably relapses due to acquired drug resistance. We hypothesized that vitamin D metabolites could be used with EGFR TKIs to prevent therapeutic failure. To test this idea, we investigated the link between serum 25-hydroxyvitamin D3 (25(OH)D3) and progression-free survival (PFS) in patients with EGFR-mutant LUAD that received EGFR TKIs (erlotinib n = 20 and afatinib n = 1). Patients who were 25(OH)D3-sufficient experienced significantly longer benefit from EGFR TKI therapy (mean 14.5 months) than those with 25(OH)D3 insufficiency (mean 10.6 months, p = 0.026). In contrast, 25(OH)D3 had no prognostic value in patients with KRAS-mutant LUAD that received cytotoxic chemotherapy. To gain mechanistic insights, we tested 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) activity in vitro. 1,25(OH)2D3 promoted epithelial differentiation and restored EGFR TKI sensitivity in models of EGFR TKI resistance that were associated with epithelial&ndash, mesenchymal transition (EMT). 1,25(OH)2D3 was ineffective in a non-EMT model of resistance. We conclude that vitamin D sufficiency portends increased PFS among EGFR-mutant LUAD patients that receive EGFR TKIs, and that vitamin D signaling maintains drug efficacy in this specific patient subset by opposing EMT.

Somatic alterations in the epidermal growth factor receptor gene (EGFR) result in aberrant activation of kinase signaling and occur in ∼15% of non-small cell lung cancers (NSCLC). Patients diagnosed with EGFR-mutant NSCLC have good initial clinical response to EGFR tyrosine kinase inhibitors (EGFR TKIs), yet tumor recurrence is common and quick to develop. Mechanisms of acquired resistance to EGFR TKIs have been studied extensively over the past decade. Great progress has been made in understanding two major routes of therapeutic failure: additional genomic alterations in the EGFR gene and activation of alternative kinase signaling (so-called “bypass activation”). Several pharmacological agents aimed at overcoming these modes of EGFR TKI resistance are FDA-approved or under clinical development. Phenotypic transformation, a less common and less well understood mechanism of EGFR TKI resistance is yet to be addressed in the clinic. In the context of acquired EGFR TKI resistance, phenotypic transformation encompasses epithelial to mesenchymal transition (EMT), transformation of adenocarcinoma of the lung (LUAD) to squamous cell carcinoma (SCC) or small cell lung cancer (SCLC). SCLC transformation, or neuroendocrine differentiation, has been linked to inactivation of TP53 and RB1 signaling. However, the exact mechanism that permits lineage switching needs further investigation. Recent reports indicate that LUAD and SCLC have a common cell of origin, and that trans-differentiation occurs under the right conditions. Options for therapeutic targeting of EGFR-mutant SCLC are limited currently to conventional genotoxic chemotherapy. Similarly, the basis of EMT-associated resistance is not clear. EMT is a complex process that can be characterized by a spectrum of intermediate states with diverse expression of epithelial and mesenchymal factors. In the context of acquired resistance to EGFR TKIs, EMT frequently co-occurs with bypass activation, making it challenging to determine the exact contribution of EMT to therapeutic failure. Reversibility of EMT-associated resistance points toward its epigenetic origin, with additional adjustments, such as genetic alterations and bypass activation, occurring later during disease progression. This review will discuss the mechanistic basis for EGFR TKI resistance linked to phenotypic transformation, as well as challenges and opportunities in addressing this type of targeted therapy resistance in EGFR-mutant NSCLC.

Despite the recognized link between aging and cancer, most preclinical studies in experimental tumor models are conducted with 6- to 8-wk-old rodents. The goal of the present study was to examine the impact of age on tumor incidence, growth, and microenvironmental characteristics in mouse models of head and neck squamous cell carcinoma (HNSCC). Experimental studies were conducted with the 4-nitroquinoline-oxide (4NQO) oral carcinogenesis model and orthotopic FaDu HNSCC xenografts, established in young (7 to 12 wk of age) and old (65 to 70 wk of age) female C57BL/6 mice ( n = 44; 4NQO model) and severe combined immunodeficient mice ( n = 13; HNSCC xenografts). Noninvasive whole body magnetic resonance imaging revealed increased subcutaneous and visceral fat in aging animals of both strains. On histologic examination, a higher incidence ( P < 0.001) of severe dysplasia/invasive squamous cell carcinoma was observed in old mice (92%) as compared with young mice (69%). Old C57BL/6 mice exposed to 4NQO exhibited increased incidence of oral and extraoral (peritoneal masses) neoplasms (42%) versus their young counterparts ( P < 0.05). The incidence of extraoral neoplasms was significantly lower (16%) in the younger cohort. Interestingly, no difference in growth rate and oxygen saturation was observed between orthotopic FaDu xenografts established in old and young severe combined immunodeficient mice. Our observations suggest that host age may have an impact on the growth kinetics and progression of HNSCC in the immunocompetent 4NQO model. Further investigation into the impact of aging on tumor response to preventive and therapeutic intervention is warranted.

