<PAGE>
                                                                               .
                                                                               .
                                                                               .

<Table>
<Caption>

<S>                                           <C>                                       <C>
CONTACTS:
LORUS THERAPEUTICS INC.                       CANADIAN MEDIA CONTACT:                   US MEDIA CONTACT:

Corporate Communications                      Hugh Mansfield                            Jennifer Taylor
Grace Tse                                     Mansfield Communications Inc.             Mansfield Communications Inc.
Tel:  (416) 798-1200, ext.380                 Tel:  (416) 599-0024                      Tel:  (212) 370-5045
Email:   ir@lorusthera.com                    Email:  hugh@mcipr.com                    E-mail:  jennifer@mcipr.com
</Table>


      LORUS THERAPEUTICS INC. PUBLISHES RESULTS OF VIRULIZIN(R) ANTI-TUMOUR
                  ACTIVITY IN PEER REVIEWED SCIENTIFIC JOURNAL

TSE:              LOR
OTC BB:           LORFF

TORONTO, CANADA, MARCH 27, 2003 - Scientists at Lorus Therapeutics Inc.
("Lorus") have published the results of experimental studies in mouse models
bearing human tumors treated with Virulizin(R), the company's lead anti-cancer
immunotherapeutic drug. The results appear in an article titled, "Anti-tumor
activity of Virulizin(R), a novel biological response modifier (BRM), in a panel
of human pancreatic cancer and melanoma xenografts," in Cancer Chemotherapy and
Pharmacology, Volume 51, Issue 3, pages 247-255, 2003.

Virulizin(R) showed significant anti-tumor activity as a monotherapy and
enhanced anti-tumor effects when used in combination with standard chemotherapy
agents against a panel of human pancreatic tumors and melanoma.

Data describing the pharmacological activity of Virulizin(R) as reported in the
publication, will be an important addition to the preclinical component of
regulatory dossiers required to obtain marketing approval for this drug.

"These results demonstrate the very promising anti-cancer properties of
Virulizin(R) and are consistent with the findings of Phase I and Phase II
clinical trials performed with Virulizin(R)," said Dr. Jim Wright, chief
executive officer. "Publishing in international peer reviewed journals reflects
Lorus' strong commitment to research and to maintaining high scientific
standards in the company's drug development process."

                                     (more)

<PAGE>

                                      - 2 -

Virulizin(R) was awarded orphan drug status and fast-track status from the
United States Food and Drug Administration in clinical studies for the treatment
of pancreatic cancer. The drug is approved in Mexico for the treatment of
melanoma and is commercially available in Mexico through Lorus' marketing
partner Mayne Pharma. Virulizin (R) is currently in a Phase III clinical trial
in North America for the treatment of pancreatic cancer in combination with
gemcitabine.


About Lorus
Lorus is a biopharmaceutical company focused on the research and development of
cancer therapies. Lorus' goal is to capitalize on its research, pre-clinical,
clinical and regulatory expertise by developing new drug candidates that can be
used, either alone, or in combination, to successfully manage cancer. Through
its own discovery efforts and an active acquisition and in-licensing program,
Lorus is building a portfolio of promising anti-cancer drugs. Late-stage
clinical developments and marketing will be done in cooperation with strategic
pharmaceutical partners. Founded in 1986, Lorus Therapeutics Inc. is a public
company listed on the Toronto Stock Exchange under the symbol LOR, and on the
OTC BB exchange under the symbol LORFF.

Except for historical information, this press release contains forward-looking
statements, which reflect the Company's current expectation regarding future
events. These forward-looking statements involve risks and uncertainties, which
may cause actual results to differ materially from those statements. Those risks
and uncertainties include, but are not limited to, changing market conditions,
the successful and timely completion of clinical studies, the establishment of
corporate alliances, the impact of competitive products and pricing, new product
development, uncertainties related to the regulatory approval process, and other
risks detailed from time-to-time in the Company's ongoing quarterly filings,
annual information form, annual reports and 20-F filings.

Lorus Therapeutics Inc.'s press releases are available through the Company's
Internet site: http://www.lorusthera.com.


                                     - 30 -