A MULTI-CENTER, OPEN LABEL PHASE 1/2 STUDY OF CYT-0851 IN PATIENTS WITH RELAPSED/REFRACTORY B-CELL MALIGNANCIES AND ADVANCED SOLID TUMORS

This clinical trial is an interventional, active-treatment, open-label, multi-center, Phase
1/2 study. The study objectives are to assess the safety, tolerability and pharmacokinetics
(PK) of CYT-0851 in patients with relapsed/refractory B-cell malignancies and advanced solid
tumors and to identify a recommended Phase 2 dose as a monotherapy and in combination with
chemotherapy for evaluation in these patients.

Key Phase 1 Inclusion Criteria

1. Male or female ≥18 years of age at time of informed consent.

1. Female subjects of childbearing potential must be non-lactating, not pregnant as
confirmed by a negative serum pregnancy test at most 30 days before enrollment
and within 72 hours before the first administration of CYT-0851

2. Female subjects of childbearing potential must not donate ova during the study
and for at least 90 days after the last dose of study drug and must agree to
continue using an effective method of contraception during the screening period
to first study drug administration until 90 days after the last dose of study
drug

3. Male subjects who have not had a vasectomy must agree to use an effective method
of contraception during the study and until 90 days after the last dose of the
study drug, and to not donate sperm during the study and for at least 90 days
after the last dose of study drug

2. ECOG Performance Status of 0-1

3. Measurable disease defined by disease-specific response criteria

4. Histologically-proven B cell malignancies, meeting the following criteria:

1. Relapsed, refractory B-cell non-Hodgkin lymphoma requiring therapy, after at
least two prior therapies, and if transplanted, then at least 3-month post
autologous stem cell transplant and if CART-treated, then evidence of progression
no sooner than 3 months post CART treatment, or

2. Relapsed, refractory chronic lymphocytic leukemia requiring therapy after at
least two prior therapies, including BTK and BCL-2 inhibitor therapy (unless
ineligible for such therapy), or

3. For multiple myeloma, relapsed or progressive on or after treatment with at least
three prior therapies that included a proteasome inhibitor, an imide,
daratumumab, and if transplant eligible, a bone marrow transplant (unless unfit
for transplant), or

5. Histologically-proven solid tumor meeting the following criteria:

1. Patients must have failed, refused, or not be eligible for further standard
therapies (including chemotherapy, hormonal therapies, Her-2 directed therapies,
as appropriate) expected to provide clinical benefit, and meeting the following
criteria

2. Metastatic breast cancer (including ER/PR positive or negative, Her-2 positive
and negative, triple negative), treated with at least 1 prior therapy for
metastatic disease, or

3. Recurrent squamous cell carcinoma of the head and neck (HNSCC) (dose escalation)
or human papilloma virus positive (HPV+) HNSCC (dose-escalation and backfill),
treated with at least 1 prior therapy, or

4. Ovarian cancer, progressive after treatment with at least prior platinum-based
chemotherapy, and therapy with a PARP inhibitor or

5. Soft tissue sarcoma, treated with at least one line of prior systemic therapy, or

6. Recurrent metastatic or locally advanced pancreatic cancer after first line
chemotherapy (backfill or combination patients only) or

7. Histologically-proven advanced small-cell lung cancer (SCLC) (monotherapy
backfill patients only).

1. Patients with mixed histology are not allowed

2. Prior treatment with platinum containing chemotherapy regimen with no
evidence of progression within 90 days of last dose of platinum agent and
anti-PD-(L)1 unless contraindicated

3. At least 1 prior line of chemotherapy, but no more than 3 prior lines of
therapy

6. Understands the procedures and requirements of the study and provides written informed
consent and authorization for protected health information disclosure

7. Willing and able to comply with the requirements of the study protocol

8. Site of disease amenable to a biopsy and willing to undergo biopsy required for
backfill, or for dose-escalation if considered unsafe (approval to participate in the
study required by the Medical Monitor) provide an archival sample ≤ 12 months old

Key Phase 2 Inclusion Criteria

1. Male or female ≥18 years of age at time of informed consent.

1. Female subjects of childbearing potential must be non-lactating, not pregnant as
confirmed by a negative serum pregnancy test at most 30 days before enrollment
and within 72 hours before the first administration of CYT-0851

2. Female subjects of childbearing potential must not donate ova during the study
and for at least 90 days after the last dose of study drug and must agree to
continue using, an effective method of contraception during the screening period
to first study drug administration until 90 days after the last dose of study
drug

3. Male subjects who have not had a vasectomy must agree to use an effective method
of contraception during the study and until 90 days after the last dose of the
study drug, and to not donate sperm during the study and for at least 90 days
after the last dose of study drug

2. ECOG Performance Status of 0-1

3. Measurable disease defined by disease-specific response criteria

4. Site of disease amenable to a biopsy and willing to undergo a biopsy for the
determination of biomarker status, or, if considered unsafe (approval to participate
in the study required by the Medical Monitor), archival sample ≤ 12 months old for
determination of biomarker status.

