In this edition of “How I will treat my next patient,” I take a look at two “chemo-free” neoadjuvant studies reported at the annual meeting of the American Society of Clinical Oncology. One summarizes the potential utility of immune checkpoint inhibitors (ICIs) in non–small cell lung cancer (NSCLC) patients who are – or can become – candidates for curative resection and the other highlights the potential utility of neoadjuvant trastuzumab emtansine (T-DM1) for HER2-positive breast cancer patients.
NEOSTAR in NSCLC
With the accumulation of comorbid conditions in an aging population, we all see NSCLC patients who are potential candidates for curative surgery, but for whom we have concerns about standard preoperative chemotherapy plus or minus radiation. At ASCO 2019, abstracts(atezolizumab, the LCMC3 trial) and (nivolumab plus or minus ipilimumab, NEOSTAR) addressed the neoadjuvant use of ICIs. I will focus on NEOSTAR, because the major pathologic response (mPR) rate – reduction in viable tumor cells to 10% or less – was higher with the combination of nivolumab plus ipilimumab in NEOSTAR than with single agent nivolumab or atezolizumab in the NEOSTAR or LCMC3 trials, respectively.
Briefly, 44 patients with stage I-IIIA NSCLC were randomized to nivolumab plus or minus ipilimumab. In total, 93% completed 6 weeks of neoadjuvant therapy and 89% were resected. The mPR rate was 33% with nivolumab plus ipilimumab (about twice as high as with nivolumab alone in NEOSTAR or atezolizumab in LCMC3).
Among resected patients, nivolumab plus ipilimumab had a 44% mPR rate and a pathologic complete response rate of 38%. Although RECIST (Response Evaluation Criteria in Solid Tumors) responses were more likely in patients who had an mPR, 11% of patients had radiographic “nodal immune flare” because of noncaseating granulomas in regional (or nonregional) nodes. Elevated baseline programmed death-ligand 1 was associated with a higher rate of mPR. Surgical complications seemed similar to expectations – 1 bronchopleural fistula and 8 air leaks among the 39 resected patients.
What this means in practice
Although the mPR endpoint has no validated association with survival and the studies were relatively small, neoadjuvant use of ICIs in patients for whom tolerance to standard chemotherapy plus or minus radiation might be problematic is attractive – especially in view of the reality of an approximately 50% relapse rate after surgical resection with standard therapy.
If I had a potential candidate for neoadjuvant ICI therapy – especially one with a high proportion of cells with PD-L1 or someone with an equivocal distant metastasis on a preoperative PET-CT – I would consider using an ICI as given in LCMC3 or NEOSTAR.
PREDIX in HER2-positive breast cancer
As, of Stanford (Calif.) University suggested in his discussion at the local/regional/adjuvant breast cancer session at ASCO 2019, the goal of HER2-targeted therapy was originally that it could replace – not supplement – the use of cytotoxic chemotherapy.
Abstracts(the KRISTINE trial: neoadjuvant T-DM1 plus pertuzumab vs. docetaxel, carboplatin, and trastuzumab plus pertuzumab); (the PREDIX study: T-DM1 vs. docetaxel plus trastuzumab plus pertuzumab [DTP] for six cycles); and (HER2 heterogeneity as a predictor of response) addressed the potential for the antibody-drug conjugate to replace standard preoperative cytotoxic chemotherapy plus HER2-targeting.
In PREDIX, it was anticipated that toxicity would be lower with T-DM1 than with DTP – and it was, with better quality of life scores. The authors found a pathologic complete response rate of 45% among 98 participants with stage IIA-IIIA HER2-positive breast cancer, with higher rates among hormone receptor–negative than hormone receptor–positive patients, as expected.
PREDIX patients were allowed to switch from T-DM1 to DTP for progression, lack of clinical/radiographic response, or toxicity. More than twice as many patients switched from DTP to T-DM1 than vice versa for progression or lack of response.