Onconova Therapeutics Announces Plans for a Phase 1/2a Trial of Narazaciclib Combined with Letrozole in Endometrial Cancer, Reports Third Quarter 2022 Financial Results, and Provides a Business Update Initiation of Phase

Onconova Therapeutics

Announces Plans for a Phase 1/2a Trial of Narazaciclib Combined with Letrozole in Endometrial Cancer, Reports Third Quarter 2022 Financial

Results, and Provides a Business Update

Initiation of Phase 1/2a endometrial cancer

trial expected in 1Q23; preliminary data expected 4Q23

Conference call and live webcast at 4:30 p.m. ET

November 14, 2022 (GLOBE NEWSWIRE) -- Onconova Therapeutics, Inc. (NASDAQ: ONTX), ("Onconova"), a clinical-stage

biopharmaceutical company focused on discovering and developing novel products for patients with cancer, today announced plans for a Phase

1/2a trial of narazaciclib combined with letrozole in recurrent metastatic low-grade endometrioid endometrial cancer (LGEEC). In addition,

the Company reported its third quarter 2022 financial results and provided a business update.

"Onconova's upcoming Phase 1/2a trial has been thoughtfully

designed to explore narazaciclib's potential as a best-in-class therapy when combined with letrozole in recurrent low grade endometrioid

endometrial cancer (LGEEC)," said Bhavana Pothuri, MD, Professor, Department of Obstetrics and Gynecology at NYU Grossman School

of Medicine and Director, Gynecologic Oncology Research; Perlmutter Cancer Center and principal investigator of the trial. "Data

from prior randomized and single-arm trials in LGEEC have validated the anti-cancer activity of letrozole combined with agents that, like

narazaciclib, potently inhibit CDK 4/6. However, currently available CDK 4/6 inhibitors are hampered by limitations related to safety,

tolerability, and treatment resistance. Moreover, none are currently FDA approved for endometrial cancer creating an urgent need for improved

treatment options for LGEEC patients. Clinical and preclinical data suggest narazaciclib's differentiated inhibitory profile may

allow it to address this unmet need, which is a hypothesis I look forward to evaluating with my colleagues in Onconova's upcoming

Endometrioid Endometrial Cancer and the Upcoming

Endometrial cancer (EC) arises in the uterine

lining and is the most common cancer of the female reproductive organs. Endometrioid endometrial cancer is the most common subtype of

EC, accounting for approximately 75% of cases. Onconova expects to initiate a multi-center Phase 1/2a trial evaluating its multi-kinase

inhibitor narazaciclib in combination with letrozole as a second- or third-line therapy for the treatment of recurrent metastatic LGEEC

in 1Q23. Both narazaciclib and letrozole will be administered orally with a continuous daily dosing schedule in the trial, which will

begin with a Phase 1 dose escalation phase before moving to a Phase 2 expansion cohort designed to enroll approximately 30 patients.

The primary objective of the Phase 1 portion of

the trial will be to evaluate safety, tolerability, pharmacokinetics and pharmacodynamics in order to determine a recommended Phase 2

dose (RP2D) of the combination. The primary objective of the Phase 2 portion will be to evaluate the efficacy of the combination at the

RP2D, as measured by progression-free survival at 24 weeks. The estrogen/progesterone receptor status of participants will be recorded

as part of an exploratory objective. The trial will be conducted at 6 to 10 sites in the United States. Initiation of the trial is expected

in 1Q23. Preliminary data are expected in 4Q23.

Third Quarter 2022 and Recent Highlights:

Steven M. Fruchtman, M.D., President and Chief

Executive Officer of Onconova, commented, "We look forward to initiating the Ph 1/ 2a trial of the narazaciclib doublet in LGEEC.

