Study of Furmonertinib in Patients With Advanced or Metastatic Non-Small Cell Lung Cancer (NSCLC) With Activating, Including Uncommon, Epidermal Growth Factor Receptor (EGFR) or Human Epidermal Growth Factor Receptor 2 (HER2) Mutations

Key Inclusion Criteria:

• Histologically or cytologically documented, locally advanced or metastatic Non-SmallCell Lung Cancer (NSCLC) not amenable to curative surgery or radiotherapy.

• Disease that has progressed after at least one available standard therapy; or forwhom standard therapy has proven to be ineffective or intolerable; or for whom aclinical trial of an investigational agent is a recognized standard of care.

• Documented radiologic disease progression during or after the last systemicanti-cancer therapy before the first dose of furmonertinib.

• For patients with Epidermal Growth Factor Receptor (EGFR) mutations sensitive toosimertinib, the patient must have received osimertinib prior to study enrollment inregions where osimertinib is approved, including the US.

Stage 1 dose escalation and backfill cohorts and Stage 2 Cohorts 1, 2, 3 and 4:

-Patients with CNS metastases (including leptomeningeal disease) may be eligible if meeting additional protocol specified criteria.

Stage 1 Dose Escalation and Backfill Cohorts Inclusion Criteria:

• Documented validated results from local testing of tumor tissue or blood confirmingthe presence of an activating, including uncommon, EGFR mutation or HER2 exon 20insertion mutation performed at a CLIA-or equivalently certified laboratory.

Stage 2 Cohort 1 Previously Treated, Locally Advanced or Metastatic NSCLC Patients with EGFR Exon 20 Insertion Mutations Inclusion Criteria

• Documented validated results from local testing of either tumor tissue or bloodconfirming the presence of EGFR Exon 20 insertion mutations, performed at a CLIA- orequivalently certified laboratory.

• The patient must have experienced disease progression or have intolerance totreatment with platinum-based chemotherapy.

Stage 2 Cohort 2 Previously treated, Locally Advanced or Metastatic NSCLC Patients with HER2 Exon 20 Insertion Mutations Inclusion Criteria

• Documented validated results from local testing of either tumor tissue or bloodconfirming the presence of HER2 Exon 20 insertion mutations, performed at a CLIA- orequivalently certified laboratory.

• The patient must have experienced disease progression or have intolerance totreatment with platinum-based chemotherapy.

• In regions in which fam-trastuzumab deruxtecan-nxki is approved and available foradult patients with unresectable or metastatic NSCLC whose tumors have activatingHER2 exon 20 mutations, the patient must have received or be considered notappropriate to receive fam-trastuzumab deruxtecan-nxki.

Stage 2 Cohort 3 Previously Treated, Locally Advanced or Metastatic NSCLC Patients with EGFR Activating Mutations Mutations, who are not eligible for Cohorts 1 and 4 Inclusion Criteria

• Documented validated results from local testing of either tumor tissue or bloodconfirming the presence of an EGFR activating mutation, performed at a CLIA- orequivalently certified laboratory.

• The patient must have experienced disease progression or have intolerance totreatment with the standard of care EGFR TKI.

• Patients with CNS metastases may be eligible if meeting additional protocolspecified criteria.

Stage 2 Cohort 4 Untreated or Previously Treated EGFR TKI-Naïve, Locally Advanced or Metastatic NSCLC Patients with EGFR Uncommon Mutations excluding EGFR Exon 20 insertions Inclusion Criteria

• Previously untreated in the locally advanced or metastatic setting or haveprogressed after at least 1 available standard therapy, or for whom standard therapyhas proven to be ineffective, intolerable, or considered inappropriate

• Documented validated results from local testing of either tumor tissue or bloodconfirming the presence of an EGFR Uncommon mutation, performed at a CLIA- orequivalently certified laboratory a. Representative mutations include, but are notlimited to, G719X, S768I, E709X, G779F, L747X, V774M, E709_T710delinsD, R776C/H,G724S, E736K, I740_K745dup, N771G, K757M/R, V769L/M, T854X, T751_I759delinsN

Key Exclusion Criteria:

• Treatment with chemotherapy, targeted therapy, biologic therapy or aninvestigational agent as anti-cancer therapy within 3 or 3 elimination weeks or fivehalf-lives prior to initiation of furmonertinib, whichever is shorter, or endocrinetherapy within 2 weeks prior to initiation of furmonertinib.

• Radiation therapy as cancer therapy within 4 weeks prior to initiation offurmonertinib.

• Palliative radiation to bone metastases within 2 weeks prior to initiation offurmonertinib.

• AE from prior anticancer therapy that have not resolved to Grade ≤ 1 except foralopecia or Grade ≤ 2 peripheral neuropathy.

Stage 2 Cohort 4 Untreated or Previously Treated EGFR TKI-Naïve, Locally Advanced or Metastatic NSCLC Patients with EGFR Uncommon Mutations Exclusion Criteria

• Prior treatment with any EGFR TKIs

• Progression during neoadjuvant or adjuvant therapy (e.g., chemotherapy,radiotherapy, immunotherapy or investigational agents) or within 12 months ofcompletion of above therapies.