Mohamed K. Khan

Nanoparticle Targeting of Anticancer Drug Improves Therapeutic Response in Animal Model of Human Epithelial Cancer

Prior studies suggested that nanoparticle drug delivery might improve the therapeutic response to anticancer drugs and allow the simultaneous monitoring of drug uptake by tumors. We employed modified PAMAM dendritic polymers <5 nm in diameter as carriers. Acetylated dendrimers were conjugated to folic acid as a targeting agent and then coupled to either methotrexate or tritium and either fluorescein or 6-carboxytetramethylrhodamine. These conjugates were injected i.v. into immunodeficient mice bearing human KB tumors that overexpress the folic acid receptor. In contrast to nontargeted polymer, folate-conjugated nanoparticles concentrated in the tumor and liver tissue over 4 days after administration. The tumor tissue localization of the folate-targeted polymer could be attenuated by prior i.v. injection of free folic acid. Confocal microscopy confirmed the internalization of the drug conjugates into the tumor cells. Targeting methotrexate increased its antitumor activity and markedly decreased its toxicity, allowing therapeutic responses not possible with a free drug.

Engineering and characterization of functional human microvessels in immunodeficient mice

Current model systems used to investigate angiogenesis in vivo rely on the interpretation of results obtained with nonhuman endothelial cells. Recent advances in tissue engineering and molecular biology suggest the possibility of engineering human microvessels in vivo. Here we show that human dermal microvascular endothelial cells (HDMEC) transplanted into severe combined immunodeficient (SCID) mice on biodegradable polymer matrices differentiate into functional human microvessels that anastomose with the mouse vasculature. HDMEC were stably transduced with Flag epitope or alkaline phosphatase to confirm the human origin of the microvessels. Endothelial cells appeared dispersed throughout the sponge 1 day after transplantation, became organized into empty tubular structures by Day 5, and differentiated into functional microvessels within 7 to 10 days. Human microvessels in SCID mice expressed the physiological markers of angiogenesis: CD31, CD34, vascular cellular adhesion molecule 1 (VCAM-1), and intercellular adhesion molecule 1 (ICAM-1). Human endothelial cells became invested by perivascular smooth muscle α-actin–expressing mouse cells 21 days after implantation. This model was used previously to demonstrate that overexpression of the antiapoptotic protein Bcl-2 in HDMEC enhances neovascularization, and that apoptotic disruption of tumor microvessels is associated with apoptosis of surrounding tumor cells. The proposed SCID mouse model of human angiogenesis is ideally suited for the study of the physiology of microvessel development, pathologic neovascular responses such as tumor angiogenesis, and for the development and investigation of strategies designed to enhance the neovascularization of engineered human tissues and organs.

3H Dendrimer Nanoparticle Organ/Tumor Distribution

AbstractPurpose. To determine the in vivo biodistribution for differently charged poly(amidoamine) (PAMAM) dendrimers in B16 melanoma and DU145 human prostate cancer mouse tumor model systems. Methods. Neutral (NSD) and positive surface charged (PSD) generation 5 (d =5 nm) PAMAM dendrimers were synthesized by using 3H-labeled acetic anhydride and tested in vivo. Dendrimer derivatives were injected intravenously, and their biodistribution was determined via liquid scintillation counting of tritium in tissue and excretory samples. Mice were also monitored for acute toxicity. Results. Both PSD and NSD localized to major organs and tumor. Dendrimers cleared rapidly from blood, with deposition peaking at 1 h for most organs and stabilizing from 24 h to 7 days postinjection. Maximal excretion occurred via urine within 24 h postinjection. Neither dendrimer showed acute toxicity. Conclusions. Changes in the net surface charge of polycationic PAMAMs modify their biodistribution. PSD deposition into tissues is higher than NSD, although the biodistribution trend is similar. Highest levels were found in lungs, liver, and kidney, followed by those in tumor, heart, pancreas, and spleen, while lowest levels were found in brain. These nanoparticles could have future utility as systemic biomedical delivery devices.

