We’ve still got some work to do before we can say with authority whether concurrent neoadjuvant chemotherapy and immunotherapy is better than concurrent adjuvant chemotherapy with immunotherapy for non–small cell lung cancer (NSCLC). While there has been some notable progress in this area, we need phase 3 trials that compare the two therapeutic approaches.
Investigators reporting at the 2022 annual meeting of American Society of Clinical Oncology focused primarily on neoadjuvant treatment, which I’ll address here.
In the randomized, phase 2 NADIM II clinical trial reported at the meeting, researchers expanded on the results of NADIM published in 2020 in the Lancet Oncology and in May 2022 in the Journal of Clinical Oncology along with CheckMate 816 results published in the New England Journal of Medicine.
In each of these three studies, researchers compared nivolumab plus chemotherapy versus chemotherapy alone (abstract 8501) as a neoadjuvant treatment for resectable stage IIIA NSCLC. In the study reported at ASCO 2022, patients with resectable clinical stage IIIA-B (per American Joint Committee on Cancer 8th edition) NSCLC and no known EGFR/ALK alterations, were randomized to receive preoperative nivolumab plus chemotherapy (paclitaxel and carboplatin; n = 57) or chemotherapy (n = 29) alone followed by surgery.
The primary endpoint was pathological complete response (pCR); secondary endpoints included major pathological response, safety and tolerability, impact on surgical issues such as delayed or canceled surgeries or length of hospital stay, overall survival and progression free survival. The pCR rate was 36.8% in the neoadjuvant nivolumab plus chemotherapy arm and 6.9% in the chemotherapy alone arm. (P = .0068). 25% of patients on the nivolumab plus chemo arm had grade 3-4 adverse events, compared with 10.3% in the control arm. 93% of patients on the nivolumab plus chemo arm underwent definitive surgery whereas 69.0% of the patients on the chemo alone arm had definitive surgery (P = .008).
What Else Did We Learn About Neoadjuvant Treatment at the Meeting?
Investigators looking at the optimal number of neoadjuvant cycles (abstract 8500) found that three cycles of sintilimab (an investigational PD-1 inhibitor) produced a numerically higher major pathological response rate, compared with two cycles (when given in concert with platinum-doublet chemotherapy). And, neoadjuvant chemoradiotherapy does not result in significant survival benefits when compared with neoadjuvant chemotherapy alone (abstract 8503).
Of course, when it comes to resectable NSCLC, the goal of treatment is to increase the cure rate and improve survival. No randomized studies have reported yet on overall survival, probably because they are too immature. Instead, disease-free survival (DFS) or event-free survival (EFS) are often used as surrogate endpoints. Since none of the studies reported at ASCO reported on DFS or EFS, we need to look elsewhere. CheckMate 816 was a phase 3 study which randomized patients with stages IB-IIIA NSCLC to receive neoadjuvant nivolumab plus platinum-based chemotherapy or neoadjuvant platinum-based chemotherapy alone, followed by resection. The median EFS was 31.6 months with nivolumab plus chemotherapy and 20.8 months with chemotherapy alone (P = .005). The percentage of patients with a pCR was 24.0% and 2.2%, respectively (P < .001).
We all know one has to be careful when doing cross-trial comparisons as these studies differ by the percentage of patients with various stages of disease, the type of immunotherapy and chemotherapy used, etc. However, I think we can agree that neoadjuvant chemoimmunotherapy results in better outcomes than chemotherapy alone.
Of course, resectable NSCLC is, by definition, resectable. And traditionally, resection is followed by adjuvant chemotherapy to eradicate micrometastases. Unfortunately, the current standard of care for completely resected early-stage NSCLC (stage I [tumor ≥ 4 cm] to IIIA) involves adjuvant platinum-based combination chemotherapy which results in only a modest 4%-5% improvement in survival versus observation.
Given these modest results, as in the neoadjuvant space, investigators have looked at the benefit of adding immunotherapy to adjuvant chemotherapy. One such study has been reported. IMpower 010 randomly assigned patients with completely resected stage IB (tumors ≥ 4 cm) to IIIA NSCLC, whose tumor cells expressed at least 1% PD-L1, to receive adjuvant atezolizumab or best supportive care after adjuvant platinum-based chemotherapy. In the stage II-IIIA population whose tumors expressed PD-L1 on 1% or more of tumor cells, 3-year DFS rates were 60% and 48% in the atezolizumab and best supportive care arms, respectively (hazard ratio, 0·66 P =·.0039). In all patients in the stage II-IIIA population, the 3-year DFS rates were 56% in the atezolizumab group and 49% in the best supportive care group, (HR, 0.79; P = .020).
