High-dose chemotherapy in solid tumours. A review of published data in selected tumours with a commentary

Assessing causal relationships between treatments and clinical outcomes: always read the fine print

Changes in clinical practice should be driven by relevant and reliable evidence. Hence, adoption of a new therapy requires demonstrating that it provides (causes) benefit. Such evidence is generally obtained from intent-to-treat analyses of randomized clinical trials (RCTs). In this paper, we review other approaches to assessing the causal relationship between treatments and outcomes: (1) inference from non-randomized (observational) studies, (2) analysis of randomized studies where patients received treatments other than those to which they were randomized and (3) analysis of studies where the outcome of interest is sometimes unobservable because of a competing event (competing risks). We conclude that for the practice-changing demonstration of a favorable benefit-to-risk ratio, the gold standard is the intent-to-treat analysis of RCTs. At the same time, we illustrate how careful application of special statistical methods for assessment of treatment-outcome causation can be instrumental in complementing existing randomized evidence and guiding design of future research.

Lessons learned from a decade of clinical trials of high-dose chemotherapy in ovarian cancer

Ovarian cancer is one of the most chemosensitive solid tumors and therefore a good example to explore high-dose chemotherapy (HDC). Interest in pursuing this treatment arose in the late 1980s following the success of HDC in treating hematological cancers and improvements in supportive care with peripheral blood stem cells. Experience from phase II trials and analysis of Bone Marrow Transplant Registry data led to the launch of several randomized phase III trials in the late 1990 s. Initial enthusiasm for this treatment was in part due to the preliminary positive data emerging from HDC in breast cancer. Five randomized trials of HDC in ovarian cancer have been conducted and all experienced difficulty in recruitment. Their different designs and results are reviewed, as well as some of the lessons that have been learned about HDC in solid tumors in the last decade.

Chemotherapy for small cell lung cancer

There were approximately 42,000 new cases of small cell lung cancer (SCLC) in 2002. Despite its initial sensitivity to chemotherapy, only 10% of all SCLC patients will have significant long-term survival. Studies have yet to show significant survival advantages for maintenance chemotherapy, and it appears that four to six cycles of chemotherapy is as effective as longer durations. As yet, there is no defined role for dose escalation in the treatment of SCLC. No one chemotherapy combination has exhibited a definitive survival advantage in extensive disease, although it appears that single-agent oral etoposide may be inferior to combination intravenous chemotherapy. In limited disease, however, cisplatin plus etoposide alone or in alternation with cyclophosphamide/doxorubicin/vincristine is superior to other approaches. There are several new agents with significant activity in SCLC awaiting further study.

High-dose chemotherapy for breast cancer: the French PEGASE experience

BACKGROUND

Early studies of high-dose chemotherapy (HDC) for breast cancer were limited by small numbers and the lack of adequate control groups. The French PEGASE Group was founded to perform larger and properly randomized comparative studies of this approach.

METHODS

The program was created to determine the effects of intensive chemotherapy for breast cancer. The seven PEGASE protocols addressed HDC as adjuvant therapy (01 and 06) and as treatment for inflammatory nonmetastatic disease (02, 05, and 07) and metastatic disease (03 and 04). Two of these protocols are ongoing.

RESULTS

The PEGASE 01 adjuvant therapy trial showed that 3-year disease-free survival was significantly better in the HDC arm but overall survival was unchanged. The ongoing phase III 06 trial is studying a higher dosage regimen. The HDC trials for metastatic and inflammatory nonmetastatic disease are encouraging.

CONCLUSIONS

Many clinicians no longer subscribe to the concept of HDC for breast cancer. Overall outcomes from management of poor-risk breast cancer remain poor, however, and it is possible that some selected subgroups of patients may benefit from such an approach.

High dose chemotherapy: rationale and results in breast carcinoma

BACKGROUND

High dose chemotherapy (HDC) with hematopoietic stem cell support is an increasingly important strategy in the management of advanced cancer. Early Phase II studies and the development of peripheral blood stem cell support to enable safe and tolerable myeloablative chemotherapy has resulted in its controversial and widespread use in the management of breast carcinoma. Recently, several randomized trials of both advanced breast carcinoma and the adjuvant setting have been reported.

