A Phase 1/2 Study Targeting Acquired Resistance Mechanisms in Patients with EGFR Mutant Non-Small Cell Lung Cancer

This is a Phase 1/2, open-label, first-in-human (FIH) study designed to evaluate the safety,
tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and anticancer activity of
BLU-945, a selective EGFR inhibitor, as monotherapy or in combination with osimertinib.

Inclusion Criteria:

1. ≥18 years of age at the time of signing the informed consent.

2. Pathologically confirmed, definitively diagnosed, metastatic NSCLC harboring an
activating EGFR mutation.

3. Previously received at least 1 prior EGFR-targeted TKI with activity against the T790M
mutation, such as osimertinib.

a. Phase 1 Part 1B and Phase 2 Group 4: Patients must have experienced progressive
disease while on osimertinib, and were able to tolerate prior osimertinib 80 mg QD
dose.

4. Tumor mutation profile determined locally via a Sponsor-approved testing methodology,
using tumor tissue (ideally from a progressing lesion) and/or ctDNA in plasma. For
Phase 1, it is preferable that samples used for analysis be obtained during or after
disease progression on the last EGFR-targeted TKI received. For Phase 2, pre-treatment
tumor sample must be obtained during or after disease progression on the last
EGFR-targeted TKI received.

1. Dose Escalation (Phase 1 Part 1A and Part 1B): At each dose level, slots may be
reserved for patients with the mutations of interest.

2. BLU-945 Monotherapy Expansion Groups (Phase 2 Group 1, Group 2, and Group 3):
Patients must have NSCLC harboring EGFR T790M and C797S mutation (Group 1); EGFR
T790M but not C797S (Group 2); or EGFR C797S but not T790M (Group 3).

3. BLU-945 with Osimertinib Expansion (Phase 2 Group 4): Slots may be reserved for
patients with mutations of interest, but at least 12 slots will be allocated to
patients with NSCLC harboring EGFR T790M and C797S mutation.

5. Pretreatment tumor sample (either an archival sample or a sample obtained by
pretreatment biopsy) submitted for central analysis. For Phase 1, it is preferable
that pretreatment tumor samples be obtained from a progression lesion, during or after
disease progression on the last EGFR-targeted TKI received. For Phase 2, pre-treatment
tumor sample must be obtained during or after disease progression on the last
EGFR-targeted TKI received.

Patients without appropriate archival tissue available, where biopsy is not considered
safe and/or medically feasible, may be discussed with the study medical monitor and
may be approved for enrollment on a case-by-case basis.

6. Phase 2 Expansion Groups: Patient has at least 1 measurable target lesion evaluable by
RECIST 1.1 as assessed by the investigator.

7. Eastern Cooperative Oncology Group (ECOG) performance status is 0-1.

8. Agrees to use contraception consistent with the protocol and local regulations

Exclusion Criteria:

1. Tumor harbors any additional known driver alterations (including but not limited to
EGFR exon 20 insertion, or pathologic abnormalities of KRAS, BRAF V600E, NTRK1/2/3,
HER2, ALK, ROS1, MET, or RET).

2. NSCLC with mixed cell histology or a tumor with histologic transformation (NSCLC to
SCLC, SCLC to NSCLC, or epithelial to mesenchymal transition).

3. Received the following anticancer therapy:

1. EGFR-targeted TKI within 7 days prior to the first dose of study drug.

2. Any immunotherapy or other antibody therapy (including EGFR-targeted antibodies
or bi-specific antibodies) within 28 days prior to the first dose of study drug
(immune-related toxicities must have resolved to < Grade 2 prior to starting BLU
945).

3. Any other systemic anticancer therapy within 14 days or 5 half-lives prior to the
first dose of study drug, whichever is the shortest, but with a minimum of 7 days
in all circumstances. BLU 945 may be started within these washout periods if
considered by the Investigator to be safe and within the best interest of the
patient, with prior Sponsor approval.

4. Radiotherapy to a large field or including a vital organ (including whole brain
radiotherapy or stereotactic radiosurgery to brain) within 14 days before the
first dose of study drug. Participant received radiotherapy to a focal site of
disease that did not include a vital organ (such as a limb) within 7 days before
the first dose of study drug.

