A Randomized Phase III Trial Comparing Bexarotene/Carboplatin/Paclitaxel vs. Carboplatin/Paclitaxel in Chemotherapy-Naive Patients with Advanced or Metastatic NSCLC (SPIRIT II Trial)

Presenter: G.R. Blumenschein, Jr., MD
Presenter's Affiliation: SPIRIT II Trial Group
Type of Session: Scientific

BackgroundMaterials and Methods1) Carboplatin (AUC=6) + paclitaxel (200mg/m2) q3wks 2) Carboplatin (AUC=6) + paclitaxel (200mg/m2) q3wks + bexarotene (400 mg/m2 qd)ResultsAuthor's Conclusions

Clinical/Scientific Implications
The results presented in this study showed no benefit to the overall population with the addition of bexarotene to standard chemotherapy with carboplatin and paclitaxel in the first-line setting with advanced and metastatic NSCLC. These results are disappointing given the promising results seen in earlier phase studies with this agent. There was no indication that bexarotene benefited the overall population, and in fact, there was a trend towards worsened PFS with bexarotene. These results mirrored the results of the SPIRIT I trial which was also presented at this meeting. In that trial, bexarotene was given with cisplatin and vinorelbine in a similar population of patients, and again, there was no improvement in median survival, OS, or PFS. Interestingly, in both trials, patients with elevated triglycerides did show improvement in survival. This was somewhat paradoxical, because patients who experienced high elevations in triglycerides despite antilipid therapy had the doses of bexarotene reduced in both trials. Therefore, the median dose of bexarotene received in patients with elevated bexarotene was significantly lower than the dose received by patients who did not have triglyceride elevation. The exact cause of the relationship between triglyceride level and response to bexarotene is unclear. It is possible that increased triglycerides serve as a biomarker for response or inherent sensitivity to the experimental drug. This relationship warrants further investigation. If it is possible to identify patients who will experience this elevation of triglycerides in response to treatment prior to the initiation of therapy, a susceptible subset of these patients could be targeted for treatment with bexarotene. Until then, the use of bexarotene should be confined to experimental protocols.

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