Recent studies highlight the importance of the RB1 tumor suppressor as a target for cancer therapy. Canonically, RB1 regulates cell cycle progression and represents the downstream target for cyclin-dependent kinase (CDK) 4/6 inhibitors that are in clinical use. However, newly discovered features of the RB1 pathway suggest new therapeutic strategies to counter resistance and improve precision medicine. These therapeutic strategies include deepening cell cycle exit with CDK4/6 inhibitor combinations, selectively targeting tumors that have lost RB1, and expanding therapeutic index by mitigating therapy-associated adverse effects. In addition, RB1 impacts immunological features of tumors and the microenvironment that can enhance sensitivity to immunotherapy. Lastly, RB1 specifies epigenetically determined cell lineage states that are disrupted during therapy resistance and could be re-installed through the direct use of epigenetic therapies. Thus, new opportunities are emerging to improve cancer therapy by exploiting the RB1 pathway.

Radiation therapy (RT) is an integral component of the standard of care for patients with head and neck squamous cell carcinoma (HNSCC). While advances in radiation delivery methods have led to improved outcomes, radioresistance poses a significant therapeutic challenge and a major cause of poor prognosis in this patient population. To date, a majority of studies investigating mechanisms of radioresistance have employed in vitro monolayer cell culture models that lack the heterogeneity and cell-extracellular matrix interactions. To overcome this limitation, we established and credentialed a panel of 3D patient-derived organoid (PDO) models of HNSCC to identify molecular signatures and signaling pathways that contribute to radiation resistance. A total of 7 PDOs were established from surgical HNSCC specimens and credentialed using a combination of histologic/immunohistochemical evaluation (H&E, cytokeratin, p16), genotyping (HPV), whole exome sequencing (WES) and RNA sequencing analysis. Radiation response of the PDO panel was also examined and assessed for concordance with patient response and PDOs were ranked based on their radiosensitivity and bioinformatic analysis was performed on radiosensitive and radioresistance PDOs to identify molecular pathways associated with resistance. All PDOs retained the histology, p16/HPV status and mutational landscape (p53, HLA-A) of donor patient tissues. Radiation response of PDOs showed excellent (100%) concordance with patient responses (n=5 with history of radiation treatment). RNA-seq revealed identified pathways associated with epithelial mesenchymal transition (IGFBP2, TIMP1, TIMP2, LAMA3, LOXL1), NOTCH signaling (NOTCH1, HES1, FZD1, FZD5, DTX1, NOTCH3, FZD7), E2F targets and G2M checkpoint signaling (MCM2, MCM7, MCM4, PCNA) and the p53 pathway (SFN, NDRG1, ALOX15B). Collectively, our findings illustrate the translational utility of PDOs as a robust platform in identifying potential therapeutic targets that could overcome radiation resistance in HNSCC. Ongoing studies are evaluating the potential of PDOs to serve as a screening platform to identify radiosensitizers through repurposing of FDA-approved drugs to facilitate rapid clinical translation. Citation Format: Vui King Vincent-Chong, Christian Gluck, Pamela A. Hershberger, Satrajit Sinha, Mukund Seshadri. Deciphering radiation resistance in head and neck cancer using patient derived organoids [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-061.

Patient-derived organoids (PDOs) are considered to be a cost-effective, high-throughput preclinical platform for studying cancer biology and evaluating novel therapeutics. While PDOs have been established and characterized for breast, prostate, colon, and pancreatic cancers, PDO models of head and neck squamous cell carcinomas (HNSCC) are limited. To address this paucity, in the present study, we established a panel of PDO models of HNSCC. Five HNSCC samples (3 larynx, 1 tongue, 1 parotid) were procured from donor patients following informed consent and processed to establish organoids. Histologic (H&E) and immunohistochemical evaluation (p16, cytokeratin) was performed along with assessment of PDO response to the alkylating agent, cisplatin, and two tyrosine kinase inhibitors, erlotinib and afatinib. Histologic analyses of established organoids revealed nested cells of squamous cell carcinoma with high N/C ratio similar to donor surgical tumor tissue. Immunohistochemistry revealed strong pan cytokeratin and absence of p16 staining in all samples. Paired PDO and PDX models also successfully retained the squamous histology. Dose-response curves revealed substantial variation in therapeutic profiles of the three agents across the organoid panel. While the IC50 of cisplatin was comparable across the larynx organoids, 2 larynx organoids were sensitive to the two TKIs while one was resistant, exhibiting ~5-fold higher IC50 values. The tongue organoid was relatively sensitive to all agents while the parotid SCC organoid was sensitive to EGFR TKIs but relatively resistant to cisplatin. Collectively, these results demonstrate the ability of organoid models to recapitulate the histologic architecture and response heterogeneity of human HNSCC. Investigation into the molecular profiles of our PDO panel is under way in our laboratory and will enable further development of organoids as a robust platform for evaluation of precision therapeutics against HNSCC. Citation Format: Vincent-Chong Vui King, Erin C. Tracy, Heinz Baumann, Pamela A Hershberger, Mukund Seshadri. Patient-derived organoids recapitulate response heterogeneity in head and neck cancer [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr A22.

