Topoisomerase I Inhibitors in the Combined Modality Therapy of Lung Cancer

Locally advanced non small-cell lung cancer (NSCLC) represents 30%-40% of all pulmonary malignancies. Despite the fact that the disease is confined to the chest, most patients will eventually succumb to their dis-ease. Therefore, the management of NSCLC is undergoing rapid evolution with hope of improving overall survival. The arrival of a new generation of chemotherapeutic agents, including the taxanes, gemcitabine, and topoisomerase inhibitors such as irinotecan and topotecan, offers the hope of real advances against this malignancy. Irinotecan and topotecan are camptothecin derivatives that are felt to exert their cytotoxic effects by targeting topoisomerase I. It is believed that topoisomerase I inhibitors stabilize a DNA-topoisomerase I cleavable complex, and interactions between this complex and the replication machinery may lead to cell death. There is a significant volume of in vitro and in vivo data demonstrating that these topoisomerase I inhibitors also act as radiosensitizers. Early clinical data with topotecan suggests that it is a more active agent in small-cell lung cancer than it is in NSCLC despite a common mechanism of action with irinotecan. With the increasing data that exist on the improved outcome with concurrent chemoradiation treatment for malignancies including lung cancer and head and neck cancers, there is an impetus to pursue the addition of other drugs that can radiosensitize tumors and further improve local control. Irinotecan is undergoing early clinical trials in the combined modality setting in several different disease sites. This paper will review the in vitro and in vivo data on the ability of irinotecan and topotecan to render tumors more susceptible to ionizing radiation. It will then focus on the experience with both drugs and thoracic radiation in the treatment of NSCLC, in which irinotecan has yielded acceptable toxicity results and response rates in excess of 60% in early trials. It is hoped that newer treatment strategies, such as the combination of radiation and topoisomerase I inhibitors in lung cancer, will have a significant impact on cure rates in the future.

Optimizing chemoradiation in locally advanced non-small-cell lung cancer

Gemcitabine (Gemzar) has demonstrated activity in a broad range of solid tumors with good tolerance. In combined-modality therapy, gemcitabine has achieved response rates ranging between 30% and 60% in patients with non-small-cell lung cancer. Initial trials of gemcitabine and radiation showed that the fields and volume of radiation as well as the dose of gemcitabine should be managed carefully so as to optimize the radiosensitizing properties of this agent. The Cancer and Leukemia Group B conducted a phase III trial in patients with unresectable stage III non-small-cell lung cancer. A total of 187 patients were randomized to one of three cisplatin (Platinol)-based combinations (with gemcitabine, paclitaxel [Taxol], or vinorelbine [Navelbine]) as induction therapy followed by concomitant chemoradiation. At a median follow-up of 9 months, the median survival for all patients was 18 months and the median progression-free survival was 10 months. The trial demonstrated that the combination of gemcitabine and cisplatin could be administered successfully as induction therapy without affecting concurrent administration of gemcitabine/cisplatin with radiation.

Taxanes in combined modality therapy for solid tumors

The taxanes, paclitaxel and docetaxel, are novel antimitotic agents that are under extensive investigation in clinical trials. Both taxanes have demonstrated significant activity against many solid tumors as single agents and in combination with other chemotherapeutic agents. In addition, taxanes arrest cells at the G2/M phase of the cell cycle, which is the most radiosensitive phase. These properties are exploited in clinical trials combining this taxane with radiation therapy. Most studies included patients with non-small cell lung cancer (NSCLC) and cancers of the head and neck and there are a few studies with concurrent taxane/RT in esophageal, gastric, pancreatic, brain and breast cancer. Information concerning the tolerability and possible utility of docetaxel is also becoming available. This manuscript will review some of the more prominent trials of the taxanes in combination with radiation therapy for solid tumors.

Combined effects of the orally active cisplatin analog, JM216, and radiation in antitumor therapy

PURPOSE

We evaluated the orally administered platinum agent, JM216, in combination with ionizing radiation both in vivo and in vitro against human tumor cells.

METHODS

H460 human lung carcinoma cells were used as a subcutaneous xenograft in nude mice. JM216 (30 mg/kg) was administered orally, and radiation treatments (2 Gy) were given 1 h after JM216 delivery for five consecutive days. For in vitro analysis, attached H460 cells were treated with JM216 (15 microM) for 1 h and then irradiated. Cells were rinsed 20 min later, and survival was determined by clonogenic assay.

RESULTS

Tumor growth delay measurements showed that the combination of JM216 and radiation was additive in vivo, with an enhancement ratio of 1.24. In vitro clonogenic survival experiments demonstrated a dose enhancement ratio of 1.23. Isobologram analysis showed that this interaction was also additive.

CONCLUSIONS

These data demonstrate that the combination of JM216 and fractionated radiotherapy is more effective against human lung cancer xenografts than either agent alone, and the in vivo results were supported by those observed using an in vitro system with the same tumor cell line.

Irinotecan in combined-modality therapy for locally advanced non-small-cell lung cancer

The management of non-small-cell lung cancer is undergoing rapid evolution. Although the advent of combined-modality therapy has led to improved survival, most patients eventually succumb to the disease. The arrival of a new generation of chemotherapeutic agents--including the taxanes, gemcitabine (Gemzar), and topoisomerase inhibitors such as irinotecan (Camptosar, CPT-11)--offers the hope of advances against this malignancy. Irinotecan, a camptothecin derivative, has shown impressive activity in a variety of solid tumors, including non-small-cell lung cancer. It is believed to act by stabilizing the topoisomerase-DNA complex formed during diverse cellular processes, including replication and transcription. A considerable body of evidence also demonstrates that camptothecin and its derivatives possess substantial radiosensitization properties. This article will review the in vitro and in vivo data on irinotecan's ability to render tumors more susceptible to ionizing radiation. It will then focus on experience with irinotecan and thoracic radiation in the treatment of non-small-cell lung cancer, which has yielded acceptable toxicity results and response rates in excess of 60% in early trials. It is hoped that newer treatment strategies--such as the combination of radiation and irinotecan in lung cancer--will significantly impact cure rates in the future.

A phase II study of paclitaxel, carboplatin, and hyperfractionated radiation therapy for locally advanced inoperable non-small-cell lung cancer (a Vanderbilt Cancer Center Affiliate Network Study)

PURPOSE

We conducted a prospective phase II study to determine the response rate, toxicity, and survival rate of concurrent weekly paclitaxel, carboplatin, and hyperfractionated radiation therapy (paclitaxel/carboplatin/HFX RT) followed by 2 cycles of paclitaxel and carboplatin for locally advanced unresectable non-small cell lung cancer (NSCLC). The weekly paclitaxel and carboplatin regimen was designed to optimize the radiosensitizing properties of paclitaxel during the concurrent phase of treatment.

METHODS AND MATERIALS

Forty-three patients with unresectable stage IIIA and IIIB NSCLC from the Vanderbilt Cancer Center and Affiliate Network (VCCAN) institutions were entered onto the study from June 1996 until May 1997. Weekly intravenous (IV) paclitaxel (50 mg/m(2)/l-hour) and weekly carboplatin (AUC 2) plus concurrent hyperfractionated chest RT (1.2 Gy/BID/69.6 Gy) were delivered for 6 weeks followed by 2 cycles of paclitaxel (200 mg/m(2)) and carboplatin (AUC 6).

