In addition to a direct comparison of iressa to chemo in the second line setting for advanced NSCLC (see recent post on INTEREST trial), as conducted with the INTEREST trial I described in a recent post, a very similar comparison of Iressa to chemo was also performed in another setting where single-agent chemo is also the treatment of choice. Specifically, the INVITE trial evaluated iressa vs. navelbine as a single agent in previously untreated advanced NSCLC (abstract here).

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As discussed in one of my early posts, there is room to debate whether single agent approaches or older patients should receive single-agent chemo or standard platinum-based doublets (particularly carboplatin-based instead of the more challenging cisplatin doublets). Among the most commonly used single chemo agents in the elderly population is navelbine (also known as vinorelbine), based on it being proven to improve survival compared with supportive care alone in the memorably named ELVIS trial (Elderly Lung Cancer Vinorelbine Italian Study – paper here). We’ve seen the results of a trial in which tarceva was compared to the chemo doublet of carbo/taxol in patients with a marginal performance status (not the same population as elderly), and as I described in a prior post, the recipients of chemo fared better than those who received tarceva. So did the INVITE trial show similar results for gefitinib in the elderly compared to a single chemo agent?

The median age of enrolled patients was 74 on both arms, and about three quarters of the patients in the trial were men. Never-smokers comprised 17% of the Iressa recipients, compared with 11% of the chemo recipients. About 20% of the elderly patients were also frail, with a few more of the marginal performance status patients randomized to Iressa than chemo (24% vs. 16%). There were a few more patients with locally advanced instead of metastatic NSCLC on the navelbine arm (perhaps favoring that arm a bit), and the iressa arm had more patients with squamous cancers than adenocarcinomas, while the navelbine arm had more patients with adenocarcinomas than squamous NSCLC. This could potentially be significant because patients with adenocarcinomas have a little more favorable prognosis in advanced NSCLC, and also we’ve seen response rates to EGFR inhibitors consistently be higher, and sometimes more than twice as high, in lung adenocarcinomas vs. squamous carcinomas. Nevertheless, this trial wasn’t huge, so there are bound to be a few imbalances here and there.

The primary endpoint of progression-free survival (PFS) was not significantly different between the two arms, 2.7 months on iressa vs. 2.9 months on navelbine, although there was a trend of about 20% better PFS with navelbine. The overall survival for the two arms were overall quite similar, but the median survival happened to come out higher with navelbine (8.0 months) compared with iressa (5.9 months) because the curves separated a little right at the median (50% survival point).

The response rates were on the low side for both arms (navelbine at 5%, iressa 3%), and when you add in stable disease to reach a disease control rate, it was 10% higher with the chemo (navelbine 53%, iressa 43%).

On the other hand, quality of life improvement was greater with Iressa, as measured by two different quality of life scales, as shown here:

Symptomatic improvement, not really the same thing as quality of life, was very similar between iressa and chemo, at about one third of patients for both arms.

Turning to the side effect profile, Iressa fared a little better, even though navelbine is a pretty gentle drug overall. The rate of any treatment-related side effects was 57% with Iressa vs. 75% with navelbine. About 5% of patients assigned to Iressa came off of the trial due to side effects, vs. 13% of those assigned to navelbine. And as you’d expect, the side effect profile was different between the two treatments: more diarrhea and rash with Iressa, while navelbine was associated with more fatigue, constipation, nausea and diminished appetite, and lowered blood counts (usually not too serious, by chemo standards).

But perhaps most puzzling was the exploratory analysis of gene amplification for EGFR. In EGFR FISH-negative patients (about 2/3), chemo and Iressa had essentially superimposable PFS results. (That’s not the puzzling part.) What was surprising was that there was a difference in the third of patients that were EGFR FISH-positive, those with amplification of the EGFR gene that is the target of Iressa, but the results clearly favored navelbine! I can’t explain why, but it illustrates how much we still need to learn about predicting who will do well or poorly with targeted therapies like EGFR inhibitors.

Overall, the INVITE trial indicated that iressa is pretty comparable to single-agent navelbine in an elderly population. But we also have the trial by Rogerio Lilenbaum of doublet chemo with carbo/taxol vs. tarceva in frail patients, which I described in detail in a prior post, and which showed that chemo pretty convincingly beat tarceva. However, you'd generally expect good performance status elderly patients (80% of the patients on the INVITE trial had a good performance status) to have a much better survival than poor performance status patients such as those on the Lilenbaum trial, but the doublet chemo of carbo/taxol on Lilenbaum's trial gave a median survival of 9.5 months in a frail population, vs. 8 months with navelbine alone on the INVITE trial. And the clearly inferior arm of tarceva on Dr. Lilenbaum's trial of poor performance status patients still gave a median survival of 6.5 months, which was numerically a little better than iressa on the INVITE trial of better performance status elderly (not likely a meaningful difference). My impression is that both carboplatin-based doublets and erlotinib are more effective than single agent chemo or iressa, respectively. But unlike Dr. Lilenbaum's trial, the INVITE study suggests that EGFR inhibitor therapy can produce similar results to light chemo in patients unable or disinclined to pursue chemotherapy.