Michaele C. Christian

New Guidelines to Evaluate the Response to Treatment in Solid Tumors

Anticancer cytotoxic agents go through a process by which their antitumor activity-on the basis of the amount of tumor shrinkage they could generate-has been investigated. In the late 1970s, the International Union Against Cancer and the World Health Organization introduced specific criteria for the codification of tumor response evaluation. In 1994, several organizations involved in clinical research combined forces to tackle the review of these criteria on the basis of the experience and knowledge acquired since then. After several years of intensive discussions, a new set of guidelines is ready that will supersede the former criteria. In parallel to this initiative, one of the participating groups developed a model by which response rates could be derived from unidimensional measurement of tumor lesions instead of the usual bidimensional approach. This new concept has been largely validated by the Response Evaluation Criteria in Solid Tumors Group and integrated into the present guidelines. This special article also provides some philosophic background to clarify the various purposes of response evaluation. It proposes a model by which a combined assessment of all existing lesions, characterized by target lesions (to be measured) and nontarget lesions, is used to extrapolate an overall response to treatment. Methods of assessing tumor lesions are better codified, briefly within the guidelines and in more detail in Appendix I. All other aspects of response evaluation have been discussed, reviewed, and amended whenever appropriate.

Relationships between drug activity in NCI preclinical in vitro and in vivo models and early clinical trials

An analysis of the activity of compounds tested in pre-clinical in vivo and in vitro assays by the National Cancer Institutes Developmental Therapeutics Program was performed. For 39 agents with both xenograft data and Phase II clinical trials results available, in vivo activity in a particular histology in a tumour model did not closely correlate with activity in the same human cancer histology, casting doubt on the correspondence of the pre-clinical models to clinical results. However, for compounds with in vivo activity in at least one-third of tested xenograft models, there was correlation with ultimate activity in at least some Phase II trials. Thus, an efficient means of predicting activity in vivo models remains desirable for compounds with anti-proliferative activity in vitro. For 564 compounds tested in the hollow fibre assay which were also tested against in vivo tumour models, the likelihood of finding xenograft activity in at least one-third of the in vivo models tested rose with increasing intraperitoneal hollow fibre activity, from 8% for all compounds tested to 20% in agents with evidence of response in more than 6 intraperitoneal fibres (P< 0.0001). Intraperitoneal hollow fibre activity was also found to be a better predictor of xenograft activity than either subcutaneous hollow fibre activity or intraperitoneal plus subcutaneous activity combined. Since hollow fibre activity was a useful indicator of potential in vivo response, correlates with hollow fibre activity were examined for 2304 compounds tested in both the NCI 60 cell line in vitro cancer drug screen and hollow fibre assay. A positive correlation was found for histologic selectivity between in vitro and hollow fibre responses. The most striking correlation was between potency in the 60 cell line screen and hollow fibre activity; 56% of compounds with mean 50% growth inhibition below 10–7.5 M were active in more than 6 intraperitoneal fibres whereas only 4% of compounds with a potency of 10–4 M achieved the same level of hollow fibre activity (P< 0.0001). Structural parameters of the drugs analysed included compound molecular weight and hydrogen-bonding factors, both of which were found to be predictive of hollow fibre activity.

New cisplatin analogues in development : a review

SummaryCisplatin was discovered to have cytotoxic properties in the 1960s, and by the end of the 1970s it had earned a place as the key ingredient in the systemic treatment of germ cell cancers. Since the early seminal work in the preclinical and clinical development of this drug, several thousand analogues have been synthesised and tested for properties that would enhance the therapeutic index of cisplatin. About 13 of these analogues have been evaluated in clinical trials, but only one (carboplatin) has provided definite advantage over cisplatin and achieved worldwide approval. However, carboplatin has afforded benefit only in reducing some cisplatin toxicities; it has not enlarged the spectrum of platinum-sensitive cancers, nor has it proved active in cisplatin-resistant cancers.The major obstacle to the efficacy of cisplatin or carboplatin is platinum resistance, either innate or acquired. The mechanisms of this resistance have been under intense study, and many of the cisplatin analogues synthesised in the past decade have been designed specifically with the hope of overcoming platinum resistance. The mechanism of the cytotoxic activity of platinum complexes has also been studied intensely. Recently synthesised analogues have been designed to interact with DNA in a manner different from cisplatin and carboplatin, with the desire of finding new structures with a superior or wider spectrum of antitumour efficacy. Most recently, water soluble platinum complexes that retain antitumour activity, but that can be effectively absorbed after oral administration, have been synthesised with the goal of improving patient quality of life.Nine platinum analogues are currently in clinical trials around the world (ormaplatin [tetraplatin], oxaliplatin, DWA2114R, enloplatin, lobaplatin, CI-973 [NK-121], 254-S, JM-216 and liposome-entrapped cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum (II) [L-NDDP]). Some of these analogues only represent attempts to reduce cisplatin toxicity and/or allow administration without forced hydration and diuresis, which carboplatin already does. Others are ‘third generation’ complexes shown to have limited or no cross-resistance with cisplatin in preclinical studies. They are being tested clinically with particular attention to this highly desirable property. Some of these complexes will undoubtedly disappear into oblivion as have most of their predecessors. It is hoped that the 1990s will see the development (and worldwide registration) of another platinum complex that represents a step forward in cancer therapy, perhaps one active in cisplatin-refractory cancers and/or capable of being administered orally.