RESULTS

Forty-two patients were evaluable for response and toxicities. Three patients achieved a complete response (7.2%) and 30 patients achieved a partial response (71.4%), for an overall response rate of 78.6% [95% C.I. (66.2%-91.0%)]. The 1- and 2-year overall and progression-free survival rates of all 43 patients were 61.6% and 35% respectively, with a median survival time of 14.3 months. The median follow-up time was 14 months. Esophagitis was the principal toxicity. Grade 3 or 4 esophagitis occurred in 11 patients (26%). There was an incidence of 7% grade 3 and 9.5% grade 4 pulmonary toxicities.

CONCLUSIONS

Weekly paclitaxel, carboplatin, plus concurrent hyperfractionated RT is a well-tolerated outpatient regimen. The response rate from this regimen is encouraging and appears to be at least equivalent to the more toxic chemoradiation trials. These findings warrant further clinical evaluation of weekly paclitaxel/carboplatin/HFX RT in a phase III study.

Combination chemoradiotherapy with gemcitabine: potential applications

Gemcitabine (Gemzar) is a novel deoxycitidine drug that has demonstrated promising single-agent activity in non-small-cell lung cancer and has been proven to be a potent radiosensitizer. Although the exact mechanism of the radiosensitizing effect is unknown, several studies have focused on the drug's effect on deoxyadenosine triphosphate (dATP) pool depletion or cell-cycle manipulation. A number of trials have evaluated this feature of gemcitabine by combining chemotherapy and radiation in various doses and schedules, and those studies are described in this article. Gemcitabine appears to be a promising agent to be combined with radiation therapy. However, further clinical trials are needed to define optimal doses, toxicity, and efficacy.

Weekly irinotecan and concurrent radiation therapy for stage III unresectable NSCLC

In preclinical studies, the topoisomerase I inhibitor irinotecan (Camptosar, CPT-11) has demonstrated activity as a radiosensitizer, probably due to its ability to inhibit potentially lethal radiation damage repair. We conducted a phase I trial to determine the maximum-tolerated dose (MTD) and dose-limiting toxicities (DLT) of weekly irinotecan with concurrent thoracic radiation therapy for patients with unresectable stage III non-small-cell lung cancer. For this study, 13 patients received three dose escalations (from 30 to 40 to 50 mg/m2/wk). At the first dose level, one patient developed grade 5 esophagitis. Accrual was expanded to seven patients. None of the remaining six patients developed esophagitis. At the second dose level (40 mg/m2/wk), the worst toxicity, which developed in one patient, was grade 2 esophagitis. At the third dose level (50 mg/m2/wk), two of three patients developed grade 4 nausea and vomiting; grade 3 or 4 esophagitis also occurred in two patients. Of the 12 evaluable patients, seven achieved a partial response, for an overall response rate of 58%. In conclusion, nausea, vomiting, and esophagitis appear to be the principal DLTs of concurrent weekly irinotecan and thoracic radiation in the outpatient setting. The MTD of concurrent weekly irinotecan with thoracic radiation therapy appears to be 40 mg/m2 weekly for 6 weeks. To confirm the MTD of this combination, this study is still open to accrual at the second dose level (40 mg/m2) in combination with carboplatin.

Preclinical evaluation of the orally active camptothecin analog, RFS-2000 (9-nitro-20(S)-camptothecin) as a radiation enhancer

PURPOSE

To test for enhancement of radiation effects in vitro and in vivo by the orally administered camptothecin derivative, 9-nitrocamptothecin (RFS-2000); to study whether the mechanism of this enhancement involves inhibition of sublethal damage recovery.

METHODS AND MATERIALS

In vitro: H460 human lung carcinoma cells were incubated with RFS-2000 for various times at 37 degrees C, irradiated, immediately rinsed, and assessed for colony-forming ability. Sublethal damage recovery (SLDR) was also assessed using two split doses of radiation. In vivo: H460 cell xenografts were used in nude mice. Tumors were grown subcutaneously on the flank, then treated with RFS-2000 (1 mg/kg) and/or radiation (2 Gy) for 5 consecutive days. Tumor growth delay was then measured for each treatment group.

RESULTS

Radiation enhancement was observed in vitro for incubation times between 4 and 24 hr with 10 nM RFS-2000. Using a 24-hr treatment, the radiation dose enhancement ratio values (DER) for 5, 10, and 15 nM were 1.22, 1.54, and 2.0, respectively. Incubation with 10 nM RFS-2000 inhibited SLDR by a factor of 2. The results of three independent in vivo experiments showed that RFS-2000 can enhance the effects of fractionated radiotherapy, with an enhancement factor (EF) of 1.64.

CONCLUSION

Our results show that RFS-2000 can enhance the effects of radiation in human lung cancer cells both in vitro and in vivo, and that the mechanism of this effect may involve the inhibition of SLDR.

A Phase I Trial of Outpatient Weekly Irinotecan/Carboplatin and Concurrent Radiation for Stage III Unresectable Non–Small-Cell Lung Cancer: A Vanderbilt-Ingram Cancer Center Affiliate Network Trial

Irinotecan (CPT-11), a topoisomerase I inhibitor, has been shown in preclinical studies to be a potent radiosensitizer. Carboplatin, a known radiosensitizer with single-agent activity in non small-cell lung cancer (NSCLC), is felt to be a rational choice in combination with irinotecan. We have completed the initial portion of a phase I study, in patients with locally unresectable lung cancer, combining irinotecan with thoracic radiation. Thirteen patients have been entered onto this study through three dose levels (30 to 50 mg/m2/week) of irinotecan. There were seven partial responses in 12 evaluable patients, for an over-all response rate of 58%. Nausea, vomiting, and esophagitis were the principal toxicities of weekly irinotecan and concurrent thoracic radiation. As the maximum tolerated dose (MTD) of irinotecan with radiation has been established at 40 mg/m2/week, we are currently accruing patients to the second phase of this study with the addition of carboplatin (AUC = 2). Thus far toxicity has primarily been esophagitis.

A Phase I Trial of Outpatient Weekly Docetaxel and Concurrent Radiation Therapy for Stage III Unresectable Non–Small-Cell Lung Cancer: A Vanderbuilt Cancer Center Affiliate Network (VCCAN) Trial

Docetaxel has demonstrated activity as a radiosensitizer in numerous preclinical studies, probably due to its role as a cell cycle synchronizer for the G2/M radiosensitive phase of the cell cycle. We conducted a phase I trial to determine the maximum-tolerated dose (MTD) and dose-limiting toxicities (DLT) of docetaxel with concurrent thoracic radiation therapy (TRT) to patients with unresectable stage III non small-cell lung cancer (NSCLC). Fifteen patients were entered into this study. Docetaxel was administered as a 1-hour intravenous (I.V.) infusion, repeated every week for 6 weeks with starting dose of 20 mg/m2. Doses were escalated in 10 mg/m2 increments in successive cohorts of three new patients, if tolerated. Unacceptable toxicity was defined as grade = 3 nonhematologic or hematologic toxicity according to Eastern Cooperative Oncology Group (ECOG) toxicity criteria. TRT was administered to the primary tumor and regional lymph nodes (40 Gy) followed by a boost to the tumor (20 Gy). At the first dose level (20 mg/m2/week), one patient developed grade 4 hyperglycemia and accrual was expanded to five patients. At the second level (30 mg/m2/week), two out of six patients developed grade 3 esophagitis. At the third level (40 mg/m2/week), two out of four patients developed grade 3 esophagitis and one patient developed grade 3 pulmonary toxicity. The weekly docetaxel MTD with concurrent radiation therapy (RT) was found to be 30 mg/m2. The DLT was esophagitis and pulmonary toxicity. Other toxicities encountered included skin reaction, nausea and vomiting, as well as diarrhea. Additionally, there were no treatment-related mortalities or late-occurring toxicities. Esophagitis was the principal DLT of concurrent weekly docetaxel and thoracic radiation in the outpatient setting. The MTD of concurrent weekly docetaxel with TRT is 30 mg/m2 weekly for 6 weeks. This study is still open to accrual with weekly docetaxel and TRT in locally advanced NSCLC patients.

