Response rate as an endpoint for evaluating new cytotoxic agents in phase II trials of non-small-cell lung cancer

Strength of Validation for Surrogate End Points Used in the US Food and Drug Administration's Approval of Oncology Drugs

OBJECTIVE

To determine the strength of the surrogate-survival correlation for cancer drug approvals based on a surrogate.

PARTICIPANTS AND METHODS

We performed a retrospective study of the US Food and Drug Administration (FDA) database, with focused searches of MEDLINE and Google Scholar. Among cancer drugs approved based on a surrogate end point, we examined previous publications assessing the strength of the surrogate-survival correlation. Specifically, we identified the percentage of surrogate approvals lacking any formal analysis of the strength of the surrogate-survival correlation, and when conducted, the strength of such correlations.

RESULTS

Between January 1, 2009, and December 31, 2014, the FDA approved marketing applications for 55 indications based on a surrogate, of which 25 were accelerated approvals and 30 were traditional approvals. We could not find any formal analyses of the strength of the surrogate-survival correlation in 14 out of 25 accelerated approvals (56%) and 11 out of 30 traditional approvals (37%). For accelerated approvals, just 4 approvals (16%) were made where a level 1 analysis (the most robust way to validate a surrogate) had been performed, with all 4 studies reporting low correlation (r≤0.7). For traditional approvals, a level 1 analysis had been performed for 15 approvals (50%): 8 (53%) reported low correlation (r≤0.7), 4 (27%) medium correlation (r>0.7 to r<0.85), and 3 (20%) high correlation (r≥0.85) with survival.

CONCLUSIONS

The use of surrogate end points for drug approval often lacks formal empirical verification of the strength of the surrogate-survival association.

Drugs for solid cancer: the productivity crisis prompts a rethink

Despite remarkable progress in cancer-drug discovery, the delivery of novel, safe, and sustainably effective products to the clinic has stalled. Using Src as a model, we examine key steps in drug development. The preclinical evidence on the relationship between Src and solid cancer is in sharp contrast with the modest anticancer effect noted in conventional clinical trials. Here, we consider Src inhibitors as an example of a promising drug class directed to invasion and metastasis and identify roadblocks in translation. We question the assumption that a drug-induced tumor shrinkage in preclinical and clinical studies predicts a successful outcome. Our analysis indicates that the key areas requiring attention are related, and include preclinical models (in vitro and mouse models), meaningful clinical trial end points, and an appreciation of the role of metastasis in morbidity and mortality. Current regulations do not reflect the natural history of the disease, and may be unrelated to the key complications: local invasion, metastasis, and the development of resistance. Alignment of preclinical and clinical studies and regulations based on mechanistic trial end points and platforms may help in overcoming these roadblocks. Viewed kaleidoscopically, most elements necessary and sufficient for a novel translational paradigm are in place.

Assessing tumor response to therapy

Most anticancer drugs are effective only in subgroups of patients, and our current understanding of tumor biology does not allow us to predict accurately which patient will benefit from a specific therapeutic regimen. Various techniques have, therefore, been developed for monitoring tumor response to therapy, but measuring tumor shrinkage on CT represents the current standard. Although response assessment on CT has been refined over many years, fundamental limitations remain. Interobserver variability in tumor size measurements is still high because of difficulties in delineating tumor tissue from secondary changes in the surrounding tissues. Furthermore, CT is inaccurate in differentiating viable tumor from necrotic or fibrotic tissue. Consequently, the degree of response may be underestimated on CT. Conversely, if tumor shrinkage is short lived and followed by rapid tumor regrowth, CT may overestimate the beneficial effects of a treatment. Finally, CT is limited in characterizing responses in tumors that do not change in size during therapy. Because the growth rate of untreated human tumors varies tremendously, an unchanged tumor size after some weeks of therapy may represent a drug effect but may also indicate a slowly growing tumor that was not affected by the applied therapy. Molecular imaging with PET and the glucose analogue (18)F-FDG PET has been shown to improve response assessment in several tumor types. In malignant lymphoma, international criteria for monitoring response to therapy have recently been revised, and the (18)F-FDG signal now plays a central role in defining tumor response. In a variety of solid tumors, single-center studies have indicated that (18)F-FDG PET may provide earlier or more accurate assessment of tumor response than CT, suggesting that (18)F-FDG PET could play a significant role in personalizing the treatment of malignant tumors. However, generally accepted criteria for response assessment in solid tumors are missing, which makes it frequently impossible to compare the results of different studies. International guidelines and criteria for response assessment by (18)F-FDG PET in solid tumors are, therefore, eagerly awaited.

A phase II randomized trial of gemcitabine-docetaxel versus gemcitabine-cisplatin in patients with advanced non-small cell lung carcinoma

PURPOSE

To test efficacy and tolerability of non-platinum regimens for advanced non-small-cell lung cancer (NSCLC).

METHODS

Chemonaive patients with measurable stage IIIB/IV NSCLC treated with gemcitabine and cisplatin (GC), or gemcitabine and docetaxel (GD), maximumsix cycles in a phase IIB trial.