Clinical Trial Designs for Cytostatic Agents: Are New Approaches Needed?

Preclinical data suggest that some new anticancer agents directed at novel targets demonstrate tumor growth inhibition but not tumor shrinkage. Such cytostatic agents may offer clinical benefits for patients in the absence of tumor shrinkage. In addition, lower doses of some of these agents may be just as effective as higher doses, implying that toxicity may not be an ideal end point for dose finding. Because of these factors, the sequence and design of traditional phase I, II, and III trials used for cytotoxic agents (which typically shrink tumors and in a dose-dependent manner) may not be appropriate for cytostatic agents. This article discusses options for modifying trial designs to accommodate cytostatic agents. Examples are given where these options have been tried or are currently being tried. Recommendations given for choosing among the trial designs depend on what is known preclinically about the agents (eg, does one have a validated and reproducible biologic end point that can be used to guide a dose escalation?), what is known about the patient population being studied (eg, does one have a well-documented historical progression-free survival rate at 1 year for comparison with the experience of the new agent?), and the numbers of agents and patients available for participation in trials. Planned and ongoing trials will test the utility of some of these new approaches.

Cardiac disturbances during the administration of taxol.

The clinical development of taxol, a new antimicrotubule agent with a unique mechanism of cytotoxic action, has proceeded slowly due to serious hypersensitivity reactions (HSRs) and shortages in its supply. Nevertheless, large-scale phase II trials have been initiated as taxol has recently demonstrated impressive activity in advanced and cisplatin-refractory ovarian carcinoma. Furthermore, the incidence of HSRs has been reduced substantially with premedications and modifications in the administration schedule. However, various manifestations of potential cardiotoxicity have been observed in several patients who participated in four phase I and II studies of taxol. Asymptomatic bradycardia has occurred in a high proportion of patients, including 29% of ovarian cancer patients who were treated with maximally tolerated doses of taxol in a phase II study. More profound cardiac disturbances, including a range of atrioventricular conduction blocks, left bundle branch block, ventricular tachycardia (VT), and manifestations of cardiac ischemia, have been observed in seven of 140 patients (5%) who received taxol. Descriptions of these events are presented in this report to alert investigators to the potential for these adverse effects. Although these disturbances did not result in serious sequelae in most patients, investigators should continue to maintain a high degree of caution until precise risk factors, frequency, and clinical significance of these adverse cardiac effects are determined.

Paclitaxel for platinum-refractory ovarian cancer: results from the first 1,000 patients registered to National Cancer Institute Treatment Referral Center 9103.

PURPOSE To provide an investigational drug, paclitaxel, now commercially available, to women with refractory ovarian cancer and to evaluate response and toxicity in these patients. PATIENTS AND METHODS Patients with platinum-refractory ovarian cancer, Eastern Cooperative Oncology Group (ECOG) performance status 0 to 3, at least three prior chemotherapy regimens, adequate hepatic and renal function, and no significant cardiac history were eligible. Patients were treated with paclitaxel 135 mg/m2 administered by 24-hour continuous intravenous infusion every 3 weeks. RESULTS Leukopenia was the most frequent toxicity, with 78% of patients experiencing grade 3 or 4 toxicity. Other grade 3 and 4 toxicities were less common: fever (33%), infection (12%), thrombocytopenia (8%), vomiting (7%), cardiac (2%), neurologic (2%), and mucositis (1%). Fifteen treatment-related deaths (1.5%) were reported. The objective response rate was 22% (4% complete response [CR], 18% partial response; 95% confidence interval [CI] for overall response, 19% to 25%). The median time to progression from treatment initiation was 7.1 months in responding patients and 4.5 months for all patients. The median survival duration was 8.8 months. CONCLUSION Paclitaxel has shown activity in women with platinum-refractory ovarian cancer, and it can be administered with an acceptable safety profile. Further research is needed to determine the optimal role of paclitaxel in the primary and salvage treatment of ovarian cancer.

Paclitaxel activity in heavily pretreated breast cancer: a National Cancer Institute Treatment Referral Center trial.

