Integrating concurrent navelbine and cisplatin to hyperfractionated radiotherapy in locally advanced non-small cell lung cancer patients treated with induction and consolidation chemotherapy: feasibility and activity results

βV-tubulin expression is associated with outcome following taxane-based chemotherapy in non-small cell lung cancer

Background:

Tubulin-binding agents (TBAs) are effective in non-small cell lung cancer (NSCLC) treatment. Both βIII- and βV-tubulins are expressed by cancer cells and may lead to resistance against TBAs.

Methods:

Pre-treatment samples from 65 locally advanced or oligometastatic NSCLC patients, who underwent uniform induction chemotherapy with paclitaxel and platinum followed by radiochemotherapy with vinorelbine and platinum were retrospectively analysed by immunohistochemistry. Protein expression of βIII- and βV-tubulin was morphometrically quantified.

Results:

Median pre-treatment H-score for βIII-tubulin was 110 (range: 0–290), and 160 for βV-tubulin (range: 0–290). Low βIII-tubulin expression was associated with improved overall survival (OS) (P=0.0127, hazard ratio (HR): 0.328). An association between high βV-tubulin expression and prolonged progression-free survival (PFS, median 19.2 vs 9.4 months in high vs low expressors; P=0.0315, HR: 1.899) was found. Further, high βV-tubulin expression was associated with objective response (median H-score 172.5 for CR+PR vs 120 for SD+PD patients, P=0.0104) or disease control following induction chemotherapy (170 for CR+PR+SD vs 100 for PD patients, P=0.0081), but not radiochemotherapy.

Conclusion:

Expression of βV-tubulin was associated with treatment response and PFS following paclitaxel-based chemotherapy of locally advanced and oligometastatic NSCLC patients. Prolonged OS was associated with low levels of βIII-tubulin. Prospective evaluation of βIII/βV-tubulin expression in NSCLC is warranted.

A Prospective Phase II Study of Induction Carboplatin and Vinorelbine followed by Concomitant Topotecan and Accelerated Radiotherapy (ART) in Locally Advanced Non-small Cell Lung Cancer (NSCLC)

BACKGROUND

Survival of locally advanced/unresectable non-small cell lung cancer (NSCLC) has improved with the use of concurrent radiation and chemotherapy over the past decades, but local and distant failure remain high. In addition, a key limiting factor in combining chemotherapy with accelerated radiotherapy (ART) is severe esophagitis. We investigated the toxicity, response rate, and overall survival (OS) with induction carboplatin and vinorelbine followed by concomitant topotecan and ART in patients with locally advanced/unresectable NSCLC.

METHODS

In this phase II trial, stage IIIA or IIIB NSCLC patients with a Karnofsky performance score >60 were eligible. Patients received induction carboplatin (area under the curve = 5.5) on days 1 and 22, and vinorelbine (25 mg/m2) on days 1, 8, 22, and 29. During the concurrent chemoradiation, patients received intravenous topotecan (0.5 mg/m2) on days 43 to 47, days 57 to 61, and days 71 to 75 before the morning radiotherapy (RT) fraction. RT was administered in an accelerated fashion at 2 Gy per fraction, twice daily for five consecutive days, every other week, to a cumulative dose of 60 Gy during a 5-week period.

RESULTS

Thirty-seven patients were accrued; of these, 35 were evaluable. Overall response rate was 71% (14% complete response, 57% partial response). Six of 35 (17%) patients had stable disease. Four (11%) patients progressed during treatment. At a median follow-up of 45 months for surviving patients, the median survival based on Kaplan-Meier estimates is 17.9 months. OS at 1, 2, and 3 years is 62%, 41%, and 33%, respectively. Actuarial 5-year OS is 21%. The median time to first relapse is 12.2 months (9.1-24.7 months). There were no cases of grade 3 or 4 esophagitis.

CONCLUSIONS

This combined-modality regimen yielded encouraging OS rates, with no severe esophagitis. Using four-dimensional RT treatment planning, we plan to further evaluate altered fractionation RT and chemotherapy for this group of patients.

Interstrand cross-links: a new type of gamma-ray damage in bromodeoxyuridine-substituted DNA

Interstrand cross-links (ICL) represent one of the most toxic types of DNA damage for dividing cells. They are induced both by natural products (e.g., psoralens + UVA) and by several chemical agents, some of which are used in chemotherapy (e.g., carboplatin and mitomycin C). Although repair mechanisms exist for interstrand cross-links, these lesions can induce mutations, chromosomal rearrangements, and cell death. Here, we report, for the first time, the formation of ICL by gamma-rays in brominated DNA. It is well established that the radiosensitization properties of bromodeoxyuridine (BrdUrd) result primarily from the electrophilic nature of the bromine, making it a good leaving group and leading to the irreversible formation of a uridinyl radical (dUrd(*)) or uridinyl anion (dUrd-) upon addition of an electron. We observe that the radiolytic loss of the bromine atom is greatly suppressed in double-stranded compared to single-stranded DNA. We have used a model DNA containing a bulge, formed by five mismatched bases, and have observed a linear dose-response for the formation of strand breaks on the single-stranded regions of both the brominated strand and the opposite nonbrominated strand. Surprisingly, we have observed the formation of interstrand cross-links exclusively in the mismatched region. Thus, we propose that the radiosensitization effects of bromodeoxyuridine in vivo will almost certainly be limited to single strand regions such as found in transcription bubbles, replication forks, mismatched DNA, and possibly the loop region of telomeres. Our results suggest that interstrand cross-links may contribute to the radiosensitization effects of BrdUrd. These findings may have profound implications for the clinical use of bromodeoxyuridine as a radiosensitizer, as well as for the development of targeted radiosensitizers.