A Phase 1/2, First-In-Human, Multi-Part, Open-Label Study to Investigate the Safety, Tolerability, Pharmacokinetics, Biological and Clinical Activity of DF9001 as a Monotherapy and in Combination with Nivolumab in Patients With Advanced (Unresectable, Recurrent, or Metastatic) Solid Tumors, and Expansion in Selected Indications.

Inclusion Criteria: General (applies to all cohorts)

1. Signed written informed consent.

2. Male or female patients aged ≥ 18 years.

3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 at study entry

and an estimated life expectancy of at least 3 months.

4. Adequate hematological function.

5. Adequate hepatic function.

6. Adequate renal function.

7. Effective contraception for women of child bearing potential (WOCBP) patients as

defined by World Health Organization (WHO) guidelines for 1 "highly effective" method

or 2 "effective" methods.

Inclusion Criteria: Dose Escalation (Monotherapy and Combination)

1. Histologically or cytologically proven locally advanced or metastatic solid tumors of

epithelial origin with documented EGFR expression on tumor tissue by IHC and must have

progressed on standard of care therapy.

2. Evidence of objective disease, but participation does not require a measurable lesion.

Inclusion Criteria: Safety PK/PD Expansion Cohorts

1. Histologically or cytologically proven locally advanced or metastatic solid tumor from

the following list, where standard therapy has failed, that has been confirmed to have

EGFR expression via archival or fresh biopsy tissue prior to study enrollment.

i. NSCLC ii. HNSCC iii. CRC iv. Esophageal adenocarcinoma v. Gastric cancer vi. Renal

cell carcinoma vii. Pancreatic cancer

2. Disease must be measurable with at least 1 unidimensional measurable lesion by RECIST

1.1.

3. Able and willing to have a fresh tumor biopsy obtained during the screening window and

an on-treatment biopsy for pharmacodynamic analysis.

Inclusion Criteria: Head and Neck Squamous Cell Carcinoma (HNSCC) Expansion Cohorts

1. Histologically or cytologically documented relapsed or metastatic HNSCC that has been

confirmed to have EGFR expression via archival or fresh biopsy tissue prior to study

enrollment. Primary tumor locations include oropharynx, oral cavity, hypopharynx, or

larynx. Participants may not have a primary tumor site of nasopharynx (any histology).

2. Participants must have radiographic disease progression while on or after having

received both platinum-based chemotherapy and an anti-PD-(L)1 antibody, administered

either concurrent or sequentially.

3. Documented EGFR expression by IHC.

4. Able and willing to have a fresh tumor biopsy obtained during the screening window and

an on-treatment biopsy for pharmacodynamic analysis.

Inclusion Criteria: Colorectal Cancer (CRC) Expansion Cohorts

1. Histologically or cytologically documented relapsed or metastatic colorectal cancer

that has been confirmed to have EGFR expression via archival or fresh biopsy tissue

prior to study enrollment.

2. Must have received 1 line of either FOLFOX, CAPOX, FOLFIRI, or FOLFOXIRI with or

without a biological agent. Prior treatment with an anti-EGFR antibody is required for

RAS wild-type participants.

3. Participants cannot be known mismatch repair (MMR)/MSI high.

4. Participants must not have received an anti-PD-(L)1.

5. Participants must have radiographic disease progression while or after receiving

treatment for their advanced (recurrent/unresectable/metastatic) disease.

6. Presence of at least 1 tumor lesion accessible for biopsy. A fresh tumor biopsy must

be obtained and shipped for analysis at the Sponsor-designated laboratory during the

screening window and while on study treatment in accordance with the study Laboratory

Manual.

Inclusion Criteria: Non-Small Cell Lung Cancer (NSCLC) Expansion Cohorts

1. Histologically confirmed NSCLC meeting stage criteria for stage IIIB, stage IV (per

the 7th IASCLC classification of NSCLC), or recurrent disease that has been confirmed

to have EGFR expression via archival or fresh biopsy tissue prior to study enrollment.

2. Patients must have recurrent or progressive disease during or after first line

combination therapy with checkpoint inhibitors and platinum-based chemotherapy. They

must not have received any subsequent lines of therapy.

3. Patients with Stage IIIB must be ineligible for local therapies with curative intent

(eg, radiotherapy or surgery).

4. Patients must have received and progressed on or after anti-PD-(L)1 therapy including

those with actionable genomic alterations.

5. Status for actionable mutations (EGFR, ALK, ROS1, RET, etc.) must be known (when

testing is available as per country/region standard of care practices); patients with

actionable mutations must have received and progressed on, have been intolerant to, or

not be a candidate for standard TKIs (as available per country/region standard of care

practices).

6. Presence of at least 1 tumor lesion accessible for biopsy. A fresh tumor biopsy must

be obtained and shipped for analysis at the Sponsor-designated laboratory during the

screening window and while on study treatment in accordance with the study Laboratory

Manual.