Calcitriol, the active metabolite of vitamin D, has been widely studied for its preventive and therapeutic activity against several cancers including oral squamous cell carcinoma (OSCC). However, the impact of dietary vitamin D supplementation on initiation and progression of OSCC is unclear. To address this gap in knowledge, we conducted preclinical trials using the 4-nitroquinoline-1-oxide (4NQO) carcinogen model of oral carcinogenesis. Female C57BL/6 mice were maintained on one of three vitamin D diets [ 25 IU, 100 IU, 10,000 IU] and exposed to 4NQO in drinking water for 16 weeks followed by regular water for 10 weeks. Body weight measurements obtained through the study duration did not reveal any differences between the three diets. Animals on 100 IU diet showed lower incidence of high-grade dysplasia/OSCC and higher CD3+ T cells compared to animals on 25 IU and 10000 IU diets. Serum 25(OH)D(3) levels were highest in animals on 10000 IU diet at week 0 (prior to carcinogen exposure) but showed ~50% reduction at week 26. Histologic evaluation revealed highest incidence of OSCC in animals maintained on 10000 IU diet. Animals on 100 IU and 10000 IU diets showed higher vitamin D receptor (VDR) and CYP24A1 immunostaining in high-grade dysplastic lesions and OSCC compared to normal tongue. Validation studies performed in a 4NQO-derived OSCC model showed that short-term treatment of animals on a 25 IU diet with calcitriol significantly inhibited tumor growth compared to controls but did not affect tumor growth in animals on reference diet (1000 IU). Collectively, our results highlight the complex dynamics between vitamin D status and oral carcinogenesis. Our observations also suggest that therapeutic benefits of short-term calcitriol treatment may be more pronounced in vitamin D deficient hosts.

Mutation in the tyrosine kinase (TK) domain of the epidermal growth factor receptor ( EGFR) gene drives the development of lung cancer. EGFR tyrosine kinase inhibitors (EGFR TKIs), including erlotinib and afatinib, are initially effective in treating EGFR mutant nonsmall cell lung cancer (NSCLC). However, drug resistance quickly develops due to several mechanisms, including induction of the epithelial-mesenchymal transition (EMT). No effective therapies are currently available for patients who develop EMT-associated EGFR TKI resistance. 1,25-Dihydroxyvitamin D3 (1,25D3) promotes epithelial differentiation and inhibits growth of NSCLC cells. 1,25D3 thus represents a promising agent for the treatment of EMT-associated EGFR TKI resistance. However, 1,25D3 induces the expression of 24-hydroxylase (24OHase), which decreases 1,25D3 activity. CTA091, a potent and selective 24OHase inhibitor, has been developed to attenuate this adverse effect. CTA091 also suppresses renal 24OHase activity and so may promote hypercalcemia. To exploit favorable effects of 1,25D3 plus CTA091 in tumor cells while avoiding problematic systemic effects of 24OHase inhibition, we developed EGFR-targeted, liposomal nanoparticles (EGFR-LP) to offer tumor-targeted co-delivery of 1,25D3 and CTA091. We then established an EMT-associated model of EGFR TKI resistance, and showed that such nanoparticles improved cellular uptake of 1,25D3 and CTA091, drove pro-epithelial signaling by upregulating E-cadherin ( CDH1), and significantly inhibited the growth of EGFR TKI resistant cells. Our results demonstrated that the delivery of vitamin D-based drug payloads via tumor-targeted EGFR-LP has promise as a new therapy for EFGR TKI resistant lung cancer. Future studies will focus on in vivo evaluation of biological activity, therapeutic benefits, and systemic toxicity prior to clinical translation.

Vitamin D metabolites exhibit chemopreventive, antiproliferative, and antimetastatic activity in preclinical models of lung cancer. Besides having direct actions on tumor cells, vitamin D may control lung cancer by favorably altering the lung tumor microenvironment and immune function. Several factors are likely to modulate vitamin D activity in lung cancer patients including active cigarette smoke exposure, somatic variation in vitamin D pathway genes, and molecular heterogeneity of lung tumors. Promising data exist regarding vitamin D actions in individuals who have chronic obstructive pulmonary disease and are at elevated risk for lung cancer. However, vitamin D-containing therapies have yet to demonstrate significant activity in unselected, advanced lung cancer patients. Future trials may benefit from a personalized medicine approach wherein the molecular profile of a patient's lung tumor and a patient's vitamin D status are used to identify individuals who are more likely to benefit from vitamin D supplementation.

1,25-dihydroxyvitamin D3 (1,25(OH)2D3) exerts anti-proliferative activity by binding to the vitamin D receptor (VDR) and regulating gene expression. We previously reported that non-small cell lung cancer (NSCLC) cells which harbor epidermal growth factor receptor (EGFR) mutations display elevated VDR expression (VDRhigh) and are vitamin D-sensitive. Conversely, those with K-ras mutations are VDRlow and vitamin D-refractory. Because EGFR mutations are found predominately in NSCLC cells with an epithelial phenotype and K-ras mutations are more common in cells with a mesenchymal phenotype, we investigated the relationship between vitamin D signaling capacity and the epithelial mesenchymal transition (EMT). Using NSCLC cell lines and publically available lung cancer cell line microarray data, we identified a relationship between VDR expression, 1,25(OH)2D3 sensitivity, and EMT phenotype. Further, we discovered that 1,25(OH)2D3 induces E-cadherin and decreases EMT-related molecules SNAIL, ZEB1, and vimentin in NSCLC cells. 1,25(OH)2D3-mediated changes in gene expression are associated with a significant decrease in cell migration and maintenance of epithelial morphology. These data indicate that 1,25(OH)2D3 opposes EMT in NSCLC cells. Because EMT is associated with increased migration, invasion, and chemoresistance, our data imply that 1,25(OH)2D3 may prevent lung cancer progression in a molecularly defined subset of NSCLC patients.