PURPOSE To provide paclitaxel, an investigational drug at the inception of this study, to women with chemotherapy-refractory metastatic breast cancer and to evaluate response and toxicity in these patients. PATIENTS AND METHODS Two hundred sixty-seven patients with progressive disease (PD) following at least two chemotherapy regimens for metastatic breast cancer and a contraindication to further doxorubicin treatment received paclitaxel either at 175 mg/m2 intravenously (IV) over 24 hours or at 135 mg/m2 if they had prior irradiation to 30% of marrow-bearing bone or a cumulative dose of mitomycin > or = 20 mg/m2. RESULTS In a subgroup of patients (n = 172) with measurable disease, four complete responses (CRs) and 36 partial responses (PRs) occurred, for an overall response rate of 23% (95% confidence interval [CI], 17% to 30%). No differences in response rates were noted according either to the number of prior chemotherapy regimens received or to whether patients were considered refractory to doxorubicin. The dose and schedule used in this trial resulted in febrile neutropenia in 45% of patients and a hospitalization rate of 49%. CONCLUSION Paclitaxels activity in this multiinstitutional trial in heavily pretreated patients confirms the encouraging results attained in single-institution trials. Although at this dose and schedule paclitaxel may be considered too myelosuppressive for palliative care, supportive measures such as colony-stimulating factors and antibiotics were not used prophylactically. Current research efforts are focusing on whether paclitaxels activity against breast cancer is dose- and/or schedule-dependent, and on what role it has in patients with less advanced disease.

The National Cancer Institute Audit of the National Surgical Adjuvant Breast and Bowel Project Protocol B-06

BACKGROUND The National Surgical Adjuvant Breast and Bowel Project (NSABP) Protocol B-06, a clinical trial sponsored by the National Cancer Institute (NCI), has provided evidence of the value of lumpectomy and breast irradiation for treating women with breast cancer in an early stage. Publicity generated by the discovery that the study included fraudulent data on patients enrolled by St. Luc Hospital in Montreal aroused concern about the overall accuracy of the data and conclusions. To address this concern, the NCI conducted an audit of other participating institutions. METHODS In 1994, data on 1554 of the 1809 randomized patients (85.9 percent) enrolled by centers other than St. Luc Hospital were audited at 37 clinical sites in North America. The audit included data on eligibility, survival, disease-free survival, the length of time to a recurrence of cancer in the ipsilateral breast, and documentation of signed informed consent. RESULTS End points were assessed for all 1554 patients, and eligibility was assessed for 1507 patients; 47 patients were excluded because their forms were not complete or not returned. A total of 1429 patients had their eligibility status verified. Of a total of 7770 data points examined with respect to the number of positive nodes at base line, treatment characteristics, first events (excluding death), recurrence of cancer in the ipsilateral breast, and survival, 7577 (97.5 percent) were verified, 123 (1.6 percent) could not be verified, and 70 (0.9 percent) were discrepant with the NSABP file. Of the 1554 patients, 1340 (86.2 percent) had all audited items (including eligibility) verified, 69 (4.4 percent) had at least one discrepant item, and 113 (7.3 percent) had at least one unverified item (as a result of missing or incomplete data); 32 (2.1 percent) were not assessed for eligibility but had no other discrepant or unverifiable items. Written informed consent was documented for 1098 patients before surgery and 210 after surgery; no date appeared on the signed form for 137. The informed-consent status was not verified for 71 patients and could not be determined for 38. The rates of verification of end-point data and documentation of written informed consent were similar among the total-mastectomy group, the lumpectomy group, and the group treated by lumpectomy and breast irradiation. CONCLUSIONS The audit confirms the adequacy of the data on which the reanalysis of Protocol B-06 and the results after 12 years of follow-up are based.

Novel Designs and End Points for Phase II Clinical Trials

The large number of negative phase III trials in oncology over the last several years has renewed interest in refining phase II oncology clinical trials to maximize the chances of success in phase III testing. More efficient phase II study designs will improve our ability to identify promising agents for testing while accurately identifying nonefficacious agents. Recognizing that new paradigms of phase II trial designs need to be developed, the Clinical Trial Design Task Force of the National Cancer Institute (NCI) Investigational Drug Steering Committee has tackled the question of improving efficiency of phase II clinical trials. In this issue of CCR Focus, four of the major topics discussed are presented. First, the task force recommended that alternate phase II end points should be studied. Second, depending on the characteristics of the specific trial and study population, historical controls or a randomized design may be more appropriate. Third, rational incorporation of biomarkers into phase II trials should be encouraged. Last, novel imaging modalities will be critical in evaluating the clinical benefit of new cytostatic agents.

Clinical Trial Designs for Cytostatic Agents

To the Editor: We read with great interest the special article on clinical trial designs for cytostatic agents written by Cancer Therapy Evaluation Program (CTEP) investigators, 1 having recently authored a similar article ourselves. 2 It is widely recognized that the historical approach to oncology drug development cannot be explicitly used for putative cytostatic agents. This is particularly applicable to phase II trials, where the historical approach of using small cohorts to look for a minimum response rate will clearly fail for drugs for which a classical partial response is not anticipated. 3 Korn et al suggest that progression-free survival in a 30to 50-patient cohort can be compared with that of historical controls. In our opinion, this approach is unlikely to be of benefit because of selection bias, lack of standardized data collection in many historical series, as well as the recent change in criteria for response and progression developed in part by CTEP investigators. 4