MADRID, Spain — New data from three trials evaluating the bispecific antibody amivantamab (Rybrevant) in EGFR-mutated advanced non–small cell lung cancer (NSCLC) have revealed a clear benefit, experts said at the recent European Society for Medical Oncology (ESMO) Annual Meeting 2023.

The results of the three trials — PAPILLON, MARIPOSA, and MARIPOSA-2 — are “really exciting” for patients harboring EGFR mutations, said Silke Gillessen, MD, head of the Department of Medical Oncology, Università della Svizzera Italiana in Lugano, Switzerland, and the ESMO 2023 scientific chair.

Presenting findings from PAPILLON, Nicolas Girard, MD, PhD, highlighted outcomes among patients with EGFR exon 20 insertion-mutated advanced NSCLC. These patients, who represent about 2% to 3% of NSCLC cases, have “historically poor” outcomes, with a 5-year overall survival rate of just 8%.

Tumors harboring exon 20 insertions are largely insensitive to targeted therapies and immune checkpoint, explained Girard, from Curie-Montsouris Thorax Institute, Institut Curie, Paris, France. That leaves platinum-based chemotherapy as the standard of care, which has “limited efficacy,” he noted.

The FDA approved amivantamab in 2021 for EGFR exon 20 insertion-mutated advanced NSCLC after progression on platinum-based chemotherapy, but the PAPILLON trial explored whether combining the two therapies upfront would provide a more meaningful benefit.

In the trial, 308 treatment-naïve patients with locally advanced or metastatic NSCLC and documented exon 20 insertions were randomly assigned to amivantamab plus chemotherapy or chemotherapy alone. The median age was about 62 years, approximately half were female, and just over 60% were Asian — a similar patient profile as MARIPOSA and MARIPOSA-2.

The results, simultaneously published in The New England Journal of Medicine, showed that amivantamab plus chemotherapy significantly increased progression-free survival (PFS). More specifically, after a median follow-up of 14.9 months, patients receiving the combination had a median PFS of 11.4 months vs 5.7 months with chemotherapy alone (hazard ratio [HR], 0.395; P < .0001). This benefit consistently occurred across predefined subgroups.

Amivantamab plus chemotherapy was associated with a lower risk of a second progression, with the median not reached vs 17.2 months with chemotherapy alone (HR, 0.493; P = .001).

A higher proportion of patients receiving the combination had an objective response —73% vs 47% — and these patients had a longer duration of response as well — 9.7 months vs 4.4 months.

The overall survival data were immature but showed a trend toward a reduced risk of death for those on the combination (HR, 0.675; P = .106).

The rates of grade ≥ 3 adverse events were 75% with amivantamab plus chemotherapy and 54% with chemotherapy alone, and adverse events leading to discontinuation of amivantamab occurred in 7% of patients. Pneumonitis/interstitial lung disease (ILD) was reported in 3% of patients in the combination therapy arm.

Girard concluded that, with a safety profile “consistent” with that seen for the individual agents, amivantamab plus chemotherapy “represents a new standard of care” for first-line treatment of EGFR exon 20 insertion-mutated advanced NSCLC.

Benjamin Besse, MD, PhD, who was not involved in the research, agreed that this combination is “definitely a new standard of care.”

The effect of giving amivantamab alongside chemotherapy “seems to be really additive,” said Besse, director of clinical research at the Gustave Roussy Institute and professor of medical oncology at Paris-Saclay University, both in Paris, France. But he noted that amivantamab is a “challenging drug in terms of toxicity.”

The MARIPOSA Trials

The two MARIPOSA trials also demonstrated that amivantamab, in combination with other agents, improved PFS among patients with EGFR-mutated advanced NSCLC.

Byoung Chul Cho, MD, PhD, Yonsei Cancer Center, Seoul, South Korea, presented results from MARIPOSA, which focused on patients with any kind of EGFR mutation.

Although the EGFR tyrosine kinase inhibitor (TKI) osimertinib is the current standard of care in this first-line setting, “resistance and disease progression are nearly inevitable,” and secondary EGFR and MET mutations may account for up to 50% of tumor resistance, Cho noted.

Early clinical data suggest that combining amivantamab with the highly selective third-generation EGFR TKI lazertinib leads to clinical activity and durable responses.

For the phase 3 MARIPOSA trial, 1074 patients with treatment-naïve locally advanced or metastatic EGFR-mutant NSCLC were randomly assigned to amivantamab plus lazertinib (n = 429), osimertinib alone (n = 429), or lazertinib alone (n = 216).

After a median follow-up of 22 months, the median PFS among patients on the combination was 23.7 months vs 16.6 months for those on osimertinib alone (HR, 0.70; P < .001) and 18.5 months for those on lazertinib alone.

The PFS benefit observed with amivantamab plus lazertinib occurred across subgroups, including among patients with brain metastases. The combination reduced the risk for extracranial progression or death by 32% and improved median PFS by 9 months compared with osimertinib alone (HR, 0.68; P < .001).