Background Cetuximab has demonstrated improved efficacy in combination with chemotherapy and radiotherapy. We evaluated the integration of cetuximab in the combined modality treatment of stage III non-small cell lung cancer (NSCLC). Methods Patients with surgically unresectable stage IIIA or IIIB NSCLC were treated with chest radiotherapy, 73.5 Gy (with lung and tissue heterogeneity corrections) in 35 fractions/7 weeks, once daily (63 Gy without heterogeneity corrections). Cetuximab was given weekly during radiotherapy and continued during consolidation therapy with carboplatin and paclitaxel up to a maximum of 26 weekly doses. The primary endpoint was overall survival. Baseline tumor tissue was analyzed for EGFR by fluorescence in situ hybridization (FISH). Results Forty patients were enrolled in this phase II study. The median overall survival was 19.4 months and the median progression-free survival 9.3 months. The best overall response rate in 31 evaluable patients was 67%. No grade 3 or 4 esophagitis was observed. Three patients experienced grade 3 rash; 16 patients (69%) developed grade 3/4 neutropenia during consolidation therapy. One patient died of pneumonitis, possibly related to cetuximab. EGFR gene copy number on baseline tumor tissues, analyzed by FISH, was not predictive of efficacy outcomes. Conclusions The addition of cetuximab to chest radiotherapy and consolidation chemotherapy was tolerated well and had modest efficacy in stage III NSCLC. Taken together with the lower incidence of esophagitis, our results support evaluation of targeted agents instead of chemotherapy with concurrent radiotherapy in this setting.

Recent data support an important role for vitamin D in respiratory health. We tested the hypothesis that dietary vitamin D3 (VD3) intake modulates diaphragm (DIA) strength. Four-week-old female A/J mice ( n = 10/group) were randomized to receive diets containing 100 IU VD3/kg (low), 1,000 IU VD3/kg (reference), or 10,000 IU VD3/kg (pharmacologic). After 6 wk of dietary intervention, plasma 25-hydroxyvitamin D3 (25D3) levels, DIA and extensor digitorum longus (EDL) in vitro contractile properties, and fiber cross-sectional area (CSA) were measured. Myosin heavy chain (MHC) composition and Akt/Foxo3A growth signaling were studied in the DIA and tibialis anterior. Mice fed the low, reference, and pharmacologic diets had average 25D3 levels of 7, 21, and 59 ng/ml, respectively. Maximal DIA force, twitch force, and fiber CSA were reduced 26%, 28%, and 10% ( P < 0.01), respectively, in mice receiving the low-VD3 diet compared with the reference and pharmacologic diets. EDL force parameters were unaltered by diet. Effects of VD3 intake on DIA force were not observed in mice that began dietary intervention at 12 wk of age. VD3 intake did not alter the MHC composition of the DIA, indicating that decreases in force and CSA in young mice were not due to a switch in fiber type. Paradoxically, low VD3 intake was associated with activation of anabolic signaling in muscle (hyperphosphorylation of Akt and Foxo3A and decreased expression of autophagy marker LC3). These studies identify a potential role of dietary VD3 in regulating DIA development and insulin sensitivity.

1Alpha,25-dihydroxyvitamin D3 (1,25D3) displays potent antiproliferative activity in a variety of tumor model systems and is currently under investigation in clinical trials in cancer. Studies were initiated to explore its potential in nonsmall cell lung cancer (NSCLC), as effective approaches to the treatment of that disease are needed. In evaluating factors that may affect activity in NSCLC, the authors found that CYP24 (25-hydroxyvitamin D3-24-hydroxylase), the enzyme that catabolizes 1,25D3, is frequently expressed in NSCLC cell lines but not in the nontumorigenic bronchial epithelial cell line, Beas2B. CYP24 expression by RT-PCR was also detected in 10/18 primary lung tumors but in only 1/11 normal lung tissue specimens. Tumor-specific CYP24 upregulation was confirmed at the protein level via immunoblot analysis of patient-matched normal lung tissue and lung tumor extracts. Enzymatically active CYP24 is expected to desensitize NSCLC cells to 1,25D3. The authors therefore implemented a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay for 1,25D3 and its CYP24-generated metabolites to determine whether NSCLC cells express active enzyme. Analysis of NSCLC cell cultures revealed time-dependent loss of 1,25D3 coincident with the appearance of CYP24-generated metabolites. MK-24(S)-S(O)(NH)-Ph-1, a specific inhibitor of CYP24, slowed the loss of 1,25D3 and increased 1,25D3 half-life. Furthermore, combination of 1,25D3 with MK-24(S)-S(O)(NH)-Ph-1 resulted in a significant decrease in the concentration of 1,25D3 required to achieve maximum growth inhibition in NSCLC cells. These data suggest that increased CYP24 expression in lung tumors restricts 1,25D3 activity and support the preclinical evaluation of CYP24 inhibitors for lung cancer treatment.