Enhancement of radiation effects in vitro by the estrogen metabolite 2-methoxyestradiol

2-Methoxyestradiol. 2-Methoxyestradiol (2-ME) is an endogenous estradiol metabolite that disrupts microtubule function, suppresses murine tumors, and inhibits angiogenesis. Since some microtubule inhibitors have been shown to alter radiosensitivity, we have evaluated 2-ME as a radiation enhancer in vitro. H460 human lung cancer cells were plated, treated with 2-ME for 24 h, and irradiated; then colony-forming ability was assessed. The radiation dose enhancement ratios (DERs) using this protocol were 1.3, 1.8 and 2.1 for 1, 1.5 and 2 microM 2-ME, respectively. Using a single-cell plating protocol, the respective DERs were 1.2, 1.5 and 1.8. The parent compound of 2-ME, beta-estradiol, did not enhance radiation effects at equally cytotoxic doses. Isobologram analysis showed that 1 microM 2-ME was additive with radiation, but that 1.5 and 2 microM were synergistic. Cell cycle analysis showed a dose-dependent increase in the percentage of cells in the radiosensitive G(2)/M phase after a 24-h treatment with 2-ME; a threefold increase in the percentage of cells in G(2)/M phase was observed using 2 microM 2-ME. Treatment with 2 microM 2-ME almost completely inhibited repair of sublethal damage (SLD) as shown using split-dose recovery. Radiosensitive, repair-deficient murine SCID (severe combined immunodeficient) cells did not show enhancement of radiation effects with 2 microM 2-ME, but enhancement was observed in the wild-type parental cells (CB-17). SCID cells complemented with human DNA-dependent protein kinase restored radioenhancement by 2-ME. In addition, MCF-7 breast cancer cells were also radiosensitized by 2 microM 2-ME (DER = 2.1). These data suggest that 2-ME is a potential radiation sensitizer, in addition to its previously reported antitumor and antiangiogenic properties. We have verified the antiangiogenic activity of 2-ME in vitro using human endothelial cells. Based on these results, we hypothesize that the mechanism of radiation enhancement may involve redistribution of cells into G(2)/M phase by 2-ME, and that the resulting population of cells is repair-deficient and thus radiosensitive.

Enhancement of radiation effects by combined docetaxel and carboplatin treatment in vitro

This study was designed to evaluate the combination of docetaxel (Taxotere) and carboplatin for radiopotentiation in vitro. H460 human lung carcinoma cells were treated with docetaxel (or paclitaxel) for 1 h and rinsed. After 24 h, the cells were treated with carboplatin for 1 h, irradiated, and colony forming ability was assesed. Using various doses of docetaxel with 100 microM carboplatin, the dose enhancement ratio (D.E.R.) for drugs only was 1.26. When 25 nM docetaxel was used with various doses of radiation, the radiation D.E.R. was 1.41. With all three agents combined, and after normalization for combined drug effects, the radiation D.E.R. was 1.55. Similar values were obtained using paclitaxel with these agents. Significant redistribution of cells into the radiosensitive G2/M phase was observed using a dose of paclitaxel (750 nM), which also caused radiation enhancement. However, an equally cytotoxic dose of docetaxel (25 nM) did not result in any cell cycle redistribution; this phenomenon was only observed at higher doses. This study shows that the combination of docetaxel and carboplatin enhance the effects of radiation in vitro more effectively than either drug seperately. In addition, our data show that the mechanism of radiopotentiation by docetaxel probably does not involve a G2/M block in H460 cells.

Patterns of practice survey for nonsmall cell lung carcinoma in the U.S

BACKGROUND

Nonsmall cell lung carcinoma comprises approximately 75% of all lung carcinoma cases in the U.S. Newly evolving strategies have created considerable controversy regarding the optimal treatment for patients diagnosed with this disease.

METHODS

A 17-item survey was designed to collect demographic data and information regarding practice patterns for nonsmall cell lung carcinoma, including patient assessment, treatment approaches, and roles of chemotherapy and radiotherapy. Surveys were mailed in the summer of 1997 to approximately 9200 oncologists of all types throughout the U.S. Practice settings included private office, private hospital, academic, university-affiliated office, government, and Veterans Administration institutions.

RESULTS

Approximately 10% of the oncologists responded (n = 979), including 499 medical oncologists (51%), 464 radiation oncologists (47%), and 16 others (2%). For the adjuvant treatment of surgically resected N1-2 disease, combined modality treatment was preferred over radiation therapy alone by medical oncologists (48% vs. 16%; P<0.001) and radiation therapy alone was preferred over combined modality treatment by radiation oncologists (55% vs. 38%; P<0.001). The combination of paclitaxel and carboplatin was the preferred first-line regimen for all stages of nonsmall cell lung carcinoma by the majority of medical oncologists (55%), whereas the majority of radiation oncologists (58%) chose the combination of etoposide and platinum. With regard to the optimal combined modality approach, respondents were divided evenly between concurrent chemoradiotherapy (34%) and sequential chemoradiotherapy (31%). Overall, respondents reported basing treatment decisions largely on published literature (55%) compared with personal experience (19%), seminars and colleagues (16%), and clinical trial availability (10%) (P<0.001).

CONCLUSIONS

This survey confirms many differences in practice patterns among medical oncologists and radiation oncologists in the treatment of patients with nonsmall cell lung carcinoma and suggests the need for the multidisciplinary management of this entity. In addition, the current study demonstrates that reliance on the medical literature as a basis for treatment steadily declines the longer the physician has been in practice.

Taxanes in combined-modality therapy for solid tumors

The taxanes, paclitaxel and docetaxel, are novel antimitotic agents that are under extensive investigation in clinical trials in patients with various solid tumors. The taxanes have demonstrated significant activity against many solid tumors as single agents and in combination with other chemotherapeutic agents. In addition, paclitaxel and docetaxel arrest cells at the G2/M phase of the cell cycle, which is the most radiosensitive phase. Numerous clinical trials have assessed paclitaxel-based chemoradiation therapy in a variety of tumor types, including non-small-cell lung cancer, small-cell lung cancer, head and neck cancers, esophageal cancer, brain tumors, pancreatic and gastric tumors, and locally advanced breast cancer. Fewer clinical trials have assessed docetaxel plus radiation therapy in these tumor types. This review highlights recent clinical trials of the taxanes in combination with radiation therapy for solid tumors.

The role of UFT in combined-modality therapy

Fluorinated pyrimidines have long been used as radiosensitizers in combined-modality therapy for solid tumors. Nonetheless, the most commonly used drug, 5-fluorouracil (5-FU), is inconvenient to administer, particularly when given by continuous intravenous infusion. Continuous infusion 5-FU does offer a survival advantage over bolus in the treatment of large bowel tumors. This holds true regardless of whether radiation therapy is concomitantly given. UFT, a combination of uracil and tegafur (in a molar ratio of 4:1), is an attractive alternative. Trials to date suggest at least chemotherapeutic equivalence compared to 5-fluorouracil, and UFT is much simpler to administer. UFT is administered orally and can safely be combined with oral leucovorin. There is profound scientific rationale for using UFT with radiation therapy, and early trials in gastrointestinal malignancies demonstrate the safety and efficacy of the combination. Further studies will determine the optimal timing and uses for concomitant UFT and radiation therapy.

