Combination of photodynamic therapy + immunotherapy + chemotherapy in murine leukiemia.

Photodynamic therapy (PDT) is a treatment for cancer based on the photosensitization of tumor cells by photosensitive drugs and their subsequent destruction on exposure to light of particular wavelength. The combination of drug uptake in malignant tissues and selective delivery of laser-generated light provides an effective therapy with efficient tumor citotoxicity and minimal normal tissue damage. Since immune response of the host is important in the control of tumor growth and spreading, PDT is able to increase the antitumor immunity. In our laboratory we examined the antitumor effect of combination of PDT, with photoactivated M-THPC (meta-tetrahydroxyphenylchlorin, FOSCAN, Temoporphirin), adoptive immunotherapy, with immune lymphocytes, and chemotherapy on advanced murine tumors. Mice bearing L1210 tumor were treated at day +4 with Navelbine (NVB 1mg/Kg), at day +5,+6 with PDT (0.3mg/Kg of mTHPC and 100mW/cm(2) x 200'' of exposure of laser light), and at day + 7 with immune lymphocytes(IL), collected from mice pretreated with PDT(2x10(7) cells). The results show that the combination NVB + PDT + IL demonstrates a significant synergistic antitumor effect while the chemotherapy treatment with low dose of the drug is uneffective. The same positive results were obtained with the combination of Cisplatin (CDDP 0.5mg/Kg), PDT and IL, while the CDDP treatment alone is completely uneffective. In conclusion, these results suggest that it is possible to completely cure animals bearing advanced tumors, with a combined therapy, PDT + adoptive immunotherapy + low dose chemotherapy.

Cell survival under nutrient stress is dependent on metabolic conditions regulated by Akt and not by autophagic vacuoles.

Akt activation assists tumor cell survival and promotes resistance to chemotherapy. Here we show that constitutively active Akt (CA-Akt) cells are highly sensitized to cell death induced by nutrient and growth factor deprivation, whereas dominant-negative Akt (DN-Akt) cells have a high rate of survival. The content of autophagosomes in starved CA-Akt cells was high, while DN-Akt cells expressed autophagic vacuoles constitutively, independently of nutrition conditions. Thus Akt down-regulation and downstream events can induce autophagosomes which were not directly determinants of cell death. Biochemical analysis in Akt-mutated cells show that (i) Akt and mTOR proteins were degraded more rapidly than the housekeeping proteins, (ii) mTOR phosphorylation at position Thr(2446) was relatively high in DN-Akt and low in CA-Akt cells, induced by starvation in mock cells only, which suggests reduced autoregulation of these pathways in Akt-mutated cells, (iii) both protein synthesis and protein degradation were significantly higher in starved CA-Akt cells than in starved DN-Akt cells or mock cells. In conclusion, constitutively active Akt, unable to control synthesis and wasting of proteins, accelerates the death of starved cells.

Antigenic changes of L5178Y lymphoma after treatment with 5-(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide in vivo.

Immunologic alteration of the L5178Y lymphoma was obtained in vivo after treatment with 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DIC). A single dose of 1,3-bis(2-chlorethyl)-1-nitrosourea (BCNU) "CURED" MICE CHALLENGED WITH L5178Y cells that had been treated with DIC (L5178Y/DIC) for four transplant generations; BCNU did not cure mice bearing the parent tumor. The L5178Y/DIC, treated in vivo for five transplant generations, id not grow in syngeneic mice. L5178Y/OIC cell growth and incidences of death were similar to those of parent cells when inoculated into heavily immunosuppressed mice. Adoptive transfer of lymphocytes from spleens of mice sensitized to the drug-altered tumor specifically protected immunosuppressed mice bearing the L5178Y/DIC tumor. Little protection was afforded by lymphocytes immune to the parent L5178Y tumor, whereas nonimmune lymphocytes or lymphocytes immune against unrelated tumors were completely ineffective. Anti-L5178Y/DIC lymphocytes did not cure mice challenged with the parent L5178Y tumor. Irradiated (400 R) mice previously sensitized to L5178Y/DIC cells rejected 10(2)-10(7) inocula of L5178Y/DIC cells and died when the parent L5178Y was used for challenge. It was concluded that antigeni( alterations of L5178Y cells occurred in (BALB/ctcr X DBA/2Cr)F1 mice after treatment with DIC in vivo.

Rapid development of resistance to antifolates in vitro: possible clinical implication.

