Flow cytometric quantification of the proliferation-associated nuclear antigen p105 and DNA content in advanced head & neck cancers: results of RTOG 91-08

PURPOSE

p105 is a proliferation-associated nuclear antigen which identifies proliferating but not resting cells. The objectives of this Radiation Therapy Oncology Group (RTOG) protocol (91-08) were: (1) to correlate tumor proliferative potential estimated using the p105 assay and deoxyribonucleic acid (DNA) analysis with treatment outcome in patients irradiated for advanced squamous cell carcinoma of the head and neck; and (2) to evaluate the potential of p105 labeling indices as a predictive assay.

METHODS AND MATERIALS

Paraffin blocks of pretreatment biopsies of the primary tumor or metastatic neck nodes of patients with Stage III or IV squamous cell carcinoma of the head and neck treated with radiotherapy alone in three previous RTOG protocols (79-13, 79-15, and 83-13) were retrospectively obtained. From these paraffin blocks, areas of tumor were selected based on histological examinations and sectioned. Nuclei suspensions were then prepared and processed for p105 antibody and DNA staining and subsequent flow cytometric quantification of p105 labeling indices and DNA content and correlation with local-regional control and survival.

RESULTS

Paraffin blocks of tumor biopsies from 148 out of a total of 598 eligible patients were available. Of these, 143 were analyzable. The median and (range) of p105 labeling index (LI-C), p105 labeling index of cells in S phase (LI-S), and p105 antigen density (AD) were: 66.6 (3.85-99.5), 9 (1.55-36), and 93.2 (7.4-628.5), respectively. Deoxyribonucleic acid was diploid in 67 (47%), aneuploid in 22 (15%) and mixed aneuploid/diploid in 54 (38%) patients. There was a strong correlation between AD and DNA ploidy. Antigen density was above median in 91.5% of the aneuploid or mixed aneuploid/diploid tumors, but only in 8.5% of the diploid tumors. Patients with aneuploid or mixed aneuploid/diploid tumors had significantly greater local-regional failures than patients with diploid tumors (p = .0180). Those with p105 LI-C below the median or p105 AD above the median also had significantly greater local-regional failures (p = .0500 and p = .0167, respectively). Patients with p105 AD below the median had significantly better survival than those above the median (p = .0444), although there was no significant difference in survival with respect to DNA ploidy or p105 LI-C. Multivariate analyses showed that T-stage (p = .0001) and p105 AD (p = .0044) were significant prognostic factors for local-regional control, and T-stage (p = .0080), N-stage (p = .0021), primary site (p = .0110), and p105 AD (p = .0326) were significant prognostic factors for survival.

CONCLUSION

These results suggest that flow cytometric quantitation of the proliferation-associated nuclear antigen p105 and DNA content of pretreatment tumor biopsies may be a potentially useful predictive assay in patients irradiated for advanced squamous cell carcinomas of the head and neck.

Lack of effect of supplemental dietary selenium on time to development of radiation-induced cutaneous tumors in rats

Sprague-Dawley 8-week-old male rats received a single dose of 1425 cGy to the skin of the back using a 6 meV electron beam. Three days later they were randomized into three groups receiving supplemental dietary selenium as sodium selenite at levels of 0 ppm, 1 ppm, and 2 ppm selenium. Cutaneous tumors first appeared 33 weeks after irradiation and the experiment was terminated at 63 weeks. A wide variety of epithelial and connective tissue tumors developed. There was no significant difference in the time to development of epithelial or connective tissue tumors between the three groups. Thus, under the conditions of this experiment an inhibitory effect of dietary selenium on radiation-induced skin tumors was not evident.

Correlations between in vivo 31P MRS measurements, tumor size, cell survival, and hypoxic fraction in the murine EMT6 tumor

Phosphorus metabolite ratios were measured using 31P magnetic resonance spectroscopy shortly before measurement of cell survival and radiobiologic hypoxic fraction (HF) in EMT6/SF tumors, transplanted into a hindlimb of Balb/c mice. A total of 58 tumors with a volume range of 180 to 1250 mm3 were examined in experiments entailing no anesthesia. Postirradiation tumor cell viability was measured using an in vitro clonogenic assay. Correlations between tumor volume, surviving fraction (SF), HF, phosphorus metabolite ratios, and intracellular pH were computed. Both SF and HF increased significantly with tumor volume as did the metabolite ratios of inorganic phosphorus and phosphomonoesters to nucleoside triphosphates (Pi/NTP and PME/NTP, respectively), as well as Pi to phosphocreatine (Pi/PCr). In comparison to HF, the ratios of Pi/NTP, Pi/PCr, and PME/NTP each yielded significant positive correlations (Kendall correlation coefficients(tau) = 0.25 to 0.33). However, these were not significantly stronger than the correlation between HF and volume (tau = 0.21). Apparent values of tumor pH did not correlate with any other measured parameter. While these results indicate a statistical relationship between HF and the measured metabolite ratios, the widely scattered data, as reflected by magnitude of tau less than 0.35, made metabolite ratios poor predictors of HF in individual tumors.

