Treatment decisions about the care of patients with non–small cell lung cancer (NSCLC) that has metastasized to the brain should always be made by a multidisciplinary team, according to a lung cancer research specialist.
The care of these patients can be quite complex, and the brain is still largely terra incognita, said Lizza Hendriks, MD, PhD, during a case-based session at the European Lung Cancer Congress (ELCC) 2024 in Prague, Czech Republic.
The approach to patients with NSCLC metastatic to the brain and central nervous system was the subject of the session presented by Dr. Hendriks of Maastricht University Medical Center in Maastricht, the Netherlands. During this session, she outlined what is known, what is believed to be true, and what is still unknown about the treatment of patients with NSCLC that has spread to the CNS.
“Immunotherapy has moderate efficacy in the brain, but it can result in long-term disease control,” she said. She added that the best treatment strategy using these agents, whether immunotherapy alone or combined with chemotherapy, is still unknown, even when patients have high levels of programmed death protein 1 (PD-1) in their tumors.
“Also, we don’t know the best sequence of treatments, and we really need more preclinical research regarding the tumor microenvironment in the CNS,” she said.
Next-generation tyrosine kinase inhibitors (TKIs) generally have good intracranial efficacy, except for KRAS G12C inhibitors, which need to be tweaked for better effectiveness in the brain. The optimal sequence for TKIs also still needs to be determined, she continued.
Decision Points
Dr. Hendriks summarized decision points for the case of a 60-year-old female patient, a smoker, who in February of 2021 was evaluated for multiple asymptomatic brain metastases. The patient, who had good performance status, had a diagnosis of stage IVB NSCLC of adenocarcinoma histology, with a tumor positive for a KRAS G12C mutation and with 50% of tumor cells expressing PD-1.
The patient was treated with whole-brain radiation therapy and single-agent immunotherapy, and, 8 months later, in October 2021, was diagnosed with extracranial progressive disease and was then started on the KRAS G12c inhibitor sotorasib (Lumakras).
In May 2023 the patient was diagnosed with CNS oligoprogressive disease (that is, isolated progressing lesions) and underwent stereotactic radiotherapy. In June 2023 the patient was found to have progressive disease and was then started on platinum-based chemotherapy, with disease progression again noted in December of that year. The patient was still alive at the time of the presentation.
The first decision point in this case, Dr. Hendriks said, was whether to treat the patient at the time of diagnosis of brain metastases with upfront systemic or local therapy for the metastases.
At the time of extracranial progressive disease, should the treatment be another immumotherapy, chemotherapy, or a targeted agent?
“And the last decision is what should we do [in the event of] CNS oligoprogression?,” she said.
First Decision
For cases such as that described by Dr. Hendriks the question is whether upfront local therapy is needed if the patient is initially asymptomatic. Other considerations concerning early local therapy include the risks for late toxicities and whether there is also extracranial disease that needs to be controlled.
If systemic therapy is considered at this point, clinicians need to consider intracranial response rates to specific agents, time to onset of response, risk of pseudoprogression, and the risk of toxicity if radiotherapy is delayed until later in the disease course.
“I think all of these patients with brain metastases really deserve multidisciplinary team decisions in order to maintain or to [move] to new treatments, improve the quality of life, and improve survival,” she said.
In the case described here, the patient had small but numerous metastases that indicated the need for extracranial control, she said.
European Society of Medical Oncology (ESMO) guidelines recommend that asymptomatic patients or those with oligosymptomatic NSCLC brain metastases with an oncogenic driver receive a brain-penetrating TKI. Those with no oncogenic drive but high PD-1 expression should receive upfront immunotherapy alone, while those with PD-1 ligand 1 (PD-L1) expression below 50% receive chemoimmunotherapy.
The joint American Society of Clinical Oncology (ASCO), Society for Neuro-Oncology (SNO), and American Society for Radiation Oncology (ASTRO) guideline for treatment of brain metastases recommends a CNS-penetrating TKI for patients with asymptomatic NSCLC brain metastases bearing EGFR or ALK alterations. If there is no oncogenic driver, the guideline recommends the option of pembrolizumab (Keytruda) with or without chemotherapy.
Both the US and European guidelines recommend initiating local treatment for patients with symptomatic metastases. The level of evidence for these recommendations is low, however.
Clinicians still need better evidence about the potential for upfront immunotherapy for these patients, more information about the NSCLC brain metastases immune environment and tumor microenvironment, data on the best treatment sequence, and new strategies for improving CNS penetration of systemic therapy, Dr. Hendriks said.
Second Decision
At the time of CNS progression, the question becomes whether patients would benefit from targeted therapy or chemotherapy.
“We quite often say that chemotherapy doesn’t work in the brain, but that’s not entirely true,” Dr. Hendriks said, noting that, depending on the regimen range, brain response rates range from 23% to as high as 50% in patients with previously untreated asymptomatic brain metastases, although the median survival times are fairly low, on the order of 4 to almost 13 months.
There is also preclinical evidence that chemotherapy uptake is higher for larger brain metastases, compared with normal tissue and cerebrospinal fluid, “so the blood-brain barrier opens if you have the larger brain metastases,” she said.
KRAS-positive NSCLC is associated with a high risk for brain metastases, and these metastases share the same mutation as the primary cancer, suggesting potential efficacy of KRAS G12c inhibitors. There is preclinical evidence that adagrasib (Krazati) has CNS penetration, and there was evidence for intracranial efficacy of the drug in the KRYSTAL-1b trial, Dr. Hendriks noted.
There are fewer data for the other Food and Drug Administration (FDA)–approved inhibitor, sotorasib, but there is evidence to suggest that its brain activity is restricted by ABCB1, a gene encoding for a transporter protein that shuttles substances out of cells.
Third Decision
For patients with CNS oligoprogression, the question is whether to adapt systemic therapy or use local therapy.
There is some evidence to support dose escalation for patients with oligoprogression of tumors with EGFR or ALK alterations, but no data to support such a strategy for those with KRAS alterations, she said.
In these situations, data support dose escalation of osimertinib (Tagrisso), especially for patients with leptomeningeal disease, and brigatinib (Alunbrig), but there is very little evidence to support dose escalation for any other drugs that might be tried, she said.
In the question-and-answer part of the session, Antonin Levy, MD, from Gustave Roussy in Villejuif, France, who also presented during the session, asked Dr. Hendriks what she would recommend for a patient with a long-term response to chemoimmunotherapy for whom treatment cessation may be recommended, but who still has oligopersistent brain metastases.
“The difficulty is that with immunotherapy patients can have persistent lesions without any tumor activity, and in the brain I think there is no reliable technique to evaluate this type of thing,” she said.
Dr. Hendriks added that she would continue to follow the patient, but also closely evaluate disease progression by reviewing all scans over the course of therapy to determine whether the tumor is truly stable, follow the patient with brain imaging, and then “don’t do anything.”
Dr. Hendriks disclosed grants/research support and financial relationships with multiple companies. Dr. Levy disclosed research grants from Beigene, AstraZeneca, PharmaMar, and Roche.
