Optimal two-stage designs for phase II clinical trials

Double modulation of 5-fluorouracil in advanced colorectal cancer with low-dose interferon-alpha 2b and folinic acid. The "GISCAD" experience. Italian Group for the Study of Digestive Tract Cancer

In advanced colorectal cancer the addition of folinic acid (FA) has been shown to lead to increased activity, at least in terms of response rate, in comparison with 5-fluorouracil (5FU) alone. Similarly, interferon-alpha (IFN) is able to potentiate 5FU, although high doses cause heavy toxicity. Given the different mechanisms of action of the two agents, the double modulation of 5FU deserves clinical evaluation. In a multicenter study (involving both primary care and referral institutions) 63 patients with advanced colorectal cancer, previously untreated with chemotherapy, received, in an outpatient setting, FA (200 mg/m2 i.v. bolus) + 5FU (400 mg/m2 i.v. in 15 min) for 5 consecutive days every 4 weeks + IFN 3 x 10(6) U on alternate days, starting 1 week before chemotherapy. During the 5 days of 5FU + FA, IFN was administered daily. The antitumour activity, the impact on response duration and survival and toxicity of the combination were evaluated according to WHO criteria. Of the 63 enrolled patients, 56 were evaluable: there were 2 complete responses (3%) and 13 partial responses (21%), giving an objective response rate of 24% (95% confidence interval 13-35%); no change was observed in 17 cases and progressive disease in 24. Median duration of response was 9 months and median survival (all patients) 13 months. Toxicity was acceptable, even though 4 patients presented reversible grade 4 side-effects (2 mucositis and 2 diarrhoea). With this schedule and these doses, addition of IFN did not lead to any increase in the activity of 5FU + FA. In colorectal cancer, further clinical studies with these drugs should be based on a deeper experimental knowledge of their mechanisms of interaction.

Chemoimmunotherapy of metastatic malignant melanoma. The Salpétrière Hospital (SOMPS) experience

Optimistic results were obtained in the treatment of 39 patients with surgically incurable metastatic malignant melanoma using a regimen including 2 to 3 monthly induction cycles of cis-diamminedichloroplatinum (CDDP), recombinant interleukin-2 (rIL-2) and interferon alpha-2a (IFN alpha-2a). 33 of 39 patients were pretreated with chemotherapy (dacarbazine and/or fotemustine:31, CDDP:6) and 17 of 39 with IFN alpha-2a. Overall response rate was 54% with 13% achieving a complete response for up to 59+ weeks. Moderate to severe side-effects were reversible on rIL-2 cessation and toxicity was manageable in a routine inpatient setting. These results are especially encouraging as they were seen in previously treated patients, classically low responders, including 3 who were resistant to cisplatin or other platinum complexes. The question remains if this regimen bypasses traditional mechanisms of drug resistance.

High dose-intensity chemotherapy, with accelerated cyclophosphamide-doxorubicin-etoposide and granulocyte-macrophage colony stimulating factor, in the treatment of small cell lung cancer

15 patients with small-cell lung cancer were treated with an "accelerated" chemotherapy consisting of standard-dose cyclophosphamide-doxorubicin-etoposide administered every 15 days (as opposed to the usual 21-day intervals) along with granulocyte-macrophage colony stimulating factor (10 micrograms/kg/day) administered prophylactically subcutaneously from day 4 to 13. The primary objective of this study was to examine the possibility of achieving a 50% dose-intensity increase by a shortening of chemotherapy intervals. 9 patients were not able to complete the planned six courses of chemotherapy owing to cumulative haematological toxicity. In fact, while leukopenia was acceptable and constant during treatment, both thrombocytopenia and anaemia progressively worsened with subsequent courses, becoming particularly severe after the 4th cycle when interruption of the treatment was often required. 13 patients who completed four courses of chemotherapy received a median of 96% of the planned dose-intensity. This corresponded with an average relative dose-intensity actually delivered of 1.44 compared with the planned dose-intensity of a standard cyclophosphamide-doxorubicin-etoposide every 21 days. In conclusion, acceleration of cyclophosphamide-doxorubicin-etoposide chemotherapy combined with granulocyte-macrophage colony stimulating factor can lead to a significant increase of dose-intensity but it is feasible only for a limited number of courses.