METHODS

The technical developments in HDC and results from the randomized clinical trials reported to date were reviewed.

RESULTS

Three randomized trials of advanced breast carcinoma and five of high risk adjuvant patients were identified. Only two relatively small trials from South Africa have so far shown an advantage for high dose chemotherapy, and the validity of these trials has recently been seriously challenged. A Scandinavian adjuvant trial showed no advantage for HDC when compared with maximum nonablative doses supported with granulocyte-colony stimulating factor (G-CSF). Four trials were too small to detect clinically realistic differences in outcome, whereas the other large adjuvant trial was reported prematurely and the results in the HDC arm were dominated by high procedure-related mortality.

CONCLUSIONS

It is difficult to make specific treatment recommendations based on the conclusions from the currently available data. The 1999 American Society of Clinical Oncology reports were inconsistent and in some cases were presented before the results were sufficiently mature to provide statistically reliable data. However, it is clear that, unlike in leukemia, lymphoma, and multiple myeloma, HDC in breast carcinoma should not be used outside the context of a clinical trial. The mature results of the ongoing trials are eagerly awaited, whereas the use of immediate as opposed to consolidation high dose treatment, tandem transplants, and developments in immunologic and genetic manipulation of the graft merit further evaluation.

Is there a role for intensive therapy in breast cancer?

With reference to survival, polychemotherapy has been demonstrated to be statistically significantly more effective than monochemotherapy both in the adjuvant setting and in the metastatic situation. Breast cancer demonstrates a dose-response relationship. Chemotherapy used in the conventional dose range should be given with adequate dose-intensity both in the adjuvant setting and for metastatic patients. More dose-intensive combinations are almost always associated with a higher response rate in patients' metastatic disease, but these results have seldom been translated into an improved survival. For marrow requiring high-dose therapy, repeated phase II studies have demonstrated the possibility of a survival tail, which may be due to stage migration and patient selection. At present we have at least 13 ongoing phase III studies in the adjuvant setting and at least 5 ongoing studies in the metastatic situation. These studies will give a definite answer on whether marrow-supported high-dose therapy is better than conventional therapy or if alternative approaches using tailored therapy will result in an equivalent outcome. In the future we must make better use of the present arsenal of drugs and examine the marked inter-individual variations in pharmacokinetic profiles for the drugs. We have to tailor the therapy to the tumour biological profile, in both the primary tumour and metastases with appreciation of heterogeneity and tumour progression. Based on these prerequisites, therapy can be either dose-intensive or in some instances continuous using lower doses.

High-dose chemotherapy: is it standard management for any common solid tumor?

High-dose chemotherapy with stem-cell support had as its basis the observation of dose-response relationships for many chemotherapeutic agents in laboratory models. The rationale to explore high-dose treatment in the clinic was further enhanced by several retrospective reviews in the 1980s which suggested delivered dose intensity of treatment was an important determinant of patient outcome. The availability of hematopoietic growth factors and technologic advances in the efficiency of stem-cell collection and administration have made the evaluation of exploring high-dose therapy safe and feasible. However, real questions remain regarding the apparently superior results of this treatment in the management of solid tumors. This paper reviews the results of high-dose chemotherapy in breast, ovarian and small cell lung cancers. Firstly the evidence for a dose-response relationship to chemotherapeutic agents in the 'standard' dosage range is examined. Secondly results of non-randomized and, where available, randomized trials of high-dose chemotherapy (HDCT) with stem-cell support are summarized and finally conclusions regarding the weight of the evidence for use of HDCT as 'standard' treatment are given. In none of these tumors is there sufficient evidence from randomized trials to consider HDCT a standard to be offered to all patients with a given stage of disease. The apparent benefit of HDCT seen in phase II trials could well be explained by such phenomena as stage shifts and patient selection. Many randomized trials in ovary and breast cancer are either ongoing or presented only as abstracts so final results must be awaited to quantify the benefit, if any of HDCT. It is acknowledged, however, that some practitioners already utilize this treatment. We speculate about the differences in philosophical approaches to cancer treatment which might contribute to early acceptance of novel therapies in the absence of adequate randomized data.