Interruptions adversely affect local control and survival with hyperfractionated radiation therapy of carcinomas of the upper respiratory and digestive tracts. New evidence for accelerated proliferation from Radiation Therapy Oncology Group Protocol 8313

Hyperfractionated radiation therapy (HFX) attempts to overcome tumor proliferation during treatment by permitting higher total doses in the same overall time as standard fractionation. Whereas interruptions, including splits, reduce local control with standard fractionation in carcinoma of the upper respiratory and digestive tracts, HFX might compensate for interruptions. Patients were randomized to receive total doses of 6720, 7200, 7680, and 8160 cGy, using 120 cGy twice daily, 5 days per week. Those analyzed received +/- 4% of assigned total dose and lived 90 days or more. Treatment was completed within 5 days of the time specified for each treatment arm in 233 patients; 48, 80, and 131 patients had delays 14, 10, and 5 days or more, respectively. Locoregional control and survival were significantly (P less than or equal to 0.03) reduced with delays of 5 days or more when corrected for prognostic factors. Late effects of radiation therapy were not affected by interruptions. These data support the hypothesis that proliferation (possibly accelerated) of tumor clonogens during treatment influences the outcome.

Early and late effects of mitomycin C and continuous low-dose-rate irradiation on the mouse skin and soft tissues of the leg

The early and late effects of combined mitomycin C and continuous low-dose-rate irradiation (CLDRI) on the skin and soft tissues were studied in the C3Hf/SED mice. Localized CLDRI of the hind leg at 0.028 Gy/min with and without mitomycin C was delivered using a 137Cs laboratory irradiator. Mitomycin C at 6 mg/kg was given by continuous infusion through intraperitoneally implanted osmotic mini-pumps during CLDRI. Acute skin reaction was scored from days 13 to 30 and late skin contraction and leg contracture were measured at days 90, 180, 270, and 360 after treatment. Mitomycin C increased the early skin reaction following CLDRI; at a dose of 60 Gy, the dose effect factor was approximately 1.1. However, there was no significant enhancement of late skin contraction or leg contracture by mitomycin C. Our results suggest that mitomycin C can be combined with low-dose-rate brachytherapy without a significant increase in early or late damage to the skin and soft tissues.

Biologic rationale of combined radiotherapy and chemotherapy

This article presents a brief review of the mechanisms by which chemotherapy can be combined with radiotherapy to improve the therapeutic ratio, the possible mechanisms of interaction between chemotherapy and radiotherapy, the various factors that may influence their combined effects, and future perspectives in this area of clinical and laboratory research.

ASTRO plenary: interfraction interval is a major determinant of late effects, with hyperfractionated radiation therapy of carcinomas of upper respiratory and digestive tracts: results from Radiation Therapy Oncology Group protocol 8313