Planned versus attained design in phase II clinical trials

The standard phase II trial problem is to decide whether or not to continue the testing of a new agent (or combination). Typically, one tests the null hypothesis HO: p = pO against the alternative HA: p = pA, where p is the probability of response. There is available a variety of two-stage phase II designs, including optimal designs according to various criteria. Practical considerations in the conduct of multicentre trials, however, make it difficult to follow designs precisely. We investigate several approaches to adapting stopping rules when the attained sample size is not the planned size. We find that a simple approach of testing HA: p = pA at the 0.02 level at the first stage and HO: p = pO at the 0.055 level at the second stage works well across a variety of powers, pOs and pAs.

Phase II study of 5-fluorouracil plus leucovorin and interferon alpha 2b in advanced colorectal cancer

15 untreated patients with advanced measurable colorectal cancer along with other 29 patients in progression after failing first line chemotherapy with fluoropyrimidines received 5-fluorouracil (5FU) 500 mg/m2 given as a weekly bolus at mid-infusion of leucovorin (LV), 500 mg/m2 administered intravenously over 2 h and interferon alpha 2b (IFN) 3 x 10(6) U given intramuscularly every other day. All patients had their previous chemotherapy at least 4 weeks prior to 5FU-LV-IFN. 5 patients discontinued the three drug regimen due to toxicity (intense weakness, fever and influenza-like symptoms in 4 patients; diarrhoea in 1 patient) however no grade IV toxicity was observed. IFN administration was reduced to twice/weekly in 5 patients due to influenza-like symptoms. 1 complete response and 5 partial responses were observed (13.6% response rate); the complete response was obtained in a patient resistant to 5FU: the response rate was only twice as much in untreated patients (3/15 patients, 20%) compared with that in patients previously treated with fluoropyrimidines (3/29 patients, 10.3%). Therefore, modulation of 5FU with LV plus IFN at the doses and schedules employed in this study may rarely overcome clinical resistance to the fluoropyrimidine and the addition of IFN does not appear to enhance the activity of 5FU plus LV.

A decade of progress in statistical methodology for clinical trials

Clinical trials played a dominant and expanding role in the evaluation of new treatments during the decade of the 1980s. There were major improvements in the quality of clinical trials in many medical fields. There were also important developments in the methodology of designing, monitoring, conducting, analysing, reporting and interpreting clinical trials. This paper attempts to review some of these developments. A comprehensive review is beyond the abilities of any one individual. Consequently, this paper attempts to offer a broad stroke description of this area and to highlight specific topics of importance based on my particular experience. An extensive, but non-comprehensive bibliography is included to provide entry points to the literature of methodologic developments for clinical trials in the 1980s.

A comparative phase II clinical trials procedure for choosing the best of three treatments

In some clinical trials one can employ adaptive designs advantageously, although in practice such techniques are rarely used, in part due to their inherent complexity. A simple and practicable decision-theoretic approach for the case of three treatments with binary responses is considered, using equal allocation to remaining treatments and, once eliminated, a treatment cannot be re-employed. Having specified the overall number of patients treated within and beyond the comparative stages of the trial, the goal is to maximize the expected total number of those successfully treated. Investigation of the method involves a computer program that can handle arbitrarily large numbers of patients. It is shown empirically that the decision procedure behaves only marginally worse than if the truly superior treatment had been known and had been given to all patients. Implementation of the method uses a minimax approach that removes dependence on prior parameters. Primarily an identification procedure, one advantage of this approach over traditional hypothesis testing methods is the potential to detect small improvements in treatment efficacy. The intended application is to assist in treatment selection during phase II trials, especially with rapid responses and when the disease involved is serious enough that design-motivating ethical considerations become paramount.

Application of the triangular test to phase II cancer clinical trials

Phase II cancer clinical trials are primarily designed to determine whether the response rate p to the treatment under study is greater than a specified value p0, that is to test the null hypothesis H0: p less than or equal to p0 against an alternative hypothesis H1 : p greater than p0 specified by p = p1. As an alternative to the single and multistage procedures and to Wald's continuous sequential probability ratio test (SPRT), we applied the group sequential methods proposed by Jones and Whitehead, namely the triangular test (TT) and the discrete SPRT, to the comparison of p with p0, and we expressed H0 and H1 in terms of the log odds-ratio statistic log [p(1 - p0)/p0(1 - p)]. A stimulation study showed that both the TT and the discrete SPRT had type I error and power close to the nominal values, and they compared favourably with multistage methods in terms of the average sample size.