Objectives The data reported are from a trial designed to determine, in patients with advanced cancer, the maximum tolerated dose and pharmacokinetics of calcitriol when administered with paclitaxel, an agent whose antitumor activity in in vitro and in vivo studies has been shown to be enhanced by calcitriol. An additional goal was to evaluate the relationship between calcitriol dose and hypercalcemia. Methods Calcitriol was given orally for 3 consecutive days each week, and paclitaxel (80 mg/m2) was given intravenously weekly. Thirty-six patients were treated in cohorts composed of 3 to 9 patients, at escalating dose levels of calcitriol. The starting dose of calcitriol was 4 μg for 3 consecutive days each week, and the maximum dose administered was 38 μg for 3 consecutive days each week. The preparation of calcitriol used in this trial was a commercially available caplet (0.5 μg per caplet). Serum calcitriol concentrations were measured by radioimmunoassay. Detailed assessments of calcitriol pharmacokinetics were performed in 26 patients. Results There was substantial interpatient variation in peak serum calcitriol concentrations (Cmax), time to reach Cmax, and area under the concentration versus time curve (AUC). Serum calcitriol AUC was not proportional to calcitriol dose (P = .0014). AUC for the 24-hour period after calcitriol administration [AUC (0–24)] at 38 μg was only 4 times that at 4 μg, instead of the 9.5-fold increase expected for a proportional relationship. Calcitriol plasma concentrations of 600 to 1440 pg/mL were achieved. No dose-limiting toxicity occurred in this trial. Conclusions Despite variability in absorption, very high doses of calcitriol can be safely administered with paclitaxel. The high calcitriol serum concentrations achieved in this study approach those that, both in vitro and in vivo, potentiate the cytotoxicity of taxanes and platinum analogs. Clinical Pharmacology & Therapeutics (2002) 72, 648–659; doi: 10.1067/mcp.2002.129305

Epidemiologic data suggest that low exposure to vitamin D or 1alpha,25-dihydroxycholecalciferol (calcitriol) increases the risk of prostate cancer. Calcitriol, a central factor in bone and mineral metabolism, is also a potent antiproliferative agent in a wide variety of malignant cell types. We have demonstrated that calcitriol has significant antitumor activity in vitro and in vivo in prostate and squamous cell carcinoma model systems. Calcitriol, in these models, induces a significant G0/G1 arrest and modulates p21(Waf1/Cip1) and p27(Kip1), the cyclin-dependent kinase inhibitors. Calcitriol induces poly (adenosine diphosphate-ribose) polymerase cleavage, increases bax/bcl-2 ratio, reduces levels of phosphorylated mitogen-activated protein kinases (P-MAPKs; also known as extracellular signal-related kinase [ERK] 1/2) and phosphorylated Akt, induces caspase-dependent mitogen-activated protein kinase kinase (MEK) cleavage and upregulation of MEK kinase-1, all potential markers of the apoptotic pathway. We also have demonstrated that dexamethasone (dex) potentiates the antitumor effect of calcitriol through effects on the vitamin D receptor and decreases calcitriol-induced hypercalcemia. We initiated phase 1 and phase 2 trials of calcitriol, either alone or in combination with carboplatin, paclitaxel, or dex. Data from these studies indicate that high-dose calcitriol is feasible on an intermittent schedule, the maximum tolerated dose (MTD) is unclear, and dex or paclitaxel appear to ameliorate hypercalcemia. Studies continue to define the MTD of calcitriol on this intermittent schedule, either alone or with other agents, and to evaluate the mechanisms of calcitriol effects in prostate cancer models.

Calcitriol or 1,25-dihydroxycholecalciferol (vitamin D) is classically known for its effects on bone and mineral metabolism. Epidemiological data suggest that low vitamin D levels increase the risk and mortality from prostate cancer. Calcitriol is also a potent anti-proliferative agent in a wide variety of malignant cell types including prostate cancer cells. In prostate model systems (PC-3, LNCaP, DU145, MLL) calcitriol has significant anti-tumor activity in vitro and in vivo. Calcitriol’s effects are associated with an increase in cell cycle arrest, apoptosis, differentiation and in the modulation of growth factor receptors. Calcitriol induces asignificant Go/Gii arrest and modulates p21Waf1/Cip1 and p27Kip1, the cyclin dependent kinase inhibitors. Calcitriol induces PARP cleavage, increases the bax/bcl-2 ratio, reduces levels of phosphorylated mitogen-activated protein kinases (P-MAPKs, P-Erk-1/2) and phosphorylated Akt (P-Akt), induces caspase-dependent MEK cleavage and up-regula tion of MEKK-1, all potential markers of the apoptotic pathway. Glucocorticoids potentiate the anti-tumor effect of calcitriol and decrease calcitriol-induced hypercalcemia. In combination with calcitriol, dexamethasone results in a significant time- and dose-dependent increase in VDR protein and an enhanced apoptotic response as compared to calcitriol alone. Calcitriol can also significantly increase cytotoxic drug-mediated anti-tumor efficacy. As a result, phase I and II trials of calcitriol either alone or in combination with the carboplatin, paclitaxel, or dexamethasone have been initiated in patients with androgen-dependent and -independent prostate cancer and advanced cancer. Patients were evaluated for toxicity, maximum tolerated dose (MTD), schedule effects, and PSA response. Data from these studies indicate that high-dose calcitriol is feasible on an intermittent schedule, the MTD is still being delineated and dexamethasone or paclitaxel appear to ameliorate toxicity. Studies continue to define the MTD of calcitriol which can be safely administered on this intermittent schedule either alone or with other agents and to evaluate the mechanisms of calcitriol effects in prostate cancer.