A prospective, randomized, multi-institutional, Phase I(LE)/II trial of HFX was conducted by the RTOG between 1983 and 1987. Patients with histologically proven, inoperable squamous cell carcinoma of the upper respiratory and digestive tracts stratified by site, nodal status, and performance status, were assigned to one of three arms, were assigned to one of three arms, 67.2 Gy, 72.0 Gy, or 76.8 Gy. Fractions of 1.2 Gy were given twice daily, 5 days per week: intervals of 4 to 8 hours were permitted between fractions. After acceptable rates of acute normal tissue effects were found, the randomization was changed to evaluate a new higher total dose, 81.6 Gy. Of 479 patients entered, 447 were analyzed, 63 on 67.2 Gy, 129 on 72.0 Gy, 117 on 76.8 Gy, and 138 on 81.6 Gy. The treatment arms were well balanced with respect to pretreatment characteristics. Acute reactions consisted almost entirely of pseudomembranous inflammation. "Severe" (Grade 3) acute reactions were reported in 33% to 41% and grade 4 reactions were found in 0 to 3% of patients, with no differences in frequencies among the four arms. Toxicities that developed or persisted beyond 90 days after the first treatment (408 patients evaluable greater than 90 days) did not differ among arms: grade 3+ reactions occurred in 10% to 14%, and grade 4+ effects (necroses) were reported in 5% at 67.2 Gy, 3% at 72.0 Gy, 7% at 76.8 Gy, and 2% at 81.6 Gy. Grade 3+ acute reactions occurred in 40% of patients when the interfraction interval was less than or equal to 4.5 hours versus 31% with greater than 4.5 hours (p = .03). Interfraction intervals less than or equal to 4.5 hours were associated with higher frequencies of grade 4+ late effects in all four arms, 8% of 197 patients with less than or equal to 4.5 hours versus 1% of 211 patients with greater than 4.5 hours. Estimates of late toxicity at 1, 2, and 3 years were 5.5%, 9.8%, and 15.4% with intervals less than or equal to 4.5 hours, versus 1.7% at all three periods for greater than 4.5 hours (p = .006). Local-regional control at 2 years was 25% for the assigned dose of 67.2 Gy compared to 43% to 45% for the three higher doses (p = .01), but a similar comparison for survival showed no significant difference (p = .35). There was no evidence for an effect of interfraction interval on either local-regional control (p = .38) or survival (p = .28).(ABSTRACT TRUNCATED AT 400 WORDS)

5-year results of cisplatin and fluorouracil infusion in head and neck cancer

As part of the developmental process for the Head and Neck Intergroup trial of adjuvant chemotherapy for advanced resectable head and neck carcinoma, in 1981 the Radiation Therapy Oncology Group, Philadelphia, Pa, conducted two nonrandomized pilot studies using chemotherapy consisting of three courses of cisplatin and fluorouracil infusion. Chemotherapy was administered prior to surgery in 42 patients (induction) and after surgery in an additional 29 patients (sequential). The populations were roughly comparable with respect to tumor site and stage. Twelve of the 42 patients in the induction group and seven of the 29 in the sequential group are alive and with no evidence of disease at the last reported follow-up. The median survival was 31 months in the sequential group vs 20 months in the induction group. Only two of the 26 patients with less than a complete clinical response following induction chemotherapy are still alive. Twenty-seven of the 42 patients who received induction chemotherapy did not undergo surgery as initially planned. Despite the lack of surgery, at 5 years the survival between the two groups was not significantly different (27% for the induction group vs 23% for the sequential group).

Early and late effects of cisplatin and radiation at acute and low dose rates on the mouse skin and soft tissues of the leg

The influence of radiation dose rate and drug dose on the combined effects of cisplatin (Cis-diamminedichloroplatinum (II] and radiation on the skin and soft tissues was studied in the C3Hf/SED mice. Localized acute-dose-rate irradiation (ADRI) at 3.345 Gy/min and continuous low-dose-rate irradiation (CLDRI) of the hind leg at 0.028 Gy/min with and without the drug was delivered using a 137Cs laboratory irradiator. Cisplatin at 6 or 11 mg/kg was given by intraperitoneal bolus injection 1 hour before ADRI or by continuous infusion during CLDRI. Acute skin reaction was scored from days 13 to 30 and late skin contraction and leg contracture were measured at days 90, 180, 270, and 360 after treatment. A marked dose-rate effect was observed for these early and late normal tissue endpoints. At a dose of 60 Gy of CLDRI, the dose rate factor (DRF = isoeffect dose at CLDRI/isoeffect dose at ADRI) was 1.82 for acute skin reaction and 1.76 for late skin contraction or leg contracture at day 270. However, there was no significant enhancement of these early and late normal tissue effects by cisplatin at 6 or 11 mg/kg at either acute or low dose rates. Thus neither drug dose nor radiation dose rate had a significant impact on the combined effects of cisplatin and radiation on the mouse skin and soft tissues of the leg.

High-dose-rate versus low-dose-rate intracavitary brachytherapy for carcinoma of the cervix

High-dose-rate (HDR) remote afterloading intracavitary brachytherapy has been widely used in the treatment of carcinoma of the cervix in Europe and Asia since the 1960's. Recently, there has been an increase of interest in the use of this technique in North America. Most of the non-randomized studies suggest similar survival, local control, and complication rates using fractionated high-dose-rate remote afterloading intracavitary brachytherapy combined with external beam irradiation compared to historical or concurrent low-dose-rate (LDR) controls. However, the techniques as well as the dose fractionation schedules used in different institutions are variable. The optimal technique and dose fractionation scheme has yet to be established through systematic clinical trials.