RESULTS

A total of 108 patients were randomized. Response rates (GC vs. GD, respectively): complete 3.6/2.0%, Partial 30.9/38.0%. Median Overall Survival (OS): 8.9 months in both groups (P = 0.53); and median time to progression (TTP): 6.2/5.5 months respectively (P = 0.61). Toxicities included (GC vs. GD, respectively): grade 3-4 neutropenia 49.1/41.2%; grade 3 thrombocytopenia 30.9/3.9%; grade 3 anemia 14.5/3.9%. Non-haematological toxicity was similar, except for nausea and vomiting, (16.3/2%); renal toxicity (3.7/0%) and hepatic toxicity (5.6/12.7%).

CONCLUSIONS

With a higher overall response rate and lower toxicity, GD is a good first treatment option for advanced NSCLC.

Relationship between Response and Survival in More Than 50,000 Patients with Advanced Non-small Cell Lung Cancer Treated with Systemic Chemotherapy in 143 Phase III Trials

BACKGROUND

The association between the objective response to chemotherapy and survival has not yet been fully evaluated using large cohorts in advanced non-small cell lung cancer.

METHODS

We searched for phase III trials conducted between 1991 and 2006 to investigate the role of systemic chemotherapy for advanced non-small cell lung cancer. Associations were tested by multiple regression analysis.

RESULTS

Of the 1255 trials screened, 143 met our criteria, involving 50,569 patients with 309 chemotherapy regimens. In the first-line setting, the median intention-to-treat objective response rate (ORR) and disease control rate (DCR) were 26.4% and 62.5%, respectively (43,551 randomized patients; 290 trials). The median of the median survival time (MST) was 8.5 months in the first-line setting, and both the ORR and DCR were significantly associated with the MST in the multivariate analysis (regression coefficient = 0.0788 [p < 0.0001] and 0.0794 [p < 0.0001], respectively). Subgroup analysis showed no correlation between the ORR and MST in patients receiving chemotherapy containing molecular-targeted agents (p = 0.3817). In the second-line or later setting, the median ORR was only 6.8%, whereas the median DCR was 42.4% (4318 randomized patients; 19 trials). The median MST (6.6 months) was not associated with the ORR (p = 0.6992), but was associated with the DCR (p = 0.0129), despite the small sample size.

CONCLUSIONS

We found that survival was associated with both the ORR and DCR in the first-line setting, although it should be interpreted cautiously because of the abstracted data-based analysis. Regarding chemotherapy regimens containing molecular-targeted agents and salvage chemotherapy regimens, further assessments are warranted to clarify the association between the parameters.

Common arm analysis: one approach to develop the basis for global standardization in clinical trials of non-small cell lung cancer

The global development of new anticancer treatments is desirable. However, whether results of clinical trials performed in one population can be fully extrapolated to another population remains in question. We retrospectively compared "common arms" of platinum-based doublet phase III trials among Japanese, European, and American patients with non-small cell lung cancer to develop the basis for global standardization in clinical trials. Patient demographics were very similar through all studies, indicating that extrinsic ethnic factors including socioeconomic factors, medical service background, and patient selection process for clinical trials may be consistent between geographically different oncology groups. The doses of docetaxel, gemcitabine, and vinorelbine were lower in Japanese studies. The toxicity profile was generally acceptable and similar among many studies. Thus, the dose and schedule of anticancer agents established in prior phase I and II studies conducted in each country were appropriate and applicable to large patient populations in these countries. Response rates seemed to be distributed randomly from one study to another, whereas patient survival might be better in Japanese studies. In conclusion, geographical differences in the dose of anticancer agents, response, survival and toxicity of lung cancer chemotherapy were actually observed. However, extrapolation of clinical data obtained in one country to another population and global clinical trials were considered possible with adequate dose adjustment based on dose finding studies using a carefully projected protocol.

Cost-minimisation analysis of three regimens of chemotherapy (docetaxel-cisplatin, paclitaxel-cisplatin, paclitaxel-carboplatin) for advanced non-small-cell lung cancer

PURPOSE

To compare the efficiency (the evaluation of efficacy in relation to costs) of three first-line treatment options for advanced non-small cell lung cancer (stage IIIB and IV) used in the Eastern Cooperative Oncology Group (ECOG) study: docetaxel/cisplatin (75/75 mg/m(2)/day, 1 h intravenous (i.v.) infusion of docetaxel), paclitaxel/cisplatin (175/75 mg/m(2)/day, 3 or 24 h i.v. infusion of paclitaxel) and paclitaxel/carboplatin (175/400 or 225/400 mg/m(2)/day, 3 h i.v. infusion of paclitaxel).

METHODS

The results of the ECOG 1594 phase III clinical trial (Proc. Am. Soc. Clin. Oncol. 19 (2000) 2) demonstrated equivalent efficacy (survival, objective response) between the treatment options. To differentiate between the treatment options, we performed a cost-minimisation analysis, using a pharmacoeconomic model.