The role of radiation, with or without chemotherapy, in the management of NSCLC

Lung cancer is the leading cause of cancer death in the United States. Surgery is the treatment of choice for early stage patients. Despite radical surgery, patients with early stage lung cancer remain at risk for recurrence. The role of adjuvant therapy remains to be clearly defined. Locally advanced non-small-cell lung cancer is too extensive for surgical resection, yet does not show evidence of metastatic disease. Historically, these patients were treated with radiation alone. More recent studies have provided the rationale for combining radiation with chemotherapy for patients with good performance status who have locally advanced disease. For patients with marginally resectable tumors, treatment is often given preoperatively (neoadjuvant) as a means of shrinking the tumor to make it resectable. In patients with clearly unresectable disease, radiation with chemotherapy has been established as better than either modality alone. Palliative radiation alone can be used for patients who cannot tolerate this aggressive approach. The optimal sequencing, as well as the best chemotherapeutic agent to use, remains under investigation. Some of the newer agents showing promise in the treatment of non-small-cell lung cancer include paclitaxel (Taxol) and carboplatin (Paraplatin). Other agents that are currently under investigation include topotecan, gemcitabine, and vinorelbine (Navelbine).

Combined chemoradiation therapy for limited-stage small-cell lung cancer

After nearly 4 decades of use in treating small-cell lung cancer (SCLC), thoracic radiation has become integral to the management of limited-stage disease. Many prospective randomized trials have demonstrated that adding thoracic radiation therapy to chemotherapy improves locoregional control and survival at 3 and 5 years. This has resulted in a greater appreciation of the role of thoracic radiation in the treatment of SCLC. Currently, the most commonly used regimens incorporate concurrent administration of cisplatin (Platinol) and etoposide (VePesid) chemotherapy and radiation doses of 45 Gy given over 5 weeks. However, issues concerning timing, volume, and dose fractionation remain to be resolved.

Concurrent chemotherapy and radiotherapy in patients with brain tumors

Because treatment for most brain tumors remains inadequate, there has been a sustained interest in using concurrent chemotherapy and radiotherapy to improve local control, prolong overall survival, and reduce treatment-related toxicity. Unfortunately, many currently available radiosensitizers are either ineffective against brain tumors or have a reduced ability to cross the blood-brain barrier when administered systemically. Many agents also have overlapping toxicities with cranial irradiation or enhance the toxicity of radiation in a way that potentially compromises care. Finally, the addition of chemotherapy to cranial irradiation complicates the assessment of tumor response. Despite these barriers, trials with a number of promising agents are currently under way. These trials have already provided crucial insights into the pharmacokinetics, clinical pharmacology, and practical management of brain tumor patients with concurrent chemotherapy and radiotherapy. These findings should rapidly lead to the safer and more effective use of combined-modality therapy in patients with central nervous system cancer.

DNA topoisomerase I-targeting drugs as radiation sensitizers

Combination chemoradiation, alone or as an adjuvant to surgery, has been shown to improve treatment outcomes in a number of human malignancies, but may be limited by normal tissue toxicities. A primary challenge in radiation oncology is the development of drugs that can selectively enhance the cytotoxicity of ionizing radiation against tumor cells. Mammalian DNA topoisomerase I is the major cytotoxic target of a number of newly developed anticancer drugs that have shown efficacy against solid tumors, including colon cancer, ovarian cancer, lung cancer, cancer of the head and neck, and pediatric cancers. Topoisomerase I-targeting drugs exert their cytotoxic effect by producing enzyme-mediated DNA damage, rather than by directly inhibiting enzyme catalytic activity. DNA topoisomerase I recently has been established as a biochemical mediator of radiosensitization in cultured mammalian cells by camptothecin derivatives. Interestingly, this sensitization appears to be schedule-dependent, cell cycle phase-specific, cell line-dependent, and not strictly dependent on drug cytotoxicity. Clinical chemoradiation trials using camptothecin derivatives are currently ongoing. Future studies aimed at better understanding the underlying mechanisms of molecular radiosensitization with topoisomerase I-targeting drugs are pivotal to the clinical application of these agents, as well as in guiding the development of more effective radiosensitizers.

Radiopotentiation by the oral platinum agent, JM216: role of repair inhibition

PURPOSE

To test for in vitro radiopotentiation by the orally-administered platinum (IV) complex, JM216; to compare these results to cisplatin and carboplatin; and to investigate whether the mechanism of radiopotentiation involves repair inhibition of radiation-induced DNA damage.

METHODS AND MATERIALS

H460 human lung carcinoma cells were incubated with the drugs for 1 h at 37 degrees C, irradiated at room temperature, and returned to 37 degrees C for 20 min. Cells were then rinsed and colony forming ability was assessed. Wild-type V79 Chinese hamster cells and radiosensitive, DNA repair-deficient mutant cells (XR-V15B) were also studied along with H460 cells. Ku86 cDNA, which encodes part of a protein involved in DNA repair, was transfected into XR-V15B cells as previously described. The effect of JM216 on sublethal damage repair (SLDR) was also assessed using split-dose recovery.

RESULTS

Using equally cytotoxic doses of JM216, cisplatin, and carboplatin, the radiation dose enhancement ratios (DER) were 1.39, 1.31, and 1.20, respectively; the DER with 20 microM JM216 was 1.57. JM216 (20 microM) did not significantly change the final slope of radiation survival curves, but greatly reduced the survival curve shoulder. V79 cells also showed radioenhancement using 20 microM JM216, but no enhancement occurred using XR-V15B cells. Transfection of Ku86 cDNA into XR-V15B cells restored radiopotentiation by JM216 to wild-type V79 levels. In addition, 20 microM JM216 completely inhibited sublethal damage repair in H460 cells.

CONCLUSION

Our results show that JM216 can potentiate the effects of radiation in human lung cancer cells, and that the mechanism of this effect is probably inhibition of DNA repair by JM216.

Single-agent paclitaxel and radiation for non-small cell lung cancer

Lung cancer must be viewed as a systemic disease, and control of latent metastases at both regional and systemic sites is the goal of therapy. Combined modalities have emerged as the dominant strategy with which to manage latent metastases, and paclitaxel has several properties, including a modest toxicity profile, significant activity, and radiosensitization potential, which contribute to its effectiveness in this setting. In phase I clinical trials, paclitaxel was administered weekly in combination with radiation therapy (60 Gy) in the outpatient setting to patients with stage III non-small cell lung cancer (NSCLC). The dose-limiting toxicity, which occurred at a paclitaxel dose of 70 mg/m2/wk, was esophagitis; thus, a paclitaxel dose of 60 mg/m2/wk was recommended for phase II evaluation. In the phase II trial in patients with inoperable stage IIIA or stage IIIB NSCLC, paclitaxel 60 mg/m2/wk (for 6 weeks) plus radiation therapy (60 Gy) resulted in an overall response rate of 86%. The overall median survival was 20 months, and projected 1-, 2-, and 3-year survival rates were 60%, 54%, and 39%, respectively. These results demonstrate the feasibility and potential efficacy of this combination in the treatment of regionally advanced malignancies. When paclitaxel is administered using this schedule, it appears to exhibit an altered pattern of toxicity, with much lower incidences of hematologic and neurologic toxicities, which may improve the overall therapeutic index of this combination. Until curative systemic therapy is developed, combined modality approaches offer the greatest potential for long-term control of advanced NSCLC. Based on the observed activity and toxicity profile, concurrent radiation therapy plus paclitaxel offers significant clinical utility for control of both local and distant metastatic disease.

