Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

[Q]: Fafhrd and the Gray Mouser are two sword-and-sorcery heroes appearing in stories written by American author Fritz Leiber.
[A]: Who is the author of Fafhrd and the Gray Mouser?

[Q]: Following the assassination of her nephew Ptolemy XI Alexander II (80 BC), Cleopatra Selene I remained the only legitimate surviving member of the Ptolemaic dynasty.
[A]: What was the noble family that Cleopatra Selene I was from?

[Q]: Patients with lung adenocarcinoma who carry epidermal growth factor receptor (EGFR) gene mutations respond remarkably well to EGFR tyrosine kinase inhibitor (EGFR-TKI), gefitinib, or erlotinib. However, the effect of EGFR-TKI treatment on the prolongation of overall survival (OS) of these patients remains uncertain, although several recent studies have shown prolongation of progression free survival compared with cytotoxic chemotherapy. A total of 304 patients with lung adenocarcinoma who had postoperative recurrent disease were studied. To eliminate potential biases as possible, the matching of four potential predictive factors of responsiveness to EGFR-TKI led to the identification of 81 pairs of patients (those who were treated with gefitinib and those who were not). A deletion mutation in exon 19 and a point mutation (L858R) in exon 21 of the EGFR gene were also analyzed. We compared the OS between the two groups. OS in the gefitinib group was significantly longer than in the control group (median, 63 vs. 41 months; p=0.015). EGFR mutations were detected in 65 out of 129 patients (50%) in the whole sample. EGFR mutational status was not an independent prognostic factor of gefitinib benefit; rather, it was a predictive factor. This study strongly suggested that gefitinib treatment improved OS of lung adenocarcinoma patients who had postoperative recurrence, especially those carrying EGFR mutations.
[A]:
Mutations in which gene determine response to both erlotinib and gefitinib?