Mechanisms for optimising photodynamic therapy: second-generation photosensitisers in combination with mitomycin C.

Mechanisms for improving photodynamic therapy (PDT) were investigated in the murine RIF1 tumour using meso-tetrahydroxyphenylchlorin (m-THPC) or bacteriochlorin a (BCA) as photosensitisers and comparing these results with Photofrin-mediated PDT. The 86Rb extraction technique was used to measure changes in perfusion at various times after interstitial PDT. Non-curative combinations of light doses with m-THPC and BCA PDT markedly decreased vascular perfusion. This decrease was more pronounced for both new photosensitisers than for Photofrin. Comparison of tumour perfusion after PDT with tumour response revealed an inverse correlation for all three photosensitisers, but the relationship was less clear for m-THPC and BCA. In vivo/in vitro experiments were performed after Photofrin or m-THPC PDT in order to assess direct tumour kill (immediate plating) vs indirect vascular effects (delayed plating). For both photosensitisers, there was little direct cell killing but clonogenic survival decreased as the interval between treatment and excision increased. When m-THPC PDT was combined with mitomycin C (MMC), light doses could be decreased by a factor of 2 for equal tumour effects. Lower light and m-THPC doses could be used compared with Photofrin PDT in combination with MMC. BCA PDT with MMC did not result in a greater tumour response compared with BCA PDT alone. Reduction in both light and photosensitiser does for effective PDT regimes in combination with MMC offers substantial clinical advantages, since both treatment time and skin photosensitisation will be reduced.     

Fractional allele loss data indicate distinct genetic populations in the development of non-small-cell lung cancer.

Allelic imbalance or loss of heterozygosity (LOH) has been widely used to assess genetic instability in tumours, and high LOH on chromosome arms 3p, 9p and 17p has been considered to be a common event in non-small-cell lung cancer (NSCLC). We have investigated allelic imbalance in 45 NSCLCs using 92 microsatellite markers on 38 chromosome arms. LOH of 38% was observed on 3p using nine markers, 58% on 9p using 15 markers and 38% on 17p using five markers. Fractional allele loss (FAL) has been calculated for each tumour (FAL is the number of chromosome arms showing LOH/number of informative chromosome arms) and a median FAL value of 0.09 was obtained in the 45 NSCLCs studied. The LOH data were examined on the basis of FAL scores: low FAL (LFAL) (0.00-0.04), medium FAL (MFAL) (0.05-0.13) and high FAL (HFAL) (0.14-0.45) based symmetrically around the median FAL value of 0.09. Tumours with HFAL values showed a very clear polarisation of the LOH data on chromosome arms 3p, 9p and 17p, such that 80% showed loss on 3p, 80% on 9p and 73% on 17p. These incidences of LOH were significantly higher than would be expected, since overall genetic instability in these HFAL tumours ranged from 14% to 45% LOH. Nine of the 14 patients in the LFAL group were found to have no LOH on 3p, 9p or 17p, but five of these had LOH at other sites: i.e. LOH on 5p, 5q, 8p, 13q, 16q and 19q. These results indicate that LFAL patients form a new subset of NSCLC tumours with distinct molecular-initating events, and may represent a discrete genetic population.     

Acute lymphoblastic leukaemia with t(4;11) follows neuroblastoma: a late effect of treatment?

The case presented is of a 7-year-old girl who developed acute lymphoblastic leukaemia (ALL) with t(4;11)(q21;q23) 5 years after the onset of neuroblastoma and 4 months after completing treatment for a first relapse. Consideration is given to the relative importance in this case of genetic factors and chemotherapeutic drugs in the etiology of ALL.     

A comparison of hyperthermia cisplatin sensitization in human ovarian carcinoma and glioma cell lines sensitive and resistant to cisplatin treatment

 Two pairs of human tumor cell lines (glioma and ovarian carcinoma (OvCa)) each having a parental cell line and cisplatin-resistant variant, were evaluated for (a) cisplatin response, (b) hyperthermia response, and (c) combined hyperthermia and cisplatin response. The two resistant lines had comparable resistant responses while for the parental lines, the OvCa was more sensitive than the glioma to cisplatin doses up to 14 μg/ml. For the hyperthermia response, the OvCa parental line was more resistant than the variant line at low-temperature hyperthermia (41° C or 42°C) but became more sensitive at high temperature (45°C). For the glioma, the parental line was more sensitive to hyperthermia at all temperatures tested. Hyperthermia caused sensitization to cisplatin in all cell lines but was generally greater in the glioma cell lines. In the OvCa system, hyperthermia had a slightly greater sensitizing effect on the resistant cell lines, while in the glioma the opposite was true. The degree of sensitization increased with hyperthermia temperature. In summary, the results showed that there is no cross-resistance for hyperthermia and cisplatin, that the degree of thermal sensitization is not reduced in cisplatin-resistant cell lines, and that cisplatin thermal sensitization is cell-line and temperature dependent. Thus, hyperthermia can effectively improve tumor cell response to cisplatin and may be useful in overcoming resistance to cisplatin. Received: 10 March 1995/Accepted: 21 July 1995     

Intensive therapy and autotransplant for patients with an incomplete response to front-line therapy for lymphoma

BACKGROUND:: Patients with Hodgkin's disease (HD) and intermediate or high-gradenon-Hodgkin's lymphoma (NHL) who fail to achieve a completeremission (CR) with standard induction therapy have a poor prognosiswith conventional-dose salvage therapy alone. We examined therole of subsequent intensive therapy and autologous bone marrowtransplantation (ABMT) in patients who demonstrated a responseto conventional-dose salvage therapy. PATIENTS AND METHODS:: Sixty-six patients with either HD (n = 30) or NHL (n = 36) underwentintensive therapy with etoposide (60 mg/kg), intravenous melphalan(160–180 mg/m²) followed by infusion of unpurged autologousbone marrow and/or blood cells. All patients had advanced stageor bulky disease at diagnosis and failed to achieve a CR afteran anthracycline-containing front-line chemotherapy regimen(NHL) or ABVD or equivalent regimen (HD). Patients who achieveda CR after involved-field radiotherapy were excluded. All patientsdemonstrated sensitivity to conventionaldose salvage treatmentbefore advancing to intensive therapy and ABMT. RESULTS:: The CR, partial response (PR) and overall response rate (RR)following ABMT for HD patients was 48%, 17% and 65%, respectively.At a median follow-up of 35 months, the predicted three-yearoverall survival (OS) is 51% (95% CI: 44%–60%) and event-freesurvival (EFS) is 34% (95% CI: 26%–54%). For patientswith NHL, the CR, PR and RR were 68%, 9% and 77%, respectively.At a median follow-up of 28 months, the predicted three-yearOS is 51% (95% CI: 35%–66%) and EFS is 39%(95% CI: 21%–57%). CONCLUSIONS:: Intensive therapy with etoposide and melphalan followed by ABMTresults in prolonged survival in selected patients with lymphomawho fail to achieve a complete remission to front-line chemotherapy.Based on our previous studies of outcome to conventionaldosesalvage chemotherapy, we estimate that of all patients failinginduction therapy, 28% with HD and 15% with NHL will be eventfreeat three years after ABMT. induction failure, Hodglun's disease, non-Hodgkin's lymphoma, refractory lymphoma