National survey on prophylactic cranial irradiation: differences in practice patterns between medical and radiation oncologists

PURPOSE

Prophylactic cranial irradiation (PCI) in the treatment of small cell lung cancer (SCLC) patients remains controversial in the oncology community because of its potential for long-term toxicity and unproven survival benefit in randomized trials. A national survey of 9176 oncologists was conducted to characterize the use of PCI with regard to physician demographics, patient characteristics, and oncologists' beliefs.

METHODS

Data was collected via a questionnaire letter survey. Biographical data, treatment patterns, and clinical impressions were analyzed by the generalized linear model and generalized estimating equations method.

RESULTS

There were 1231 responders overall (13.4% of those surveyed), including 628 (51%) radiation oncologists (RO), 587 (48%) medical oncologists (MO), 8 (0.6%) surgical oncologists, and 8 (0.6%) from other oncology subspecialties. Of respondents, 74% overall recommend PCI in limited-stage patients, including 65% of MO and 82% RO (p = 0.001). Of responders who recommend PCI in limited-stage patients, 67% do so only after complete response to initial therapy. Only 30% of respondents recommend PCI for extensive-stage SCLC patients (p = 0.001), and 94% of these recommend PCI only when those patients have a complete response after initial therapy. Interestingly, 38% of responding MO feel that PCI improves survival of limited-stage patients, but only 11% believe PCI improves quality of life. Of the RO, 48% believe PCI improves survival in limited-stage SCLC, and 36% feel PCI improves quality of life (p < 0.05 and p < 0.01, respectively). MO responders believe PCI causes late neurological sequelae more often than do RO responders (95% vs. 84%, p < 0.05), with impaired memory (37%), chronic fatigue (19%), and loss of motivation (13%) as most commonly seen side effects. Only 1.5% overall, however, routinely obtain neuropsychiatric testing in PCI patients, and 42% overall never obtain them.

CONCLUSION

Results confirm that oncologic subspecialists have statistically significant differences in opinion regarding the use of PCI. However, these differences may not translate into large differences in clinical practice. Most oncologists continue to recommend PCI in limited-stage SCLC patients, despite many believing PCI may not provide a survival advantage nor improve quality of life.

Concurrent paclitaxel and thoracic irradiation for locally advanced esophageal cancer

Esophageal cancer is a major cause of morbidity and mortality worldwide. Although patients often present with apparently resectable disease, systemic spread frequently occurs before the development of symptoms and detection of tumor. The use of combined chemoradiation therapy, particularly before resection, appears to prolong survival and increase cure rates in certain histologic subtypes. Four randomized phase III trials compared preoperative chemoradiotherapy plus surgery with surgery alone. In trials including only patients with squamous histology, no improvement in survival was observed with preoperative chemoradiation therapy; however, in a trial including only patients with adenocarcinoma histology, improved median and overall survival were observed. Paclitaxel has been evaluated as a single agent in a phase II trial in previously untreated patients with locally advanced unresectable or metastatic esophageal cancer; the overall response rate was 32% and median survival was 13.2 months. Paclitaxel-based combinations also have been evaluated in esophageal cancer; particularly encouraging preliminary results have been achieved with paclitaxel/cisplatin/5-fluorouracil. Because paclitaxel is a potent radiosensitizer, it also has been evaluated in combination with radiation therapy for esophageal and other thoracic cancers, alone and in combination with other chemotherapeutic agents. Preliminary results suggest that neoadjuvant therapy with paclitaxel-based combinations (including 5-fluorouracil and cisplatin) and radiation is highly active, with variable toxicity. A goal of future trials is to assess paclitaxel-based combined modality therapy in combination with other new chemotherapeutic agents.

Esophagitis in combined modality therapy for locally advanced non-small cell lung cancer

Within the last 10 to 15 years, several randomized trials have validated the importance of chemotherapy in the treatment of locally advanced non-small cell lung cancer and have shown that combined modality therapy improves survival compared with radiotherapy alone. Esophagitis appears to be the primary toxicity, with an increased incidence in combined modality trials. Esophagitis is an inflammatory response of the esophageal mucosa. Treatment with chemotherapy or radiotherapy destroys rapidly dividing cells, such as those in the basal epithelial cell layer. Cell death decreases the renewal rate of the basal epithelium, causing mucosal atrophy, ulceration, and initiation of the inflammatory response. Synergy between chemotherapy and radiotherapy may increase the severity and extent of esophagitis observed with combined modality therapy. Based on Radiation Therapy Oncology Group criteria, the incidence of >/=grade 3 esophagitis following radiation therapy alone or combined modality therapy ranges from less than 5% to 53%. Four sequential, multi-institutional phase I or II studies were conducted during the last 5 years to explore the use of paclitaxel in combined modality therapy for patients with non-small cell lung cancer. In the three phase II trials, esophagitis was the main toxicity, with incidences ranging from 17% to 26% using Radiation Therapy Oncology Group criteria. A multivariate analysis identified a statistically significant correlation between esophageal toxicity and both response to therapy and performance status. Other factors, including gender, age, histology, survival, and length of esophagus within the primary and boost radiation field, were not significantly correlated with esophageal toxicity.

Concurrent paclitaxel, carboplatin, and radiation therapy for locally advanced non-small cell lung cancer

Combination chemotherapy plus radiation therapy for non-small cell lung cancer has several theoretical advantages: the potential of chemotherapy to radiosensitize tumors, the possibility of improved local control due to combined treatment, and the opportunity for spatial cooperation, attacking disease both locally and systemically and thus potentially increasing response and, ultimately, survival. The combination of radiotherapy plus standard chemotherapy (etoposide plus cisplatin) has yielded limited success; therefore, new and novel chemotherapies have been sought. Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), the prototype of a novel class of drugs, the taxanes, has proven feasible both alone and with other agents in combined-modality regimens with radiation. Concurrent paclitaxel/carboplatin/radiotherapy appears to offer a relatively safe and more active regimen to control local and metastatic non-small cell lung cancer than the current standard. This report reviews the range of experience with paclitaxel-based combined-modality therapy.

Multiinstitutional phase II trial of paclitaxel, carboplatin, and concurrent radiation therapy for locally advanced non-small-cell lung cancer

PURPOSE

Combined modality therapy for non-small-cell lung cancer (NSCLC) has produced promising results. A multiinstitutional phase II clinical trial was conducted to evaluate the activity and toxicity of paclitaxel, carboplatin, and concurrent radiation therapy on patients with locally advanced NSCLC.

PATIENTS AND METHODS

Forty previously untreated patients with inoperable locally advanced NSCLC entered onto a phase II study from March 1995 to December 1996. On an outpatient basis for 7 weeks, patients received paclitaxel 50 mg/m2 weekly over 1 hour; carboplatin at (area under the curve) AUC 2 weekly; and radiation therapy of 66 Gy in 33 fractions. After chemoradiation therapy, patients received an additional two cycles of paclitaxel 200 mg/m2 over 3 hours and carboplatin at AUC 6 every 3 weeks.