4. CNS metastases or spinal cord compression that is associated with progressive
neurological symptoms or requires increasing doses of corticosteroids to control the
CNS disease. If a patient requires corticosteroids for management of CNS disease, the
dose must have been stable for the 2 weeks preceding treatment. Asymptomatic CNS and
leptomeningeal disease is allowed and, when measurable, should be captured as target
lesions.

5. Any of the following abnormalities on the most recent laboratory test prior to the
first dose of study drug (ie, Cycle 1 Day 1 [C1D1] or screening):

1. Absolute neutrophil count (ANC) <1.0×109/L.

2. Platelet count <75×109/L.

3. Hemoglobin ≤8.0 g/dL (red blood cell transfusion and erythropoietin may be used
to reach at least 8.0 g/dL, but must have been administered at least 2 weeks
prior to the first dose of study drug).

4. Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) >3× the upper
limit of normal (ULN) if no hepatic metastases are present; >5× ULN if hepatic
metastases are present.

5. Total bilirubin >1.5× ULN; >3× ULN in presence of Gilbert's disease.

6. Estimated (Cockroft-Gault formula) or measured creatinine clearance <40 mL/min.

7. International normalized ratio (INR) >2.3 or prothrombin time (PT) >6 seconds
above control or a patient-specific INR or PT abnormality that the treating
investigator considers clinically relevant and/or increases the risk for
hemorrhage in that individual patient.

6. Known intracranial hemorrhage and/or bleeding diatheses.

7. Clinically active ongoing interstitial lung disease (ILD) of any etiology, including
drug-induced ILD, and radiation pneumonitis within 28 days prior to initiation of
study treatment. Patients with prior ILD associated with clinically resolved COVID 19
infection may be enrolled upon discussion with, and approval by, the Medical Monitor.

8. Any unresolved toxicities from prior therapy greater than Common Terminology Criteria
for Adverse Events (CTCAE) Grade 1 or that have not resolved to baseline at the time
of starting the study. Exceptions include alopecia and fatigue, and, upon discussion
with and approval by the Medical Monitor, other toxicities that are not thought to
present a risk to patient safety.

9. Mean resting QT interval corrected using Fridericia's formula (QTcF) >450 msec, a
history of prolonged QT syndrome or Torsades de pointes, or a familial history of
prolonged QT syndrome.

10. Clinically significant, uncontrolled, cardiovascular disease including congestive
heart failure Grade III or IV according to the New York Heart Association
classification; myocardial infarction or unstable angina within the previous 6 months,
uncontrolled hypertension, or clinically significant, uncontrolled arrhythmias,
including bradyarrhythmia that may cause QT prolongation (eg, Type II second degree
heart block or third-degree heart block).

11. History of another primary malignancy (other than completely resected carcinomas in
situ) that has been diagnosed or required therapy within 2 years prior to initiation
of study treatment. However, upon discussion with the Sponsor, the following
categories of patients with prior malignancy are eligible to participate:

1. Patients with a previous malignancy that completed all anticancer treatment at
least 2 years before and with no evidence of residual disease from the prior
malignancy at registration

2. Patients who have another concurrent malignancy (not lung cancer) that is
clinically stable and does not require tumor-directed treatment. (Examples
include, but are not limited to, completely resected basal cell carcinoma and
squamous cell carcinoma of skin, curatively treated prostate cancer, breast
cancer and early gastric cancer cured by endoscopic mucosal resection or
endoscopic submucosal dissection.)

12. Active, uncontrolled infection (viral, bacterial, or fungal) or active tuberculosis,
hepatitis B, hepatitis C, AIDS-related illness, or known COVID 19 infection.
Controlled infections, including HIV and "cured" hepatitis C (no active fever, no
evidence of systemic inflammatory response syndrome) that are stable on antiviral
treatment may be eligible if benefit/risk is justified and permission is granted from
the Sponsor.

13. Dose-escalation (Parts 1A and 1B): Received neutrophil or platelet growth factor
support within 14 days of the first dose of study drug.

14. Requires treatment with a prohibited medication or herbal remedy that cannot be
discontinued at least 2 weeks before the start of study drug administration. BLU 945
may be started within 14 days or 5 half-lives of these therapies if considered by the
Investigator to be safe and within the best interest of the patient, with prior
Sponsor approval.

15. Major surgical procedure within 14 days of the first dose of study drug (procedures
such as central venous catheter placement, tumor needle biopsy, and feeding tube
placement are not considered major surgical procedures).