The risk for a second progression was also lower with the combination (HR, 0.75).

Interim overall survival data suggested a benefit with the combination therapy compared with osimertinib alone (HR, 0.80; P = .11).

Grade 3 or higher adverse events were more common among patients treated with the combination vs osimertinib alone — 75% vs 43%. Higher rates of treatment-related discontinuation of any agent were observed in the combination group — 35% vs 14% — though rates of adverse events leading to death were similar between the groups — 8% and 7%, respectively.

As in PAPILLON, rates of ILD/pneumonitis were “low,” said Cho, at approximately 3% in both treatment arms. However, he noted, rates of venous thromboembolism were higher with the combination, with grade ≥ 3 events occurring in 11% vs 3.7% of patients on osimertinib.

Based on the findings, amivantamab plus lazertinib “represents a new standard of care in first-line EGFR-mutant advanced NSCLC,” Cho said. “It has been a long way and we finally made it.”

Next up MARIPOSA-2, which evaluated patients with EGFR-mutated locally advanced or metastatic NSCLC who had progressed on or after osimertinib.

In this trial, 657 patients were randomly assigned to amivantamab plus lazertinib and chemotherapy (n = 263), amivantamab plus chemotherapy (n = 263), or chemotherapy alone (n = 131).

Given the increased risk for hematologic toxicities, the study protocol was adjusted in the triple therapy arm so that patients received lazertinib after completing carboplatin.

The findings, presented by study investigator Antonio Passaro, MD, PhD, were simultaneously published in Annals of Oncology.

After a median follow-up of 8.7 months, the triple therapy reduced the risk for progression or death by 56% (HR, 0.44) and amivantamab plus chemotherapy reduced the risk for progression or death by 52% (HR, 0.48). Overall, the median PFS was 8.3 months in the triple combination arm, 6.3 months in the amivantamab plus chemotherapy arm, and 4.2 months in the chemotherapy arm.

This PFS benefit was observed across prespecified subgroups with both combination therapies. The combinations also reduced the risk for intracranial progression (HR, 0.58 in the triple therapy arm; HR, 0.55 in the amivantamab plus chemotherapy arm).

The current interim analysis did not show an overall survival benefit with either combination therapy vs chemotherapy alone, although the survival curve hinted at a benefit in the amivantamab plus chemotherapy arm.

The median duration of response was 9.4 months for triple therapy, 6.9 months for the double combination, and 5.6 months for monotherapy.

Rates of grade ≥ 3 adverse events were notably higher in the combination groups — 92% of patients on triple therapy, 72% on double, and 48% on chemotherapy alone. But the treatment duration was longer in the combination groups and adverse events leading to death were low, as was discontinuation.

Amivantamab plus chemotherapy or plus lazertinib and chemotherapy are the “first regimens to demonstrate improved PFS versus chemotherapy in EGFR-mutated NSCLC after disease progression on osimertinib,” concluded Passaro, from the European Institute of Oncology IRCCS, Milan, Italy, who presented the findings.

Passaro added that, given the consistent efficacy and more favorable safety profile, “we can say that amivantamab plus chemotherapy is the new standard of care for patients that are progressing after osimertinib,” although more follow-up is required to understand its “real impact” in the clinic.

Zofia Piotrowska, MD, who was not involved in either MARIPOSA trial, said both “are really important” in the EGFR-mutant NSCLC space.

The studies “addressed two different questions,” but both were “positive, and I think clinically significantly,” said Piotrowska, a lung cancer specialist at Massachusetts General Hospital Cancer Center, Boston, Massachusetts.

However, Piotrowska noted that a core question for the community will be “how we find that balance between the clinical benefits [and] the toxicities.”

“There’s not going to be one easy answer” and treatment selection will have to be made on a “patient-by-patient basis,” she said.

PAPILLON, MARIPOSA, and MARIPOSA-2 were funded by Janssen Pharmaceuticals. Girard declared relationships with AstraZeneca, Boehringer-Ingelheim, Bristol Myers Squibb, Hoffmann La Roche, Lilly, Merck Sharp Dohme, Novartis, Pfizer, and others. Cho declared relationships with Novartis, AstraZeneca, Boehringer-Ingelheim, Roche, BMS, Onegene Biotechnology, Pfizer, Eli Lilly, and others. Passaro declared relationships with AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Janssen, Pfizer, Roche, Bayer, Boehringer-Ingelheim, Merck Sharp & Dohme, Mundipharma, Daiichi Sankyo, Medscape, eCancer. Besse declared institutional relationships with AbbVie, Amgen, AstraZeneca, BeiGene, Blueprint Medicines, Daiichi-Sankyo, Eli Lilly, EISAI, Genzyme Corporation, GSK, and others. Piotrowska declared relationships with numerous companies including AstraZeneca, Novartis, and Takeda.

European Society for Medical Oncology (ESMO) Annual Meeting 2023: Abstracts LBA5, LBA14, and LBA15. Presented October 21 and 23, 2023.

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Ann Oncol. Published online October 23, 2023. Full text

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