CDK 4/6 inhibitors are not health authority approved in this space that has a great unmet medical need for novel approaches. The advancement

of rigosertib's investigator-sponsored studies have complemented efforts in our lead narazaciclib program. Recently reported data

from a Phase 1/2a trial showed rigosertib when combined with a PD-1 checkpoint inhibitor to drive complete and partial responses in advanced

KRAS-mutated non-small cell lung cancer. These responses were achieved in patients with three distinct KRAS mutations who had failed prior

checkpoint inhibitor therapy, thereby confirming rigosertib's KRAS mutation-agnostic mechanism of action and potential to synergize

with anti-PD-1 agents. We will be reporting additional data from this trial as patient accrual continues, which will be key to informing

our next steps in this program."

Third Quarter Financials

Cash and cash equivalents as of September 30,

2022 were $42.6 million compared with $55.1 million as of December 31, 2021. The Company believes that its cash and cash equivalents

will be sufficient to fund ongoing clinical trials and business operations into 2024.

Research and development expenses were $3.6 million

for the third quarter of 2022, compared with $1.8 million for the third quarter of 2021.

General and administrative expenses were $2.1

million for the third quarter of 2022, compared with $2.3 million for the third quarter of 2021.

Net loss for the third quarter of 2022 was $5.4

million, or $0.26 per share on 20.9 million weighted shared outstanding, compared with a net loss of $3.5 million, or $0.22 per share

for the third quarter of 2021 on 16.0 million weighted shared outstanding.

Conference Call and Webcast

Onconova will host an investment community conference

call beginning at 4:30 p.m. Eastern Time, during which management will discuss financial results for the third quarter of 2022, provide

a business update, and answer questions. Interested parties can participate by dialing (800) 715-9871 (domestic callers) or (646) 307-1963

(international callers) and using conference ID 6078502.

of the conference call will be available in the Investors & Media section of the Company's website at www.onconova.com.

A replay of the webcast will be available on the Onconova website for 90 days following the call.

About Onconova Therapeutics, Inc.

Onconova Therapeutics is a clinical-stage biopharmaceutical

company focused on discovering and developing novel products for patients with cancer. The Company has proprietary targeted anti-cancer

agents designed to disrupt specific cellular pathways that are important for cancer cell proliferation.

Onconova's novel, proprietary multi-kinase

inhibitor narazaciclib (formerly ON 123300) is being evaluated in two separate and complementary Phase 1 dose-escalation and expansion

studies. These trials are currently underway in the United States and China.

Onconova's product candidate rigosertib

is being studied in an investigator-sponsored study program, including in a dose-escalation and expansion Phase 1/2a investigator-sponsored

study with oral rigosertib in combination with nivolumab for patients with KRAS+ non-small cell lung cancer.

For more information,

please visit www.onconova.com.

the statements in this release are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as

amended, Section 21E of the Securities Exchange Act of 1934, as amended, and the Private Securities Litigation Reform Act of 1995,

and involve risks and uncertainties. These statements relate to Onconova's expectations regarding the timing of Onconova's

and investigator-initiated clinical development and trial data, and the mechanisms, therapeutic effects, and indications for Onconova's

product candidates. Onconova has attempted to identify forward-looking statements by terminology including "believes," "estimates,"

"anticipates," "expects," "plans," "intends," "may," "could," "might,"

"will," "should," "preliminary," "encouraging," "approximately" or other words

that convey uncertainty of future events or outcomes. Although Onconova believes that the expectations reflected in such forward-looking

statements are reasonable as of the date made, expectations may prove to have been materially different from the results expressed or

implied by such forward-looking statements. These statements are only predictions and involve known and unknown risks, uncertainties,

and other factors, including the success and timing of Onconova's clinical trials, investigator-initiated trials and regulatory agency

and institutional review board approvals of protocols, Onconova's collaborations, market conditions and those discussed under the

heading "Risk Factors" in Onconova's most recent Annual Report on Form 10-K and quarterly reports on Form 10-Q. Any

forward-looking statements contained in this release speak only as of its date. Onconova undertakes no obligation to update any forward-looking

statements contained in this release to reflect events or circumstances occurring after its date or to reflect the occurrence of unanticipated events.

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