In Vivo Biodistribution of Dendrimers and Dendrimer Nanocomposites — Implications for Cancer Imaging and Therapy

Our results indicate that the surface chemistry, composition, and 3-D structure of nanoparticles are critical in determining their in vivo biodistribution, and therefore the efficacy of nanodevice imaging and therapies. We demonstrate that gold/dendrimer nanocomposites in vivo, present biodistribution characteristics different from PAMAM dendrimers in a B16 mouse tumor model system. We review important chemical and biologic uses of these nanodevices and discuss the potential of nanocomposite devices to greatly improve cancer imaging and therapy, in particular radiation therapy. We also discuss major issues confronting the use of nanoparticles in the near future, with consideration of toxicity analysis and whether biodegradable devices are needed or even desirable.

Radiation Treatment Interruptions Greater Than One Week and Low Hemoglobin Levels (12 g/dL) are Predictors of Local Regional Failure After Definitive Concurrent Chemotherapy and Intensity- Modulated Radiation Therapy for Squamous Cell Carcinoma of the Head and Neck

Purpose:To determine whether baseline hemoglobin level and radiation treatment interruptions predict for loco-regional failure after intensity-modulated radiation therapy (IMRT) with concurrent chemotherapy for definitive treatment of squamous cell carcinoma of the head and neck (SCCHN). Methods:This retrospective review identified 78 consecutive patients treated with definitive concurrent chemoradiation for SCCHN. Patients were treated with IMRT to 70 Gy in 35 daily fractions to the high-dose target volume and 56 Gy to the elective target volume. Results:Median age of the cohort was 62 (37–81). Median follow-up was 12 months. Tumor sites included: oropharynx (54%), larynx (36%), oral cavity (5%), and hypopharynx (5%). Fifteen of 78 patients (19%) experienced loco-regional failure. These included: 6 primary site failures, 5 regional failures, and 4 failures in both the primary site and regional lymph nodes. All but one failure occurred in the high-dose target volume. Only duration of radiation treatment and baseline hemoglobin levels were significant predictors of local control. Loco-regional failure occurred in 6 of 13 patients (46%) with radiation treatment interruptions (>1 week) versus 9 of 65 patients (14%) completing radiation therapy without interruption (P = 0.0148). Loco-regional failure occurred in 7 of 19 patients (37%) whose pretreatment hemoglobin level was <12 g/dL compared with 8 of 59 patients (14%) with hemoglobin levels ≥12 (P = 0.042). Conclusion:Overall radiation treatment time and pretreatment hemoglobin level were significant predictors for loco-regional failure after definitive concurrent chemotherapy and IMRT for SCCHN.

Pretreatment nutritional status and locoregional failure of patients with head and neck cancer undergoing definitive concurrent chemoradiation therapy.

This study was carried out to determine if markers of nutritional status predict for locoregional failure following intensity‐modulated radiation therapy (IMRT) with concurrent chemoradiotherapy (CCRT) for squamous cell carcinoma of the head and neck (SCCHN).

In vivo toxicity evaluation of gold-dendrimer composite nanodevices with different surface charges

Abstract Composite nanodevices (CNDs) are multifunctional nanomaterials with potential uses in cancer imaging and therapy. Poly(amidoamine) dendrimer-based composite nanodevices are important members of this group and consist of an organic dendrimer component and an incorporated inorganic component, in this case, gold. This study addresses the short- (14 days) and long-term (78 days) in vivo toxicity of generation-5 (G5; 5 nm) PAMAM dendrimer-based gold-CNDs (Au-CNDs) with varying surface charges (positive, negative and neutral) in C57BL/6J male mice. Detailed toxicological analyses of (1) body weight changes, (2) serum chemistry and (3) histopathological examination of 22 organs showed no evidence of organ injury or organ function compromise. Zeta potential of Au-CNDs showed significant change from their parent dendrimers upon gold incorporation, making the normally lethal positive surface dendrimer biologically safe. Also homeostatic mechanisms in vivo may compensate/repair toxic effects, something not seen with in vitro assays.

Patient-reported Long-term Cosmetic Outcomes Following Short Fractionation Whole Breast Radiotherapy With Boost.

