Table 1. Identification of EGFR ECD mutations in circulating ctDNA of CRC patients.

Serum samples were collected and analyzed by ddPCR in a subset (n = 11) of patients enrolled in the phase 1 clinical trial NCT01520389. These patients represented a subset of study patients who received MM-151 after the emergence of acquired resistance to previous anti-EGFR treatment and had remaining serum available for analysis. The EGFR ECD mutations detected at baseline are noted for each patient. ND, not detected; SD, stable disease; PD, progressive disease. Among the nine patients in this subset who received MM-151 as a monotherapy, two of the three patients who remained on treatment beyond the first scanning interval harbored these EGFR ECD mutations. The remaining patient had indolent disease, having been diagnosed with metastatic disease 7 years earlier and achieving stable disease on five of six previous therapies. One additional patient of the 11 achieved stable disease and received MM-151 in combination with irinotecan.

Subject IDStudy treatmentEGFR ECD mutationsBest RECIST v.1.1 response on MM-151
005-30-008MM-151 monotherapyNDPD
010-30-007MM-151 monotherapyNDPD
010-42-020MM-151 monotherapyNDSD
054-62-051MM-151 monotherapyEGFR p.S464L
EGFR p.G465R
SD
065-72-065MM-151 monotherapyNDPD
054-92-095MM-151 monotherapyEGFR p.G465E
EGFR p.G465R
SD (29.7% reduction)
065-92-103MM-151 monotherapyNDPD
005-02-109MM-151 monotherapyNDPD
065-02-093MM-151 monotherapyNDPD
054-03-106MM-151 + irinotecanNDPD
010-03-086MM-151 + irinotecanNDSD