Activation of the epidermal growth factor receptor (EGFR) pathway is an early event in head and neck carcinogenesis. As a result, targeting EGFR for chemoprevention of head and neck squamous cell carcinomas (HNSCC) has received considerable attention. In the present study, we examined the impact of 1,25(OH)2D3, the active metabolite of the nutritional supplement vitamin D on the chemopreventive efficacy of the EGFR inhibitor, erlotinib, against HNSCC. Experimental studies were conducted in patient-derived xenografts (PDX) and the 4-nitroquinoline-1-oxide (4NQO) carcinogen-induced model of HNSCC. Short-term treatment (4 weeks) of PDX-bearing mice with 1,25(OH)2D3 and erlotinib resulted in significant inhibition of tumor growth. Noninvasive MRI enabled longitudinal monitoring of disease progression in the 4NQO model with 100% of control animals showing evidence of neoplastic lesions by 24 weeks. Among the experimental groups, animals treated with the combination regimen showed the greatest reduction in tumor incidence and volume (P < 0.05). Combination treatment was well tolerated and was not associated with any significant change in body weight. Histopathologic assessment revealed a significant reduction in the degree of dysplasia with combination treatment. Immunoblot analysis of whole tongue extracts showed downregulation of phospho-EGFR and phospho-Akt with the combination regimen. These results highlight the potential of 1,25(OH)2D3 to augment the efficacy of erlotinib against HNSCC. Further optimization of schedule and sequence of this combination regimen along with investigation into the activity of less calcemic analogues or dietary vitamin D is essential to fully realize the potential of this approach. Cancer Prev Res; 8(9); 765–76. ©2015 AACR.

Recent data provides evidence for an important role of vitamin (Vit) D in respiratory muscle health. We tested the hypothesis that Vit D deficiency will reduce diaphragm muscle strength. Fifteen A/...

Background. Despite remarkable initial therapeutic responses, most patients develop resistance to the first generation of EGFR tyrosine kinase inhibitors (TKIs), erlotinib and gefitinib, within one year of treatment initiation. Epithelial-mesenchymal transition (EMT) is one of the key mechanisms of resistance to EGFR TKIs. We recently demonstrated that vitamin D promotes epithelial phenotype in NSCLC cells. We hypothesized that we could prevent/overcome EMT-driven resistance by combining vitamin D with EGFR TKIs. Methods. EGFR-mutant, erlotinib sensitive HCC827 cells were treated with: vehicle control, 100nM 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), 1ng/ml TGF-β, or 1,25(OH)2D3+TGF-β for 14 days. Expression of EMT markers was determined by q-RT PCR and immunoblot. Sensitivity to erlotinib was analyzed by MTT assay. For the in-vivo study, HCC 827 tumor xenografts were established in vitamin-D deficient mice. Mice were stratified based on tumor volume to receive diets containing 25 IU vitamin D3/kg (deficient) or 10,000 IU vitamin D3/kg (supplemented). Erlotinib treatment (12.5 mg/kg) was initiated two weeks after the diet switch and administered 5 days per week for the duration of the study. Tumors were collected two weeks after the diet switch (baseline), 48 hours after the erlotinib initiation (acute response) and upon treatment failure (outgrowth). Results. Vitamin D attenuated expression of mesenchymal markers in the presence of TGF-β in-vitro and opposed TGF-β driven resistance to erlotinib. Erlotinib EC50 values were 9.85 nM, 122 nM and 3.83 nM for vehicle, TGF-β, and 1,25(OH)2D3+TGF-β treated cells, respectively. In-vivo, vitamin D supplementation enhanced acute response to erlotinib. We documented a greater decrease in tumor volume after 48h of erlotinib initiation (1.1% of baseline ±19.3% in vitamin D deficient diet and 25.9% ±29.5% in supplemented diet). Greater efficacy was accompanied by increased suppression of STAT3 phosphorylation and decreased vimentin expression in the vitamin D supplemented group. Although we observed a trend towards a longer progression-free survival in animals maintained on vitamin D supplemented diet (8 vs 5.5 weeks), statistical significance was not achieved. The outgrowth tumors in both groups maintained their epithelial phenotype but exhibited a significant increase in the expression of AXL tyrosine kinase. However, outgrowth tumors from the vitamin D supplemented group had lower AXL expression than those from the vitamin D deficient group. Conclusion. Vitamin D supports epithelial phenotype in-vitro and enhances acute response to erlotinib in-vivo, possibly, by suppressing STAT3 signaling. Vitamin D supplementation also attenuates overexpression of AXL tyrosine kinase in erlotinib resistant tumors. The clinical implication of our work is that patients diagnosed with EGFR mutant NSCLC who receive erlotinib may benefit from vitamin D supplementation. Citation Format: Tatiana Shaurova, Suzanne F. Shoemaker, Pamela A. Hershberger. Vitamin D enhances erlotinib response in EGFR-mutant non-small cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4674.