Objectives:To evaluate the cosmetic effect of a tumor-bed boost after hypofractionated whole breast irradiation (HF-WBI+B) using a patient-reported questionnaire. Materials and Methods:Between 2000 and 2005, 4392 women aged 75 years and younger with unilateral early-stage breast cancer received HF-WBI alone or HF-WBI+B. From each group, 800 randomly sampled surviving and nonrelapsed women were invited to complete the Breast Cancer Treatment Outcomes Scale questionnaire. Results:A total of 312 women completed the questionnaire: 154 received HF-WBI alone and 158 received HF-WBI+B. Median ages of respondents were 57 years for HF-WBI alone and 52 years for HF-WBI+B (P<0.001). Women receiving HF-WBI+B had a shorter follow-up interval, higher T stage, higher grade, and were more likely to have had nodal radiotherapy and chemotherapy. There were similar responses comparing the overall appearance of the treated to untreated breast (42% stating no or slight difference for HF-WBI alone vs. 41% for HF-WBI+B, P=0.87). The HF-WBI+B group was: (a) slightly worse on the cosmetic subscale (2.3 vs. 2.1, P=0.02); (b) worse on the pain subscale (2.0 vs. 1.6, P<0.0001); but (c) better on the functional subscale (1.5 vs. 1.8, P<0.001). When the pain subscale was applied to the area around the scar (a surrogate for the tumor-bed), the 2 groups were similar (2.0 vs. 2.0, P=0.71). Conclusions:Similar to conventional fractionated whole breast radiotherapy with a tumor-bed boost, women who received short fractionation whole breast radiotherapy with boost self-report only slightly worse long-term cosmetic and pain outcomes compared with women who received short fractionation alone.

Toxicity evaluation of gold-dendrimer composite nanodevices in vitro – difference found between tumour and proliferating endothelial cells

Composite nanodevices (CNDs) are a well-studied class of multifunctional nanomaterials with several potential medical uses, including cancer imaging and therapy. Gold/ dendrimer CNDs are organic/inorganic hybrid materials consisting of physical networks of dendrimer(s) and inorganic materials. This design permits properties of dendrimers and inorganic materials to be individually modified and optimized. A detailed understanding of factors regulating toxicity is lacking. We develop and test toxicity assays for CNDs in vitro both for cancer cells and for normal endothelial cells. We show how CND surface charge (positive, negative or neutral) and exposure time affects biosafety for d = 5 nm nanodevices. We also show that formation of the CND (incorporation of gold into a dendrimer template) can lower toxicity of a dendrimer. Interestingly, we also show that tumour cells and proliferating endothelial cells have different toxicity profiles.

Abstract P4-16-01: Accelerated hypofractionated whole breast radiotherapy for localized breast cancer: the effect of a boost on patient reported long-term cosmetic outcome

PURPOSE: Equivalent long-term local control and cosmetic outcomes between conventional and accelerated, hypofractionated whole breast radiotherapy (AWBRT) for early-stage breast cancer have been demonstrated. However, there is uncertainty about the long-term cosmetic outcome of a boost to the tumor bed following AWBRT (AWBRT+B). The primary outcome of this study was to evaluate the cosmetic effect of a boost using a patient reported questionnaire. The cosmetic subscale in the questionnaire was used to compare the appearance of the treated versus non treated breast between the boost and non-boost groups. MATERIALS AND METHODS: Between 2000 and 2005, 4392 women 75 years and under with unilateral early-stage breast cancer received AWBRT alone or AWBRT+B. Random samples of 800 women treated with AWBRT alone and 800 women treated with AWBRT+B were identified from the 3960 women still alive at least 5 years after treatment without contralateral disease. The women were contacted by mail to complete a questionnaire based on the Breast Cancer Treatment Outcomes Scale (22 questions regarding cosmetic, pain and functional outcomes). Cochrane-Armitage (CA) trend test and Wilcoxon Rank-sum (WR) were used to compare baseline patient and treatment variables to long-term cosmetic outcomes between the two treatment groups. RESULTS: 312 women (154 received AWBRT alone and 158 received AWBRT+B) completed the questionnaire. The median (range) age of respondents was 57 (40–75) years in the AWBRT alone group and 52 (32–75) years in the AWBRT+B group (p When comparing the overall appearance of the treated to untreated breast, there was no significant difference between the women who received AWBRT alone and those who received AWBRT+B (42% stating no or slight difference vs. 41%) (p = 0.87 CA). Focusing on the cosmetic subscale in the questionnaire, the average summed score for the AWBRT alone group was slightly worse to the score for the AWBRT+B group (2.3 vs. 2.1, p = 0.02 WR). On the functional subscale, the average summed score for the AWBRT alone group was worse than the AWBRT+B group (1.8 versus 1.5, p CONCLUSION: Similar to conventionally fractionated WBRT, patients who receive a boost after AWBRT self-report long-term slightly worse cosmetic and pain outcomes compared AWBRT alone. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-16-01.