TP53 Status and Treatment Toxicity Burden Guide Sequencing in EGFR-Mutated NSCLC

With TP53 comutation status now regarded as a marker of prognosis rather than an independent trigger for treatment intensification, medical oncologists convened to weigh how comutation status and toxicity burden should shape first- and second-line treatment decisions in EGFR-mutated non–small cell lung cancer (NSCLC).¹

“I don’t think TP53 changes much of what I do, because the emphasis when I’m talking to the patient is to stress the EGFR [driver],” said Sanjay Sharma, MD, of St. Jude Heritage Health Foundation, during a recent OncLive® Scientific Interchange and Workshop held in conjunction with the 27th Annual International Lung Cancer Congress. Moderated by Millie Das, MD, of Stanford University, the discussion moved from frontline regimen selection through second-line sequencing and the practical barriers that shape care.

Does TP53 comutation status support frontline treatment intensification in EGFR-mutated NSCLC?

TP53, the most frequently mutated gene in NSCLC, is associated with poor prognosis and treatment resistance.² Panelists estimated TP53 comutations in 40% to 50% of EGFR-mutated patients, treating it as one of several overlapping high-risk features including brain, liver, or bone metastases, detectable circulating tumor DNA, and an L858R mutation that affect roughly 90% of patients, rather than a stand-alone trigger for escalation.

Retrospective analyses of the phase 3 FLAURA2 trial (NCT04035486), which evaluated osimertinib (Tagrisso) plus platinum-pemetrexed, and the phase 3 MARIPOSA trial (NCT04487080), which evaluated amivantamab-vmjw (Rybrevant) plus lazertinib (Lazcluze), had suggested a survival benefit from combination therapy regardless of TP53 status.^3,4 The phase 3 TOP trial (NCT04695925) tested this prospectively by randomly assigning 294 patients with TP53 and EGFR comutations to osimertinib plus chemotherapy or osimertinib alone. Results showed an approximate doubling in median progression-free survival (PFS), at 34.0 months (95% CI, 24.9-36.4) vs 15.6 months (95% CI, 13.0-18.3), respectively (HR, 0.44; 95% CI, 0.32-0.60; P < .001) and improved response rates (82.9% vs 71.6%), with a trend toward an overall survival (OS) benefit in immature data (HR, 0.57; 95% CI, 0.38-0.88).⁵

Faculty said the trial reinforced practice many had adopted. “I don't think TP53 changes much of what I do,” Sharma said, noting he still discloses the mutation but keeps the conversation centered on the actionable driver. Andy Jang, MD, of Kaiser Permanente Riverside Medical Center, said the data leave little room to withhold combination therapy. “You can only find reason not to [administer] combination [therapy]... you can only de-escalate from there on.” Several panelists noted TOP enrolled exclusively in China, raising generalizability questions.

What is the optimal second-line regimen after frontline osimertinib or combination therapy?

No consensus second-line regimen emerged. In the phase 3 MARIPOSA-2 trial (NCT04988295), amivantamab plus chemotherapy improved PFS over chemotherapy alone in patients with TP53 comutations (HR, 0.63; 95% CI, 0.44-0.92; P = .014) and MET amplification (HR, 0.51; 95% CI, 0.24-1.11), at a higher rate of grade 3 or greater toxicity (72% vs 48%).^6,7 Datopotamab deruxtecan (Dato-DXd; Datroway), a TROP2-directed antibody-drug conjugate (ADC), produced an objective response rate (ORR) of 42.7% (95% CI, 33.6%-52.2%) and median PFS of 5.8 months (95% CI, 5.4-8.2) in a pooled EGFR-mutated analysis of the phase 3 TROPION-Lung01 (NCT04656652) and phase 2 TROPION-Lung05 (NCT04484142) trials, with intracranial response approaching 38% (95% CI, 15%-65%) in TROPION-Lung01.^8,9

Panelists split between defaulting to amivantamab-chemotherapy and reserving Dato-DXd for the third line, or the reverse. “By default, Dato-DXd is the way to go,” said Dan Sotirescu, MD, of Cancer Care Associates of York. Arati Chand, MD, of Cancer and Blood Specialty Clinics, said amivantamab “still scares me” and favored Dato-DXd in an older patient with TP53-mutated disease who tolerated it well, reserving amivantamab for younger patients with better performance status. No validated biomarker distinguishes ADC candidates, panelists agreed. “Every company comes up with their own… assay,” said Muhammad Mirza, MD, of Mercy Hospital–St. Louis. “The mutation is nice because it’s a yes or no... but [with ADC biomarkers], it’s really frustrating.” Preclinical TROP2-overexpression data have not yet translated into a selection tool, prompting Das to call current practice “shooting in the dark.” For a prolonged pemetrexed-free interval after frontline osimertinib-chemotherapy, platinum rechallenge was broadly favored, with a 3-year OS rate of 77% (95% CI, 60%-87%) after a median interval of 19.8 (range, 0.5-42.3) months.¹⁰

How are toxicity and access barriers shaping second-line treatment selection?

Toxicity and time burden factored as heavily as efficacy data into regimen choice. A time-toxicity analysis estimated 367.68 hours of first-year clinic time, administration, and prophylaxis management with intravenous amivantamab-lazertinib (311.43 hours subcutaneous), vs 73.25 hours for osimertinib-chemotherapy and 35.83 hours for osimertinib alone.¹¹ Dermatologic toxicity was named the leading driver of amivantamab dose reduction or discontinuation despite COCOON (NCT06120140)-protocol prophylaxis. Olivia Fankuchen, MD, of NYU Langone Health, said the burden falls unevenly on patients with fewer resources: many of hers “are food workers or they’re doing a lot of things with chemical handling,” making the regimen hard to sustain “even if they can stick to the full regimen.”

Ocular toxicity associated with Dato-DXd surfaced a parallel access gap. Pamela Miel, MD, FACP, of The Oncology Institute of Hope and Innovation, said community ophthalmologists often underestimate the urgency of these events, recalling one who offered a 6-month follow-up when closer monitoring was warranted. Insurance authorization delays and multiweek trial-screening timelines were also cited as referral barriers; Chand said enrollment can take roughly 4 weeks even for symptomatic patients able to start treatment immediately.

What unmet needs did the panel identify?

Faculty named standardized, validated ADC-selection biomarkers as the field's most pressing gap, alongside global confirmatory data for emerging MET- and TROP2-targeted strategies including osimertinib-Dato-DXd as seen in the phase 2 ORCHARD trial (NCT03944772), sacituzumab tirumotecan as seen in the phase 3 OptiTROP-Lung04 trial (NCT05870319), and savolitinib-osimertinib as seen in the phase 2 SAVANNAH trial (NCT03778229).^12-14 Repeat biopsy at progression was flagged as underused, since liquid biopsy alone cannot identify transformation to small cell or squamous histology; patients with baseline TP53, particularly with concurrent RB1 comutations, warrant particular vigilance. Jang predicted the broader trajectory: “Across the tumor type, ADCs are just going to replace the existing chemotherapy... they are more precise, they’re more effective.” The panel agreed that closing practical gaps like time toxicity, specialty access, and authorization delays will matter as much as new efficacy data for patients with EGFR-mutated NSCLC.

References

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