© 2001 AlphaMed Press
Carboplatin/Paclitaxel or Carboplatin/Vinorelbine Followed by Accelerated Hyperfractionated Conformal Radiation Therapy: A Preliminary Report of a Phase I Dose Escalation Trial from the Carolina Conformal Therapy ConsortiumDepartments of Radiation Oncology, Medical Oncology, and Biometry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Duke University Medical Center, Durham, North Carolina, USA; Wake Forest University, Winston Salem, North Carolina, USA; and Medical University of South Carolina, Columbia, South Carolina, USA Correspondence: M. A. Socinski, M.D., Multidisciplinary Thoracic Oncology Program, University of North Carolina, Chapel Hill, Division of Hematology/Oncology, CB 7305, Chapel Hill, North Carolina 27514, USA. Telephone: 919-966-4431; Fax: 919-966-6735; e-mail: socinski{at}med.unc.edu
The maximum tolerated dose of conformal radiation therapy delivered at 1.6 Gy bid is being assessed in patients with unresectable stage IIB-IIIB non-small cell lung cancer who have been treated with induction regimens consisting of carboplatin plus paclitaxel or carboplatin plus vinorelbine. Data from the early stages of this parallel phase I study show that the two induction regimens are similar in toxicity and that both induce partial responses in 45% of patients. Both regimens can be followed by conformal radiotherapy using an accelerated hyperfractionated schedule to a dose of at least 80 Gy without experiencing unacceptable toxicity. Key morbidity observed thus far has involved the esophagus. Further cohorts of patients will receive higher doses of conformal radiotherapy (in 6.4 Gy increments) until the maximum tolerated dose is reached. Key Words. Carboplatin • Paclitaxel • Vinorelbine • AHCRT • TRT
Conventional doses of thoracic radiation therapy (TRT) (i.e., 60-66 Gy) have been ineffective at sterilizing local tumor in patients with unresectable stage III non-small cell lung cancer (NSCLC) [1-4]. Attempts at dose escalation of TRT have been limited because of toxicity issues when higher doses are used. Using conformal planning techniques, it is possible to increase the radiation dose administered, perhaps by improving tumor targeting and limiting excessive dose to normal tissue [5]. Other strategies with fractionated accelerated schedules may also lead to improved local efficacy of TRT. In a trial in which 49 patients received TRT therapy alone, a novel concurrent boost technique (in which treatment was administered at 1.6 Gy bid) enabled a total radiation dose of 73.6 Gy to be delivered without incurring unacceptable toxicity [6]. In this study, the median survival was 15.3 months. The two-year survival rate of 46% was also promising, and 64% of these patients were free from local progression at two years. Occult systemic involvement is often present at the time of diagnosis in the form of micrometastases in patients with unresectable stage III NSCLC [7-10]. The rationale for the use of induction chemotherapy in stage IIIA/IIIB NSCLC includes eradication of systemic micrometastases, which has been suggested by Arriagada and colleagues [11]. Several trials comparing platinum-based induction regimens followed by TRT, compared to TRT alone in unresectable stage IIIA/B disease, have reported longer median and long-term survival among patients receiving the induction chemotherapy [3, 12-14]. Unfortunately both local and distant control remains suboptimal, and novel approaches addressing strategies designed to improve both local and distant control are needed [3, 5, 12-14]. The trial (C-3DRC 9701) presented in this paper was undertaken to address these issues. The primary purpose of the study was to incorporate conformal planning techniques in a dose-escalation trial of accelerated hyperfractionated conformal radiation therapy (AHCRT) in patients who had received one of two "modern" induction chemotherapy regimens. In essence, the design of the trial was that of two phase I studies run in parallel. The induction chemotherapy regimens consisted of paclitaxel plus carboplatin (CP) and vinorelbine plus carboplatin (CV). The reasons for the inclusion of carboplatin were based on the improved survival observed with the platinum-based induction regimens in previous randomized trials and the potential for a lower incidence of adverse events. Vinorelbine or paclitaxel combined with platinum have demonstrated appreciable activity as induction therapies, with manageable safety profiles [15-21].
The primary objective of the trial was to determine the maximum tolerated dose (MTD) of three-dimensional AHCRT in patients with inoperable stage IIB or IIIA/B NSCLC following induction chemotherapy.