Correlations between in vivo 31P NMR spectroscopy measurements, tumor size, hypoxic fraction and cell survival after radiotherapy

Phosphorus metabolite levels were measured non-invasively using 31P magnetic resonance spectroscopy (MRS) in SCCVII/SF tumors, subcutaneously transplanted into the legs of unanesthetized C3Hf/Sed mice. Shortly after MRS measurements, tumors were irradiated with a single dose of 20 Gy, and cell survival and radiobiologic hypoxic fraction were determined with an in vitro cloning assay. Significant correlations were found between tumor size and surviving fraction, hypoxic fraction, pH, and phosphorus metabolite ratios. With increase of tumor size, surviving fraction and hypoxic fraction both increased, the ratios of inorganic phosphate and phosphomonoesters to nucleoside triphosphates (Pi/NTP and PME/NTP, respectively) and inorganic phosphate to phosphocreatine (Pi/PCr) increased and pH decreased. However, considerable heterogeneity of MRS spectral parameters, even in tumors of similar size, precluded accurate prediction of hypoxic fraction and cell survival after radiotherapy.

Dose-response for local control with hyperfractionated radiation therapy in advanced carcinomas of the upper aerodigestive tracts: preliminary report of radiation therapy oncology group protocol 83-13

A prospective, randomized Phase Ilate/II trial of hyperfractionated radiation therapy was conducted: 1.2 Gy minimum tumor dose was administered twice daily with a minimum interval of 4 hr, 5 days per week. Patients with Stage III and IV carcinomas of the oral cavity, oropharynx, nasopharynx, hypopharynx, and supraglottic larynx were stratified by site, presence or absence of nodal metastases, and performance status. They were assigned to four total doses between 67.2 Gy and 81.6 Gy to all known tumors. The highest dose arm was opened after preliminary assessment indicated acceptable late morbidity rates with the three lower doses. Of 479 patients entered, 260 patients were randomized to the three lower total doses and 237 were analyzed for this preliminary report: 63 were assigned to receive 67.2 Gy, 58 to 72.0 Gy, and 116 to 76.8 Gy. Estimates of grade 4 necrosis at 2 years were 10.0%, 5.1%, and 13.9%, respectively, for patients who received total doses of 67.2 Gy, 72.0 Gy, and 76.8 Gy. There was a suggestion of a trend toward increased local control at 24 months (Kaplan-Meier estimates of 25% for 67.2 Gy, 37% for 72.0 Gy, and 42% for 76.8 Gy) (p = .08). No difference was observed in survival. Assessment of the results using Cox regression models to correct for slight inequalities of pretreatment prognostic variables supported a total dose-tumor control relationship (p = .054). Results for the lowest dose arm were comparable to previous RTOG studies of common fractionation with similar total doses. The higher local control rates with 72.0 and 76.8 Gy using hyperfractionated radiation therapy suggest an improvement in outcome with radiation therapy for advanced carcinomas of the upper aerodigestive tracts. These preliminary findings have led to a Phase III comparison of hyperfractionated radiation therapy with 1.2 Gy b.i.d. with standard fractionation.

Combined total body X-ray irradiation and total skin electron beam radiotherapy with an improved technique for mycosis fungoides

Twelve consecutive patients with advanced stage mycosis fungoides (MF) were treated with combined total body X ray irradiation (TBI) and total skin electron beam radiotherapy (EBRT). Six had generalized plaque disease and dermatopathic nodes, three had tumor stage disease and node biopsy positive for mycosis fungoides, and three had erythroderma/Sezary syndrome. The treatment regimen consisted of split course total body X ray irradiation, given in twice weekly 15 cGy fractions to 75 cGy, then total skin electron beam radiation therapy given in once weekly 400 cGy fractions to a total dose of 2400 cGy. Underdosed areas and areas of greatest initial involvement were boosted 400 cGy twice weekly for an additional 1200 cGy. This was followed by a second course of total body X ray irradiation, to a total dose of 150 cGy. The total skin electron beam radiotherapy technique is a modification of an established six position EBRT technique for mycosis fungoides. Measurements to characterize the beam with and without a lexan scattering plate, demonstrated that the combination of no-plate beams produced better dose uniformity with a much higher dose rate. This improved technique is particularly advantageous for elderly and/or frail patients. Nine (75%) of the 12 patients achieved complete response (CR). The other three had significant improvement with greater than 80% clearing of their disease and resolution of symptoms. All six patients with generalized plaque disease achieved complete response and remained free of disease from 2 to 16 months. Two of three node positive patients also achieved complete response; one, with massive biopsy-documented mycosis fungoides nodal disease and deep open tumors, remained relapse-free over 2 years. Only one of the three patients with erythroderma/Sezary syndrome achieved a complete response, which was short lived. Therapy was well tolerated. No significant hematological toxicity occurred. Although total body X ray irradiation and total skin electron beam radiotherapy produced excellent palliation of patients with advanced stage mycosis fungoides, new strategies to provide more effective systemic treatment are needed.