RESULTS

Thirty-nine patients were eligible for the study. The survival rates at 12 months were 56.3%, and at 24 months, 38.3%, with a median overall survival of 20.5 months. The progression-free survival rates at 12 months were 43.6%, and at 24 months, 34.7%, with a median progression-free survival of 9.0 months. Two patients did not receive more than 2 weeks of concurrent chemoradiotherapy and were not assessable for toxicity and response. The overall response rate (partial plus complete response) of 37 assessable patients was 75.7%. The major toxicity was esophagitis. Seventeen patients (46%) developed grade 3 or 4 esophagitis. However, only two patients developed late esophageal toxicity with stricture at 3 and 6 months posttreatment.

CONCLUSION

Combined modality therapy with paclitaxel, carboplatin, and radiation is a promising treatment for locally advanced NSCLC that has a high response rate and acceptable toxicity and survival rates. A randomized trial will be necessary to fully evaluate the usefulness of these findings.

Histologic evidence of a radiosensitizing effect of Taxol in patients with astrocytomas

The new anticancer agent Taxol appears to potentiate the effects of radiation on brain tumor cell lines in vitro and was recently evaluated by our group as a radiosensitizer in a phase I study for primary brain tumors. In that study, we administered Taxol as a three-hour IV infusion repeated every week for six weeks and gave daily cranial irradiation concurrently for a total of 6000 rads. We reviewed the charts of the 60 patients who participated in the study, and identified twelve patients who underwent a second surgery after treatment because of progressive symptoms and an enlarging intracranial mass on MRI. Pathologically, each patient showed prominent radionecrosis, and other evidence of accelerated radiation changes (confluent areas of coagulative necrosis, bizarre nuclei, marked thickening and fibrinoid changes in multiple blood vessels). These changes were noted many weeks earlier than would be expected after radiation therapy alone and were independent of age, and tumor histology. We postulate that the accelerated radiation changes may be due to the radiation sensitizing effects of Taxol. We also noted a change of the pattern of tumor recurrence, compared to historic reports, and a dose-necrosis relationship where the resected tumor is formed completely of necrotic tissue in patients who received 150 mg/m2 or higher dose of Taxol. These observations may be of significance for future study design.

Phase II trial of weekly paclitaxel and concurrent radiation therapy for locally advanced non-small cell lung cancer

We conducted a prospective Phase II study to determine the response rate, toxicity, and 2-year survival rate of concurrent weekly paclitaxel and radiation therapy (RT) for locally advanced unresectable non-small cell lung cancer. The weekly paclitaxel regimen was designed to optimize the radiosensitizing properties of paclitaxel. Thirty-three patients with unresectable stage IIIA and IIIB non-small cell lung cancer from six institutions were entered into the study between March 1994 and February 1995. Weekly i.v. paclitaxel (60 mg/m2; 3-h infusion) plus concurrent chest RT (60 Gy over 6 weeks) was delivered for 6 weeks. Twenty-nine patients were evaluable for response. Three patients achieved a complete response (10%), and 22 patients (76%) achieved a partial response, for an overall response rate of 86% (95% confidence interval, 68-96%). One patient progressed during the therapy, and three patients had stable disease. Esophagitis was the principal toxicity. Grade 3 or 4 esophagitis occurred in 11 patients (37%). One patient died of pneumonia after completion of therapy. Additional grade > or =3 toxicities included pneumonitis (12%) and neutropenia (6%). One patient had a grade 3 hypersensitivity reaction. The median overall survival duration for all 33 patients who entered the study was 20 months, and 1-, 2-, and 3-year overall survival rates were 60.6%, 33.3%, and 18.2%, respectively. The median progression-free survival duration for all 33 patients was 10.7 months, and 1-, 2-, and 3-year progression-free survival rates were 39.4%, 12.1%, and 6.1%, respectively. Weekly paclitaxel plus concurrent RT is a well-tolerated outpatient regimen. The survival outcome from this regimen is encouraging and seems to be at least equivalent to that of other chemotherapy/radiation trials. These findings warrant further clinical evaluation of weekly paclitaxel/RT in Phase II trials in the neoadjuvant setting and in combination with other cytotoxic agents.

Prognosis of adenocarcinoma arising in Barrett's esophagus

BACKGROUND

The rising incidence of adenocarcinoma of the esophagus, as well as its association with Barrett's esophagus, has been reported previously. We report our experience in treating patients with adenocarcinoma arising in Barrett's esophagus.

METHODS

A retrospective review was performed of 70 consecutive patients with adenocarcinoma of the esophagus treated between November 1988 and April 1996 with preoperative chemoradiation and resection. Demographics, pathologic features, and survival were compared with patients who developed adenocarcinoma of the esophagus without Barrett's. Statistical analyses was performed using Student's t test, Fisher's exact test, and Kaplan-Meier where appropriate.

RESULTS

Thirty-two (46%) patients had adenocarcinoma arising in Barrett's esophagus. During the last 4 years, 72% (23 of 32) of patients with adenocarcinoma had coexistent Barrett's. No differences in patients with or without Barrett's with regard to age, sex, race, tumor location, preoperative chemotherapy, type of operation, or operative stage were observed. Tumors in patients with Barrett's were larger (p = 0.017), had better differentiation (p = 0.002), and were less likely to have a complete response to preoperative chemoradiation (p = 0.05). Actuarial survival, however, was better in the group with associated Barrett's esophagus (p = 0.033).

CONCLUSIONS

The incidence of adenocarcinoma of the esophagus arising in Barrett's esophagus appears to be increasing. It may be distinct clinically and biologically from adenocarcinoma of the esophagus that does not develop in association with Barrett's epithelium. Long-term survival was better in our patients with adenocarcinoma associated with Barrett's esophagus.

Phase I trial of weekly paclitaxel in advanced lung cancer

PURPOSE

We conducted a phase I study in chemotherapy-naive patients with advanced non-small-cell lung cancer (NSCLC) to determine the maximum-tolerated dose (MTD) of paclitaxel using an extended weekly schedule.

PATIENTS AND METHODS

Patients with stage IIIB/IV NSCLC were treated with paclitaxel administered weekly over 3 hours for 6 weeks of an 8-week cycle. Doses were modified for granulocyte counts less than 1,800/microL or neurotoxicity greater than grade I. Groups of three patients were entered at each dose level. The dose was escalated to the next level if less than 50% of patients developed unacceptable toxicity and received more than 80% of the intended first-cycle dose.

RESULTS

Twenty-six patients were entered through six dose levels (100, 125, 135, 150, 175, and 200 mg/m2/wk). Four of six patients at the 175-mg/m2 dose level and only one of six patients at the 200-mg/m2 level received all scheduled doses of paclitaxel during cycle 1. Neutropenia was dose-limiting. Fourteen patients were treated with subsequent cycles of paclitaxel. Grade II to III neuropathy developed in five of 24 patients. It occurred more commonly with greater duration of therapy, but improved following dose reduction. Nine of 26 (35% +/- 10%) patients demonstrated an objective response.

CONCLUSION

The MTD of paclitaxel using a weekly schedule is 175 mg/m2/wk for 6 of 8 weeks. Neutropenia limits dosing acutely, but neuropathy is limiting with sustained therapy. This schedule of paclitaxel results in a twofold to threefold increase in dose-intensity with less toxicity than anticipated from conventional dosing. Further evaluation of this schedule is warranted to assess efficacy and toxicity of prolonged administration.