The study has several secondary objectives. First, it was intended to compare the pattern of toxicities of the two induction regimens in the context of subsequent escalating doses of AHCRT. Second, it was designed to examine the influence of AHCRT and chemotherapy regimen on survival, failure-free survival and sites of relapse. Third (although no data on this aspect of the trial are available to date), the study contains a correlative science component: toxicity (particularly lung toxicity) is to be examined in relation to serial levels of transforming growth factor-ß/macrophage inflammatory protein-1
Eligible patients had a histologic or cytologic diagnosis of NSCLC and inoperable stage IIB or stage IIIA/B disease. Patients with supraclavicular or contralateral hilar lymphadenopathy were excluded, as were those with malignant pleural effusion. Patients were required to have a performance status (PS) of 0-2, a forced expiratory ventilation in one second (FEV1) greater than 1L, or a predicted post-radiation FEV1 of 0.8L or greater, and adequate end-organ function. All patients received two cycles of induction chemotherapy, followed by escalating doses of AHCRT starting on day 43 of treatment. The MTD of radiation therapy is to be determined separately for patients receiving CP and those receiving CV. At each dose level of radiation, it was intended that seven patients be accrued to each chemotherapy regimen, and dose level of AHCRT with a minimum of five patients evaluable for toxicity. Toxicity was assessed using the SOMA-LENT criteria [22]. The MTD was determined according to two criteria. The first related to the numbers of patients experiencing toxicities of a defined grade within a minimum of six weeks following the completion of radiotherapy. Thus does escalation was stopped (and hence the MTD reached) if there were three or more cases of grade 3 toxicity, two or more cases of grade 4-5 toxicity, or two cases of grade 3 toxicity plus one case of grade 4-5 toxicity. The second stopping rule required an end to does escalation if toxicity necessitated a does delay in AHCRT of more than two weeks in 50% or more patients.
Chemotherapy
Radiation Therapy Induction chemotherapy was followed by escalating doses of conformally planned (PLUNC: Plan University of North Carolina) AHCRT. Regional lymph nodes received a minimum of 1.25 Gy bid to a total of 45 Gy. The initial cohort of patients received a total dose of 73.6 Gy. This dose was raised by 6.4 Gy for the second cohort and will then be further raised in two further stages to total doses of 86.4 Gy and 92.8 Gy (cohorts 3 and 4). The initial 57.6 Gy (in 36 fractions) were given using the concurrent boost technique (1.25 Gy bid to the clinical target volume and 1.6 Gy total to all areas of prechemotherapy gross disease). The remaining dose was delivered to the post-chemotherapy gross target volume. The normal tissue tolerances were taken as spinal cord <50 Gy, heart <40 Gy, esophagus <73.6 Gy to >6 cm, and chest wall <70 Gy.
Patients The data presented here relate to the first 29 patients studied, representing the first two cohorts in the trial, i.e., those treated at AHCRT doses of 73.6 Gy and 80 Gy. Their median age was 61; 19 were male. One patient had stage IIB disease, 21 were stage IIIA and seven stage IIIB. The median tumor size was 4.5 cm and median tumor volume 71 cc. The patients' PS was 0 in 17 cases, 1 in 11, and 2 in 1. Six patients (21%) had experienced weight loss of greater than 5%. The most common histology was squamous carcinoma (11 patients), with the remainder divided among adenocarcinoma, large cell carcinoma, and carcinoma not otherwise specified.
Treatment A total of 14 patients received CP induction chemotherapy and 15 received CV. Of the former, half were enrolled in the first cohort and half in the second; all seven patients in the first group and six patients in the second group were evaluable for radiation therapy MTD. Of the 15 CV patients, eight were enrolled to receive 73.6 Gy radiation and seven to receive 80 Gy. In both groups, six patients were evaluable for radiation toxicity. The four non-evaluable exhibited progressive disease and therefore did not complete AHCRT. Of the five non-evaluable patients, three progressed, one expired before radiotherapy, and one removed herself from the study.
Induction Chemotherapy: Adverse Events and Response
The rates of response observed with the two induction regimens were similar, and the response rate in this study following two cycles of CP was similar to other published studies using this regimen (Table 1
Adverse Events Following Radiotherapy On the basis of these data, radiotherapy dose escalation continues in both arms of the study. Currently, patients are being treated to an AHCRT dose of 86.4 Gy.
Overall Response and Survival
This study, which is still in progress, provides data suggesting that either paclitaxel or vinorelbine can be used in combination with carboplatin in induction chemotherapy for patients who will subsequently be treated with AHCRT. The 29 patients for whom data are available at this stage are representative of the wider population of patients with unresectable stage IIB/IIIB NSCLC. The exciting aspect of this trial involved the novel radiotherapy strategy which utilizes conformal planning techniques to escalate the total dose of radiation delivered in this disease setting. Our preliminary data suggest that dose escalation of AHCRT on this schedule is possible at least to 80 Gy with acceptable levels of toxicity. Accrual continues in a phase I fashion to determine the MTD of AHCRT following induction CP and CV.
Supported in part by a grant from Glaxo Wellcome. Thanks to Robert Clough and Andrea Tisch for data management support.
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