KEYNOTE-091, reported at the 2021 annual meeting of the European Society for Medical Oncology, randomized early-stage NSCLC patients following complete resection and adjuvant chemotherapy to pembrolizumab or placebo. Median DFS for the overall population was 53.6 months for patients in the pembro arm versus 42 months in the placebo arm (HR, 0.76; P = .0014). Interestingly, the benefit was not seen in patients with PD-L1 with at least 50%, where the 18-month DFS rate was 71.7% in the pembro arm and 70.2% in the placebo arm (HR, 0.82; P = .14). Although the contradictory results of PD-L1 as a biomarker is puzzling, I think we can agree that the addition of immunotherapy following adjuvant chemotherapy improves outcomes compared to adjuvant chemotherapy alone.
What to Do When a Patient Presents With Resectable Disease?
Cross-trial comparisons are fraught with danger. Until we have a phase 3 study comparing concurrent neoadjuvant chemo/immunotherapy with concurrent adjuvant chemo/immunotherapy, I do not think we can answer the question “which is better?” However, there are some caveats to keep in mind when deciding on which approach to recommend to our patients: First, neoadjuvant treatment requires biomarker testing to ensure the patient does not have EGFR or ALK mutations. This will necessitate a delay in the operation. Will patients be willing to wait? Will the surgeon? Or, would patients prefer to proceed with surgery while the results are pending? Yes, neoadjuvant therapy gives you information regarding the pCR rate, but does that help you in subsequent management of the patient? We do not know.
Secondly, the two adjuvant studies used adjuvant chemotherapy followed by adjuvant immunotherapy, as contrasted to the neoadjuvant study which used concurrent chemo/immunotherapy. Given the longer duration of treatment in postoperative sequential adjuvant studies, there tends to be more drop off because of patients being unwilling or unfit postoperatively to receive long courses of therapy. In IMpower 010, 1,269 patients completed adjuvant chemotherapy; 1,005 were randomized, and of the 507 assigned to the atezolizumab/chemo group, only 323 completed treatment.
Finally, we must beware of using neoadjuvant chemo/immunotherapy to “down-stage” a patient. KEYNOTE-091 included patients with IIIA disease and no benefit to adjuvant chemotherapy followed by immunotherapy was found in this subgroup of patients, which leads me to wonder if these patients were appropriately selected as surgical candidates. In the NADIM II trials, 9 of 29 patients on the neoadjuvant chemotherapy were not resected.
So, many questions remain. In addition to the ones we’ve raised, there is a clear and immediate need for predictive and prognostic biomarkers. In the NADIM II trial, PD-L1 expression was a predictive biomarker of response. The pCR rate for patients with a PD-L1 tumor expression of less than 1%, 1%-49%, and 50% or higher was 15%, 41.7%, and 61.1%, respectively. However, in KEYNOTE-091, the benefit was not seen in patients with PD-L1 of at least than 50%, where the 18-month DFS rate was 71.7% in the pembro arm and 70.2% in the placebo arm.
Another possible biomarker: circulating tumor DNA. In the first NADIM study, three low pretreatment levels of ctDNA were significantly associated with improved progression-free survival and overall survival (HR, 0.20 and HR, 0.07, respectively). Although clinical response did not predict survival outcomes, undetectable ctDNA levels after neoadjuvant treatment were significantly associated with progression-free survival and overall survival (HR, 0.26 and HR0.04, respectively). Similarly, in CheckMate 816, clearance of ctDNA was associated with longer EFS in patients with ctDNA clearance than in those without ctDNA clearance in both the nivolumab/chemotherapy group (HR, 0.60) and the chemotherapy-alone group (HR, 0.63).
Hopefully, ASCO 2023 will provide more answers.
Schiller is a medical oncologist and founding member of Oncologists United for Climate and Health. She is a former board member of the International Association for the Study of Lung Cancer and a current board member of the Lung Cancer Research Foundation.
This story originally appeared on MDedge.com, part of the Medscape Professional Network.
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