Protein test predicts NSCLC survival benefit for chemotherapy over erlotinib

By Sarah Pritchard, medwireNews Reporter

Italian study results confirm that a multivariate serum protein test predicts improved survival after treatment with chemotherapy versus erlotinib for non-small-cell lung cancer (NSCLC), but only among patients who are likely to have a poor outcome with the latter treatment type.

Specifically, patients predicted to have poor survival outcomes with epidermal growth factor receptor–tyrosine kinase inhibitors (EGFR–TKI) according to the proteomic test survived a median 3 months longer when treated with chemotherapy than their counterparts who received the EGFR–TKI erlotinib.

By contrast, neither treatment regimen was associated with superior overall survival among patients whose predicted outcomes were good.

Vanesa Gregorc (Ospedale San Raffaele, Milan) and co-workers assessed the predictive power of the proteomic test – which compares the intensity of eight regions in patients’ mass spectra with those of a reference set – among 129 NSCLC patients randomly assigned to receive chemotherapy (pemetrexed 500 mg/m² or docetaxel 75 mg/m² every 21 days) and 134 assigned to receive erlotinib (150 mg/day).

Overall, 70% patients had a proteomic test classification of “good” while the remaining 30% were classified as “poor”.

After a median 32.4 months of follow-up, overall survival did not differ significantly according to treatment type, at 9.0 months in the chemotherapy group and 7.7 months in the erlotinib group. Conversely, patients with a proteomic test classification of good had significantly better overall survival than those with a classification of poor, at 11.0 versus 3.7 months.

Within the proteomic test classification groups, patients classified as poor and treated with erlotinib were 72% more likely to have died during follow-up than their counterparts who received chemotherapy (median overall survival, 3.0 vs 6.4 months), while Gregorc and colleagues found no significant difference in overall survival length among patients with a good proteomic test classification, at around 11 months for both groups.

Furthermore, progression-free survival did not differ significantly per treatment regimen according to proteomic test classification, adds the team in TheLancet Oncology.

The researchers note that the biological rationale for the difference in overall survival according to proteomic classification is being studied, but one “notable hypothesis” is that “patients who have a poor proteomic test classification have a systemic inflammatory response to their tumours that promotes tumour growth and apoptotic resistance”, which could enhance tumour aggressiveness and provide a means to “bypass EGFR blockade”.

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