FEC mobilized stem cells for high-dose therapy in breast cancer patients. SB6 9401 Study Group

The feasibility of mobilizing peripheral blood stem cells (PBSC) using anthracycline containing polychemotherapy and G-CSF on the first 50 patients randomized to the high-dose arm in the adjuvant SBG 9401 is investigated. The patients were treated with standard FEC (5-fluorouracil 600 mg/m2, epirubicin 60 mg/m2, cyclophosphamide 600 mg/m2) for two courses followed by a modified third FEC course with a C dose of 1200 mg/m2 supported with subcutaneous G-CSF (filgrastim) at 5 mg/kg followed by harvest around day 11. The mean yield of CD34+ cells per patient was 10.6x10(6)/kg (range 2.6-29.1). The side effects after the third course were low and only one patient developed an uncomplicated granulopenic fever. Our data indicated a correlation between number of transfused CD34+ cells and days to neutrophil and platelet recovery. In conclusion, the modified FEC regimen followed by G-CSF is a feasible method for PBSC mobilization in the adjuvant setting.

Cytotoxic activity of doxorubicin "loaded" neutrophils against human mammary carcinoma (HTB-19)

Neutrophils were intra-cellularly "loaded" with the chemotherapeutic agent, doxorubicin applying a variety of incubation conditions in order to identify parameters which maximize chemotherapeutic incorporation, while simultaneously preserving optimal viability and chemotactic responsiveness. Doxorubicin "loaded" neutrophils (DLN) were produced in triplicate at different combinations of incubation conditions such as temperature (4 degrees C, 37 degrees C); duration (0, 1, 2 hours); and doxorubicin concentration (20, 40, 60 micrograms/ml). Chemotactic responsiveness of rinsed DLN preparations was subsequently assessed against the neutrophil peptide chemotactic agent, formyl methionyl leucyl phenylalanine (fMLP, 10(-6) M) utilizing a modified 96-well Boyden chemotactic chamber apparatus. Viable, fMLP-responsive DLN preparations were subsequently detected with MTT vitality staining reagent. At sub-physiological incubation temperatures (4 degrees C), profound declines in the viability of DLN preparations were detected when simultaneously incubated with doxorubicin formulated at concentrations greater than 10 micrograms/ml. In contrast, DLN preparations incubated at 37 degrees C displayed diminished viability only when incubated with doxorubicin formulated at a concentration of 60 micrograms/ml. Viable DLN populations were subsequently evaluated to determine their ability to exert in vitro cytotoxic activity against monolayer populations of human mammary carcinoma (HTB-19) propagated in a tissue culture environment. The lethal effect which DLN preparations inflicted towards HTB-19 populations was substantially greater than was observed with an equivalent population of untreated neutrophils. Maximal in vitro cytotoxic activity was detected with DLN preparations produced at 37 degrees C in the presence of doxorubicin formulated at a concentration of 40 micrograms/ml. In contrast, DLN preparations produced at an incubation temperature of 37 degrees C, and a doxorubicin concentration of 20 micrograms/ml displayed relatively lower levels of in vitro cytotoxic activity against HTB-19 monolayer populations. The degree of in vitro cytotoxic activity exerted against HTB-19 monolayer populations by DLN preparations was directly influenced by the duration of the challenge period. Maximal in vitro cytotoxic activity was observed when HTB-19 monolayer populations were challenged with DLN preparations for a period of 96-hours duration at 37 degrees C. Challenge periods of 48-hours duration produced levels of in vitro cytotoxic activity which were substantially lower than those observed for challenge periods of 96-hours duration. Optimal in vitro cytotoxic activity was recognized when DLN preparations were allowed to establish direct contact with HTB-19 monolayer populations at an estimated DLN:HTB-19 cellular ratio of approximately 5:1 (37 degrees C, CO2, 6%). Significantly less in vitro cytotoxic activity was recognized when DLN preparations were only permitted indirect cellular contact with HTB-19 monolayer populations which was achieved through the application of a semi-permeable 3 microM pore membrane partition. In vitro cytotoxic activity of DLN populations was not inhibited by the anti-oxidant agent, dimethyl sulfoxide (DMSO), but was inhibited in the presence of glutathione (GSH), superoxide dismutase (SOD), and vitamin E (alpha-tocopherol). Similarly, in vitro cytotoxic activity of DLN populations was also inhibited in the presence of sodium heparin (serine esterase inhibitor), and dexamethasone (inhibitor of neutrophil activation-degranulation phenomenon). Experimental results observed in these investigations collectively imply that the in vitro cytotoxic activity exerted by DLN preparations against HTB-19 populations is in part attributable to neutrophil-mediated cytotoxic immunity. This innate property of neutrophil populations involves their capacity to generate highly reactive oxygen "free" radical species (O2, HO, H2O2), and synthes