Improved dose distribution with customized I-125 source loading in temporary interstitial implants

I-125 sources are being used in temporary interstitial implants of various sites. Radiation safety considerations favor its use over other available radioisotopes. Cost containment is achieved by using the same sources for a number of patients. Loading I-125 seeds into implant catheters at our institutions permit customized source arrangement to optimize the implant dose patterns. Clinical examples are given for which the dose distributions achieved with customized source loading are superior to those achievable with standard Ir-192 ribbons.

Combined radiotherapy and chemotherapy with bleomycin and methotrexate for advanced inoperable head and neck cancer: update of a Northern California Oncology Group randomized trial

Between 1978 and 1984, the Northern California Oncology Group (NCOG) conducted a randomized trial to study the efficacy of combined radiotherapy (RT) and chemotherapy (CT) for stage III or IV inoperable head and neck cancer. One hundred four patients were randomized to receive: (1) RT alone, or (2) RT plus CT. RT consisted of 7,000 cGy to the involved areas and 5,000 cGy to uninvolved neck at 180 cGy/fraction, five fractions/wk. CT consisted of bleomycin, 5 U intravenously (IV), twice weekly during RT, followed by bleomycin, 15 U IV, and methotrexate, 25 mg/m2 IV weekly for 16 weeks after completion of RT. Fifty-one patients in the RT alone group and 45 in the combined treatment group were evaluable. The local-regional complete response (CR) rate was 45% v 67% (P = .056); the 2-year local-regional control rate, including salvage surgery, was 26% v 64% (P = .001); and the incidence of distant metastasis was 24% v 38% (P greater than .25), for the RT alone and RT plus CT groups, respectively. The relapse-free survival curves were significantly different (P = .041), favoring the combined treatment. However, the survival curves were not significantly different (P = .16). Patient compliance to maintenance CT was poor. Bleomycin significantly increased the acute radiation mucositis, although the difference in late normal tissue toxicity was not statistically significant. Thus, bleomycin and concurrent RT produced a more favorable CR rate, local-regional control rate, and relapse-free survival, but the difference in survival was not statistically significant.

Cisplatin, doxorubicin, and 5-fluorouracil chemotherapy for salivary gland malignancies: a pilot study of the Northern California Oncology Group

Seventeen patients with advanced or recurrent salivary gland cancer were treated with cisplatin, doxorubicin, and 5-fluorouracil combination chemotherapy (PAF). Two patients achieved a complete response and four patients achieved a partial response, for an overall response rate of 35%. Six of the nine patients who received PAF in the neoadjuvant setting did not respond and proceeded to surgery and/or radiation therapy. No difference in response rate was found between those patients treated for recurrent disease v those treated with neoadjuvant chemotherapy. All three patients with adenocarcinoma responded. The response duration in patients with metastatic or recurrent disease ranged from 6 to 15 months. The PAF regimen was delivered primarily in the outpatient setting and was associated with acceptable toxicity. PAF demonstrates activity in salivary gland malignancies, and further evaluation of this combination seems warranted.

Carcinoma of the tonsillar region

A retrospective analysis of 171 patients with carcinoma of the tonsillar region is presented. The majority of patients (79%) presented with stage III and IV disease. Three year determinate survival was 81% - T1, 74% - T2, 59% - T3, and 20% - T4. The presence of nodal disease decreased survival by one half. Radiotherapy alone was highly successful in controlling early T1 and T2 lesions of the tonsillar fossa. Surgery alone or combined radiotherapy and surgery was more successful than radiotherapy in controlling early T1 and T2 lesions of the tonsillar pillar. More advanced T3 and T4 lesions also did poorly with radiotherapy alone. An analysis of these results and a review of the literature is presented.