Exclusion Criteria

1. Participants must not have had chemotherapy, radiotherapy (other than palliative

bone-directed radiotherapy), or major surgery, or received another investigational

agent within 28 days or 5-half-lives of the drug (if known), whichever is shorter,

before the start of study treatment.

2. Concurrent anticancer treatment (eg, cytoreductive therapy, radiotherapy [except for

palliative bone-directed radiotherapy], immune therapy, or cytokine therapy [except

for erythropoietin]), major surgery (excluding prior diagnostic biopsy), concurrent

systemic therapy with steroids or other immunosuppressive agents, or use of any

investigational drug within 28 days or 5-half-lives of the drug (if known), whichever

is shorter, before the start of study treatment. Short-term administration of systemic

steroids (eg, for allergic reactions or the management of irAEs) is allowed.

Note: Participants receiving bisphosphonate or denosumab are eligible, provided

treatment was initiated at least 14 days before the first dose of DF9001.

3. Previous malignant disease other than the target malignancy to be investigated in this

study within the last 3 years, with the exception of basal or squamous cell carcinoma

of the skin, low-grade prostate cancer (Gleason score of ≤6), or cervical carcinoma in

situ.

4. Life expectancy of less than 3 months.

5. Participants with brain metastases are excluded, unless all of the following criteria

are met:

- Central nervous system (CNS) lesions are asymptomatic, previously treated and no

active therapy is required (i.e., no steroids for edema).

- Imaging demonstrates stability of disease 28 days from last treatment for CNS

metastases.

6. Receipt of any organ transplantation, including autologous or allogeneic stem-cell

transplantation.

7. Significant acute or chronic infections (including historic positive test for human

immunodeficiency virus [HIV], or active or latent hepatitis B or active hepatitis C

tested during the screening window). If HBsAg is negative and the anti-hepatitis B

core antibody is positive, then hepatitis B viral DNA load must be undetectable.

8. Preexisting autoimmune disease (except for participants with vitiligo) needing

treatment with systemic immunosuppressive agents for more than 28 days within the last

3 years, or clinically relevant immunodeficiencies (eg, dysgammaglobulinemia or

congenital immunodeficiencies). Participants with a history of immune related

endocrinopathies (e.g. hypothyroidism, type 1 diabetes mellitus [TIDM] and adrenal

insufficiency) that are stable on hormone replacement therapy may be eligible for this

study.

9. Participants with a known medical history that may place them at risk of known

toxicities of EGFR-blockage.

- History of or ongoing keratitis, ulcerative keratitis, or corneal perforation,

- History of cardiopulmonary arrest unless this was caused by an acute, reversible

etiology that is no longer present.

- History of or ongoing pulmonary fibrosis or interstitial lung disease.

10. Known severe hypersensitivity reactions to monoclonal antibodies (≥Grade 3 of the

NCI-CTCAE v5.0), any history of anaphylaxis, or uncontrolled asthma (ie, 3 or more

features of partly controlled asthma).

11. Persisting toxicity related to prior therapy >Grade 1 NCI-CTCAE v5.0; however,

alopecia ≤Grade 2, endocrinopathies ≤Grade 2, and sensory neuropathy ≤Grade 2 is

acceptable.

12. Participants who have received an anti-PD-(L)1 as a previous line of therapy are

eligible for the study, unless they have experienced either:

- a Grade 3 or 4 drug-related toxicity during and attributed to treatment with the

anti-PD-(L)1.

- a Grade 2 drug-related toxicity that impacted either the lungs or the nervous

system, caused by the administration of the anti-PD-(L)1.

13. Pregnancy or lactation in females during the study.

14. Known alcohol or drug abuse.

15. Serious cardiac illness or medical conditions, including but not limited to:

- History of New York Heart Association class III or IV heart failure or systolic

dysfunction (left ventricular ejection fraction [LVEF] <55%).

- High-risk uncontrolled arrhythmias (eg, tachycardia with a heart rate >100/min at

rest).

- Significant ventricular arrhythmia (ventricular tachycardia) or higher-grade

atrioventricular (AV) block (eg, AV-block, second degree AV block Type 2 [Mobitz

2], or third-degree AV-block).

- Angina pectoris requiring anti-anginal medication.

- Clinically significant valvular heart disease.

- Evidence of transmural infarction on ECGs.

- Poorly controlled hypertension (defined as systolic >160 mm Hg or diastolic >100

mm Hg).

- Clinically relevant uncontrolled cardiac risk factors, clinically relevant

pulmonary disease, or any clinically relevant medical condition in the opinion of

the Investigator that may limit participation in this study.

- Severe dyspnea at rest due to complications of advanced malignancy or requiring

supplementary oxygen therapy.

16. All other significant diseases (eg, inflammatory bowel disease), which, in the opinion

of the Investigator, might impair the participant's ability to participate.

17. Any psychiatric condition that would prohibit the understanding or rendering of

informed consent.

18. Legal incapacity or limited legal capacity.

19. Incapable of giving signed informed consent, which includes compliance with the

requirements and restrictions listed in the ICF and in this protocol.