The limits of chemotherapy dose intensification using granulocyte colony stimulating factor alone in extensive small cell lung cancer

Human Recombinant Granulocyte Colony Stimulating Factor (G-CSF) allows rapid neutrophil recovery after chemotherapy-induced leukopenia. In a prospective series of 54 patients with extensive small cell lung cancer, we evaluated the feasibility and efficacy of accelerated delivery of the AVI chemotherapy regimen. Treatment consisted of Doxorubicin 50 mg/m2 day 1, Etoposide 120 mg/m2 day 1-3 and Ifosfamide 2 g/m2 (+ Mesna 4 g) day 1 and 2 given every 2 weeks and followed by G-CSF (Neupogen, Amgen Roche 5 micrograms/kg/day s.c. day 4-14). Twenty-seven (50%) patients could not receive the total of six courses, seven because of severe septic complication, 10 because of Grade 4 thrombopenia, seven because of non-response and three because of patient refusal. Chemotherapy had to be delayed in 58 out of the 244 administered courses and this was due to thrombopenia in 48% of cases. The probability of optimal dose-on-time administration was 64% at three courses. The mean actually received dose intensity was 93% at six courses (27 patients treated). It was increased by 76% compared to our previously published conventional 3-week interval chemotherapy. The median neutrophil nadirs were stable during the successive treatment courses while haemoglobin and platelet values significantly worsened from cycle 1 to cycle 6. The overall response rate after three courses was 77% in the 48 evaluable patients. The median survival is 8 months overall and 5 months disease free. The actuarial survival is 22% at 2 years. We conclude that substantial dose intensification with accelerated chemotherapy and G-CSF support is feasible. However, the rate of severe infectious episodes is too high and thrombopenia is the main limiting factor. Either growth factors active on the megacaryocytic lineage or haematological rescue with peripheral blood stem cells might be useful in this setting.

Selecting high-risk early breast cancer patients: what to add to the number of metastatic nodes?

High-risk early breast cancer patients are usually identified by the number of metastatic axillary nodes. To study whether other easily and inexpensively detectable morphological factors are able to detect high-risk patients, we performed a retrospective analysis of tumor size, and skin/fascia and nipple invasion. The data consisted of 941 node-positive cases registered between 1978 and 1991. Tumour size, and skin/fascia and nipple invasion were closely associated with the number of metastatic nodes (chi 2 test). The number of metastatic nodes, tumour size, skin/fascia and nipple invasion significantly affected disease free survival (DFS) and overall survival (OS) at univariate analysis. These results were confirmed by multivariate analysis with a model containing the number of metastatic nodes, tumour diameter categories, skin/fascia invasion, nipple invasion and adjuvant therapy as covariates: all variables significantly and independently affected risk of relapse and of death. All the variables studied were prognostic, within individual nodal categories, for both DFS and OS. In conclusion, the number of metastatic nodes is not the only prognostic tool with which to select high-risk patients for new intensive adjuvant programmes. Tumour size, and skin/fascia invasion or nipple invasion, taken singly or combined, are valuable prognostic factors that can identify patients with few metastatic nodes and poor outcome. On the basis of our data, we believe that a reconsideration of the pT4 category within the pTNM classification is in order, that is, chest wall invasion should be substituted by fascia invasion, and combined skin/fascia invasion could be a subcategory of each class defined by tumour size.