5. Biomarker positive on recent biopsy or bone marrow sample if required for the specific
cohort.

6. Histologically-proven B cell malignancies, meeting the following criteria:

1. DLBCL Cohort

1. Histologically-documented DLBCL or double hit lymphoma (B-cell lymphoma,
unclassifiable, with features intermediate between diffuse large B-cell
lymphoma and Burkitt lymphoma with BCL2 and MYC translocations (WHO
Classification)

2. Progressing on or after treatment with at least two prior lines of therapy,
including R-CHOP or equivalent first line therapy

3. If transplanted, then at least 3-month post autologous stem cell transplant

4. If CART-treated, then evidence of progression no sooner than 3 months post
CART treatment

2. MCL Cohort

1. Histologically-documented MCL

2. Any stage at diagnosis

3. Progressing on or after treatment with at least 2 prior lines of therapy,
including a Bruton tyrosine kinase (BTK) inhibitor, after a 14-day washout
period

3. Multiple Myeloma Cohort

1. Relapsed or progressing after treatment with at least 3 prior therapies that
include a proteasome inhibitor, an Immunomodulatory imide drug (IMiD),
daratumumab, and, if transplant eligible, a bone marrow transplant (unless
unfit for transplant)

7. Or Histologically-proven solid tumors meeting the following criterial

1. Patients must have failed, refused, or not be eligible for further standard
therapies (including chemotherapy, hormonal therapies, Her-2 directed therapies,
as appropriate) expected to provide clinical benefit, and meeting the following
criteria

2. Triple Negative Breast Cancer Cohort

1. Histologically-documented triple negative breast cancer, ER/PR negative
(defined as <10% of cells expressing hormonal receptors via
immunohistochemistry (IHC) analysis), and HER2-negative, defined as either
of the following by local laboratory assessment:

- In situ hybridization (ISH) non-amplified (ratio of HER2 to CEP17 < 2.0
or single probe average HER2 gene copy number < 4 signals/cell), or

- IHC 0 or IHC 1+

2. At least 1 prior line of chemotherapy, but no more than 5 prior lines of
chemotherapy

3. Ovarian Cancer Cohort

1. Histologically-proven metastatic epithelial ovarian cancer

2. Prior treatment with a platinum containing chemotherapy regimen

3. At least 1 prior line of therapy, but no more than 5 prior lines of
chemotherapy

4. Pancreatic Cancer Cohort

1. Histologically-proven metastatic or locally advanced pancreatic cancer

2. At least 1 prior line of chemotherapy but no more than 4 prior lines of
systemic therapy

5. Soft Tissue Sarcoma Cohort 1) Histologically-proven advanced soft-tissue sarcoma
excluding all types of adipocytic sarcoma and GIST 2) At least 1 prior line of
systemic therapy (unless no standard of care exists), but no more than 5 prior
lines of systemic therapy

8. Follicular Lymphoma Cohort

1. Histologically-documented follicular lymphoma

2. Relapsed, refractory follicular lymphoma requiring therapy, after at least two
prior therapies, and if CART-treated, then evidence of progression no sooner than
3 months post CART treatment

9. Understands the procedures and requirements of the study and provides written informed
consent and authorization for protected health information disclosure

10. Willing and able to comply with the requirements of the study protocol

Key Exclusion Criteria

1. Medical Conditions

1. Known history of HIV

2. Known history of viral hepatitis B unless HBV viral load is below the limit of
quantification and off viral suppressive therapy

3. Know history of hepatitis C unless antiviral treatment with curative intent
completed and HCV viral load is below the limit of quantification.

