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Early Report: SATURN Trial of Maintenance Tarceva Positive for Improvement in Progression-Free Survival

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Well, it happened again that the first word came from the financial community (report here), as we learned today that a large trial testing the value of maintenance tarceva (erlotinib), the oral EGFR inhibitor, provides a significant improvement in progression-free survival (PFS). In the following slide, I show the design for two similar trials that test the value of tarceva after four cycles of first line treatment of advanced NSCLC.

ATLAS and SATURN

The first, called the ATLAS trial, is for avastin-eligible patients who would typically receive avastin alone as maintenance therapy after initial chemo/avastin. It randomizes patients to maintenance avastin/tarceva vs. avastin alone. We don’t have results from that trial yet. The results we have are from the SATURN trial, which asks a similar question but without the avastin: is there a significant delay in progression if patients who haven’t progressed after four cycles of platinum-based standard chemotherapy (and no avastin) receive tarceva as a maintenance therapy, compared with an oral placebo?

The answer we received as that yes, there is a significant benefit for PFS among the 889 enrolled patients, but we don’t yet know the absolute magnitude of that benefit or whether it’s accompanied by an improvement in overall survival (OS).

This result isn’t surprising to me. I had been following this very timely question of whether we should now standardly offer maintenance therapy to patients who aren’t progressing after 4-6 cycles of initial treatment. As I highlighted in a recent prior post, I have been impressed that the limited evidence with both taxotere (docetaxel) and alimta (pemetrexed) is quite convincingly positive for a highly significant improvement in PFS and a nearly statistically significant improvement in OS (nearly three months in both of the chemo trials). Moreover, my impression of the overall data out there for these three agents is that they’re quite comparable overall in their efficacy in a broad population, although there are certainly a minority of patients who show stunning benefits from EGFR inhibitors, and the clinical benefit with alimta appears to be limited to patients with non-squamous NSCLC. I would have been surprised if a similar trend hadn’t been seen with the third drug that we commonly recognize as being active in previously treated patients with advanced NSCLC.

We have yet to learn any details, though next week I’ll be attending the largest meeting dedicated to lung cancer this year, in Chicago, so we may see a presentation of this information. With such a large trial, it’s possible that the absolute difference in outcomes isn’t enough to lead to significant changes in practice, particularly if there is little or no improvement in survival. Thus far, there hasn’t been much of a movement toward accepting maintenance chemotherapy after first line treatment yet, and many of the detractors cite the absence of a significant survival benefit as a key reason (I happen to disagree on this point — see prior post). But the concept of giving patients an oral, generally well-tolerated therapy may be more appealing in the maintenance setting than more standard IV chemotherapy.

I’ll certainly add more information about this trial when it becomes available. I’ll also be interested to learn from people who have been on both standard chemo and tarceva whether they’d be more amenable to an oral strategy like tarceva, whether they’d be perfectly comfortable continuing on chemo, or whether they’d just really welcome a break from treatment after 3-4 months of initial chemo +/- avastin.


4 Responses to Early Report: SATURN Trial of Maintenance Tarceva Positive for Improvement in Progression-Free Survival

  • bigdhombre says:

    Hi Dr. West,

    I had 1 comment and 2 questions.
    This almost seems like a ‘time-shifted’ approach to TRIBUTE/TALENT/INTACT, where instead of giving erlotinib (or gefitinib) concurrently with chemo, they have shifted to a sequential approach.

    Do you know if they are looking at efficacy by histology in SATURN? Would be interesting if benefit observed in squamous histology – I believe that in BR.21, even smokers with squamous showed a benefit with erlotinib vs. placebo.
    Also, it is interesting that whereas in S0023, maintenance EGFR TKI was detrimental, but here it appears to be beneficial (although as you mention, we don’t know the actual numbers). I realize that the S0023 study is with CRT in stage III, and this is in metastatic – I was wondering why we might see different outcomes with maintenance EGFR TKIs?

    Thanks!

  • Dr. West says:

    I am not 100% certain that they’re breaking down SATURN results by histology, but I very strongly suspect they will, since that’s now a relevant second tier question in any NSCLC trial now that histology has been established as a relevant variable. Histology information may not be presented at the first unveiling of the trial results, but instead may become available only after more detailed analysis of the trial later. You’re absolutely right that there is a survival benefit in patients with squamous NSCLC on BR.21, and even in male smokers with squamous NSCLC.

    You’re right that both the SATURN trial and BR.21 showed a survival benefit for an EGFR TKI after chemo, which isn’t that different from SWOG 0023. Dr. Karen Kelly noted this in one major presentation of the data and speculated whether the radiation in the SWOG trial somehow altered the effect of the EGFR inhibitor, but if that’s the case, it’s not something any of us can explain based on what we know right now about how these drugs work. It’s also true that the SWOG trial used iressa instead of tarceva, but almost all of us think the drugs are similar enough that it’s nearly impossible to imagine that the results would ahve been favorable with a different EGFR tyrosine kinase inhibitor. The short answer is that I can’t explain the inconsistency, nor has anyone else been able to, as far as I’m aware.

    -Dr. West

  • oreo91 says:

    Dr. West,
    We have made the choice to stay on chemo for now–16 rounds of carbo/taxol/avastin were the first line and this week my brother will have his 16 round of alimta/avastin. He has had relatively few side effects and the cancer is very, very stable. Our doctor gave the choice of going off chemo to see if was his own immunity working now but we are just too afraid. Do not know if this is the right choice and we are looking at some clinical trials of vaccines but still afraid to move to anything when the cancer is stable and few side effects. So I guess you could say we are afraid to take a break!

    Jean

  • Dr. West says:

    I think another very important factor that isn’t measured here is the patient’s own mindset. Some people feel very uncomfortable being off treatment because they feel more vulnerable. Others may be so weary of treatment that they can’t be convinced that continuing on treatment is worth the side effects and extra effort.

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