Promising new therapies in the treatment of advanced ovarian cancer

Advanced stage ovarian cancer is the most lethal gynecologic cancer. Despite initial response rates of 60-80% with platinum-based chemotherapy, more than 75% of women with this malignancy die of complications associated with this disease. There is a pressing need to find new chemotherapeutic agents for patients with advanced ovarian cancer. Phase II studies have identified paclitaxel as the most active drug in ovarian cancer since the introduction of cisplatin in the 1970s. Phase III studies will define the role of paclitaxel as initial therapy. Camptothecins (topotecan, CPT-11, 9-amino-camptothecin) inhibit topoisomerase I. CPT-11 and topotecan have shown activity in Phase II trials. Gemcitabine, a pyrimidine antimetabolite, has shown activity in Phase II trials. Other promising drugs (docetaxel, treosulfan) are under investigation. Modulation of drug resistance is being explored in Phase I/II studies. Clinical trials have been initiated with buthionine-sulfoximine, an inhibitor of glutathione biosynthesis, which decreases the ability of resistant cells to inactivate platinum compounds and alkylating agents. Cyclosporin has been shown to increase cisplatin cytotoxicity. Phase I trials have demonstrated the feasibility of combining cyclosporin and cisplatin. Phase II trials of cyclosporin analogs (PSC 833) and paclitaxel in refractory ovarian cancer are ongoing. Promising leads in drug development should provide new therapies for patients with ovarian cancer. Further research in the modulation of drug resistance may identify new mechanisms or strategies with which to prevent the emergence of drug resistance.

High-dose therapy with autologous bone marrow stem cell support in primary and metastatic human breast cancer. A review

A dose-response relationship has been demonstrated for metastatic human breast cancer. This increased response using moderately increased doses is generally not translated into an improved survival. The use of high-dose therapy to selected patients with metastases/recurrence responding to conventional doses of polychemotherapy may lead to an improved survival tail. Conventional doses of polychemotherapy in the adjuvant setting will reduce the relative mortality by around 25% 10 years after primary diagnosis. The use of high-dose therapy supported by autologous bone marrow stem cells may be markedly more effective in the adjuvant setting, especially to high-risk patients, compared with standard polychemotherapy. Several randomized studies are being planned or have already started in order to answer different aspects of this issue.

Dealing with initial chemotherapy doses: a new basis for treatment optimisation in limited small-cell lung cancer

Treatment of patients with small-cell lung cancer (SCLC) remains disappointing despite initially high complete response rates. The dramatic initial chemosensitivity of tumor cells is rapidly thwarted by the early emergence of chemoresistant clonogenic cells, regardless of front line treatments. Although a dose-response relationship is well established its effect on survival is inconclusive. From 1980 to 1988, 202 patients with limited SCLC were included in four consecutive trials using an alternating schedule of thoracic radiotherapy and chemotherapy. Despite an increase in chemotherapy and/or the total radiation dose, no significant difference was observed between the four trials in terms of response, disease-free or overall survival. However, a retrospective analysis performed on a total of 131 consecutive patients led us to postulate that a moderate increase in the initial dose, i.e. first course, of cisplatin and cyclophosphamide, could improve overall survival. From 1988 to 1991, 105 consecutive patients were included in a large randomized trial to address this question. The difference in treatment options only concerned the initial doses of cisplatin (80 vs. 100 mg/m2) and cyclophosphamide (900 vs. 1200 mg/m2). According to the triangular test used in this study the trial was closed after inclusion of 105 patients, 32 months after the start of the study because, at that time, overall survival was significantly better in the higher-dose group (p = 0.001). This debatable concept of dose-intensity having an impact on survival offers new possibilities for the management of SCLC. The contribution of hematopoietic support may help to validate this concept.