4. Myocardial infarction or stroke within 6 months

5. Uncontrolled hypertension (systolic blood pressure (SBP) > 160 or diastolic blood
pressure (DBP) >100 on maximal medical therapy)

6. History of interstitial pulmonary disease

7. Unresolved pneumonitis

8. Grade ≥ 3 neuropathy

9. Known active central nervous system (CNS) metastases. Subjects with previously
treated CNS metastases may participate as long as clinically and radiologically
stable for at least 4 weeks after treatment, have no evidence of new or enlarging
lesions and are off steroids and asymptomatic for 28 days prior to dosing with
study medication

10. Known history of meningeal involvement or meningeal carcinomatosis

11. Spinal cord compression not definitively treated with surgery and/or radiation,
or previously diagnosed and treated spinal cord compression without evidence that
disease has been clinically stable for > 2 weeks prior to screening visit

12. Presence of clinically significant cataracts

13. Second malignancy, except treated basal cell or localized squamous skin
carcinomas, localized prostate cancer, or other malignancy that is in remission
or stable and for which patients have not been on active anti-cancer therapy for
2 years

14. Pregnant or lactating. If β-HCG is elevated, eligible if ultrasound confirms
absence of a pregnancy.

15. Dementia or significantly altered metal status

16. Bowel obstruction requiring medical management less than 4 weeks prior to
screening

17. Inability to tolerate oral intake that includes 2 full meals per day (or
equivalent) or swallow pills.

18. Recurrent ascites requiring paracentesis more frequently than every 4 weeks or
within 14 days of screening.

19. Weight loss of more than 10% over the preceding 3 months prior to screening

2. Prior/Concomitant Therapy

1. Prior allogeneic stem cell transplant

2. On systemic antibiotic, antifungal or anti-viral therapy

3. White blood cell (WBC) growth factors administered within 14 days of screening
visit

4. Cancer therapy within 14 days prior to treatment with study drug

5. On narrow therapeutic index medications that are sensitive substrates of CYP3A,
P-gp or BCRP (or caution is warranted with approval by the Sponsor).

6. On any drug known to prolong QTc interval (eg, certain antiarrhythmic,
antimicrobials) that cannot be discontinued or interrupted 72 hours before the
Day 1 dose through Day 2, and 72 hours before the Day 15 dose until Day 16 (BID
dosing) or the Day 22 dose until Day 23 (QD dosing), in Cycle 1 (see Section
7.6.1 for a list of drugs).

7. On systemic corticosteroid treatment for non-tumor indication at a daily dose
equivalent to >10mg of Prednisone

3. Prior/Concurrent Clinical Study Experience a. Participation in another clinical trial
(unless in the observation phase, or an observational study), or exposure to any
investigational agent within 14 days prior to treatment with study drug

4. Laboratory assessments

1. Complete blood count (CBC):

Monotherapy and Chemotherapy Combinations 1 and 2:

1. ANC < 1.0 × 10^9/L

2. PLT < 75 × 10^9/L

3. Hgb < 9.0 g/dL

Chemotherapy Combination Group 3:

1) ANC < 1.5 × 10^9/L 2) PLT < 100 × 10^9/L 3) Hgb < 9.0 g/dL

Monotherapy and Chemotherapy Combination Groups 1 and 2:

2. Calculated Creatinine clearance (Cockcroft-Gault) < 40 mL/min

Chemotherapy Combination Group 3:

b. Calculated Creatinine clearance (Cockcroft-Gault) < 50 mL/min c. Hepatic function

1. AST > 2.0 × ULN

2. ALT > 2.0 × ULN d. Total bilirubin > 1.5 x ULN e. Albumin < 2.8 g/dL 5. ECG Exclusion
a. Screening QTc interval > 450 milliseconds for males and QTc > 470 ms for females
(corrected by Fridericia) 6. Other Exclusions

1. Unwilling or unable to make all planned study visits

2. Unwilling or unable to provide a recent biopsy or bone marrow sample prior to
enrollment and during study; Note: certain exceptions may be permitted allowing
archival specimens prior to treatment or for subjects where a specimen is not
required for biomarker positive testing

3. Significant medical diseases or conditions, as assessed by the Investigators and
Cyteir that would substantially increase the risk-benefit ratio of participating
in the study. This includes but is not limited to acute myocardial infarction,
arterial thrombosis, significant gastrointestinal bleed, or unstable angina
within the last 6 months uncontrolled diabetes mellitus, current active
infections, severely immunocompromised state, and congestive heart failure New
York Heart Association (NYHA) Class III-IV, left ventricular ejection fraction
(LVEF) < 40% d: Chemotherapy Combination Group 3 only: known history of
dhydropyrimidine dehydrogenase deficiency