Paclitaxel, carboplatin and radiation therapy for non-small-cell lung cancer

Preclinically, the taxanes appear to potentiate radiation more effectively than do the platinum compounds. In our phase I trial (LUN-17) in patients with advanced non-small-cell lung cancer, we defined the maximum tolerated dose and toxicity profile of concomitant radiation and paclitaxel (Taxol). We then conducted a series of phase II clinical trials in patients with stage III A or stage III B non-small-cell lung cancer to explore the role of paclitaxel in a combined-modality approach; these trials were based on the very low paclitaxel concentrations needed to enhance radiation in the phase I trial and the relatively high response rate achieved. Our LUN-27 trial of weekly paclitaxel and concurrent radiation for 6 weeks with no adjuvant chemotherapy produced substantial response and survival rates with acceptable toxicity. LUN-56 added weekly carboplatin (Paraplatin) during the initial concurrent phase as well as two cycles of standard-dose paclitaxel and carboplatin. The ongoing LUN-63 phase II study delivers concurrent weekly paclitaxel and carboplatin with hyperfractionated radiation, followed by two cycles of adjuvant paclitaxel and carboplatin, to further improve local control and overall survival. We are currently extending the investigation of concurrent weekly paclitaxel plus radiation in a large-scale, three-arm, randomized phase II trial. To date, toxicity in all trials has been acceptable and compares favorably with other regimens. The major side effect, esophagitis, occurs predictably and is managed easily, abating shortly after therapy is completed. The rates of overall response and 1- and 2-year survival are very encouraging, and phase III evaluation is warranted.

Preliminary analysis of a phase II study of paclitaxel, carboplatin, and hyperfractionated radiation therapy for locally advanced inoperable non-small cell lung cancer

We conducted a prospective phase II study to determine the response rate, toxicity profile, and survival rate among patients with locally advanced unresectable non-small cell lung cancer receiving concurrent weekly paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), carboplatin, and hyperfractionated radiation therapy followed by two cycles of adjuvant paclitaxel and carboplatin. The weekly paclitaxel/carboplatin regimen was designed to optimize the radiosensitizing properties of paclitaxel during the concurrent phase of treatment. Thirty-two patients with unresectable stage IIIA and IIIB non-small cell lung cancer from Vanderbilt Cancer Center Affiliate Network institutions entered the study from June 1996 until February 1997. Weekly intravenous paclitaxel (50 mg/m2 over 1 hour) and weekly carboplatin (area under the concentration-time curve of 2) plus concurrent hyperfractionated chest radiotherapy (1.2 Gy twice daily [69.6 Gy total]) delivered for 6 weeks were followed by two cycles of paclitaxel (200 mg/m2) and carboplatin (area under the concentration-time curve of 6). Among 22 patients evaluable for response, one (4.5%) achieved a complete response and 16 (72.7%) achieved partial response, for an overall response rate of 77%. Among 23 patients evaluable for toxicity, esophagitis was the principal finding: grade 3 or 4 esophagitis occurred in eight patients (35%). Grade 3 and 4 pulmonary toxicities each occurred in 26% of patients. Thus, weekly paclitaxel/carboplatin plus concurrent hyperfractionated radiotherapy is a well-tolerated outpatient regimen with an encouraging response rate that is at least equivalent to more toxic chemoradiation regimens. These findings indicate that further clinical evaluation of weekly paclitaxel/carboplatin/hyperfractionated radiotherapy is warranted in phase III trials.

Prophylactic cranial irradiation in small cell lung cancer: rationale, results, and recommendations

The utility of prophylactic cranial irradiation (PCI) in patients with small cell lung cancer (SCLC) constitutes one of the longest running debates in oncology. Despite dozens of prospective and retrospective studies and decades of individual experience, a consensus has been reached on only two issues: (1) when administered to all patients with SCLC, PCI decreases the likelihood of developing brain metastases by about half, but (2) PCI does not significantly prolong survival. Uncertainty persists over many critical questions, including whether, when, and how to administer PCI; whether identifiable subgroups of patients benefit more tangibly from PCI; how frequent and severe the long-term side effects of PCI are; whether withholding treatment until brain metastases are diagnosed is clinically responsible and cost effective; and how newer forms of treatment for brain metastases should be integrated into the picture. In this review, we discuss the epidemiology and natural history of brain metastases in patients with SCLC, the results of studies examining the efficacy of PCI, data on the early and late toxicities of PCI, and the status of alternative therapies for patients with brain metastases from SCLC. Based on this information, an approach to newly diagnosed patients is suggested, and recommendations for future study are made.

Weekly paclitaxel in patients with advanced lung cancer: preliminary data from a phase II trial

We conducted a phase II trial in chemotherapy-naive patients with advanced non-small cell lung cancer to determine the efficacy of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) delivered at a maximum tolerated dose of 175 mg/m2 on an extended weekly schedule. Patients with stage IIIB/IV non-small cell lung cancer were eligible if they had an Eastern Cooperative Oncology Group performance status of 0 to 2, had received no previous chemotherapy, demonstrated normal hematologic and hepatic function, and could provide informed consent. Paclitaxel 175 mg/m2 was administered as an intravenous infusion weekly over 3 hours with standard premedication, for 6 weeks of an 8-week cycle. Doses were modified for absolute neutrophil count less than 1.5 x 10(9)/L or neuropathy greater than grade I on the day of therapy. Patients without progressive disease received subsequent cycles at the same dose. To date, 30 patients have been enrolled; data are available for 25. The median age was 65 years (range, 38 to 78 years), 23 patients were performance status 0 or 1, and 14 had received prior radiation. Sites of disease included the lung (23 patients), central nervous system (11), bone (seven), liver (one), kidney (one), and soft tissue (eight). Eighty-three percent, 75%, 58%, and 50% of intended doses were delivered during cycles 1 though 4, respectively. Grade 2/3 neuropathy occurred in nine patients, but improved in all nine following dose reduction. Grade 3/4 neutropenia occurred in 10 patients. Partial responses occurred in 14 of 25 patients (56%; 95% confidence interval, 46% to 66%). Median duration of response was 6.5 months, and the 1-year survival rate was 53%. The extended weekly paclitaxel schedule results in enhanced dose intensity, marked activity, and acceptable toxicity. Paclitaxel given weekly at maximum dose intensity may be more effective than conventional paclitaxel administration schedules.

Paclitaxel and concurrent radiation for locally advanced pancreatic and gastric cancer: a phase I study

PURPOSE

To determine the maximum-tolerated dose (MTD), dose-limiting toxicities, and potential antitumor activity of weekly paclitaxel with concurrent radiation (RT) for locally advanced pancreatic and gastric cancer.

PATIENTS AND METHODS

Thirty-four patients with locally advanced adenocarcinoma of the pancreas or stomach were studied. The initial dose of paclitaxel was 30 mg/m2 by 3-hour intravenous (I.V.) infusion repeated every week for 6 weeks with 50 Gy RT. Doses were escalated at 10-mg/m2 increments in successive cohorts of three new patients until dose-limiting toxicity was observed.

RESULTS

The dose-limiting toxicities at 60 mg/m2/wk were abdominal pain within the RT field, nausea, and anorexia. Of 23 patients with assessable disease, 11 (seven with gastric, four with pancreatic cancer) had objective responses for an overall response rate of 48%.

CONCLUSION

Concurrent paclitaxel with upper abdominal RT is well tolerated at dosages that have substantial activity. A phase II trial of neoadjuvant paclitaxel and RT at the MTD of 50 mg/m2/wk is underway.