Within three repeated 7-day incubation periods with either methotrexate (MTX) or trimetrexate (TMTX), human colon adenocarcinoma cells (HCT-8) developed high levels of resistance to these drugs, as evidenced by approximately 20- and 50-fold increases, respectively, in the median effective doses. Similarly, within six short-term exposures (4 hours) to the same drugs, a high degree of resistance developed in the cells. Alternating 4-hour treatment cycles with MTX and TMTX did not delay the onset of resistance to these antimetabolites in the HCT-8 cells. The same strategy produced no better results than giving either MTX or TMTX alone to (C57BL/6 x DBA/2)F1 mice bearing murine leukemia P388 cells. Furthermore, HCT-8 cells resistant to short-term (4-hour) exposure to MTX were cross-resistant to the same drug given for 7 days continuously, and cells resistant to MTX given continuously for 7 days were cross-resistant to the same drug given for 4 hours. Analogous results were obtained with TMTX, indicating that, under these circumstances, changing the schedule of administration of the same agent does not overcome resistance to it. The clinical relevance of these data to prolonged adjuvant chemotherapy, as well as loco-regional and continuous-infusion chemotherapy, is discussed.

Evaluation of growth fractions with monoclonal antibodies to human alpha-DNA polymerase.

We have established and partially characterized a panel of monoclonal antibodies against alpha-DNA polymerase. One of the hybridomas, clone 5F, has been exploited for cell kinetic studies on three colon cancer cell lines, LOVO, SW 620, and SW 403, which are endowed with different growth patterns and differentiation status. By an immunoperoxidase method, we could demonstrate the specific intranuclear localization of alpha-DNA polymerase during the exponential phase of in vitro growth and contrast it with the diffuse distribution of the enzyme throughout the cytoplasm during the resting state. The percentage of intranuclear staining positive cells, evaluated at successive time points of in vitro growth, changed from 75 to 95% (assayed on Days 3 and 7) to 15 to 25% in confluent and resting populations assayed on Days 12 to 14. In agreement with the assumption that the enzyme moves from nucleus to cytoplasm after entering quiescence, alpha-DNA polymerase was still present in the cytoplasm or in the cytoplasmic perinuclear area of cells in resting phase cultures. Comparisons between traditional kinetic parameters (thymidine labeling index and primer-dependent alpha-DNA polymerase) and proliferative state determined by the monoclonal antibody supported the feasibility of this approach to define the proportion of actively proliferating elements in a tumor cell population. Moreover, parallel flow cytometric analysis performed on Days 5 and 14 of continuous culture showed fluctuations of alpha-DNA polymerase content in relation to exponential and steady-state phases, with a significant increase in the amount of alpha-DNA polymerase in actively proliferating populations and a progressive reduction of the enzyme as the cultures entered the resting stage.

In vitro lymphocyte stimulation and the generation of cytotoxic lymphocytes with drug-induced antigenic lymphomas.

New antigenic specificities, not detectable on parental cells and transmissible after the withdrawal of the drug treatment, have been induced in mouse lymphomas. Studies were conducted of proliferative stimulation of syngeneic lymphocytes and the generation of cytotoxic lymphocytes (CL's) in a mixed lymphocyte-tumor cell culture system by 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DTIC)-induced antigens in L1210 and EL4 leukemia sublines. The DTIC-induced antigens were observed to stimulate [3H]thymidine uptake by normal and primed syngeneic lymphocytes and to generate specific CL's to DTIC-altered cells. The specificity of the in vitro immune reactivity was demonstrated. Characteristics of lymphocyte triggering, including the optimal ratio of stimulating cells to responding cells, the kinetics of CL activation, and the quantitation of CL activity, were also evaluated. DTIC antigens on leukemic cells can activate syngeneic lymphocytes and can act as target antigens in cell-mediated immunity. The experimental data support the transplantation antigen-like nature of DTIC-induced antigens.

Immunosensitivity and histocompatibility antigens in drug-altered leukemic cells.