RESULTS

The average estimated treatment cost per patient (median, 4 cycles) with docetaxel/cisplatin would be 1067836 Spanish pesetas (Ptas) (6418 Euros; 5741 US dollars (USD)), 1365304 or 1439369 Ptas (8205 or 8651 Euros; 7340 or 7738 USD) with paclitaxel/cisplatin (3 or 24 h infusions, respectively), and 1417995 or 1616784 Ptas (8522 or 9717 Euros; 7623 or 8692 USD) (paclitaxel dose of 175 or 225 mg/m(2)/day, respectively) with paclitaxel/carboplatin.

CONCLUSION

According to our study, the treatment option docetaxel/cisplatin, with equal efficacy, would result in a cost saving of between 297468 and 548948 Ptas (1788 and 3299 Euros; 1599 and 2951 USD) per patient treated. This difference is mainly due to the lower treatment cost of docetaxel.

Novel combination chemotherapy in the treatment of non-small cell lung cancer

Treatment of patients with advanced non-small cell lung cancer (NSCLC) remains a vexing problem and long-term survival beyond 5 years is extremely rare. Five new agents, paclitaxel, docetaxel, vinorelbine, gemcitabine and irinotecan, have been introduced for the treatment of NSCLC and investigated extensively both preclinically and clinically. Monotherapy with one of these agents has produced survival benefits over the best supportive care in Phase III studies. Combination chemotherapy with a new agent and platinum produced a higher response rate than conventional cisplatin-based chemotherapy and improved survival was observed in some randomised trials. There was little difference in efficacy and toxicity between the chemotherapeutic regimens with a new agent and a platinum in Phase III trials, suggesting the clinical utility of these regimens is similar. Many trials have focused on regimens containing two new agents, with or without platinum. Preliminary results of Phase III trials of three drug combinations versus two drug combinations suggested the former to be more promising, in terms of response rates and survival. Whether the era of platinum-based chemotherapy in the treatment of NSCLC should continue or not must be determined by Phase III trials, evaluating the use of a platinum agent with one of the new agent combinations. These aggressive chemotherapeutic combinations will hopefully improve survival and quality of life for patients with advanced NSCLC.

Phase I study of cisplatin and docetaxel plus mitomycin C in patients with metastatic non-small cell lung cancer

BACKGROUND

Docetaxel, cisplatin and mitomycin C are some of the active drugs used in the treatment of patients with metastatic non-small cell lung cancer (NSCLC). The purpose of this study was to determine the maximum tolerated dose (MTD) and recommended dose of the three drugs in combination for such patients.

METHODS

Chemotherapy-native patients with metastatic NSCLC were enrolled in this study. The doses of docetaxel and cisplatin were fixed at 60 and 80 mg/m2, respectively. It was planned to increase the dose of mitomycin C from 4 to 6 and 8 mg/m2. All drugs were administered on day 1 and repeated every 3-4 weeks.

RESULTS

All six patients received 60 mg/m2 of docetaxel and 80 mg/m2 of cisplatin, three of them with 4 mg/m2 of mitomycin C (level 1) and the other three with 6 mg/m2 of mitomycin C (level 2). Two of the three level 2 patients experienced dose-limiting toxicities (DLTs) in first cycle: febrile neutropenia and grade 3 hyponatremia. Based on these data, the MTD was concluded to be 60 mg/m2 for docetaxel, 80 mg/m2 for cisplatin and 6 mg/m2 for mitomycin C. Evaluation of the data from all of the cycles, however, showed that four of the six patients experienced DLTs.

CONCLUSIONS

The addition of mitomycin C to docetaxel and cisplatin resulted in relatively high toxicities. It was impossible to use a high enough dose of mitomycin C to improve the survival of NSCLC patients. We therefore concluded that further evaluation of this combination is unwarranted.

Progressive disease rate as a surrogate endpoint of phase II trials for non-small-cell lung cancer

BACKGROUND

Although the potential activity of anticancer agents has been traditionally assessed by the response rate (RR) in phase II trials, there is an increasing need to identify alternative endpoints to evaluate the efficacy of novel types of antineoplastic agents such as cytostatic agents. However, none of the proposed alternatives have been validated.

DESIGN

RR, rate of progressive disease (PD), and median survival time (MST) were obtained from 44 treatment arms in 42 single-agent phase II trials for non-small-cell lung cancer (NSCLC). Correlations between these parameters and their significance in selection of promising drugs were evaluated.

RESULTS

The median (range) RR and PD rate per treatment arm were 17% (0%-40%) and 41% (8%-93%), respectively. The PD rate correlated more closely with MST (correlation coefficient (r) = 0.80, P < 0.001) than did the RR (r = 0.62, P < 0.001). The RR of active agents against NSCLC ranged broadly from 7% to 40%, whereas their PD rates were all 50% or less. In addition, all treatment arms with a PD rate over 50% had a poor MST of six months or shorter.

CONCLUSIONS

The PD rate was potentially as good an endpoint as RR, and it may be a good candidate for the primary endpoint of phase II trials for novel types of anticancer agents.