Vitamin D has been shown to have anti-proliferative effects in a wide variety of cancers including lung cancer. The anticancer effects of vitamin D are mediated primarily by its active metabolite, 1,25-dihydroxyvitamin D (calcitriol), through vitamin D receptor (VDR) signaling. However, thus far there have been no studies evaluating the association between VDR expression and survival outcome in lung cancer. Using immunohistochemical analysis, we evaluated VDR expression, separately in the nucleus and cytoplasm, in lung cancer samples from 73 non-small cell lung carcinoma (NSCLC) patients with no prior therapy, and investigated the association between VDR expression and overall survival (OS). Cox proportional hazard models were used for our primary analyses. There were 44 deaths during a median follow-up of 51 months (range 13-93 months). High nuclear VDR expression was associated with improved OS after adjusting for age, gender, stage, smoking status, and histology (adjusted hazard ratio, 0.36; 95% confidence interval, 0.17-0.79). There was no association between cytoplasmic VDR expression and OS. Our results suggest that nuclear VDR status may be a prognostic marker in NSCLC. Future large studies to replicate our findings and to assess the impact of VDR gene polymorphisms on VDR expression are required as therapies targeting the vitamin D signaling pathway may be influenced by VDR status in the target lung cancer tissue.

Lung cancer has long been thought of as a cancer that mainly affects men, but over the past several decades, because of the high increase in tobacco use by women, there has been a corresponding dramatic increase in lung cancer among women. Since 1998, lung cancer deaths in women have surpassed those caused by breast cancer in the United States. Annual lung cancer deaths among US women currently surpass those caused by breast, ovarian, and cervical cancers combined. Women are more likely than men to be diagnosed with adenocarcinoma and small cell carcinoma of the lung compared to squamous cell carcinoma, and never-smokers diagnosed with lung cancer are almost three times more likely to be female than male. These observations in the population, coupled to the findings that both estrogen receptors (ERs) and aromatase, the enzyme that synthesizes 17beta-estradiol, are expressed by lung tumors, suggest a role for female steroid hormones in control of lung cancer growth. Preclinical data and clinical data are increasingly emerging to support this concept, and to suggest that a local production of estrogen and expression of ERs occurs in lung tumors that arise in men as well as in women. An additional protein that recognizes 17beta-estradiol with high affinity, GPR30, also is expressed in lung tumors at high levels and may be responsible for some of the proliferation signals induced by estrogen.

1,25-Dihydroxycholecalciferol (calcitriol) is recognized widely for its effects on bone and mineral metabolism. Epidemiological data suggest that low Vitamin D levels may play a role in the genesis of prostate cancer and perhaps other tumors. Calcitriol is a potent anti-proliferative agent in a wide variety of malignant cell types. In prostate, breast, colorectal, head/neck and lung cancer as well as lymphoma, leukemia and myeloma model systems calcitriol has significant anti-tumor activity in vitro and in vivo. Calcitriol effects are associated with an increase in G0/G1 arrest, induction of apoptosis and differentiation, modulation of expression of growth factor receptors. Glucocorticoids potentiate the anti-tumor effect of calcitriol and decrease calcitriol-induced hypercalcemia. Calcitriol potentiates the antitumor effects of many cytotoxic agents and inhibits motility and invasiveness of tumor cells and formation of new blood vessels. Phase I and II trials of calcitriol either alone or in combination with carboplatin, taxanes or dexamethasone have been initiated in patients with androgen dependent and independent prostate cancer and advanced cancer. Data indicate that high-dose calcitriol is feasible on an intermittent schedule, no dose-limiting toxicity has been encountered and optimal dose and schedule are being delineated. Clinical responses have been seen with the combination of high dose calcitriol+dexamethasone in androgen independent prostate cancer (AIPC) and apparent potentiation of the antitumor effects of docetaxel have been seen in AIPC. These results demonstrate that high intermittent doses of calcitriol can be administered to patients without toxicity, that the MTD is yet to be determined and that calcitriol has potential as an anti-cancer agent.

Progress has recently been made in identifying populations at risk for lung cancer using genetic, clinical and demographic information. The N-nitroso-tris-chloroethylurea (NTCU) mouse model, in which animals develop premalignant histopathology similar to that seen in humans, is used to examine the potential efficacy of chemoprevention agents to be utilized in at risk populations. We identified 25 µl of 40 mM NTCU /week as the optimal dosing regimen in SWR/J mice for chemoprevention studies. At this dose, topical treatments of NTCU induce predominantly low-grade dysplastic lesions by 15 weeks (w) and high-grade dysplastic (HGD) lesions by 25 w in the large airways. Additionally we found that NTCU stimulates a state of chronic inflammation associated with the development of dysplasias. Epidemiologic studies indicate that there is an inverse relationship between vitamin D and the risk and prognosis of lung cancer. Vitamin D acts through the vitamin D receptor to promote cellular differentiation and inhibit proliferation and inflammation. The effect of vitamin D on cancer progression was tested in the NTCU model, using dietary vitamin D3 (0 or 2000 IU/kg) alone and in combination with intraperitoneal injections of the active metabolite of vitamin D, calcitriol (80 ug/kg). Female mice were randomized to 6 treatment groups (n=15 mice/group/time point (15 and 25 w)). Disease was evaluated by enumerating the percentage of HGD lesions, per the total area in serial H&E sections of the lung. The percentage of HGD lesions in the large airways was reduced in the vitamin D sufficient mice (SN) (8.72%, P Furthermore, there was a significant increase in proliferation associated with increased HGD. Following 25 w of NTCU treatment there was a 2-fold increase in Ki-67 staining all groups compared all groups after 15 w of NTCU. However, the was 30% more Ki-67staining in the DN (P Citation Format: Sarah A. Mazzilli, Mary E. Reid, Paul N. Bogner, Kristopher Attwood, Pamela A. Hershberger, Donald L. Trump, Candace S. Johnson. Vitamin D sufficiency slows the progression of dysplasic lesions in the NTCU mouse model of lung squamous cell carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 238. doi:10.1158/1538-7445.AM2014-238