New antigenic properties of experimental lymphomas have been reported previously following in vivo treatment with antitumor agents. 5-(3,3-Dimethyl-1-triazeno)imidazole-4-carboxamide (DIC) induced new antigenic characteristics on L1210 and L5178Y lymphomas, that were previously investigated in studies in animals compatible with the original untreated parental tumors. Here the L1210/DIC and L5178Y/DIC susceptibility to the cytotoxic effects of allogeneic and xenogeneic lymphocytes and sera obtained from animals sensitized to DBA/2 histocompatibility antigens were studied. The original and the DIC tumors showed the same sensitivity to anti-DBA/2 cellular and humoral cytotoxicity. The immune response electied in allogeneic mice by the original and DIC sublines was evaluated by in vitro cell-mediated and humoral cytotoxic assay. Beyond the immune response to histocompatibility antigens, a specific, anti-DIC-antigen immunoreaction was not found. Inhibition assay of the cell-mediated cytotoxicity and absorption of the humoral cytotoxicity demonstrated that DIC-induced antigens are not reciprocally related in cell-surface concentration to the natural DBA/2 histocompatibility antigens associated with tumor cells of DIC lines. An experiment was conducted in which specific activity against the DIC-treated L5178Y/DIC cells was observed with anti-L5178Y/DIC rabbit immune serum absorbed with the parental L5178Y lymphoma. This finding provides additional support to previous studies indicating that treatment with DIC induced new antigens on the lymphoma cells.

Chemotherapy and immunotherapy of L1210 leukemic mice with antigenic tumor sublines.

Tumor cells, treated in vivo with anticancer compounds, may acquire new antigenic specificities in addition to any original antigens associated with parental tumors. Treatment of mice carrying the parental leukemias L1210 Ha or L1210 Cr with leukemia cells antigenically altered by treatment with 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (L1210 Ha/DTIC and L1210 Cr/DTIC, respectively) was essentially ineffective in prolonging the life span of the animals. However, synergic therapeutic activity was exhibited by administration of L1210 Ha/DTIC cells plus 1,3-bis(2-chloroethyl)-1-nitrosourea in the treatment of the moderately immunogenic L1210 Ha leukemia and by the combination of L1210 Cr/DTIC cells and lymphocytes immune to L1210 Cr/DTIC administered with 1,3-lymphocytes immune to L1210 Cr/DTIC administered with 1,3-bis(2-chloroethyl)-1-nitrosourea in the treatment of the low immunogenic L1210 Cr leukemia. Early and advanced L1210 Cr-bearing mice showed marked increases in survival time and a significant number of tumor-free survivors on treatment with cyclophosphamide followed by transfer of lymphocytes immune to L1210 Cr/DTIC cells. When parental tumor cells were used as the immunogen, the therapeutic effect was diminished. Thus, in the current investigation, although immunotherapy per se was essentially ineffective, the immunochemotherapeutic modalities used were successful in markedly increasing the survival time of leukemic animals and resulted in an incidence of cures.

Hematoporphyrin derivative rescue from toxicity caused by chemotherapy or radiation in a murine leukemia model (L1210).

Hematoporphyrin [1,3,5,8-tetramethyl-2,4-bis(hydroxyethyl)-porphin-6,7-dipropio nic acid dihydrochloride derivative] (HPD) is a compound that was studied in a number of laboratories because of its cytocidal activity after activation by light. Modification of immune function seen during the photochemotherapeutic studies prompted attempts to determine the effect of HPD on the immune and hemopoietic systems. Splenic hyperplasia as well as marrow hypercellularity were noted in mice treated with HPD. In vitro phytohemagglutinin or lipopolysaccharide stimulation of spleen lymphocytes caused normal or scant increases in blast transformation compared to the stimulation index for lymphocytes from untreated animals. HPD treatment did not significantly alter production of antibody to sheep red blood cells, as evaluated by hemagglutination or hemolytic assay. In contrast, HPD treatment did promote an increased number of spleen colonies in lethally irradiated mice transfused with syngeneic bone marrow. The capacity of HPD to increase the number of bone marrow and spleen cells has been exploited to accelerate the recovery from peripheral leukopenia induced in animals by previous drug or radiation treatment. The time for full return from severe leukopenia induced by an antimetabolite compound (5-fluorouracil) or an alkylating agent (cyclophosphamide or X-rays was significantly shorter in mice treated with HPD than in controls. Furthermore, improved survival was demonstrated in irradiated mice after HPD treatment. Finally, HPD treatment of L1210 leukemic mice did not affect the antitumor activity of cyclophosphamide. If the properties described here be confirmed, HPD might contribute to recovery of leukopenic cancer patients.

Chemotherapy following estrogen-induced expansion of the growth fraction of human breast cancer.

