Intraventricular Methotrexate May Improve Survival in Medulloblastoma Subtypes

July 20, 2020

Adding intraventricular methotrexate to systemic chemotherapy produced favorable survival outcomes in patients with desmoplastic medulloblastoma (DMB) and medulloblastoma with extensive nodularity (MBEN), according to research published in the Journal of Clinical Oncology.

Investigators conducted a prospective trial of 87 children diagnosed with nonmetastatic medulloblastoma before the age of 4 years who were treated from 2001-2011.

At 5 years after diagnosis, the 42 DMB/MBEN patients had a 93% progression-free survival (PFS) rate, a 100% overall survival (OS) rate, and a 93% craniospinal irradiation (CSI)–free survival rate.

"Our results suggest that ... poor outcomes of patients treated with systemic chemotherapy alone can be improved by the addition of intraventricular [methotrexate]," wrote Martin Mynarek, MD, of the University Medical Center Hamburg-Eppendorf (Germany), and colleagues.

However, it was a different story for the 45 patients with classic medulloblastoma (CMB) or large-cell/anaplastic medulloblastoma (CLA), in which outcomes are historically worse. At 5 years, the PFS was 37%, the OS was 62%, and the CSI-free survival was 39% in these patients.

In 2006, the CMB and CLA patients started receiving local radiotherapy in addition to chemotherapy and intraventricular methotrexate, but the radiotherapy did not seem to help with their disease.

"Because data suggest no effects, or even adverse effects, of local radiotherapy, additional development of this approach does not seem justified," the investigators wrote.

"Interestingly, almost all patients with CMB/LCA had distant or combined relapses after local radiotherapy," they added. "One might speculate that local radiotherapy reduced disease burden of the primary tumor and subclinical metastasis in the posterior fossa, leading to a survival advantage of distant subclinical metastasis over local residues."

Treatment Details

The 87 patients were enrolled in the BIS4 arm of the HIT 2000 trial (NCT00303810), which was designed to test six protocols and identify the optimal approach for treating young patients with medulloblastoma, supratentorial primitive neuroectodermal tumor, or ependymoma.

Patients started "HIT-SKK" chemotherapy within 2-4 weeks of surgery. They received three cycles of intravenous cyclophosphamide, vincristine, methotrexate (followed by leucovorin rescue after 42 hours), carboplatin, and etoposide, with concomitant intraventricular methotrexate, for a duration of 6 months (Neuro Oncol. 2011 Jun;13[6]:669-79).

Among patients who achieved a complete remission, treatment was ended after two additional cycles of chemotherapy. For other patients, secondary surgery, radiotherapy, and consolidation chemotherapy were recommended.

Starting in 2006, DMB and MBEN patients without complete remissions, as well as those with CMB or LCA, received 54 Gy of focal radiotherapy to the tumor bed after the first three treatment cycles.

SHH-I vs. SHH-II DMB/MBEN

DNA methylation profiling was available for 50 of the 87 patients in this analysis, 28 of whom had infantile sonic hedgehog (SHH)–activated DMB/MBEN. Data from these 28 patients – and 71 patients in a validation cohort – revealed no significant difference in 5-year PFS or OS based on methylation subtype.

The 5-year PFS was 73% in SHH-I patients and 83% in SHH-II patients (P = .25). The 5-year OS was 88% and 97%, respectively (P = .099).

"This suggests that the higher risk of relapse in the less favorable [SHH-I subtype] can be abrogated by the addition of intraventricular [methotrexate] to systemic chemotherapy," the investigators wrote.

The results suggest SHH-I patients "markedly benefit" from the addition of intraventricular chemotherapy, according to the authors of a related editorial, Giles Robinson, MD, and Amar Gajjar, MD, of St. Jude Children's Research Hospital in Memphis, Tenn.

"However, cross-trial comparison of PFS among the SHH-II subtype does not suggest that SHH-II patients derive the same benefit," the editorialists wrote.

These data divide SHH medulloblastoma into SHH-I, which benefits from chemotherapy with intraventricular methotrexate, and SHH-II, which can be cured without intraventricular methotrexate, high-dose chemotherapy, or focal radiotherapy, according to the editorialists.

This new information might prompt investigation of a risk-adapted approach. SHH-II patients would receive a reduced-intensity regimen with systemic chemotherapy only, and SHH-I patients would receive systemic chemotherapy combined with intraventricular methotrexate. This could avoid exposing young children to "more intensive therapy than necessary," according to the editorialists.

Non-WNT/Non-SHH Disease

Patients with non-WNT/non-SHH medulloblastoma (CMB or LCA) were divided into molecularly defined subtypes group 3 (n = 14) and group 4 (n = 6). The patients in group 3 had lower survival rates than patients in group 4. The 5-year PFS rate was 36% and 83%, respectively (P < .001 ). The 5-year OS rate was 49% and 100%, respectively (P < .001).

"This represents the third recent publication to describe a poor PFS for group 3, and it signals a desperate need for better therapy," the editorialists wrote. As for the "encouraging" survival rate for group 4 patients, there were only six subjects, which makes this finding "worthy of follow-up but not actionable."

Even so, the investigators noted that "although poor survival has been reported for non-SHH CMB/LCA in almost every series of patients treated with CSI-sparing approaches, again, use of intraventricular [methotrexate] might be associated with slightly higher PFS, compared with conventional chemotherapy alone."

As expected, IQ was significantly lower in patients who received CSI salvage. The mean IQ was 74 in patients who received CSI and 90 in patients who did not (P = .012). Neurocognitive outcomes were poor in general among CMB/LCA survivors, "which was closely related to use of radiotherapy," according to the investigators.

"It is important to recognize that these studies were not designed to define outcome on the basis of molecular subgroup or subtype and that the sample size in all these studies is small," Dr. Robinson and Dr. Gajjar wrote. "Thus, caution should be used when basing any treatment recommendation on these results, and it is our strong-held opinion that any treatment change be done on a well-planned and well-monitored clinical trial."

This research was supported by the German Childhood Cancer Foundation, Styrian Childhood Cancer Foundation, and other organizations. Dr. Mynarek and colleagues disclosed relationships with Medac, Novartis, Eli Lilly, Bayer, Roche, and numerous other companies. Dr. Robinson disclosed relationships with Eli Lilly, Genentech, and Novartis. Dr. Gajjar reported relationships with Genentech and Kazia Therapeutics.

SOURCE: Mynarek M et al. J Clin Oncol. 2020 Jun 20;38(18):2028-40.

This story originally appeared on MDedge.com.

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