Celecoxib (Celebrex) has been studied in combination with chemo for NSCLC and has generated enough promising results to raise expectations but also enough negative data to produce disappointment. Dr. Altorki’s trial (abstract here) gave 29 patients with stage IIIA, resectable NSCLC celebrex at 400 mg by mouth twice daily (higher than standard arthritis dosing, but the dose used to reverse colon polyps in patients with a high risk pre-malignant condition for colon cancer called familial adenomatous polyposis, or FAP) along with two cycles of carbo/taxol every three weeks as an induction therapy. It showed a good response rate (tumor shrinkage by 50% or more) of 65% (17% with a “complete response” (CR) of no residual disease visible on CT scans, and 48% with significant shrinkage but residual disease seen). The greatest encouragement came from the 24% of patients who had a “near pathologic CR” in which there was just a small focus of residual disease seen on the microscopic review of tissue after surgery. This was viewed as particularly encouraging since we expect the complete pathologic CR rate to be only perhaps 5-10%, but I must admit that I was less enthralled by this statistic, since no prior studies ever reported a “near pathologic CR” with just slight residual disease, and for all we knew, many other trials had 20-50% near pathologic CRs but never reported them. To me this seemed like being just a little pregnant if the real victory is NO cancer visible under the microscope.

Nevertheless, this was certainly encouraging enough to lead to a follow-up randomized phase II study of 110 stage resectable stage IIIA patients with pre-operative carbo/taxol alone or with celebrex at 400 mg PO BID, which is ongoing.

A recent trial by Lilenbaum and colleagues (abstract here) reported on two chemo combinations by themselves or with celebrex added. This was a study of 133 patients in the second line setting for advanced NSCLC who received either taxotere/irinotecan or gemcitabine/irinotecan alone or with celebrex 400 mg by mouth twice daily. None of the arms appeared to do clearly better than you'd expect from our current standard second-line single agent approaches (most commonly taxotere, alimta, or tarceva), but the combination of celebrex with irinotecan and taxotere seemed to have a worse survival AND more toxicity, particularly diarrhea, compared with the same chemo combination alone. However, questions remained about whether this was too low a dose, and whether the results would be different if only patients with significant expression of COX-2 on their tumors were included.

Dr. Marty Edelman from the University of Maryland presented a randomized phase II trial by the CALGB that examined the potential role of celebrex and/or zileuton (abstract here). Zileuton is a 5-lipoxygenase inhibitor, which blocks a different pathway of the eicosanoids, a complex collection of signaling molecules that are centrally involved in inflammation and other biochemical processes. The schema of this trial is shown here:

(click to enlarge)

The drug Zileuton didn't have any obvious impact on time to progression or survival, nor did celebrex seem to have any dramatic effect overall. When the investigators did an exploratory analysis of the results as a function of whether the patients on the trial had tumors with or without significant COX-2 expression on their tumors (tissue available for just a subset of patients), they found that:

1) in patients who did not receive celebrex, those with tumors that showed COX-2 expression/overexpression had a worse survival than patients with tumors that didn't show COX-2 expression/overexpression (cut off for where to separate positive from negative with COX-2 protein staining isn't clear, so they looked at several cut-off points, with same trend overall)

2) This trend toward worse survival was reversed in the patients who received celebrex. In other words, the patients with COX-2 expression that would generally suggest doing more poorly ended up doing more favorably if they received celebrex.

These results were based on quite small numbers of patients (the curve shown above is based on 14 and 6 patients per arm there), so it's not possible to make any conclusive statements. However, these findings at least suggested the possibility that the COX-2 story in combination with chemo may not be dead, but perhaps could be salvaged if the focus in the future is just on patients with tumors that overexpress the COX-2 protein. My understanding is that there is discussion of developing future trials in this more limited population.

In the meantime, there is a randomized phase III trial being conducted in Sweden that is attempting to enroll 760 patients with first-line (previously untreated) advanced NSCLC to receive either platinum-based chemo (anticipated to most likely be carboplatin with either navelbine or gemcitabine) alone or in combination with celebrex 400 mg by mouth twice daily. This should give us a more definitive answer about the value of celebrex in a larger, general population.

In addition, some of the work with celebrex in combination with Tarceva has also raised the question of whether the lack of impressive results with celebrex in lung cancer thus far may be because the dose needed, either with tarceva or with chemo or in combinations in general, needs to be in the range of 600 mg twice daily or higher. Thus, these earlier trials may not capture the value of celebrex because the typically used dose of 400 mg twice daily may be too low.

For now, though, the weight of the evidence hasn't shown a clear benefit and even raises the question of potentially worse survival and greater side effects when celebrex is added to chemo in an unselected population. However, some results of the combination of celebrex with tarceva have appeared promising enough to generate enthusiastic interest. We'll cover that next.