Natural anti-tumor serum reactivity in BALB/c mice. II. Control by regulator T-cells

Recent advances in polymeric micelles for anti-cancer drug delivery

Block co-polymeric micelles receive increased attention due to their ability to load therapeutics, deliver the cargo to the site of action, improve the pharmacokinetic of the loaded drug and reduce off-target cytotoxicity. While polymeric micelles can be developed with improved drug loading capabilities by modulating hydrophobicity and hydrophilicity of the micelle forming block co-polymers, they can also be successfully cancer targeted by surface modifying with tumor-homing ligands. However, maintenance of the integrity of the self-assembled system in the circulation and disassembly for drug release at the site of drug action remain a challenge. Therefore, stimuli-responsive polymeric micelles for on demand drug delivery with minimal off-target effect has been developed and extensively investigated to assess their sensitivity. This review focuses on discussing various polymeric micelles currently utilized for the delivery of chemotherapeutic drugs. Designs of various stimuli-sensitive micelles that are able to control drug release in response to specific stimuli, either endogenous or exogenous have been delineated.

Antinucleosome antibody-modified liposomes and lipid-core micelles for tumor-targeted delivery of therapeutic and diagnostic agents

Liposomes and lipid-core micelles prepared of polyethylene glycol-phosphatidylethanolamine (PEG-PE) conjugates have been modified with nucleosome-specific monoclonal antinuclear autoantibody (ANA) 2C5 (mAb 2C5) specifically recognizing a broad variety of cancer cells through the cancer cell surface-bound nucleosomes. mAb 2C5 preserves its specific properties upon the binding with the lipid-based pharmaceutical nanocarriers, and 2C5-modified immunoliposomes and immunomicelles demonstrate an enhanced binding with tumor cells both in vitro and in vivo. We have investigated the delivery of therapeutic and diagnostic agents with such tumor-targeted immunoliposomes and immunomicelles to various tumors in vivo and in vitro. Both lipid-based nanocarriers provided enhanced tumor delivery of imaging agents ((111)In) and antitumor drugs (doxorubicin and photodynamic therapy agents) to tumor cells under different experimental settings. Pharmaceutical lipid-based nanoparticular carriers modified with mAb 2C5 could represent universal systems for tumor-specific delivery of various soluble and insoluble pharmaceuticals.

Intratumor immunologic heterogeneity

Tumor cells express a great variety of antigens including tumor specific transplantation antigens, tumor-associated antigens, differentiation antigens, histocompatibility antigens, lectin-binding sites and receptors for natural killer cells and natural antibodies. These antigens are distributed unevenly on tumor subpopulations and each subpopulation may induce different immune responses to the same determinant. Intratumor immunologic heterogeneity arises early in cancer, possibly during preneoplasia, and exists throughout the course of progression. Metastatic subpopulations are not generally less antigenic than subpopulations within primary tumors. Different arrays of antigenic determinants are displayed by subpopulations but variability in cell surface expression of a single determinant is also a fundamental type of immunologic heterogeneity. Antigenic specificity patterns commonly reveal one-way cross-reactions between tumor subpopulations. One-way cross-reactions might occur due to quantitative differences, cell-cycle variations, modulation, masking, H-2 expression and restriction phenomena, or alteration in the carbohydrate side-chains of glycoproteins. Interactions which occur when subpopulations co-exist may alter immune responses so that the response to the mixture is not the sum of the responses to the individual subpopulations. It is suggested that the exploitation of the mechanisms involved in immunologic heterogeneity may lead to new therapeutic approaches and that the great diversity of determinants expressed by tumor cells could lead to development of multivalent panel of monoclonal antisera which, acting synergistically, could preferentially lyse tumor cells.

Immunocompetence, immunosuppression, and human breast cancer. III. Prognostic significance of initial level of immunocompetence in early and advanced disease

The prognostic significance of immunocompetence determined at diagnosis was analyzed in 158 operable breast cancer patients followed for 3--6 years, in terms of disease recurrence and of length of disease-free period (DFP) and in 52 patients with metastatic disease in terms of length of survival. In vitro lymphocyte stimulation by PPD and PHA were of higher predictive value with respect to probability of disease recurrence than in vivo cutaneous reactivity to PPD and DNCB. Conversely, length of DFP and of survival were found to correlate better with in vivo than within vitro parameters. Absolute number of peripheral blood lymphocytes (PBL) and percent of E-rosette-forming cells (E-RFC) proved devoid of prognostic value. Prognostic separation was best brought out upon analysis by integrated score of immunocompetence, comprising the four functional parameters. Probability of disease recurrence was 0.43 for all operable patients, as calculated by actuarial method 48 months postoperatively; it was 0.26 for optimal and 0.61 for suboptimal responders (P less than 0.0001). Separate analysis of Stage 1 (N0) and Stage II (N+) patients revealed prognostic segregation within each stage: probability of recurrence in Stage I was 0.06 for optimal vs. 0.41 for suboptimal responders (P less than 0.001) and in Stage II it was 0.45 vs. 0.79, respectively (P less than 0.01). These findings may prove valuable for a more selective patient allocation for post-mastectomy adjuvant therapy. Length of DFP was found inversely proportional to initial immunocompetence, with a mean of 23.5 months for good responders and 12.8 months for poor responders (P less than 0.01). Length of survival of metastatic patients was found to correlate with initial (pretreatment) levels of immunocompetence, mean survival being 29.5 months for those with preserved immune function and 12.3 months for the immunosuppressed (P less than 0.001). It was concluded that initial immunocompetence, determined by parameters of cell-mediated immunity, shows strong prognostic association with the subsequently observed course of human breast cancer.