Weekly paclitaxel with and without concurrent radiation therapy: toxicity, pharmacokinetics, and response

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has shown in vitro and clinical activity against non-small cell lung cancer and astrocytic brain tumors, tumors traditionally thought of as relatively resistant to chemotherapy and radiotherapy. Because of its ability to block dividing cells in the G2/M portion of the cell cycle (the most radiosensitive phase of the cell cycle), paclitaxel is also a potentially potent radiosensitizer. To exploit these and other properties of paclitaxel, we explored a weekly, outpatient administration schedule, with and without concurrent radiation therapy, in patients with non-small cell lung cancer and astrocytic brain tumors. Our experience has shown that weekly outpatient administration is feasible, that remarkably high dose intensities can be achieved with acceptable toxicity, and that the specific dose-limiting toxicity appears to depend on administration schedule, type of concurrent radiotherapy, and certain patient characteristics. Preliminary response data are very encouraging. At the same time, pharmacokinetic studies have suggested possible reasons for our ability to use such exorbitant dose intensities safely, and also have shown that sustained plasma paclitaxel levels above the putative radiosensitizing threshold can be achieved continuously during a 6-week course of radiotherapy. Specific results, dosing recommendations, and plans for future studies are discussed.

Paclitaxel plus carboplatin and concurrent radiation therapy for patients with locally advanced non-small cell lung cancer

Previously untreated patients with stages IIIA or IIIB non-small cell lung cancer entered this phase II study to evaluate the activity and toxicity of combined paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) and carboplatin and concurrent radiation. Patients received paclitaxel 50 mg/m2/wk as a 1-hour infusion and carboplatin area under the concentration-time curve of 2/wk for 7 weeks with radiation to the primary tumor and regional lymph nodes (44 Gy) followed by a boost to the tumor (22 Gy). In addition, patients received two additional cycles of paclitaxel 200 mg/m2 and carboplatin (area under the concentration-time curve of 6) 3 weeks apart. From March 1995 to February 1996, 23 patients entered the study and their overall response rate (complete plus partial responses) was 82%. The major toxicity was esophagitis. Nine patients (45%) had experienced grades 3 or 4 esophagitis by the end of the 7-week concurrent phase. Seven of the nine patients recovered from the esophagitis within 2 weeks and received the additional two cycles of paclitaxel 200 mg/m2 and carboplatin (area under the concentration-time curve of 6). Only one patient (4%) had grade 4 pneumonitis; this patient also recovered within 2 weeks and received the final two doses of combined chemotherapy. Therapy with paclitaxel, carboplatin, and concurrent radiation is a promising treatment for patients with locally advanced non-small cell lung cancer; it has a high response rate and acceptable toxicity.

Preliminary results of a phase I study of weekly paclitaxel infusion in patients with non-small cell lung cancer

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has a broad spectrum of activity, but the optimal schedule has not yet been determined. As a phase-specific agent, more frequent administration theoretically may be more effective. We have previously demonstrated that a weekly schedule of paclitaxel used as a radiation sensitizer is well tolerated by outpatients. We therefore conducted a phase I study of weekly paclitaxel in patients with chemotherapy-naive metastatic non-small cell lung cancer to determine the maximum tolerated dose of this alternative schedule. In all, 26 patients were entered into this study through six paclitaxel dose levels (100, 125, 135, 150, 175, and 200 mg/m2/wk) administered weekly for 6 of 8 weeks. All patients had a performance status of 0 through 2, with a median age of 65 years (age range, 37 to 80 years). Sites of disease included lung, bone, liver, soft tissue, and brain. Of the 26 entered, 24 patients completed the first 8-week cycle and are evaluable for toxicity. Dose-limiting toxicity, which consisted of neutropenia, occurred in four of six patients at 200 mg/m2/wk and in two of six at 175 mg/m2/wk. Only one evaluable patient required admission for febrile neutropenia. Other toxicities included rash, pulmonary infiltrate, myalgia, neuropathy, and alopecia. Nine (38%) of the 24 patients demonstrated objective responses. One patient with stable disease completed 48 weeks of therapy. Others remain in active treatment. We conclude that the maximum tolerated dose of paclitaxel administered for 6 consecutive weeks of an 8-week cycle is 175 mg/m2/wk and is limited principally by neutropenia. The response rate with this schedule is encouraging and merits further investigation.

p53 mutations do not predict response to paclitaxel/radiation for nonsmall cell lung carcinoma

BACKGROUND

Mutations in the tumor suppressor gene p53 have been associated with resistance to ionizing radiation and chemotherapy. Paclitaxel and concurrent radiation (paclitaxel/RT) achieve high response rates with locally advanced nonsmall cell lung carcinoma (NSCLC). In vitro data and animal studies suggest that paclitaxel may have a unique ability to activate tumor cell apoptosis in the absence of wild-type p53 function. The authors sought to determine whether p53 mutations affect response to paclitaxel/RT in patients with locally advanced NSCLC.

METHODS

Thirty patients with Stage IIIA or IIIB NSCLC who participated in Brown University Oncology Group protocols utilizing paclitaxel/RT had tumor tissue that was adequate for analysis. Mutations were detected in tumor tissue by single-strand conformation polymorphism analysis of exons 5 through 8 of the p53 gene, and confirmed by direct sequencing.

RESULTS

Mutations in p53 were found in 12 of 30 patients (40%). The response rates (complete plus partial) of 75% for patients with tumors with p53 mutations, and 83% for patients with wild-type p53, did not differ significantly (P = 0.70).

CONCLUSIONS

p53 mutations do not predict response of patients with NSCLC to paclitaxel/RT. This finding is in striking contrast to results with other chemotherapeutic agents and ionizing radiation. These clinical data support in vitro data and animal studies regarding the unique mechanism of the action of paclitaxel. Further investigation is needed to determine the mechanism of lung tumor cell death after paclitaxel/RT. These results suggest that paclitaxel/RT may be an active regimen for patients with other locally advanced neoplasms with high rates of p53 gene mutations.

A randomized, blinded, placebo-controlled trial of divalproex sodium prophylaxis in adults with newly diagnosed brain tumors

BACKGROUND

Seizures occur after the diagnosis of brain tumors in up to 40% of patients. Prophylactic anticonvulsants are widely advocated despite a lack of convincing evidence of their efficacy in preventing first seizures. We conducted a randomized, double-blind, placebo-controlled study comparing the incidence of first seizures in divalproex sodium- and placebo-treated patients with newly diagnosed brain tumors.

PATIENTS AND METHODS

Patients who had not previously had a seizure were randomized within 14 days of diagnosis of their brain tumor to receive either divalproex sodium or placebo. All patients had at least one supratentorial brain lesion, a Karnofsky Performance Score (KPS) > or = 50%, and no previous anticonvulsant use or other brain disease. Compliance and adequacy of dosing were assessed by pill counts and monthly blood levels.

RESULTS

Seventy-four of 75 consecutive eligible patients were entered in this study. Median follow-up was 7 months. The drug and placebo groups did not differ significantly in age, sex, KPS, primary tumor type, number or location of brain lesions, frequency of brain surgery, or pretreatment EEG. Thirteen of 37 patients (35%) receiving divalproex sodium and 9 of 37 patients (24%) on placebo had seizures. The odds ratio for a seizure in the divalproex sodium arm relative to the placebo arm was 1.7 (95% CI 0.6 to 4.6; p = 0.3). The hypothesis that anticonvulsant prophylaxis provides a reduction in the frequency of first seizure as small as 30% was rejected (p = 0.05).

CONCLUSIONS

Anticonvulsant prophylaxis with divalproex sodium is not indicated for patients with brain tumors who have not had seizures.