Pilot study of a high-dose carboplatin-based salvage strategy for relapsing or refractory germ cell cancer

Eleven patients with germ cell cancer relapsing from a complete remission and 7 patients with refractory germ cell cancer and/or an unresectable partial remission received salvage chemotherapy with one to two courses of carboplatin (800 mg/m2) and etoposide (500 mg/m2 on days 1, 3, and 5), followed by either one or two courses of carboplatin (1600 mg/m2), cyclophosphamide (6 g/m2), and thiotepa (480 mg/m2) divided over 4 days with autologous bone marrow transplantation and/or peripheral stem cell support. Eight of 11 relapsing patients (73%) were salvaged (with a follow-up of 21+ to 56+ months), but only 1 of the 7 refractory patients survived (34+ months). The high-dose carboplatin-based salvage regimen is feasible and deserves further evaluation in patients relapsing from a complete remission. Even more intensive treatment strategies may be required to salvage patients who are refractory to standard doses of platinating agents.

Phase II trial of intravenous melphalan in advanced colorectal carcinoma

BACKGROUND

Relatively few studies have examined the activity of alkylating agents in the treatment of advanced colorectal adenocarcinoma. Recent reports have suggested possible therapeutic activity for high-dose intravenous melphalan administered with autologous bone marrow transplantation (BMT) support. We conducted a phase II study to determine the efficacy of administering intravenous melphalan at doses that do not require BMT support in patients with advanced colorectal adenocarcinoma.

PATIENTS AND METHODS

Fifteen patients with histologically proven, bidimensionally measurable disease were treated. The starting dose of melphalan was 30 mg/m2, with dose escalation permitted.

RESULTS

No objective responses were observed. Toxic effects were primarily reversible granulocytopenia and thrombocytopenia. There were no treatment-associated deaths.

CONCLUSION

Melphalan's lack of efficacy at the doses administered does not disprove the steep chemotherapy dose-response relationship postulated for many solid tumors. However, we feel that it is unlikely that repetitive courses of high dose melphalan with autologous BMT support will be a practical approach to the management of advanced colorectal adenocarcinoma.

Initial chemotherapeutic doses and survival in patients with limited small-cell lung cancer

BACKGROUND

Moderate increases in the initial doses of certain chemotherapeutic drugs, such as cisplatin and cyclophosphamide, may prolong overall survival in patients with limited small-cell lung cancer.

METHODS

We conducted a prospective study of 105 patients with limited small-cell lung cancer. The patients were randomly assigned to receive higher or lower initial doses of cisplatin (100 or 80 mg per square meter of body-surface area) and cyclophosphamide (300 or 225 mg per square meter daily for four days); all patients received the same doses of doxorubicin and etoposide. The first course of chemotherapy was followed by five additional courses and by three courses of radiotherapy. All patients received the lower doses of cisplatin and cyclophosphamide and the same doses of doxorubicin and etoposide from the second through the sixth cycle of chemotherapy.

RESULTS

The median follow-up was 33 months. The two-year survival rate for the 55 patients who received the higher doses of chemotherapy was 43 percent, as compared with 26 percent for the 50 patients who received the lower doses (P = 0.02). The rates of complete response at six months were 67 percent in the higher-dose group and 54 percent in the lower-dose group (P = 0.16). Disease-free survival at two years was 28 percent in the higher-dose group, as compared with 8 percent in the lower-dose group (P = 0.02). Side effects from treatment were not increased in the higher-dose group.

CONCLUSIONS

Higher initial doses of cyclophosphamide and cisplatin improve disease-free and overall survival in patients with limited small-cell lung cancer.