We have evaluated the feasibility of a cytokinetically oriented regimen based on the induction of cell recruitment by diethylstilbestrol (DES) in locally advanced human breast cancer. Tumor proliferative activity was evaluated by the thymidine labeling index and the primer-dependent alpha-DNA polymerase labeling index, which gives an in vitro estimation of the growth fraction. Sixteen previously untreated patients received DES (1 mg daily for 3 days) followed by FAC [5-fluorouracil (600 mg/m2): Adriamycin (50 mg/m2): Cytoxan (600 mg/m2)] i.v. on day 4 every 21 days. Radical surgery was delayed to allow for three DES-FAC regimens in responsive patients. Proliferative activity on tumor biopsies was evaluated immediately before and after treatment with DES, 24 h after chemotherapy and, in nine patients, at the time of radical surgery. DES was able to induce a significant increase in thymidine labeling index in 8 of 16 patients, while the primer-dependent alpha-DNA polymerase labeling index was significantly increased in 13 of 16 tumors, independently of their estrogen receptor content. Subsequently administered chemotherapy induced an early decrease in tumor proliferation. In the nine patients submitted to surgery after three DES plus FAC courses, the average thymidine labeling index and primer-dependent alpha-DNA polymerase labeling index were 27.8 and 73% of the pretreatment values. Our preliminary results provide the rationale for the design of new therapeutic schemes in which antitumor drugs are given at the time of estrogen-induced tumor cell recruitment. Further extended studies are required to establish whether induction of tumor cell recruitment will actually translate into appreciable improvement of the clinical response to chemotherapy.

Damaged microtubules can inactivate BCL-2 by means of the mTOR kinase.

Rapamycin, a specific inhibitor of the serine/threonine mTOR kinase, markedly inhibited both cell growth and apoptosis in human B-cell lines. Besides arresting cells in G(1) by increasing p27(kip1), rapamycin tripled the cellular level of the BCL-2 protein. The activity was dose-dependent and specific for the p27(kip1) and BCL-2 proteins. Rapamycin did not affect bcl-2 mRNA although it increased cellular BCL-2 concentration by inhibiting phosphorylation, a mechanism initiating the decay process. To add new insight, we combined rapamycin treatment with treatment by taxol, which, by damaging microtubules, can phosphorylate BCL-2 and activate apoptosis. It was found that the mTOR kinase was activated in cells treated with taxol or with nocodazole although it was inhibited in cells pre-treated with rapamycin. BCL-2 phosphorylation, apoptosis and hyperdiploidy were also inhibited by rapamycin. In contrast, taxol-induced microtubule stabilization or metaphase synchronization were not inhibited by rapamycin. Taken together, these findings indicate that mTOR belongs to the enzymatic cascade that, starting from damaged microtubules, phosphorylates BCL-2. By regulating apoptosis, in addition to the control of a multitude of growth-related pathways, mTOR plays a nodal role in signaling G(1) and G(2)-M events.

A bcl-2/IgH antisense transcript deregulates bcl-2 gene expression in human follicular lymphoma t(14;18) cell lines.

The 14;18 chromosome translocation, characteristic of most human follicular B-cell lymphomas, juxtaposes the bcl-2 gene with the IgH locus, creating a bcl-2/IgH hybrid gene. By mechanisms that are still under investigation, this event increases the cellular levels of the bcl-2 mRNA and thereby induces an overproduction of the antiapoptotic BCL-2 protein which is likely responsible for neoplastic transformation. In an effort to identify potential upregulators of bcl-2 activity in t(14;18) cells, we found, by strand-specific RT-PCR, a bcl-2 antisense transcript that is present in the t(14;18) DOHH2 and SU-DHL-4 but not in the t(14;18)-negative Raji and Jurkat lymphoid cell lines, and thus appears to be dependent on the bcl-2/IgH fusion. This antisense transcript is a hybrid bc1-2/IgH RNA, that originates in the IgH locus, encompasses the t(14;18) fusion site and spans at least the complete 3' UTR region of the bcl-2 mRNA. To achieve some insight into its biological function, we treated the t(14;18) DOHH2 cell line with oligonucleotides (ODNs) by specifically targeting the bc1-2/IgH antisense strand. These ODNs lowered bcl-2 gene expression, inhibited neoplastic cell growth by inducing apoptosis. We would like to propose the hypothesis that the bc1-2/IgH antisense transcript may contribute, by an unknown mechanism, to upregulation of bcl-2 gene expression in t(14;18) cells. The possibility has been considered that the hybrid antisense transcript mask AU-rich motifs present in the 3' UTR of the bcl-2 mRNA characterized in other genes as mRNA destabilizing elements.