The influence of time sequence of cisplatin administration and continuous low dose rate irradiation (CLDRI) on their combined effects on a murine squamous cell carcinoma

The influence of time sequence of cis-dichlorodiammine platinum (cisplatin) administration and continuous low dose rate irradiation (CLDRI) on their combined effects was studied in the SCC VII/SF tumor, a murine squamous cell carcinoma. Concurrent cisplatin i.p. infusion at 0.22 mg/kg/hr and CLDRI at 0.6 Gy/hr had a supraadditive effect on the survival of the SCC VII/SF tumor cells. Cisplatin by itself was more effective against the SCC VII/SF tumor when given by bolus injection than by continuous infusion i.p. However, when cisplatin at a dose of 6 mg/kg was given by bolus i.p. injection either immediately before or after CLDRI, the combined effects on the SCC VII/SF tumor cell survival were no more than additive. Exposure to CLDRI at 0.6 Gy/hr for 24 hours did not sensitize the SCC VII/SF tumor to subsequent treatment with cisplatin. These results suggest that when cisplatin is combined with CLDRI, for the optimal anti-tumor effect, it is best to infuse the cisplatin continuously during the course of CLDRI.

Biological basis for the interaction of chemotherapeutic agents and radiation therapy

The ultimate goal of combining chemotherapy and radiotherapy is to improve the therapeutic ratio. When chemotherapy is combined with radiotherapy, improved therapeutic effects may occur as a result of the following: (1) spatial cooperation; (2) enhancement of tumor response with less or no enhancement of normal tissue injury, and (3) diminution of normal tissue injury with less or no diminution of tumor response. Possible mechanisms of interaction between chemotherapeutic agents and radiation that result in an enhanced effect include (1) changes in the slope of the dose response curve, (2) decreased accumulation or inhibition of repair of sublethal damage, (3) decreased recovery from potentially lethal damage, (4) perturbation in cell kinetics with an increase of proportion of cells in the sensitive cell cycle phase and proliferative state, (5) decreased tumor bulk and improved blood supply leading to reoxygenation and recruitment and increased radiosensitivity and chemosensitivity, and (6) increased drug delivery and uptake. The combined effects may be influenced by (1) tumor and normal tissue type, (2) drug type, (3) drug dose and schedule, (4) time sequence between drug and radiation administration, (5) radiation dose and fractionation schedule, and (6) radiation dose rate. Most experimental and clinical data suggest that enhanced tumor effects most often result from simple additivity and therefore do not require direct interaction between drug and radiation, whereas enhanced normal tissue effects are observed most often when drugs are administered in close temporal proximity to radiation. Thus, for the optimal therapeutic effect, it would seem more advantageous to administer chemotherapeutic drugs and radiation in a sequential or alternating manner rather than simultaneously.

Modification of the effects of continuous low dose rate irradiation by concurrent chemotherapy infusion

The combined effects of continuous low dose rate irradiation (CLDRI) and concurrent infusion of bleomycin, cyclophosphamide, cis-platinum, 5-fluorouracil, actinomycin D, and mitomycin C were studied in the SCC VII/SF tumor, a squamous cell carcinoma and the jejunal crypt cells in the mouse. For the SCC VII/SF tumor, enhanced cell killing was seen with each of the six drugs when infused concurrently with CLDRI; the greatest enhancement was seen with mitomycin C and cis-platinum. For the jejunal crypt cells, enhanced cell killing was seen primarily with bleomycin. At a dose of 20 Gy, the dose effect factor (DEF) ranged from 1.13-1.64 for the SCC VII/SF tumor and 0.92-1.19 for the jejunal crypt cells. Our results suggest a therapeutic gain with concurrent CLDRI and chemotherapy infusion for five of the six chemotherapeutic drugs studied with the exception of bleomycin.

Delivery of therapeutic doses of doxorubicin to the mouse lung using lung-accumulating liposomes proves unsuccessful

Addition of solid doxorubicin or solutions to pre-formed liposomes proved to be the optimal method for incorporating the drug into liposomes whilst maintaining their size distribution and hence ability to accumulate in the lung. Liposomes prepared in this way lost doxorubicin only slowly on dialysis but dilution with an equal volume of saline at 37 degrees C resulted in the loss of 80% of the incorporated doxorubicin within 30 min. These liposomes were thus ineffective in altering doxorubicin disposition in vivo and produced no enhanced activity compared with free drug and a non-lung-accumulating carrier liposome in the EMT6 cell-Balb/c mouse model lung tumour.