7019 Background: C, an anti-EGFR monoclonal antibody, enhances the efficacy of both RT and CT. We evaluated a novel strategy of RT plus C followed by consolidation CT plus C for the treatment of st...

Introduction: TMZ is a non-classical alkylating agent that induces DNA damage leading to cytotoxicity, with modest clinical activity in metastatic melanoma. DNA repair modulation with PARP inhibitors enhances TMZ cytotoxicity in vitro and in vivo, and this strategy is being investigated in clinical trials. We hypothesized that HDAC inhibition with SAHA would lead to increased DNA damage and potentiate the effect of the PARP inhibitor MK-4827 on TMZ cytotoxicity. Methods: Human melanoma cell lines A375 and FEMX-1 were used. Cells were treated in the absence or presence of TMZ, SAHA, and MK-4827 at the indicated concentrations for 72 hr in 96-well plates. Cell viability was determined using MTS assays and normalized to vehicle-treated control cells. Drugs were used at the final concentrations indicated in Table 1. Results: MK-4827 at 10 nM increased the cytotoxicity of TMZ in FEMX-1 but not in A375 cells, however 100 and 200 nM MK-4827 moderately potentiated TMZ cytotoxicity in both cell lines. The combination of TMZ with 1 µM SAHA and 200 nM MK-4827 resulted in profound cytotoxicity at reduced doses of TMZ (0.2 mM in FEMX-1 and 1.0 mM in A375), much lower than TMZ alone or in combination with either SAHA or MK-4827. >80% cell kill was achieved in A375 and >95% in FEMX-1 near the IC50 concentration of TMZ and at clinically achievable concentrations. Conclusion: PARP inhibition offers a strategy to reverse melanoma TMZ resistance. The concomitant inhibition of HDAC with SAHA and of PARP with MK-4827 profoundly enhanced TMZ cytotoxicity at clinically achievable doses of all 3 agents. We are presently optimizing the dosing schedules of the 3 drugs in preclinical models and investigating the mechanism(s) underlying this potentiation. These findings support the investigation of the triple drug combination (TMZ+SAHA+MK-4827) for metastatic melanoma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5499. doi:10.1158/1538-7445.AM2011-5499

10567 Background: Vorinostat, a Histone Deacetylase (HDAC) inhibitor is a novel targeted antineoplastic agent with promising activity when combined with carboplatin-paclitaxel against NSCLC. The exact molecular mechanism underlying its growth inhibitory and apoptotic effects is not well understood. We investigated the influence of p53 gene status on the interaction of vorinostat and carboplatin (a DNA targeting agent) in various NSCLC cell lines. Methods: NSCLC cells with wild type p53 (A549, 128.88T), mutant p53 (201T) and p53 null phenotype (Calu-1) were used. Cytotoxicity induced by serial dilution of carboplatin in the presence and absence of a fixed dose (1μM) of vorinostat was assessed by MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay. In a separate experiment, cells were also transiently transfected with a p21 promoter-luciferase reporter construct to assess p53 activation following a 24 h exposure to vorinostat, carboplatin, or vorinostat/Carboplatin combination. Luciferase activity was quantified by luminometry and corrected for total protein. Results: Vorinostat displayed single agent activity in each cell line, with greater growth inhibition observed in the p53 mutant and null cells. Synergistic interactions between carboplatin and vorinostat were observed in p53 wild type cells and the IC50 for carboplatin was reduced 3- to 5-fold. In contrast, the interaction between vorinostat and carboplatin was additive or less than additive in p53 mutant and p53 null cells. Vorinostat also increased expression of the p21 reporter construct in each of the cell lines. Conclusions: Vorinostat regulates p21 gene expression and elicits anti-tumor activity in NSCLC cells independent of their p53 status. Vorinostat potentiates carboplatin-induced cytotoxicity in NSCLC with wild type p53 but not p53 deficient cells, suggesting involvement of a p53 dependent pathway. The addition of vorinostat may allow for a reduction in standard dose of carboplatin with improvement in overall therapeutic index. A phase II/III clinical trial is in progress to evaluate vorinostat in combination with carboplatin-based regimen in advanced NSCLC. Support: CA099168–01, ASCO Foundation CDA No significant financial relationships to disclose.