Assimilation of LDL by experimental tumours in mice.

We have studied the uptake of 125I-labelled low-density lipoprotein (LDL) by seven experimental murine tumours in vivo. Four tumours (Lewis Lung carcinoma, B-16, MS-2 and Colon 26) showed a higher relative uptake of lipoprotein as compared to the liver, two (L-1210 and P-388) had a very low lipoprotein uptake, while lipoprotein uptake by tumour M5 was similar to that of the liver. The data was confirmed by tracing tissue uptake of lipoproteins using [14C]sucrose-labeled LDL. These in vivo findings correlated well with the in vitro specific binding of 125I-beta-VLDL to membranes prepared from tumours, thus suggesting that the expression of the LDL receptor in the tumours is related to the in vivo uptake of lipoprotein. Further analysis of the LDL receptor by ligand blotting showed that the tumor receptor has several of the liver LDL receptor characteristics (including apparent Mr, sensitivity to proteinases, and Ca2+ requirement of lipoprotein binding). In summary, our data show that experimental murine tumours express the LDL receptor and suggest that the high relative in vivo uptake of LDL is determined by the elevated LDL-receptor expression in the tumours.

Antisense oligonucleotide drug design.

Maneuvering single gene expression is not only an optimal way to study gene function but also an ambitious goal, which will lead to the treatment of a variety of human diseases whose main pathogenetic event is a genetic alteration. The recent efforts focusing on the genome project have led to array based, high throughput, gene expression analysis techniques that allow the study of complex molecular networks. Combining these powerful new technologies with modulation of gene expressions is making it possible to unravel complex molecular networks or, vice versa, to find new gene products responsible for pathological conditions on which exogenous modulation can be productive. Efficient and specific modulation of gene expression can be obtained either by producing transgenic or gene knockout organisms or cells (gene targeting), or by treating organisms or cells with short synthetic nucleic acid segments in antisense orientation with respect to the targeted mRNAs (mRNA targeting by antisense strategy). While genome manipulation is a time consuming and expensive approach, requiring invasive intervention, the "antisense strategy" is characterized by high flexibility resulting from safeness, specificity, reversibility, modulability, and low cost. The rationale of the antisense strategy is that, once one gene sequence is known, its expression can be silenced by application of synthetic single-strand nucleic acid segments (oligonucleotides) whose sequence is in antisense orientation compared to the targeted mRNA. Recently, this "informational" strategy has been boosted by the discovery of the RNA interference: a natural mechanism by which cells are thought to fight detrimental exogenous viruses and endogenous transposons. Despite promising futures, antisense-based therapeutics are far from being an established reality. This review analyses the recent improvements in antisense-based gene expression modulation, focuses on the treatment of diseases in the light of the past, and provides our personal findings on this topic.

Rapamycin increases the cellular concentration of the BCL-2 protein and exerts an anti-apoptotic effect.

The immunosuppressant rapamycin, an immunophilin-binding antibiotic, has been studied in follicular B-cell lymphoma lines that express the highest level of the BCL-2 protein. The growth rate of human follicular B-cell lymphoma lines was slowed more efficiently than that of other human B-cell lines or non-B-cell lines. This effect was dependent on the arrest of cells in the G(1) phase; the number of apoptotic cells was not increased. Rapamycin inhibited apoptosis or caspase activation induced by cytotoxic drugs, whereas caspase activation by doxorubicin was not inhibited. The increase in the cellular concentration of BCL-2 protein was related to its concentration in the steady state and was unrelated to the amount of bcl-2 mRNA. The increase of BCL-2 level in the cells rather than its level in the steady state may be important for drug resistance. The biochemical target of rapamycin, the mTOR kinase, may be a candidate sensitising agent for chemotherapy. This effect of rapamycin shows that G(1) arrest and protection from apoptosis are combined events susceptible to regulation by pharmacological means.

Thymidine labelling index as prognostic factor in resected non-small cell lung cancer.

To assess the prognostic value of tumor proliferative activity, 89 patients with operable non-small cell lung cancer were studied. Tumor samples were obtained during surgery and cell kinetics were analyzed by the in vitro thymidine labelling index (TLI). The overall median TLI (2.9) was used to identify two subsets of patients with high and low proliferating tumors. In univariate analysis survival was significantly longer in patients with lower TLI (P = 0.047) and with stage I-II (P = 0.003) and T1-T2 tumors (P = 0.043). In multivariate analysis, stage was the most important prognostic parameter (P = 0.004). The risk of death for patients with TLI higher than 2.9 was increased (hazard ratio = 2.01, CI = 0.96-4.27).

Phenotypic and functional characterization of T cell clones following allogeneic bone marrow transplantation.

T cell clones (n = 456) were derived from 9 patients following allogeneic bone marrow transplantation (BMT) with or without acute graft versus host disease (aGVHD) and from 4 healthy donors. The cloning efficiency was 63.2% in controls, 13.2% and 12.1% in patients with or without aGVHD. Once established, T cell clones were typed for surface markers (CD3, CD4, CD8) and tested for production of IL-2 and expression of cytolytic activities in a lectin-dependent cellular cytotoxicity assay (LDCC) and against the K562 target cell line to detect natural killer activity. We found the expected imbalance of CD4/CD8 clones in BMT patients, as compared to controls. A higher proportion of IL-2-producing clones was observed in patients with aGVHD (83.5%; P less than 0.02) as compared to patients without aGVHD (64.8%) and controls (68.5%). No major differences were found in terms of LDCC, whereas an increased percentage of clones with NK-like activity was found in patients with aGVHD (34.7%, P less than 0.05) as compared to patients without aGVHD (29.5%) and controls (21.3%). The clones were also tested for inhibition of IL-2 production mediated by cyclosporine. Such inhibition could be obtained in virtually all clones both in patients with or without aGVHD, suggesting that the latter is probably not due to the emergence of CsA-resistant clones. In conclusion, this study demonstrates a low cloning efficiency in BMT patients associated with the well-known CD4/CD8 imbalance. A higher production of IL-2, an increased NK activity, but not the presence of CsA-resistant clones appear to differentiate patients with from patients without aGVHD.

Efficacy of photodynamic therapy against doxorubicin-resistant murine tumors.

Photodynamic therapy (PDT) is a relatively new cancer treatment modality that employs light excitation of a photosensitizer to yield cytotoxic oxygen-related species. In the present study we explored whether PDT would have therapeutic effect against doxorubicin-resistant murine tumors. We compared the efficacy of PDT with aluminium disulphonated phthalocyanine (A1S2Pc) and laser light on the doxorubicin-sensitive murine tumors, B16 melanoma (B16), L1210 leukemia (L1210), P388 lymphoma (P388) and the corresponding doxorubicin-resistant lines (B16/Dx, L1210/Dx and P388/Dx). Mice bearing L1210-L1210/Dx, P388-P388/Dx and B16-B16/Dx, were treated with 5 mg/kg of A1S2Pc and laser light (100 mW/cm2 x 10 min of exposure) or with doxorubicin (10 or 12 mg/kg i.v.). The results show that PDT is active versus all tumors while doxorubicin is effective only against the three sensitive tumor lines (L1210, P388 and B16). These observations suggest that PDT might be a beneficial alternative treatment for drug-resistant tumors.

Hematoporphyrin derivative photoradiation therapy in murine solid tumors.

The cytocidal activity of light-activated hematoporphyrin derivative (Hpd) in experimental and human tumors is under investigation in many laboratories. This activity is based upon preferential incorporation of Hpd in malignant tissues and its photosensibilization by red light. Treatment of mice bearing MS-2 fibrosarcoma and B16 melanoma, a metastastic tumor, with Hpd and laser light, externally or delivered through a quartz fiber optic imbedded directly into the tumor, significantly prolonged the median survival time. This therapy was compared with surgical excision of primary tumors, and preliminary results on metastatic neoplasm suggest that the photoradiation therapy is more effective than surgery.

In vivo assimilation of low density lipoproteins by a fibrosarcoma tumour line in mice.

A tumour line inoculated in mice showed high affinity binding for lipoproteins in vitro. Studies in vivo demonstrated that the assimilation of human low density lipoprotein (LDL) by the tumour was very high. Both receptor and non-receptor mediated catabolism of the lipoprotein by the tumour increased as compared to other tissues known to be sites of lipoprotein catabolism (liver, spleen etc.). These findings suggest that lipoproteins may be useful markers for tumours as well as carriers for cytotoxic drugs to target tissues in vivo.